text: /*
   * services/listen_dnsport.c - listen on port 53 for incoming DNS queries.
   *
   * Copyright (c) 2007, NLnet Labs. All rights reserved.
   *
   * This software is open source.
   * 
   * Redistribution and use in source and binary forms, with or without
   * modification, are permitted provided that the following conditions
   * are met:
   * 
   * Redistributions of source code must retain the above copyright notice,
   * this list of conditions and the following disclaimer.
   * 
   * Redistributions in binary form must reproduce the above copyright notice,
   * this list of conditions and the following disclaimer in the documentation
   * and/or other materials provided with the distribution.
   * 
   * Neither the name of the NLNET LABS nor the names of its contributors may
   * be used to endorse or promote products derived from this software without
   * specific prior written permission.
   * 
   * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
   * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
   * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
   * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
   * HOLDER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
   * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED
   * TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
   * PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF
   * LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING
   * NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
   * SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
   */
  
  /**
   * \file
   *
   * This file has functions to get queries from clients.
   */
  #include "config.h"
  #ifdef HAVE_SYS_TYPES_H
  #  include <sys/types.h>
  #endif
  #include <sys/time.h>
  #include <limits.h>
  #ifdef USE_TCP_FASTOPEN
  #include <netinet/tcp.h>
  #endif
  #include "services/listen_dnsport.h"
  #include "services/outside_network.h"
  #include "util/netevent.h"
  #include "util/log.h"
  #include "util/config_file.h"
  #include "util/net_help.h"
  #include "sldns/sbuffer.h"
  #include "sldns/parseutil.h"
  #include "services/mesh.h"
  #include "util/fptr_wlist.h"
  #include "util/locks.h"
  
  #ifdef HAVE_NETDB_H
  #include <netdb.h>
  #endif
  #include <fcntl.h>
  
  #ifdef HAVE_SYS_UN_H
  #include <sys/un.h>
  #endif
  
  #ifdef HAVE_SYSTEMD
  #include <systemd/sd-daemon.h>
  #endif
  
  #ifdef HAVE_IFADDRS_H
  #include <ifaddrs.h>
  #endif
  #ifdef HAVE_NET_IF_H
  #include <net/if.h>
  #endif
  
  /** number of queued TCP connections for listen() */
  #define TCP_BACKLOG 256 
  
  #ifndef THREADS_DISABLED
  /** lock on the counter of stream buffer memory */
  static lock_basic_type stream_wait_count_lock;
  /** lock on the counter of HTTP2 query buffer memory */
  static lock_basic_type http2_query_buffer_count_lock;
  /** lock on the counter of HTTP2 response buffer memory */
  static lock_basic_type http2_response_buffer_count_lock;
  #endif
  /** size (in bytes) of stream wait buffers */
  static size_t stream_wait_count = 0;
  /** is the lock initialised for stream wait buffers */
  static int stream_wait_lock_inited = 0;
  /** size (in bytes) of HTTP2 query buffers */
  static size_t http2_query_buffer_count = 0;
  /** is the lock initialised for HTTP2 query buffers */
  static int http2_query_buffer_lock_inited = 0;
  /** size (in bytes) of HTTP2 response buffers */
  static size_t http2_response_buffer_count = 0;
  /** is the lock initialised for HTTP2 response buffers */
  static int http2_response_buffer_lock_inited = 0;
  
  /**
   * Debug print of the getaddrinfo returned address.
   * @param addr: the address returned.
   */
  static void
  verbose_print_addr(struct addrinfo *addr)
  {
  	if(verbosity >= VERB_ALGO) {
  		char buf[100];
  		void* sinaddr = &((struct sockaddr_in*)addr->ai_addr)->sin_addr;
  #ifdef INET6
  		if(addr->ai_family == AF_INET6)
  			sinaddr = &((struct sockaddr_in6*)addr->ai_addr)->
  				sin6_addr;
  #endif /* INET6 */
  		if(inet_ntop(addr->ai_family, sinaddr, buf,
  			(socklen_t)sizeof(buf)) == 0) {
  			(void)strlcpy(buf, "(null)", sizeof(buf));
  		}
  		buf[sizeof(buf)-1] = 0;
  		verbose(VERB_ALGO, "creating %s%s socket %s %d", 
  			addr->ai_socktype==SOCK_DGRAM?"udp":
  			addr->ai_socktype==SOCK_STREAM?"tcp":"otherproto",
  			addr->ai_family==AF_INET?"4":
  			addr->ai_family==AF_INET6?"6":
  			"_otherfam", buf, 
  			ntohs(((struct sockaddr_in*)addr->ai_addr)->sin_port));
  	}
  }
  
  #ifdef HAVE_SYSTEMD
  static int
  systemd_get_activated(int family, int socktype, int listen,
  		      struct sockaddr *addr, socklen_t addrlen,
  		      const char *path)
  {
  	int i = 0;
  	int r = 0;
  	int s = -1;
  	const char* listen_pid, *listen_fds;
  
  	/* We should use "listen" option only for stream protocols. For UDP it should be -1 */
  
  	if((r = sd_booted()) < 1) {
  		if(r == 0)
  			log_warn("systemd is not running");
  		else
  			log_err("systemd sd_booted(): %s", strerror(-r));
  		return -1;
  	}
  
  	listen_pid = getenv("LISTEN_PID");
  	listen_fds = getenv("LISTEN_FDS");
  
  	if (!listen_pid) {
  		log_warn("Systemd mandatory ENV variable is not defined: LISTEN_PID");
  		return -1;
  	}
  
  	if (!listen_fds) {
  		log_warn("Systemd mandatory ENV variable is not defined: LISTEN_FDS");
  		return -1;
  	}
  
  	if((r = sd_listen_fds(0)) < 1) {
  		if(r == 0)
  			log_warn("systemd: did not return socket, check unit configuration");
  		else
  			log_err("systemd sd_listen_fds(): %s", strerror(-r));
  		return -1;
  	}
  	
  	for(i = 0; i < r; i++) {
  		if(sd_is_socket(SD_LISTEN_FDS_START + i, family, socktype, listen)) {
  			s = SD_LISTEN_FDS_START + i;
  			break;
  		}
  	}
  	if (s == -1) {
  		if (addr)
  			log_err_addr("systemd sd_listen_fds()",
  				     "no such socket",
  				     (struct sockaddr_storage *)addr, addrlen);
  		else
  			log_err("systemd sd_listen_fds(): %s", path);
  	}
  	return s;
  }
  #endif
  
  int
  create_udp_sock(int family, int socktype, struct sockaddr* addr,
          socklen_t addrlen, int v6only, int* inuse, int* noproto,
  	int rcv, int snd, int listen, int* reuseport, int transparent,
  	int freebind, int use_systemd, int dscp)
  {
  	int s;
  	char* err;
  #if defined(SO_REUSEADDR) || defined(SO_REUSEPORT) || defined(IPV6_USE_MIN_MTU)  || defined(IP_TRANSPARENT) || defined(IP_BINDANY) || defined(IP_FREEBIND) || defined (SO_BINDANY)
  	int on=1;
  #endif
  #ifdef IPV6_MTU
  	int mtu = IPV6_MIN_MTU;
  #endif
  #if !defined(SO_RCVBUFFORCE) && !defined(SO_RCVBUF)
  	(void)rcv;
  #endif
  #if !defined(SO_SNDBUFFORCE) && !defined(SO_SNDBUF)
  	(void)snd;
  #endif
  #ifndef IPV6_V6ONLY
  	(void)v6only;
  #endif
  #if !defined(IP_TRANSPARENT) && !defined(IP_BINDANY) && !defined(SO_BINDANY)
  	(void)transparent;
  #endif
  #if !defined(IP_FREEBIND)
  	(void)freebind;
  #endif
  #ifdef HAVE_SYSTEMD
  	int got_fd_from_systemd = 0;
  
  	if (!use_systemd
  	    || (use_systemd
  		&& (s = systemd_get_activated(family, socktype, -1, addr,
  					      addrlen, NULL)) == -1)) {
  #else
  	(void)use_systemd;
  #endif
  	if((s = socket(family, socktype, 0)) == -1) {
  		*inuse = 0;
  #ifndef USE_WINSOCK
  		if(errno == EAFNOSUPPORT || errno == EPROTONOSUPPORT) {
  			*noproto = 1;
  			return -1;
  		}
  #else
  		if(WSAGetLastError() == WSAEAFNOSUPPORT || 
  			WSAGetLastError() == WSAEPROTONOSUPPORT) {
  			*noproto = 1;
  			return -1;
  		}
  #endif
  		log_err("can't create socket: %s", sock_strerror(errno));
  		*noproto = 0;
  		return -1;
  	}
  #ifdef HAVE_SYSTEMD
  	} else {
  		got_fd_from_systemd = 1;
  	}
  #endif
  	if(listen) {
  #ifdef SO_REUSEADDR
  		if(setsockopt(s, SOL_SOCKET, SO_REUSEADDR, (void*)&on, 
  			(socklen_t)sizeof(on)) < 0) {
  			log_err("setsockopt(.. SO_REUSEADDR ..) failed: %s",
  				sock_strerror(errno));
  #ifndef USE_WINSOCK
  			if(errno != ENOSYS) {
  				close(s);
  				*noproto = 0;
  				*inuse = 0;
  				return -1;
  			}
  #else
  			closesocket(s);
  			*noproto = 0;
  			*inuse = 0;
  			return -1;
  #endif
  		}
  #endif /* SO_REUSEADDR */
  #ifdef SO_REUSEPORT
  #  ifdef SO_REUSEPORT_LB
  		/* on FreeBSD 12 we have SO_REUSEPORT_LB that does loadbalance
  		 * like SO_REUSEPORT on Linux.  This is what the users want
  		 * with the config option in unbound.conf; if we actually
  		 * need local address and port reuse they'll also need to
  		 * have SO_REUSEPORT set for them, assume it was _LB they want.
  		 */
  		if (reuseport && *reuseport &&
  		    setsockopt(s, SOL_SOCKET, SO_REUSEPORT_LB, (void*)&on,
  			(socklen_t)sizeof(on)) < 0) {
  #ifdef ENOPROTOOPT
  			if(errno != ENOPROTOOPT || verbosity >= 3)
  				log_warn("setsockopt(.. SO_REUSEPORT_LB ..) failed: %s",
  					strerror(errno));
  #endif
  			/* this option is not essential, we can continue */
  			*reuseport = 0;
  		}
  #  else /* no SO_REUSEPORT_LB */
  
  		/* try to set SO_REUSEPORT so that incoming
  		 * queries are distributed evenly among the receiving threads.
  		 * Each thread must have its own socket bound to the same port,
  		 * with SO_REUSEPORT set on each socket.
  		 */
  		if (reuseport && *reuseport &&
  		    setsockopt(s, SOL_SOCKET, SO_REUSEPORT, (void*)&on,
  			(socklen_t)sizeof(on)) < 0) {
  #ifdef ENOPROTOOPT
  			if(errno != ENOPROTOOPT || verbosity >= 3)
  				log_warn("setsockopt(.. SO_REUSEPORT ..) failed: %s",
  					strerror(errno));
  #endif
  			/* this option is not essential, we can continue */
  			*reuseport = 0;
  		}
  #  endif /* SO_REUSEPORT_LB */
  #else
  		(void)reuseport;
  #endif /* defined(SO_REUSEPORT) */
  #ifdef IP_TRANSPARENT
  		if (transparent &&
  		    setsockopt(s, IPPROTO_IP, IP_TRANSPARENT, (void*)&on,
  		    (socklen_t)sizeof(on)) < 0) {
  			log_warn("setsockopt(.. IP_TRANSPARENT ..) failed: %s",
  			strerror(errno));
  		}
  #elif defined(IP_BINDANY)
  		if (transparent &&
  		    setsockopt(s, (family==AF_INET6? IPPROTO_IPV6:IPPROTO_IP),
  		    (family == AF_INET6? IPV6_BINDANY:IP_BINDANY),
  		    (void*)&on, (socklen_t)sizeof(on)) < 0) {
  			log_warn("setsockopt(.. IP%s_BINDANY ..) failed: %s",
  			(family==AF_INET6?"V6":""), strerror(errno));
  		}
  #elif defined(SO_BINDANY)
  		if (transparent &&
  		    setsockopt(s, SOL_SOCKET, SO_BINDANY, (void*)&on,
  		    (socklen_t)sizeof(on)) < 0) {
  			log_warn("setsockopt(.. SO_BINDANY ..) failed: %s",
  			strerror(errno));
  		}
  #endif /* IP_TRANSPARENT || IP_BINDANY || SO_BINDANY */
  	}
  #ifdef IP_FREEBIND
  	if(freebind &&
  	    setsockopt(s, IPPROTO_IP, IP_FREEBIND, (void*)&on,
  	    (socklen_t)sizeof(on)) < 0) {
  		log_warn("setsockopt(.. IP_FREEBIND ..) failed: %s",
  		strerror(errno));
  	}
  #endif /* IP_FREEBIND */
  	if(rcv) {
  #ifdef SO_RCVBUF
  		int got;
  		socklen_t slen = (socklen_t)sizeof(got);
  #  ifdef SO_RCVBUFFORCE
  		/* Linux specific: try to use root permission to override
  		 * system limits on rcvbuf. The limit is stored in 
  		 * /proc/sys/net/core/rmem_max or sysctl net.core.rmem_max */
  		if(setsockopt(s, SOL_SOCKET, SO_RCVBUFFORCE, (void*)&rcv, 
  			(socklen_t)sizeof(rcv)) < 0) {
  			if(errno != EPERM) {
  				log_err("setsockopt(..., SO_RCVBUFFORCE, "
  					"...) failed: %s", sock_strerror(errno));
  				sock_close(s);
  				*noproto = 0;
  				*inuse = 0;
  				return -1;
  			}
  #  endif /* SO_RCVBUFFORCE */
  			if(setsockopt(s, SOL_SOCKET, SO_RCVBUF, (void*)&rcv, 
  				(socklen_t)sizeof(rcv)) < 0) {
  				log_err("setsockopt(..., SO_RCVBUF, "
  					"...) failed: %s", sock_strerror(errno));
  				sock_close(s);
  				*noproto = 0;
  				*inuse = 0;
  				return -1;
  			}
  			/* check if we got the right thing or if system
  			 * reduced to some system max.  Warn if so */
  			if(getsockopt(s, SOL_SOCKET, SO_RCVBUF, (void*)&got, 
  				&slen) >= 0 && got < rcv/2) {
  				log_warn("so-rcvbuf %u was not granted. "
  					"Got %u. To fix: start with "
  					"root permissions(linux) or sysctl "
  					"bigger net.core.rmem_max(linux) or "
  					"kern.ipc.maxsockbuf(bsd) values.",
  					(unsigned)rcv, (unsigned)got);
  			}
  #  ifdef SO_RCVBUFFORCE
  		}
  #  endif
  #endif /* SO_RCVBUF */
  	}
  	/* first do RCVBUF as the receive buffer is more important */
  	if(snd) {
  #ifdef SO_SNDBUF
  		int got;
  		socklen_t slen = (socklen_t)sizeof(got);
  #  ifdef SO_SNDBUFFORCE
  		/* Linux specific: try to use root permission to override
  		 * system limits on sndbuf. The limit is stored in 
  		 * /proc/sys/net/core/wmem_max or sysctl net.core.wmem_max */
  		if(setsockopt(s, SOL_SOCKET, SO_SNDBUFFORCE, (void*)&snd, 
  			(socklen_t)sizeof(snd)) < 0) {
  			if(errno != EPERM) {
  				log_err("setsockopt(..., SO_SNDBUFFORCE, "
  					"...) failed: %s", sock_strerror(errno));
  				sock_close(s);
  				*noproto = 0;
  				*inuse = 0;
  				return -1;
  			}
  #  endif /* SO_SNDBUFFORCE */
  			if(setsockopt(s, SOL_SOCKET, SO_SNDBUF, (void*)&snd, 
  				(socklen_t)sizeof(snd)) < 0) {
  				log_err("setsockopt(..., SO_SNDBUF, "
  					"...) failed: %s", sock_strerror(errno));
  				sock_close(s);
  				*noproto = 0;
  				*inuse = 0;
  				return -1;
  			}
  			/* check if we got the right thing or if system
  			 * reduced to some system max.  Warn if so */
  			if(getsockopt(s, SOL_SOCKET, SO_SNDBUF, (void*)&got, 
  				&slen) >= 0 && got < snd/2) {
  				log_warn("so-sndbuf %u was not granted. "
  					"Got %u. To fix: start with "
  					"root permissions(linux) or sysctl "
  					"bigger net.core.wmem_max(linux) or "
  					"kern.ipc.maxsockbuf(bsd) values.",
  					(unsigned)snd, (unsigned)got);
  			}
  #  ifdef SO_SNDBUFFORCE
  		}
  #  endif
  #endif /* SO_SNDBUF */
  	}
  	err = set_ip_dscp(s, family, dscp);
  	if(err != NULL)
  		log_warn("error setting IP DiffServ codepoint %d on UDP socket: %s", dscp, err);
  	if(family == AF_INET6) {
  # if defined(IPV6_V6ONLY)
  		if(v6only) {
  			int val=(v6only==2)?0:1;
  			if (setsockopt(s, IPPROTO_IPV6, IPV6_V6ONLY, 
  				(void*)&val, (socklen_t)sizeof(val)) < 0) {
  				log_err("setsockopt(..., IPV6_V6ONLY"
  					", ...) failed: %s", sock_strerror(errno));
  				sock_close(s);
  				*noproto = 0;
  				*inuse = 0;
  				return -1;
  			}
  		}
  # endif
  # if defined(IPV6_USE_MIN_MTU)
  		/*
  		 * There is no fragmentation of IPv6 datagrams
  		 * during forwarding in the network. Therefore
  		 * we do not send UDP datagrams larger than
  		 * the minimum IPv6 MTU of 1280 octets. The
  		 * EDNS0 message length can be larger if the
  		 * network stack supports IPV6_USE_MIN_MTU.
  		 */
  		if (setsockopt(s, IPPROTO_IPV6, IPV6_USE_MIN_MTU,
  			(void*)&on, (socklen_t)sizeof(on)) < 0) {
  			log_err("setsockopt(..., IPV6_USE_MIN_MTU, "
  				"...) failed: %s", sock_strerror(errno));
  			sock_close(s);
  			*noproto = 0;
  			*inuse = 0;
  			return -1;
  		}
  # elif defined(IPV6_MTU)
  		/*
  		 * On Linux, to send no larger than 1280, the PMTUD is
  		 * disabled by default for datagrams anyway, so we set
  		 * the MTU to use.
  		 */
  		if (setsockopt(s, IPPROTO_IPV6, IPV6_MTU,
  			(void*)&mtu, (socklen_t)sizeof(mtu)) < 0) {
  			log_err("setsockopt(..., IPV6_MTU, ...) failed: %s", 
  				sock_strerror(errno));
  			sock_close(s);
  			*noproto = 0;
  			*inuse = 0;
  			return -1;
  		}
  # endif /* IPv6 MTU */
  	} else if(family == AF_INET) {
  #  if defined(IP_MTU_DISCOVER) && defined(IP_PMTUDISC_DONT)
  /* linux 3.15 has IP_PMTUDISC_OMIT, Hannes Frederic Sowa made it so that
   * PMTU information is not accepted, but fragmentation is allowed
   * if and only if the packet size exceeds the outgoing interface MTU
   * (and also uses the interface mtu to determine the size of the packets).
   * So there won't be any EMSGSIZE error.  Against DNS fragmentation attacks.
   * FreeBSD already has same semantics without setting the option. */
  		int omit_set = 0;
  		int action;
  #   if defined(IP_PMTUDISC_OMIT)
  		action = IP_PMTUDISC_OMIT;
  		if (setsockopt(s, IPPROTO_IP, IP_MTU_DISCOVER, 
  			&action, (socklen_t)sizeof(action)) < 0) {
  
  			if (errno != EINVAL) {
  				log_err("setsockopt(..., IP_MTU_DISCOVER, IP_PMTUDISC_OMIT...) failed: %s",
  					strerror(errno));
  				sock_close(s);
  				*noproto = 0;
  				*inuse = 0;
  				return -1;
  			}
  		}
  		else
  		{
  		    omit_set = 1;
  		}
  #   endif
  		if (omit_set == 0) {
     			action = IP_PMTUDISC_DONT;
  			if (setsockopt(s, IPPROTO_IP, IP_MTU_DISCOVER,
  				&action, (socklen_t)sizeof(action)) < 0) {
  				log_err("setsockopt(..., IP_MTU_DISCOVER, IP_PMTUDISC_DONT...) failed: %s",
  					strerror(errno));
  				sock_close(s);
  				*noproto = 0;
  				*inuse = 0;
  				return -1;
  			}
  		}
  #  elif defined(IP_DONTFRAG) && !defined(__APPLE__)
  		/* the IP_DONTFRAG option if defined in the 11.0 OSX headers,
  		 * but does not work on that version, so we exclude it */
  		int off = 0;
  		if (setsockopt(s, IPPROTO_IP, IP_DONTFRAG, 
  			&off, (socklen_t)sizeof(off)) < 0) {
  			log_err("setsockopt(..., IP_DONTFRAG, ...) failed: %s",
  				strerror(errno));
  			sock_close(s);
  			*noproto = 0;
  			*inuse = 0;
  			return -1;
  		}
  #  endif /* IPv4 MTU */
  	}
  	if(
  #ifdef HAVE_SYSTEMD
  		!got_fd_from_systemd &&
  #endif
  		bind(s, (struct sockaddr*)addr, addrlen) != 0) {
  		*noproto = 0;
  		*inuse = 0;
  #ifndef USE_WINSOCK
  #ifdef EADDRINUSE
  		*inuse = (errno == EADDRINUSE);
  		/* detect freebsd jail with no ipv6 permission */
  		if(family==AF_INET6 && errno==EINVAL)
  			*noproto = 1;
  		else if(errno != EADDRINUSE &&
  			!(errno == EACCES && verbosity < 4 && !listen)
  #ifdef EADDRNOTAVAIL
  			&& !(errno == EADDRNOTAVAIL && verbosity < 4 && !listen)
  #endif
  			) {
  			log_err_addr("can't bind socket", strerror(errno),
  				(struct sockaddr_storage*)addr, addrlen);
  		}
  #endif /* EADDRINUSE */
  #else /* USE_WINSOCK */
  		if(WSAGetLastError() != WSAEADDRINUSE &&
  			WSAGetLastError() != WSAEADDRNOTAVAIL &&
  			!(WSAGetLastError() == WSAEACCES && verbosity < 4 && !listen)) {
  			log_err_addr("can't bind socket", 
  				wsa_strerror(WSAGetLastError()),
  				(struct sockaddr_storage*)addr, addrlen);
  		}
  #endif /* USE_WINSOCK */
  		sock_close(s);
  		return -1;
  	}
  	if(!fd_set_nonblock(s)) {
  		*noproto = 0;
  		*inuse = 0;
  		sock_close(s);
  		return -1;
  	}
  	return s;
  }
  
  int
  create_tcp_accept_sock(struct addrinfo *addr, int v6only, int* noproto,
  	int* reuseport, int transparent, int mss, int nodelay, int freebind,
  	int use_systemd, int dscp)
  {
  	int s;
  	char* err;
  #if defined(SO_REUSEADDR) || defined(SO_REUSEPORT) || defined(IPV6_V6ONLY) || defined(IP_TRANSPARENT) || defined(IP_BINDANY) || defined(IP_FREEBIND) || defined(SO_BINDANY)
  	int on = 1;
  #endif
  #ifdef HAVE_SYSTEMD
  	int got_fd_from_systemd = 0;
  #endif
  #ifdef USE_TCP_FASTOPEN
  	int qlen;
  #endif
  #if !defined(IP_TRANSPARENT) && !defined(IP_BINDANY) && !defined(SO_BINDANY)
  	(void)transparent;
  #endif
  #if !defined(IP_FREEBIND)
  	(void)freebind;
  #endif
  	verbose_print_addr(addr);
  	*noproto = 0;
  #ifdef HAVE_SYSTEMD
  	if (!use_systemd ||
  	    (use_systemd
  	     && (s = systemd_get_activated(addr->ai_family, addr->ai_socktype, 1,
  					   addr->ai_addr, addr->ai_addrlen,
  					   NULL)) == -1)) {
  #else
  	(void)use_systemd;
  #endif
  	if((s = socket(addr->ai_family, addr->ai_socktype, 0)) == -1) {
  #ifndef USE_WINSOCK
  		if(errno == EAFNOSUPPORT || errno == EPROTONOSUPPORT) {
  			*noproto = 1;
  			return -1;
  		}
  #else
  		if(WSAGetLastError() == WSAEAFNOSUPPORT ||
  			WSAGetLastError() == WSAEPROTONOSUPPORT) {
  			*noproto = 1;
  			return -1;
  		}
  #endif
  		log_err("can't create socket: %s", sock_strerror(errno));
  		return -1;
  	}
  	if(nodelay) {
  #if defined(IPPROTO_TCP) && defined(TCP_NODELAY)
  		if(setsockopt(s, IPPROTO_TCP, TCP_NODELAY, (void*)&on,
  			(socklen_t)sizeof(on)) < 0) {
  			#ifndef USE_WINSOCK
  			log_err(" setsockopt(.. TCP_NODELAY ..) failed: %s",
  				strerror(errno));
  			#else
  			log_err(" setsockopt(.. TCP_NODELAY ..) failed: %s",
  				wsa_strerror(WSAGetLastError()));
  			#endif
  		}
  #else
  		log_warn(" setsockopt(TCP_NODELAY) unsupported");
  #endif /* defined(IPPROTO_TCP) && defined(TCP_NODELAY) */
  	}
  	if (mss > 0) {
  #if defined(IPPROTO_TCP) && defined(TCP_MAXSEG)
  		if(setsockopt(s, IPPROTO_TCP, TCP_MAXSEG, (void*)&mss,
  			(socklen_t)sizeof(mss)) < 0) {
  			log_err(" setsockopt(.. TCP_MAXSEG ..) failed: %s",
  				sock_strerror(errno));
  		} else {
  			verbose(VERB_ALGO,
  				" tcp socket mss set to %d", mss);
  		}
  #else
  		log_warn(" setsockopt(TCP_MAXSEG) unsupported");
  #endif /* defined(IPPROTO_TCP) && defined(TCP_MAXSEG) */
  	}
  #ifdef HAVE_SYSTEMD
  	} else {
  		got_fd_from_systemd = 1;
      }
  #endif
  #ifdef SO_REUSEADDR
  	if(setsockopt(s, SOL_SOCKET, SO_REUSEADDR, (void*)&on, 
  		(socklen_t)sizeof(on)) < 0) {
  		log_err("setsockopt(.. SO_REUSEADDR ..) failed: %s",
  			sock_strerror(errno));
  		sock_close(s);
  		return -1;
  	}
  #endif /* SO_REUSEADDR */
  #ifdef IP_FREEBIND
  	if (freebind && setsockopt(s, IPPROTO_IP, IP_FREEBIND, (void*)&on,
  	    (socklen_t)sizeof(on)) < 0) {
  		log_warn("setsockopt(.. IP_FREEBIND ..) failed: %s",
  		strerror(errno));
  	}
  #endif /* IP_FREEBIND */
  #ifdef SO_REUSEPORT
  	/* try to set SO_REUSEPORT so that incoming
  	 * connections are distributed evenly among the receiving threads.
  	 * Each thread must have its own socket bound to the same port,
  	 * with SO_REUSEPORT set on each socket.
  	 */
  	if (reuseport && *reuseport &&
  		setsockopt(s, SOL_SOCKET, SO_REUSEPORT, (void*)&on,
  		(socklen_t)sizeof(on)) < 0) {
  #ifdef ENOPROTOOPT
  		if(errno != ENOPROTOOPT || verbosity >= 3)
  			log_warn("setsockopt(.. SO_REUSEPORT ..) failed: %s",
  				strerror(errno));
  #endif
  		/* this option is not essential, we can continue */
  		*reuseport = 0;
  	}
  #else
  	(void)reuseport;
  #endif /* defined(SO_REUSEPORT) */
  #if defined(IPV6_V6ONLY)
  	if(addr->ai_family == AF_INET6 && v6only) {
  		if(setsockopt(s, IPPROTO_IPV6, IPV6_V6ONLY, 
  			(void*)&on, (socklen_t)sizeof(on)) < 0) {
  			log_err("setsockopt(..., IPV6_V6ONLY, ...) failed: %s",
  				sock_strerror(errno));
  			sock_close(s);
  			return -1;
  		}
  	}
  #else
  	(void)v6only;
  #endif /* IPV6_V6ONLY */
  #ifdef IP_TRANSPARENT
  	if (transparent &&
  	    setsockopt(s, IPPROTO_IP, IP_TRANSPARENT, (void*)&on,
  	    (socklen_t)sizeof(on)) < 0) {
  		log_warn("setsockopt(.. IP_TRANSPARENT ..) failed: %s",
  			strerror(errno));
  	}
  #elif defined(IP_BINDANY)
  	if (transparent &&
  	    setsockopt(s, (addr->ai_family==AF_INET6? IPPROTO_IPV6:IPPROTO_IP),
  	    (addr->ai_family == AF_INET6? IPV6_BINDANY:IP_BINDANY),
  	    (void*)&on, (socklen_t)sizeof(on)) < 0) {
  		log_warn("setsockopt(.. IP%s_BINDANY ..) failed: %s",
  		(addr->ai_family==AF_INET6?"V6":""), strerror(errno));
  	}
  #elif defined(SO_BINDANY)
  	if (transparent &&
  	    setsockopt(s, SOL_SOCKET, SO_BINDANY, (void*)&on, (socklen_t)
  	    sizeof(on)) < 0) {
  		log_warn("setsockopt(.. SO_BINDANY ..) failed: %s",
  		strerror(errno));
  	}
  #endif /* IP_TRANSPARENT || IP_BINDANY || SO_BINDANY */
  	err = set_ip_dscp(s, addr->ai_family, dscp);
  	if(err != NULL)
  		log_warn("error setting IP DiffServ codepoint %d on TCP socket: %s", dscp, err);
  	if(
  #ifdef HAVE_SYSTEMD
  		!got_fd_from_systemd &&
  #endif
          bind(s, addr->ai_addr, addr->ai_addrlen) != 0) {
  #ifndef USE_WINSOCK
  		/* detect freebsd jail with no ipv6 permission */
  		if(addr->ai_family==AF_INET6 && errno==EINVAL)
  			*noproto = 1;
  		else {
  			log_err_addr("can't bind socket", strerror(errno),
  				(struct sockaddr_storage*)addr->ai_addr,
  				addr->ai_addrlen);
  		}
  #else
  		log_err_addr("can't bind socket", 
  			wsa_strerror(WSAGetLastError()),
  			(struct sockaddr_storage*)addr->ai_addr,
  			addr->ai_addrlen);
  #endif
  		sock_close(s);
  		return -1;
  	}
  	if(!fd_set_nonblock(s)) {
  		sock_close(s);
  		return -1;
  	}
  	if(listen(s, TCP_BACKLOG) == -1) {
  		log_err("can't listen: %s", sock_strerror(errno));
  		sock_close(s);
  		return -1;
  	}
  #ifdef USE_TCP_FASTOPEN
  	/* qlen specifies how many outstanding TFO requests to allow. Limit is a defense
  	   against IP spoofing attacks as suggested in RFC7413 */
  #ifdef __APPLE__
  	/* OS X implementation only supports qlen of 1 via this call. Actual
  	   value is configured by the net.inet.tcp.fastopen_backlog kernel parm. */
  	qlen = 1;
  #else
  	/* 5 is recommended on linux */
  	qlen = 5;
  #endif
  	if ((setsockopt(s, IPPROTO_TCP, TCP_FASTOPEN, &qlen, 
  		  sizeof(qlen))) == -1 ) {
  #ifdef ENOPROTOOPT
  		/* squelch ENOPROTOOPT: freebsd server mode with kernel support
  		   disabled, except when verbosity enabled for debugging */
  		if(errno != ENOPROTOOPT || verbosity >= 3) {
  #endif
  		  if(errno == EPERM) {
  		  	log_warn("Setting TCP Fast Open as server failed: %s ; this could likely be because sysctl net.inet.tcp.fastopen.enabled, net.inet.tcp.fastopen.server_enable, or net.ipv4.tcp_fastopen is disabled", strerror(errno));
  		  } else {
  		  	log_err("Setting TCP Fast Open as server failed: %s", strerror(errno));
  		  }
  #ifdef ENOPROTOOPT
  		}
  #endif
  	}
  #endif
  	return s;
  }
  
  char*
  set_ip_dscp(int socket, int addrfamily, int dscp)
  {
  	int ds;
  
  	if(dscp == 0)
  		return NULL;
  	ds = dscp << 2;
  	switch(addrfamily) {
  	case AF_INET6:
  		if(setsockopt(socket, IPPROTO_IPV6, IPV6_TCLASS, (void*)&ds, sizeof(ds)) < 0)
  			return sock_strerror(errno);
  		break;
  	default:
  		if(setsockopt(socket, IPPROTO_IP, IP_TOS, (void*)&ds, sizeof(ds)) < 0)
  			return sock_strerror(errno);
  		break;
  	}
  	return NULL;
  }
  
  int
  create_local_accept_sock(const char *path, int* noproto, int use_systemd)
  {
  #ifdef HAVE_SYSTEMD
  	int ret;
  
  	if (use_systemd && (ret = systemd_get_activated(AF_LOCAL, SOCK_STREAM, 1, NULL, 0, path)) != -1)
  		return ret;
  	else {
  #endif
  #ifdef HAVE_SYS_UN_H
  	int s;
  	struct sockaddr_un usock;
  #ifndef HAVE_SYSTEMD
  	(void)use_systemd;
  #endif
  
  	verbose(VERB_ALGO, "creating unix socket %s", path);
  #ifdef HAVE_STRUCT_SOCKADDR_UN_SUN_LEN
  	/* this member exists on BSDs, not Linux */
  	usock.sun_len = (unsigned)sizeof(usock);
  #endif
  	usock.sun_family = AF_LOCAL;
  	/* length is 92-108, 104 on FreeBSD */
  	(void)strlcpy(usock.sun_path, path, sizeof(usock.sun_path));
  
  	if ((s = socket(AF_LOCAL, SOCK_STREAM, 0)) == -1) {
  		log_err("Cannot create local socket %s (%s)",
  			path, strerror(errno));
  		return -1;
  	}
  
  	if (unlink(path) && errno != ENOENT) {
  		/* The socket already exists and cannot be removed */
  		log_err("Cannot remove old local socket %s (%s)",
  			path, strerror(errno));
  		goto err;
  	}
  
  	if (bind(s, (struct sockaddr *)&usock,
  		(socklen_t)sizeof(struct sockaddr_un)) == -1) {
  		log_err("Cannot bind local socket %s (%s)",
  			path, strerror(errno));
  		goto err;
  	}
  
  	if (!fd_set_nonblock(s)) {
  		log_err("Cannot set non-blocking mode");
  		goto err;
  	}
  
  	if (listen(s, TCP_BACKLOG) == -1) {
  		log_err("can't listen: %s", strerror(errno));
  		goto err;
  	}
  
  	(void)noproto; /*unused*/
  	return s;
  
  err:
  	sock_close(s);
  	return -1;
  
  #ifdef HAVE_SYSTEMD
  	}
  #endif
  #else
  	(void)use_systemd;
  	(void)path;
  	log_err("Local sockets are not supported");
  	*noproto = 1;
  	return -1;
  #endif
  }
  
  
  /**
   * Create socket from getaddrinfo results
   */
  static int
  make_sock(int stype, const char* ifname, const char* port, 
  	struct addrinfo *hints, int v6only, int* noip6, size_t rcv, size_t snd,
  	int* reuseport, int transparent, int tcp_mss, int nodelay, int freebind,
  	int use_systemd, int dscp)
  {
  	struct addrinfo *res = NULL;
  	int r, s, inuse, noproto;
  	hints->ai_socktype = stype;
  	*noip6 = 0;
  	if((r=getaddrinfo(ifname, port, hints, &res)) != 0 || !res) {
  #ifdef USE_WINSOCK
  		if(r == EAI_NONAME && hints->ai_family == AF_INET6){
  			*noip6 = 1; /* 'Host not found' for IP6 on winXP */
  			return -1;
  		}
  #endif
  		log_err("node %s:%s getaddrinfo: %s %s", 
  			ifname?ifname:"default", port, gai_strerror(r),
  #ifdef EAI_SYSTEM
  			r==EAI_SYSTEM?(char*)strerror(errno):""
  #else
  			""
  #endif
  		);
  		return -1;
  	}
  	if(stype == SOCK_DGRAM) {
  		verbose_print_addr(res);
  		s = create_udp_sock(res->ai_family, res->ai_socktype,
  			(struct sockaddr*)res->ai_addr, res->ai_addrlen,
  			v6only, &inuse, &noproto, (int)rcv, (int)snd, 1,
  			reuseport, transparent, freebind, use_systemd, dscp);
  		if(s == -1 && inuse) {
  			log_err("bind: address already in use");
  		} else if(s == -1 && noproto && hints->ai_family == AF_INET6){
  			*noip6 = 1;
  		}
  	} else	{
  		s = create_tcp_accept_sock(res, v6only, &noproto, reuseport,
  			transparent, tcp_mss, nodelay, freebind, use_systemd,
  			dscp);
  		if(s == -1 && noproto && hints->ai_family == AF_INET6){
  			*noip6 = 1;
  		}
  	}
  	freeaddrinfo(res);
  	return s;
  }
  
  /** make socket and first see if ifname contains port override info */
  static int
  make_sock_port(int stype, const char* ifname, const char* port, 
  	struct addrinfo *hints, int v6only, int* noip6, size_t rcv, size_t snd,
  	int* reuseport, int transparent, int tcp_mss, int nodelay, int freebind,
  	int use_systemd, int dscp)
  {
  	char* s = strchr(ifname, '@');
  	if(s) {
  		/* override port with ifspec@port */
  		char p[16];
  		char newif[128];
  		if((size_t)(s-ifname) >= sizeof(newif)) {
  			log_err("ifname too long: %s", ifname);
  			*noip6 = 0;
  			return -1;
  		}
  		if(strlen(s+1) >= sizeof(p)) {
  			log_err("portnumber too long: %s", ifname);
  			*noip6 = 0;
  			return -1;
  		}
  		(void)strlcpy(newif, ifname, sizeof(newif));
  		newif[s-ifname] = 0;
  		(void)strlcpy(p, s+1, sizeof(p));
  		p[strlen(s+1)]=0;
  		return make_sock(stype, newif, p, hints, v6only, noip6, rcv,
  			snd, reuseport, transparent, tcp_mss, nodelay, freebind,
  			use_systemd, dscp);
  	}
  	return make_sock(stype, ifname, port, hints, v6only, noip6, rcv, snd,
  		reuseport, transparent, tcp_mss, nodelay, freebind, use_systemd,
  		dscp);
  }
  
  /**
   * Add port to open ports list.
   * @param list: list head. changed.
   * @param s: fd.
   * @param ftype: if fd is UDP.
   * @return false on failure. list in unchanged then.
   */
  static int
  port_insert(struct listen_port** list, int s, enum listen_type ftype)
  {
  	struct listen_port* item = (struct listen_port*)malloc(
  		sizeof(struct listen_port));
  	if(!item)
  		return 0;
  	item->next = *list;
  	item->fd = s;
  	item->ftype = ftype;
  	*list = item;
  	return 1;
  }
  
  /** set fd to receive source address packet info */
  static int
  set_recvpktinfo(int s, int family) 
  {
  #if defined(IPV6_RECVPKTINFO) || defined(IPV6_PKTINFO) || (defined(IP_RECVDSTADDR) && defined(IP_SENDSRCADDR)) || defined(IP_PKTINFO)
  	int on = 1;
  #else
  	(void)s;
  #endif
  	if(family == AF_INET6) {
  #           ifdef IPV6_RECVPKTINFO
  		if(setsockopt(s, IPPROTO_IPV6, IPV6_RECVPKTINFO,
  			(void*)&on, (socklen_t)sizeof(on)) < 0) {
  			log_err("setsockopt(..., IPV6_RECVPKTINFO, ...) failed: %s",
  				strerror(errno));
  			return 0;
  		}
  #           elif defined(IPV6_PKTINFO)
  		if(setsockopt(s, IPPROTO_IPV6, IPV6_PKTINFO,
  			(void*)&on, (socklen_t)sizeof(on)) < 0) {
  			log_err("setsockopt(..., IPV6_PKTINFO, ...) failed: %s",
  				strerror(errno));
  			return 0;
  		}
  #           else
  		log_err("no IPV6_RECVPKTINFO and no IPV6_PKTINFO option, please "
  			"disable interface-automatic or do-ip6 in config");
  		return 0;
  #           endif /* defined IPV6_RECVPKTINFO */
  
  	} else if(family == AF_INET) {
  #           ifdef IP_PKTINFO
  		if(setsockopt(s, IPPROTO_IP, IP_PKTINFO,
  			(void*)&on, (socklen_t)sizeof(on)) < 0) {
  			log_err("setsockopt(..., IP_PKTINFO, ...) failed: %s",
  				strerror(errno));
  			return 0;
  		}
  #           elif defined(IP_RECVDSTADDR) && defined(IP_SENDSRCADDR)
  		if(setsockopt(s, IPPROTO_IP, IP_RECVDSTADDR,
  			(void*)&on, (socklen_t)sizeof(on)) < 0) {
  			log_err("setsockopt(..., IP_RECVDSTADDR, ...) failed: %s",
  				strerror(errno));
  			return 0;
  		}
  #           else
  		log_err("no IP_SENDSRCADDR or IP_PKTINFO option, please disable "
  			"interface-automatic or do-ip4 in config");
  		return 0;
  #           endif /* IP_PKTINFO */
  
  	}
  	return 1;
  }
  
  /** see if interface is ssl, its port number == the ssl port number */
  static int
  if_is_ssl(const char* ifname, const char* port, int ssl_port,
  	struct config_strlist* tls_additional_port)
  {
  	struct config_strlist* s;
  	char* p = strchr(ifname, '@');
  	if(!p && atoi(port) == ssl_port)
  		return 1;
  	if(p && atoi(p+1) == ssl_port)
  		return 1;
  	for(s = tls_additional_port; s; s = s->next) {
  		if(p && atoi(p+1) == atoi(s->str))
  			return 1;
  		if(!p && atoi(port) == atoi(s->str))
  			return 1;
  	}
  	return 0;
  }
  
  /** see if interface is https, its port number == the https port number */
  static int
  if_is_https(const char* ifname, const char* port, int https_port)
  {
  	char* p = strchr(ifname, '@');
  	if(!p && atoi(port) == https_port)
  		return 1;
  	if(p && atoi(p+1) == https_port)
  		return 1;
  	return 0;
  }
  
  /**
   * Helper for ports_open. Creates one interface (or NULL for default).
   * @param ifname: The interface ip address.
   * @param do_auto: use automatic interface detection.
   * 	If enabled, then ifname must be the wildcard name.
   * @param do_udp: if udp should be used.
   * @param do_tcp: if udp should be used.
   * @param hints: for getaddrinfo. family and flags have to be set by caller.
   * @param port: Port number to use (as string).
   * @param list: list of open ports, appended to, changed to point to list head.
   * @param rcv: receive buffer size for UDP
   * @param snd: send buffer size for UDP
   * @param ssl_port: ssl service port number
   * @param tls_additional_port: list of additional ssl service port numbers.
   * @param https_port: DoH service port number
   * @param reuseport: try to set SO_REUSEPORT if nonNULL and true.
   * 	set to false on exit if reuseport failed due to no kernel support.
   * @param transparent: set IP_TRANSPARENT socket option.
   * @param tcp_mss: maximum segment size of tcp socket. default if zero.
   * @param freebind: set IP_FREEBIND socket option.
   * @param http2_nodelay: set TCP_NODELAY on HTTP/2 connection
   * @param use_systemd: if true, fetch sockets from systemd.
   * @param dnscrypt_port: dnscrypt service port number
   * @param dscp: DSCP to use.
   * @return: returns false on error.
   */
  static int
  ports_create_if(const char* ifname, int do_auto, int do_udp, int do_tcp, 
  	struct addrinfo *hints, const char* port, struct listen_port** list,
  	size_t rcv, size_t snd, int ssl_port,
  	struct config_strlist* tls_additional_port, int https_port,
  	int* reuseport, int transparent, int tcp_mss, int freebind,
  	int http2_nodelay, int use_systemd, int dnscrypt_port, int dscp)
  {
  	int s, noip6=0;
  	int is_https = if_is_https(ifname, port, https_port);
  	int nodelay = is_https && http2_nodelay;
  #ifdef USE_DNSCRYPT
  	int is_dnscrypt = ((strchr(ifname, '@') && 
  			atoi(strchr(ifname, '@')+1) == dnscrypt_port) ||
  			(!strchr(ifname, '@') && atoi(port) == dnscrypt_port));
  #else
  	int is_dnscrypt = 0;
  	(void)dnscrypt_port;
  #endif
  
  	if(!do_udp && !do_tcp)
  		return 0;
  	if(do_auto) {
  		if((s = make_sock_port(SOCK_DGRAM, ifname, port, hints, 1, 
  			&noip6, rcv, snd, reuseport, transparent,
  			tcp_mss, nodelay, freebind, use_systemd, dscp)) == -1) {
  			if(noip6) {
  				log_warn("IPv6 protocol not available");
  				return 1;
  			}
  			return 0;
  		}
  		/* getting source addr packet info is highly non-portable */
  		if(!set_recvpktinfo(s, hints->ai_family)) {
  			sock_close(s);
  			return 0;
  		}
  		if(!port_insert(list, s,
  		   is_dnscrypt?listen_type_udpancil_dnscrypt:listen_type_udpancil)) {
  			sock_close(s);
  			return 0;
  		}
  	} else if(do_udp) {
  		/* regular udp socket */
  		if((s = make_sock_port(SOCK_DGRAM, ifname, port, hints, 1, 
  			&noip6, rcv, snd, reuseport, transparent,
  			tcp_mss, nodelay, freebind, use_systemd, dscp)) == -1) {
  			if(noip6) {
  				log_warn("IPv6 protocol not available");
  				return 1;
  			}
  			return 0;
  		}
  		if(!port_insert(list, s,
  		   is_dnscrypt?listen_type_udp_dnscrypt:listen_type_udp)) {
  			sock_close(s);
  			return 0;
  		}
  	}
  	if(do_tcp) {
  		int is_ssl = if_is_ssl(ifname, port, ssl_port,
  			tls_additional_port);
  		enum listen_type port_type;
  		if(is_ssl)
  			port_type = listen_type_ssl;
  		else if(is_https)
  			port_type = listen_type_http;
  		else if(is_dnscrypt)
  			port_type = listen_type_tcp_dnscrypt;
  		else
  			port_type = listen_type_tcp;
  		if((s = make_sock_port(SOCK_STREAM, ifname, port, hints, 1, 
  			&noip6, 0, 0, reuseport, transparent, tcp_mss, nodelay,
  			freebind, use_systemd, dscp)) == -1) {
  			if(noip6) {
  				/*log_warn("IPv6 protocol not available");*/
  				return 1;
  			}
  			return 0;
  		}
  		if(is_ssl)
  			verbose(VERB_ALGO, "setup TCP for SSL service");
  		if(!port_insert(list, s, port_type)) {
  			sock_close(s);
  			return 0;
  		}
  	}
  	return 1;
  }
  
  /** 
   * Add items to commpoint list in front.
   * @param c: commpoint to add.
   * @param front: listen struct.
   * @return: false on failure.
   */
  static int
  listen_cp_insert(struct comm_point* c, struct listen_dnsport* front)
  {
  	struct listen_list* item = (struct listen_list*)malloc(
  		sizeof(struct listen_list));
  	if(!item)
  		return 0;
  	item->com = c;
  	item->next = front->cps;
  	front->cps = item;
  	return 1;
  }
  
  struct listen_dnsport* 
  listen_create(struct comm_base* base, struct listen_port* ports,
  	size_t bufsize, int tcp_accept_count, int tcp_idle_timeout,
  	int harden_large_queries, uint32_t http_max_streams,
  	char* http_endpoint, int http_notls, struct tcl_list* tcp_conn_limit,
  	void* sslctx, struct dt_env* dtenv, comm_point_callback_type* cb,
  	void *cb_arg)
  {
  	struct listen_dnsport* front = (struct listen_dnsport*)
  		malloc(sizeof(struct listen_dnsport));
  	if(!front)
  		return NULL;
  	front->cps = NULL;
  	front->udp_buff = sldns_buffer_new(bufsize);
  #ifdef USE_DNSCRYPT
  	front->dnscrypt_udp_buff = NULL;
  #endif
  	if(!front->udp_buff) {
  		free(front);
  		return NULL;
  	}
  	if(!stream_wait_lock_inited) {
  		lock_basic_init(&stream_wait_count_lock);
  		stream_wait_lock_inited = 1;
  	}
  	if(!http2_query_buffer_lock_inited) {
  		lock_basic_init(&http2_query_buffer_count_lock);
  		http2_query_buffer_lock_inited = 1;
  	}
  	if(!http2_response_buffer_lock_inited) {
  		lock_basic_init(&http2_response_buffer_count_lock);
  		http2_response_buffer_lock_inited = 1;
  	}
  
  	/* create comm points as needed */
  	while(ports) {
  		struct comm_point* cp = NULL;
  		if(ports->ftype == listen_type_udp ||
  		   ports->ftype == listen_type_udp_dnscrypt)
  			cp = comm_point_create_udp(base, ports->fd, 
  				front->udp_buff, cb, cb_arg);
  		else if(ports->ftype == listen_type_tcp ||
  				ports->ftype == listen_type_tcp_dnscrypt)
  			cp = comm_point_create_tcp(base, ports->fd, 
  				tcp_accept_count, tcp_idle_timeout,
  				harden_large_queries, 0, NULL,
  				tcp_conn_limit, bufsize, front->udp_buff,
  				ports->ftype, cb, cb_arg);
  		else if(ports->ftype == listen_type_ssl ||
  			ports->ftype == listen_type_http) {
  			cp = comm_point_create_tcp(base, ports->fd, 
  				tcp_accept_count, tcp_idle_timeout,
  				harden_large_queries,
  				http_max_streams, http_endpoint,
  				tcp_conn_limit, bufsize, front->udp_buff,
  				ports->ftype, cb, cb_arg);
  			if(http_notls && ports->ftype == listen_type_http)
  				cp->ssl = NULL;
  			else
  				cp->ssl = sslctx;
  			if(ports->ftype == listen_type_http) {
  				if(!sslctx && !http_notls) {
  				  log_warn("HTTPS port configured, but no TLS "
  					"tls-service-key or tls-service-pem "
  					"set");
  				}
  #ifndef HAVE_SSL_CTX_SET_ALPN_SELECT_CB
  				if(!http_notls)
  				  log_warn("Unbound is not compiled with an "
  					"OpenSSL version supporting ALPN "
  					" (OpenSSL >= 1.0.2). This is required "
  					"to use DNS-over-HTTPS");
  #endif
  #ifndef HAVE_NGHTTP2_NGHTTP2_H
  				log_warn("Unbound is not compiled with "
  					"nghttp2. This is required to use "
  					"DNS-over-HTTPS.");
  #endif
  			}
  		} else if(ports->ftype == listen_type_udpancil ||
  				  ports->ftype == listen_type_udpancil_dnscrypt)
  			cp = comm_point_create_udp_ancil(base, ports->fd, 
  				front->udp_buff, cb, cb_arg);
  		if(!cp) {
  			log_err("can't create commpoint");	
  			listen_delete(front);
  			return NULL;
  		}
  		cp->dtenv = dtenv;
  		cp->do_not_close = 1;
  #ifdef USE_DNSCRYPT
  		if (ports->ftype == listen_type_udp_dnscrypt ||
  			ports->ftype == listen_type_tcp_dnscrypt ||
  			ports->ftype == listen_type_udpancil_dnscrypt) {
  			cp->dnscrypt = 1;
  			cp->dnscrypt_buffer = sldns_buffer_new(bufsize);
  			if(!cp->dnscrypt_buffer) {
  				log_err("can't alloc dnscrypt_buffer");
  				comm_point_delete(cp);
  				listen_delete(front);
  				return NULL;
  			}
  			front->dnscrypt_udp_buff = cp->dnscrypt_buffer;
  		}
  #endif
  		if(!listen_cp_insert(cp, front)) {
  			log_err("malloc failed");
  			comm_point_delete(cp);
  			listen_delete(front);
  			return NULL;
  		}
  		ports = ports->next;
  	}
  	if(!front->cps) {
  		log_err("Could not open sockets to accept queries.");
  		listen_delete(front);
  		return NULL;
  	}
  
  	return front;
  }
  
  void
  listen_list_delete(struct listen_list* list)
  {
  	struct listen_list *p = list, *pn;
  	while(p) {
  		pn = p->next;
  		comm_point_delete(p->com);
  		free(p);
  		p = pn;
  	}
  }
  
  void 
  listen_delete(struct listen_dnsport* front)
  {
  	if(!front) 
  		return;
  	listen_list_delete(front->cps);
  #ifdef USE_DNSCRYPT
  	if(front->dnscrypt_udp_buff &&
  		front->udp_buff != front->dnscrypt_udp_buff) {
  		sldns_buffer_free(front->dnscrypt_udp_buff);
  	}
  #endif
  	sldns_buffer_free(front->udp_buff);
  	free(front);
  	if(stream_wait_lock_inited) {
  		stream_wait_lock_inited = 0;
  		lock_basic_destroy(&stream_wait_count_lock);
  	}
  	if(http2_query_buffer_lock_inited) {
  		http2_query_buffer_lock_inited = 0;
  		lock_basic_destroy(&http2_query_buffer_count_lock);
  	}
  	if(http2_response_buffer_lock_inited) {
  		http2_response_buffer_lock_inited = 0;
  		lock_basic_destroy(&http2_response_buffer_count_lock);
  	}
  }
  
  #ifdef HAVE_GETIFADDRS
  static int
  resolve_ifa_name(struct ifaddrs *ifas, const char *search_ifa, char ***ip_addresses, int *ip_addresses_size)
  {
  	struct ifaddrs *ifa;
  	void *tmpbuf;
  	int last_ip_addresses_size = *ip_addresses_size;
  
  	for(ifa = ifas; ifa != NULL; ifa = ifa->ifa_next) {
  		sa_family_t family;
  		const char* atsign;
  #ifdef INET6      /* |   address ip    | % |  ifa name  | @ |  port  | nul */
  		char addr_buf[INET6_ADDRSTRLEN + 1 + IF_NAMESIZE + 1 + 16 + 1];
  #else
  		char addr_buf[INET_ADDRSTRLEN + 1 + 16 + 1];
  #endif
  
  		if((atsign=strrchr(search_ifa, '@')) != NULL) {
  			if(strlen(ifa->ifa_name) != (size_t)(atsign-search_ifa)
  			   || strncmp(ifa->ifa_name, search_ifa,
  			   atsign-search_ifa) != 0)
  				continue;
  		} else {
  			if(strcmp(ifa->ifa_name, search_ifa) != 0)
  				continue;
  			atsign = "";
  		}
  
  		if(ifa->ifa_addr == NULL)
  			continue;
  
  		family = ifa->ifa_addr->sa_family;
  		if(family == AF_INET) {
  			char a4[INET_ADDRSTRLEN + 1];
  			struct sockaddr_in *in4 = (struct sockaddr_in *)
  				ifa->ifa_addr;
  			if(!inet_ntop(family, &in4->sin_addr, a4, sizeof(a4))) {
  				log_err("inet_ntop failed");
  				return 0;
  			}
  			snprintf(addr_buf, sizeof(addr_buf), "%s%s",
  				a4, atsign);
  		}
  #ifdef INET6
  		else if(family == AF_INET6) {
  			struct sockaddr_in6 *in6 = (struct sockaddr_in6 *)
  				ifa->ifa_addr;
  			char a6[INET6_ADDRSTRLEN + 1];
  			char if_index_name[IF_NAMESIZE + 1];
  			if_index_name[0] = 0;
  			if(!inet_ntop(family, &in6->sin6_addr, a6, sizeof(a6))) {
  				log_err("inet_ntop failed");
  				return 0;
  			}
  			(void)if_indextoname(in6->sin6_scope_id,
  				(char *)if_index_name);
  			if (strlen(if_index_name) != 0) {
  				snprintf(addr_buf, sizeof(addr_buf),
  					"%s%%%s%s", a6, if_index_name, atsign);
  			} else {
  				snprintf(addr_buf, sizeof(addr_buf), "%s%s",
  					a6, atsign);
  			}
  		}
  #endif
  		else {
  			continue;
  		}
  		verbose(4, "interface %s has address %s", search_ifa, addr_buf);
  
  		tmpbuf = realloc(*ip_addresses, sizeof(char *) * (*ip_addresses_size + 1));
  		if(!tmpbuf) {
  			log_err("realloc failed: out of memory");
  			return 0;
  		} else {
  			*ip_addresses = tmpbuf;
  		}
  		(*ip_addresses)[*ip_addresses_size] = strdup(addr_buf);
  		if(!(*ip_addresses)[*ip_addresses_size]) {
  			log_err("strdup failed: out of memory");
  			return 0;
  		}
  		(*ip_addresses_size)++;
  	}
  
  	if (*ip_addresses_size == last_ip_addresses_size) {
  		tmpbuf = realloc(*ip_addresses, sizeof(char *) * (*ip_addresses_size + 1));
  		if(!tmpbuf) {
  			log_err("realloc failed: out of memory");
  			return 0;
  		} else {
  			*ip_addresses = tmpbuf;
  		}
  		(*ip_addresses)[*ip_addresses_size] = strdup(search_ifa);
  		if(!(*ip_addresses)[*ip_addresses_size]) {
  			log_err("strdup failed: out of memory");
  			return 0;
  		}
  		(*ip_addresses_size)++;
  	}
  	return 1;
  }
  #endif /* HAVE_GETIFADDRS */
  
  int resolve_interface_names(struct config_file* cfg, char*** resif,
  	int* num_resif)
  {
  #ifdef HAVE_GETIFADDRS
  	int i;
  	struct ifaddrs *addrs = NULL;
  	if(cfg->num_ifs == 0) {
  		*resif = NULL;
  		*num_resif = 0;
  		return 1;
  	}
  	if(getifaddrs(&addrs) == -1) {
  		log_err("failed to list interfaces: getifaddrs: %s",
  			strerror(errno));
  		freeifaddrs(addrs);
  		return 0;
  	}
  	for(i=0; i<cfg->num_ifs; i++) {
  		if(!resolve_ifa_name(addrs, cfg->ifs[i], resif, num_resif)) {
  			freeifaddrs(addrs);
  			config_del_strarray(*resif, *num_resif);
  			*resif = NULL;
  			*num_resif = 0;
  			return 0;
  		}
  	}
  	freeifaddrs(addrs);
  	return 1;
  #else
  	int i;
  	if(cfg->num_ifs == 0) {
  		*resif = NULL;
  		*num_resif = 0;
  		return 1;
  	}
  	*num_resif = cfg->num_ifs;
  	*resif = calloc(*num_resif, sizeof(**resif));
  	if(!*resif) {
  		log_err("out of memory");
  		return 0;
  	}
  	for(i=0; i<*num_resif; i++) {
  		(*resif)[i] = strdup(cfg->ifs[i]);
  		if(!((*resif)[i])) {
  			log_err("out of memory");
  			config_del_strarray(*resif, *num_resif);
  			*resif = NULL;
  			*num_resif = 0;
  			return 0;
  		}
  	}
  	return 1;
  #endif /* HAVE_GETIFADDRS */
  }
  
  struct listen_port* 
  listening_ports_open(struct config_file* cfg, char** ifs, int num_ifs,
  	int* reuseport)
  {
  	struct listen_port* list = NULL;
  	struct addrinfo hints;
  	int i, do_ip4, do_ip6;
  	int do_tcp, do_auto;
  	char portbuf[32];
  	snprintf(portbuf, sizeof(portbuf), "%d", cfg->port);
  	do_ip4 = cfg->do_ip4;
  	do_ip6 = cfg->do_ip6;
  	do_tcp = cfg->do_tcp;
  	do_auto = cfg->if_automatic && cfg->do_udp;
  	if(cfg->incoming_num_tcp == 0)
  		do_tcp = 0;
  
  	/* getaddrinfo */
  	memset(&hints, 0, sizeof(hints));
  	hints.ai_flags = AI_PASSIVE;
  	/* no name lookups on our listening ports */
  	if(num_ifs > 0)
  		hints.ai_flags |= AI_NUMERICHOST;
  	hints.ai_family = AF_UNSPEC;
  #ifndef INET6
  	do_ip6 = 0;
  #endif
  	if(!do_ip4 && !do_ip6) {
  		return NULL;
  	}
  	/* create ip4 and ip6 ports so that return addresses are nice. */
  	if(do_auto || num_ifs == 0) {
  		if(do_ip6) {
  			hints.ai_family = AF_INET6;
  			if(!ports_create_if(do_auto?"::0":"::1", 
  				do_auto, cfg->do_udp, do_tcp, 
  				&hints, portbuf, &list,
  				cfg->so_rcvbuf, cfg->so_sndbuf,
  				cfg->ssl_port, cfg->tls_additional_port,
  				cfg->https_port, reuseport, cfg->ip_transparent,
  				cfg->tcp_mss, cfg->ip_freebind,
  				cfg->http_nodelay, cfg->use_systemd,
  				cfg->dnscrypt_port, cfg->ip_dscp)) {
  				listening_ports_free(list);
  				return NULL;
  			}
  		}
  		if(do_ip4) {
  			hints.ai_family = AF_INET;
  			if(!ports_create_if(do_auto?"0.0.0.0":"127.0.0.1", 
  				do_auto, cfg->do_udp, do_tcp, 
  				&hints, portbuf, &list,
  				cfg->so_rcvbuf, cfg->so_sndbuf,
  				cfg->ssl_port, cfg->tls_additional_port,
  				cfg->https_port, reuseport, cfg->ip_transparent,
  				cfg->tcp_mss, cfg->ip_freebind,
  				cfg->http_nodelay, cfg->use_systemd,
  				cfg->dnscrypt_port, cfg->ip_dscp)) {
  				listening_ports_free(list);
  				return NULL;
  			}
  		}
  	} else for(i = 0; i<num_ifs; i++) {
  		if(str_is_ip6(ifs[i])) {
  			if(!do_ip6)
  				continue;
  			hints.ai_family = AF_INET6;
  			if(!ports_create_if(ifs[i], 0, cfg->do_udp,
  				do_tcp, &hints, portbuf, &list, 
  				cfg->so_rcvbuf, cfg->so_sndbuf,
  				cfg->ssl_port, cfg->tls_additional_port,
  				cfg->https_port, reuseport, cfg->ip_transparent,
  				cfg->tcp_mss, cfg->ip_freebind,
  				cfg->http_nodelay, cfg->use_systemd,
  				cfg->dnscrypt_port, cfg->ip_dscp)) {
  				listening_ports_free(list);
  				return NULL;
  			}
  		} else {
  			if(!do_ip4)
  				continue;
  			hints.ai_family = AF_INET;
  			if(!ports_create_if(ifs[i], 0, cfg->do_udp,
  				do_tcp, &hints, portbuf, &list, 
  				cfg->so_rcvbuf, cfg->so_sndbuf,
  				cfg->ssl_port, cfg->tls_additional_port,
  				cfg->https_port, reuseport, cfg->ip_transparent,
  				cfg->tcp_mss, cfg->ip_freebind,
  				cfg->http_nodelay, cfg->use_systemd,
  				cfg->dnscrypt_port, cfg->ip_dscp)) {
  				listening_ports_free(list);
  				return NULL;
  			}
  		}
  	}
  	return list;
  }
  
  void listening_ports_free(struct listen_port* list)
  {
  	struct listen_port* nx;
  	while(list) {
  		nx = list->next;
  		if(list->fd != -1) {
  			sock_close(list->fd);
  		}
  		free(list);
  		list = nx;
  	}
  }
  
  size_t listen_get_mem(struct listen_dnsport* listen)
  {
  	struct listen_list* p;
  	size_t s = sizeof(*listen) + sizeof(*listen->base) + 
  		sizeof(*listen->udp_buff) + 
  		sldns_buffer_capacity(listen->udp_buff);
  #ifdef USE_DNSCRYPT
  	s += sizeof(*listen->dnscrypt_udp_buff);
  	if(listen->udp_buff != listen->dnscrypt_udp_buff){
  		s += sldns_buffer_capacity(listen->dnscrypt_udp_buff);
  	}
  #endif
  	for(p = listen->cps; p; p = p->next) {
  		s += sizeof(*p);
  		s += comm_point_get_mem(p->com);
  	}
  	return s;
  }
  
  void listen_stop_accept(struct listen_dnsport* listen)
  {
  	/* do not stop the ones that have no tcp_free list
  	 * (they have already stopped listening) */
  	struct listen_list* p;
  	for(p=listen->cps; p; p=p->next) {
  		if(p->com->type == comm_tcp_accept &&
  			p->com->tcp_free != NULL) {
  			comm_point_stop_listening(p->com);
  		}
  	}
  }
  
  void listen_start_accept(struct listen_dnsport* listen)
  {
  	/* do not start the ones that have no tcp_free list, it is no
  	 * use to listen to them because they have no free tcp handlers */
  	struct listen_list* p;
  	for(p=listen->cps; p; p=p->next) {
  		if(p->com->type == comm_tcp_accept &&
  			p->com->tcp_free != NULL) {
  			comm_point_start_listening(p->com, -1, -1);
  		}
  	}
  }
  
  struct tcp_req_info*
  tcp_req_info_create(struct sldns_buffer* spoolbuf)
  {
  	struct tcp_req_info* req = (struct tcp_req_info*)malloc(sizeof(*req));
  	if(!req) {
  		log_err("malloc failure for new stream outoforder processing structure");
  		return NULL;
  	}
  	memset(req, 0, sizeof(*req));
  	req->spool_buffer = spoolbuf;
  	return req;
  }
  
  void
  tcp_req_info_delete(struct tcp_req_info* req)
  {
  	if(!req) return;
  	tcp_req_info_clear(req);
  	/* cp is pointer back to commpoint that owns this struct and
  	 * called delete on us */
  	/* spool_buffer is shared udp buffer, not deleted here */
  	free(req);
  }
  
  void tcp_req_info_clear(struct tcp_req_info* req)
  {
  	struct tcp_req_open_item* open, *nopen;
  	struct tcp_req_done_item* item, *nitem;
  	if(!req) return;
  
  	/* free outstanding request mesh reply entries */
  	open = req->open_req_list;
  	while(open) {
  		nopen = open->next;
  		mesh_state_remove_reply(open->mesh, open->mesh_state, req->cp);
  		free(open);
  		open = nopen;
  	}
  	req->open_req_list = NULL;
  	req->num_open_req = 0;
  	
  	/* free pending writable result packets */
  	item = req->done_req_list;
  	while(item) {
  		nitem = item->next;
  		lock_basic_lock(&stream_wait_count_lock);
  		stream_wait_count -= (sizeof(struct tcp_req_done_item)
  			+item->len);
  		lock_basic_unlock(&stream_wait_count_lock);
  		free(item->buf);
  		free(item);
  		item = nitem;
  	}
  	req->done_req_list = NULL;
  	req->num_done_req = 0;
  	req->read_is_closed = 0;
  }
  
  void
  tcp_req_info_remove_mesh_state(struct tcp_req_info* req, struct mesh_state* m)
  {
  	struct tcp_req_open_item* open, *prev = NULL;
  	if(!req || !m) return;
  	open = req->open_req_list;
  	while(open) {
  		if(open->mesh_state == m) {
  			struct tcp_req_open_item* next;
  			if(prev) prev->next = open->next;
  			else req->open_req_list = open->next;
  			/* caller has to manage the mesh state reply entry */
  			next = open->next;
  			free(open);
  			req->num_open_req --;
  
  			/* prev = prev; */
  			open = next;
  			continue;
  		}
  		prev = open;
  		open = open->next;
  	}
  }
  
  /** setup listening for read or write */
  static void
  tcp_req_info_setup_listen(struct tcp_req_info* req)
  {
  	int wr = 0;
  	int rd = 0;
  
  	if(req->cp->tcp_byte_count != 0) {
  		/* cannot change, halfway through */
  		return;
  	}
  
  	if(!req->cp->tcp_is_reading)
  		wr = 1;
  	if(!req->read_is_closed)
  		rd = 1;
  	
  	if(wr) {
  		req->cp->tcp_is_reading = 0;
  		comm_point_stop_listening(req->cp);
  		comm_point_start_listening(req->cp, -1,
  			adjusted_tcp_timeout(req->cp));
  	} else if(rd) {
  		req->cp->tcp_is_reading = 1;
  		comm_point_stop_listening(req->cp);
  		comm_point_start_listening(req->cp, -1,
  			adjusted_tcp_timeout(req->cp));
  		/* and also read it (from SSL stack buffers), so
  		 * no event read event is expected since the remainder of
  		 * the TLS frame is sitting in the buffers. */
  		req->read_again = 1;
  	} else {
  		comm_point_stop_listening(req->cp);
  		comm_point_start_listening(req->cp, -1,
  			adjusted_tcp_timeout(req->cp));
  		comm_point_listen_for_rw(req->cp, 0, 0);
  	}
  }
  
  /** remove first item from list of pending results */
  static struct tcp_req_done_item*
  tcp_req_info_pop_done(struct tcp_req_info* req)
  {
  	struct tcp_req_done_item* item;
  	log_assert(req->num_done_req > 0 && req->done_req_list);
  	item = req->done_req_list;
  	lock_basic_lock(&stream_wait_count_lock);
  	stream_wait_count -= (sizeof(struct tcp_req_done_item)+item->len);
  	lock_basic_unlock(&stream_wait_count_lock);
  	req->done_req_list = req->done_req_list->next;
  	req->num_done_req --;
  	return item;
  }
  
  /** Send given buffer and setup to write */
  static void
  tcp_req_info_start_write_buf(struct tcp_req_info* req, uint8_t* buf,
  	size_t len)
  {
  	sldns_buffer_clear(req->cp->buffer);
  	sldns_buffer_write(req->cp->buffer, buf, len);
  	sldns_buffer_flip(req->cp->buffer);
  
  	req->cp->tcp_is_reading = 0; /* we are now writing */
  }
  
  /** pick up the next result and start writing it to the channel */
  static void
  tcp_req_pickup_next_result(struct tcp_req_info* req)
  {
  	if(req->num_done_req > 0) {
  		/* unlist the done item from the list of pending results */
  		struct tcp_req_done_item* item = tcp_req_info_pop_done(req);
  		tcp_req_info_start_write_buf(req, item->buf, item->len);
  		free(item->buf);
  		free(item);
  	}
  }
  
  /** the read channel has closed */
  int
  tcp_req_info_handle_read_close(struct tcp_req_info* req)
  {
  	verbose(VERB_ALGO, "tcp channel read side closed %d", req->cp->fd);
  	/* reset byte count for (potential) partial read */
  	req->cp->tcp_byte_count = 0;
  	/* if we still have results to write, pick up next and write it */
  	if(req->num_done_req != 0) {
  		tcp_req_pickup_next_result(req);
  		tcp_req_info_setup_listen(req);
  		return 1;
  	}
  	/* if nothing to do, this closes the connection */
  	if(req->num_open_req == 0 && req->num_done_req == 0)
  		return 0;
  	/* otherwise, we must be waiting for dns resolve, wait with timeout */
  	req->read_is_closed = 1;
  	tcp_req_info_setup_listen(req);
  	return 1;
  }
  
  void
  tcp_req_info_handle_writedone(struct tcp_req_info* req)
  {
  	/* back to reading state, we finished this write event */
  	sldns_buffer_clear(req->cp->buffer);
  	if(req->num_done_req == 0 && req->read_is_closed) {
  		/* no more to write and nothing to read, close it */
  		comm_point_drop_reply(&req->cp->repinfo);
  		return;
  	}
  	req->cp->tcp_is_reading = 1;
  	/* see if another result needs writing */
  	tcp_req_pickup_next_result(req);
  
  	/* see if there is more to write, if not stop_listening for writing */
  	/* see if new requests are allowed, if so, start_listening
  	 * for reading */
  	tcp_req_info_setup_listen(req);
  }
  
  void
  tcp_req_info_handle_readdone(struct tcp_req_info* req)
  {
  	struct comm_point* c = req->cp;
  
  	/* we want to read up several requests, unless there are
  	 * pending answers */
  
  	req->is_drop = 0;
  	req->is_reply = 0;
  	req->in_worker_handle = 1;
  	sldns_buffer_set_limit(req->spool_buffer, 0);
  	/* handle the current request */
  	/* this calls the worker handle request routine that could give
  	 * a cache response, or localdata response, or drop the reply,
  	 * or schedule a mesh entry for later */
  	fptr_ok(fptr_whitelist_comm_point(c->callback));
  	if( (*c->callback)(c, c->cb_arg, NETEVENT_NOERROR, &c->repinfo) ) {
  		req->in_worker_handle = 0;
  		/* there is an answer, put it up.  It is already in the
  		 * c->buffer, just send it. */
  		/* since we were just reading a query, the channel is
  		 * clear to write to */
  	send_it:
  		c->tcp_is_reading = 0;
  		comm_point_stop_listening(c);
  		comm_point_start_listening(c, -1, adjusted_tcp_timeout(c));
  		return;
  	}
  	req->in_worker_handle = 0;
  	/* it should be waiting in the mesh for recursion.
  	 * If mesh failed to add a new entry and called commpoint_drop_reply. 
  	 * Then the mesh state has been cleared. */
  	if(req->is_drop) {
  		/* the reply has been dropped, stream has been closed. */
  		return;
  	}
  	/* If mesh failed(mallocfail) and called commpoint_send_reply with
  	 * something like servfail then we pick up that reply below. */
  	if(req->is_reply) {
  		goto send_it;
  	}
  
  	sldns_buffer_clear(c->buffer);
  	/* if pending answers, pick up an answer and start sending it */
  	tcp_req_pickup_next_result(req);
  
  	/* if answers pending, start sending answers */
  	/* read more requests if we can have more requests */
  	tcp_req_info_setup_listen(req);
  }
  
  int
  tcp_req_info_add_meshstate(struct tcp_req_info* req,
  	struct mesh_area* mesh, struct mesh_state* m)
  {
  	struct tcp_req_open_item* item;
  	log_assert(req && mesh && m);
  	item = (struct tcp_req_open_item*)malloc(sizeof(*item));
  	if(!item) return 0;
  	item->next = req->open_req_list;
  	item->mesh = mesh;
  	item->mesh_state = m;
  	req->open_req_list = item;
  	req->num_open_req++;
  	return 1;
  }
  
  /** Add a result to the result list.  At the end. */
  static int
  tcp_req_info_add_result(struct tcp_req_info* req, uint8_t* buf, size_t len)
  {
  	struct tcp_req_done_item* last = NULL;
  	struct tcp_req_done_item* item;
  	size_t space;
  
  	/* see if we have space */
  	space = sizeof(struct tcp_req_done_item) + len;
  	lock_basic_lock(&stream_wait_count_lock);
  	if(stream_wait_count + space > stream_wait_max) {
  		lock_basic_unlock(&stream_wait_count_lock);
  		verbose(VERB_ALGO, "drop stream reply, no space left, in stream-wait-size");
  		return 0;
  	}
  	stream_wait_count += space;
  	lock_basic_unlock(&stream_wait_count_lock);
  
  	/* find last element */
  	last = req->done_req_list;
  	while(last && last->next)
  		last = last->next;
  	
  	/* create new element */
  	item = (struct tcp_req_done_item*)malloc(sizeof(*item));
  	if(!item) {
  		log_err("malloc failure, for stream result list");
  		return 0;
  	}
  	item->next = NULL;
  	item->len = len;
  	item->buf = memdup(buf, len);
  	if(!item->buf) {
  		free(item);
  		log_err("malloc failure, adding reply to stream result list");
  		return 0;
  	}
  
  	/* link in */
  	if(last) last->next = item;
  	else req->done_req_list = item;
  	req->num_done_req++;
  	return 1;
  }
  
  void
  tcp_req_info_send_reply(struct tcp_req_info* req)
  {
  	if(req->in_worker_handle) {
  		/* reply from mesh is in the spool_buffer */
  		/* copy now, so that the spool buffer is free for other tasks
  		 * before the callback is done */
  		sldns_buffer_clear(req->cp->buffer);
  		sldns_buffer_write(req->cp->buffer,
  			sldns_buffer_begin(req->spool_buffer),
  			sldns_buffer_limit(req->spool_buffer));
  		sldns_buffer_flip(req->cp->buffer);
  		req->is_reply = 1;
  		return;
  	}
  	/* now that the query has been handled, that mesh_reply entry
  	 * should be removed, from the tcp_req_info list,
  	 * the mesh state cleanup removes then with region_cleanup and
  	 * replies_sent true. */
  	/* see if we can send it straight away (we are not doing
  	 * anything else).  If so, copy to buffer and start */
  	if(req->cp->tcp_is_reading && req->cp->tcp_byte_count == 0) {
  		/* buffer is free, and was ready to read new query into,
  		 * but we are now going to use it to send this answer */
  		tcp_req_info_start_write_buf(req,
  			sldns_buffer_begin(req->spool_buffer),
  			sldns_buffer_limit(req->spool_buffer));
  		/* switch to listen to write events */
  		comm_point_stop_listening(req->cp);
  		comm_point_start_listening(req->cp, -1,
  			adjusted_tcp_timeout(req->cp));
  		return;
  	}
  	/* queue up the answer behind the others already pending */
  	if(!tcp_req_info_add_result(req, sldns_buffer_begin(req->spool_buffer),
  		sldns_buffer_limit(req->spool_buffer))) {
  		/* drop the connection, we are out of resources */
  		comm_point_drop_reply(&req->cp->repinfo);
  	}
  }
  
  size_t tcp_req_info_get_stream_buffer_size(void)
  {
  	size_t s;
  	if(!stream_wait_lock_inited)
  		return stream_wait_count;
  	lock_basic_lock(&stream_wait_count_lock);
  	s = stream_wait_count;
  	lock_basic_unlock(&stream_wait_count_lock);
  	return s;
  }
  
  size_t http2_get_query_buffer_size(void)
  {
  	size_t s;
  	if(!http2_query_buffer_lock_inited)
  		return http2_query_buffer_count;
  	lock_basic_lock(&http2_query_buffer_count_lock);
  	s = http2_query_buffer_count;
  	lock_basic_unlock(&http2_query_buffer_count_lock);
  	return s;
  }
  
  size_t http2_get_response_buffer_size(void)
  {
  	size_t s;
  	if(!http2_response_buffer_lock_inited)
  		return http2_response_buffer_count;
  	lock_basic_lock(&http2_response_buffer_count_lock);
  	s = http2_response_buffer_count;
  	lock_basic_unlock(&http2_response_buffer_count_lock);
  	return s;
  }
  
  #ifdef HAVE_NGHTTP2
  /** nghttp2 callback. Used to copy response from rbuffer to nghttp2 session */
  static ssize_t http2_submit_response_read_callback(
  	nghttp2_session* ATTR_UNUSED(session),
  	int32_t stream_id, uint8_t* buf, size_t length, uint32_t* data_flags,
  	nghttp2_data_source* source, void* ATTR_UNUSED(cb_arg))
  {
  	struct http2_stream* h2_stream;
  	struct http2_session* h2_session = source->ptr;
  	size_t copylen = length;
  	if(!(h2_stream = nghttp2_session_get_stream_user_data(
  		h2_session->session, stream_id))) {
  		verbose(VERB_QUERY, "http2: cannot get stream data, closing "
  			"stream");
  		return NGHTTP2_ERR_TEMPORAL_CALLBACK_FAILURE;
  	}
  	if(!h2_stream->rbuffer ||
  		sldns_buffer_remaining(h2_stream->rbuffer) == 0) {
  		verbose(VERB_QUERY, "http2: cannot submit buffer. No data "
  			"available in rbuffer");
  		/* rbuffer will be free'd in frame close cb */
  		return NGHTTP2_ERR_TEMPORAL_CALLBACK_FAILURE;
  	}
  
  	if(copylen > sldns_buffer_remaining(h2_stream->rbuffer))
  		copylen = sldns_buffer_remaining(h2_stream->rbuffer);
  	if(copylen > SSIZE_MAX)
  		copylen = SSIZE_MAX; /* will probably never happen */
  
  	memcpy(buf, sldns_buffer_current(h2_stream->rbuffer), copylen);
  	sldns_buffer_skip(h2_stream->rbuffer, copylen);
  
  	if(sldns_buffer_remaining(h2_stream->rbuffer) == 0) {
  		*data_flags |= NGHTTP2_DATA_FLAG_EOF;
  		lock_basic_lock(&http2_response_buffer_count_lock);
  		http2_response_buffer_count -=
  			sldns_buffer_capacity(h2_stream->rbuffer);
  		lock_basic_unlock(&http2_response_buffer_count_lock);
  		sldns_buffer_free(h2_stream->rbuffer);
  		h2_stream->rbuffer = NULL;
  	}
  
  	return copylen;
  }
  
  /**
   * Send RST_STREAM frame for stream.
   * @param h2_session: http2 session to submit frame to
   * @param h2_stream: http2 stream containing frame ID to use in RST_STREAM
   * @return 0 on error, 1 otherwise
   */
  static int http2_submit_rst_stream(struct http2_session* h2_session,
  		struct http2_stream* h2_stream)
  {
  	int ret = nghttp2_submit_rst_stream(h2_session->session,
  		NGHTTP2_FLAG_NONE, h2_stream->stream_id,
  		NGHTTP2_INTERNAL_ERROR);
  	if(ret) {
  		verbose(VERB_QUERY, "http2: nghttp2_submit_rst_stream failed, "
  			"error: %s", nghttp2_strerror(ret));
  		return 0;
  	}
  	return 1;
  }
  
  /**
   * DNS response ready to be submitted to nghttp2, to be prepared for sending
   * out. Response is stored in c->buffer. Copy to rbuffer because the c->buffer
   * might be used before this will be sent out.
   * @param h2_session: http2 session, containing c->buffer which contains answer
   * @return 0 on error, 1 otherwise
   */
  int http2_submit_dns_response(struct http2_session* h2_session)
  {
  	int ret;
  	nghttp2_data_provider data_prd;
  	char status[4];
  	nghttp2_nv headers[3];
  	struct http2_stream* h2_stream = h2_session->c->h2_stream;
  	size_t rlen;
  	char rlen_str[32];
  
  	if(h2_stream->rbuffer) {
  		log_err("http2 submit response error: rbuffer already "
  			"exists");
  		return 0;
  	}
  	if(sldns_buffer_remaining(h2_session->c->buffer) == 0) {
  		log_err("http2 submit response error: c->buffer not complete");
  		return 0;
  	}
  
  	if(snprintf(status, 4, "%d", h2_stream->status) != 3) {
  		verbose(VERB_QUERY, "http2: submit response error: "
  			"invalid status");
  		return 0;
  	}
  
  	rlen = sldns_buffer_remaining(h2_session->c->buffer);
  	snprintf(rlen_str, sizeof(rlen_str), "%u", (unsigned)rlen);
  
  	lock_basic_lock(&http2_response_buffer_count_lock);
  	if(http2_response_buffer_count + rlen > http2_response_buffer_max) {
  		lock_basic_unlock(&http2_response_buffer_count_lock);
  		verbose(VERB_ALGO, "reset HTTP2 stream, no space left, "
  			"in https-response-buffer-size");
  		return http2_submit_rst_stream(h2_session, h2_stream);
  	}
  	http2_response_buffer_count += rlen;
  	lock_basic_unlock(&http2_response_buffer_count_lock);
  
  	if(!(h2_stream->rbuffer = sldns_buffer_new(rlen))) {
  		lock_basic_lock(&http2_response_buffer_count_lock);
  		http2_response_buffer_count -= rlen;
  		lock_basic_unlock(&http2_response_buffer_count_lock);
  		log_err("http2 submit response error: malloc failure");
  		return 0;
  	}
  
  	headers[0].name = (uint8_t*)":status";
  	headers[0].namelen = 7;
  	headers[0].value = (uint8_t*)status;
  	headers[0].valuelen = 3;
  	headers[0].flags = NGHTTP2_NV_FLAG_NONE;
  
  	headers[1].name = (uint8_t*)"content-type";
  	headers[1].namelen = 12;
  	headers[1].value = (uint8_t*)"application/dns-message";
  	headers[1].valuelen = 23;
  	headers[1].flags = NGHTTP2_NV_FLAG_NONE;
  
  	headers[2].name = (uint8_t*)"content-length";
  	headers[2].namelen = 14;
  	headers[2].value = (uint8_t*)rlen_str;
  	headers[2].valuelen = strlen(rlen_str);
  	headers[2].flags = NGHTTP2_NV_FLAG_NONE;
  
  	sldns_buffer_write(h2_stream->rbuffer,
  		sldns_buffer_current(h2_session->c->buffer),
  		sldns_buffer_remaining(h2_session->c->buffer));
  	sldns_buffer_flip(h2_stream->rbuffer);
  
  	data_prd.source.ptr = h2_session;
  	data_prd.read_callback = http2_submit_response_read_callback;
  	ret = nghttp2_submit_response(h2_session->session, h2_stream->stream_id,
  		headers, 3, &data_prd);
  	if(ret) {
  		verbose(VERB_QUERY, "http2: set_stream_user_data failed, "
  			"error: %s", nghttp2_strerror(ret));
  		return 0;
  	}
  	return 1;
  }
  #else
  int http2_submit_dns_response(void* ATTR_UNUSED(v))
  {
  	return 0;
  }
  #endif
  
  #ifdef HAVE_NGHTTP2
  /** HTTP status to descriptive string */
  static char* http_status_to_str(enum http_status s)
  {
  	switch(s) {
  		case HTTP_STATUS_OK:
  			return "OK";
  		case HTTP_STATUS_BAD_REQUEST:
  			return "Bad Request";
  		case HTTP_STATUS_NOT_FOUND:
  			return "Not Found";
  		case HTTP_STATUS_PAYLOAD_TOO_LARGE:
  			return "Payload Too Large";
  		case HTTP_STATUS_URI_TOO_LONG:
  			return "URI Too Long";
  		case HTTP_STATUS_UNSUPPORTED_MEDIA_TYPE:
  			return "Unsupported Media Type";
  		case HTTP_STATUS_NOT_IMPLEMENTED:
  			return "Not Implemented";
  	}
  	return "Status Unknown";
  }
  
  /** nghttp2 callback. Used to copy error message to nghttp2 session */
  static ssize_t http2_submit_error_read_callback(
  	nghttp2_session* ATTR_UNUSED(session),
  	int32_t stream_id, uint8_t* buf, size_t length, uint32_t* data_flags,
  	nghttp2_data_source* source, void* ATTR_UNUSED(cb_arg))
  {
  	struct http2_stream* h2_stream;
  	struct http2_session* h2_session = source->ptr;
  	char* msg;
  	if(!(h2_stream = nghttp2_session_get_stream_user_data(
  		h2_session->session, stream_id))) {
  		verbose(VERB_QUERY, "http2: cannot get stream data, closing "
  			"stream");
  		return NGHTTP2_ERR_TEMPORAL_CALLBACK_FAILURE;
  	}
  	*data_flags |= NGHTTP2_DATA_FLAG_EOF;
  	msg = http_status_to_str(h2_stream->status);
  	if(length < strlen(msg))
  		return 0; /* not worth trying over multiple frames */
  	memcpy(buf, msg, strlen(msg));
  	return strlen(msg);
  
  }
  
  /**
   * HTTP error response ready to be submitted to nghttp2, to be prepared for
   * sending out. Message body will contain descriptive string for HTTP status.
   * @param h2_session: http2 session to submit to
   * @param h2_stream: http2 stream containing HTTP status to use for error
   * @return 0 on error, 1 otherwise
   */
  static int http2_submit_error(struct http2_session* h2_session,
  	struct http2_stream* h2_stream)
  {
  	int ret;
  	char status[4];
  	nghttp2_data_provider data_prd;
  	nghttp2_nv headers[1]; /* will be copied by nghttp */
  	if(snprintf(status, 4, "%d", h2_stream->status) != 3) {
  		verbose(VERB_QUERY, "http2: submit error failed, "
  			"invalid status");
  		return 0;
  	}
  	headers[0].name = (uint8_t*)":status";
  	headers[0].namelen = 7;
  	headers[0].value = (uint8_t*)status;
  	headers[0].valuelen = 3;
  	headers[0].flags = NGHTTP2_NV_FLAG_NONE;
  
  	data_prd.source.ptr = h2_session;
  	data_prd.read_callback = http2_submit_error_read_callback;
  
  	ret = nghttp2_submit_response(h2_session->session, h2_stream->stream_id,
  		headers, 1, &data_prd);
  	if(ret) {
  		verbose(VERB_QUERY, "http2: submit error failed, "
  			"error: %s", nghttp2_strerror(ret));
  		return 0;
  	}
  	return 1;
  }
  
  /**
   * Start query handling. Query is stored in the stream, and will be free'd here.
   * @param h2_session: http2 session, containing comm point
   * @param h2_stream: stream containing buffered query
   * @return: -1 on error, 1 if answer is stored in c->buffer, 0 if there is no
   * reply available (yet).
   */
  static int http2_query_read_done(struct http2_session* h2_session,
  	struct http2_stream* h2_stream)
  {
  	log_assert(h2_stream->qbuffer);
  
  	if(h2_session->c->h2_stream) {
  		verbose(VERB_ALGO, "http2_query_read_done failure: shared "
  			"buffer already assigned to stream");
  		return -1;
  	}
  	if(sldns_buffer_remaining(h2_session->c->buffer) <
  		sldns_buffer_remaining(h2_stream->qbuffer)) {
  		/* qbuffer will be free'd in frame close cb */
  		sldns_buffer_clear(h2_session->c->buffer);
  		verbose(VERB_ALGO, "http2_query_read_done failure: can't fit "
  			"qbuffer in c->buffer");
  		return -1;
  	}
  
  	sldns_buffer_write(h2_session->c->buffer,
  		sldns_buffer_current(h2_stream->qbuffer),
  		sldns_buffer_remaining(h2_stream->qbuffer));
  
  	lock_basic_lock(&http2_query_buffer_count_lock);
  	http2_query_buffer_count -= sldns_buffer_capacity(h2_stream->qbuffer);
  	lock_basic_unlock(&http2_query_buffer_count_lock);
  	sldns_buffer_free(h2_stream->qbuffer);
  	h2_stream->qbuffer = NULL;
  
  	sldns_buffer_flip(h2_session->c->buffer);
  	h2_session->c->h2_stream = h2_stream;
  	fptr_ok(fptr_whitelist_comm_point(h2_session->c->callback));
  	if((*h2_session->c->callback)(h2_session->c, h2_session->c->cb_arg,
  		NETEVENT_NOERROR, &h2_session->c->repinfo)) {
  		return 1; /* answer in c->buffer */
  	}
  	sldns_buffer_clear(h2_session->c->buffer);
  	h2_session->c->h2_stream = NULL;
  	return 0; /* mesh state added, or dropped */
  }
  
  /** nghttp2 callback. Used to check if the received frame indicates the end of a
   * stream. Gather collected request data and start query handling. */
  static int http2_req_frame_recv_cb(nghttp2_session* session,
  	const nghttp2_frame* frame, void* cb_arg)
  {
  	struct http2_session* h2_session = (struct http2_session*)cb_arg;
  	struct http2_stream* h2_stream;
  	int query_read_done;
  
  	if((frame->hd.type != NGHTTP2_DATA &&
  		frame->hd.type != NGHTTP2_HEADERS) ||
  		!(frame->hd.flags & NGHTTP2_FLAG_END_STREAM)) {
  			return 0;
  	}
  
  	if(!(h2_stream = nghttp2_session_get_stream_user_data(
  		session, frame->hd.stream_id)))
  		return 0;
  
  	if(h2_stream->invalid_endpoint) {
  		h2_stream->status = HTTP_STATUS_NOT_FOUND;
  		goto submit_http_error;
  	}
  
  	if(h2_stream->invalid_content_type) {
  		h2_stream->status = HTTP_STATUS_UNSUPPORTED_MEDIA_TYPE;
  		goto submit_http_error;
  	}
  
  	if(h2_stream->http_method != HTTP_METHOD_GET &&
  		h2_stream->http_method != HTTP_METHOD_POST) {
  		h2_stream->status = HTTP_STATUS_NOT_IMPLEMENTED;
  		goto submit_http_error;
  	}
  
  	if(h2_stream->query_too_large) {
  		if(h2_stream->http_method == HTTP_METHOD_POST)
  			h2_stream->status = HTTP_STATUS_PAYLOAD_TOO_LARGE;
  		else
  			h2_stream->status = HTTP_STATUS_URI_TOO_LONG;
  		goto submit_http_error;
  	}
  
  	if(!h2_stream->qbuffer) {
  		h2_stream->status = HTTP_STATUS_BAD_REQUEST;
  		goto submit_http_error;
  	}
  
  	if(h2_stream->status) {
  submit_http_error:
  		verbose(VERB_QUERY, "http2 request invalid, returning :status="
  			"%d", h2_stream->status);
  		if(!http2_submit_error(h2_session, h2_stream)) {
  			return NGHTTP2_ERR_CALLBACK_FAILURE;
  		}
  		return 0;
  	}
  	h2_stream->status = HTTP_STATUS_OK;
  
  	sldns_buffer_flip(h2_stream->qbuffer);
  	h2_session->postpone_drop = 1;
  	query_read_done = http2_query_read_done(h2_session, h2_stream);
  	if(query_read_done < 0)
  		return NGHTTP2_ERR_CALLBACK_FAILURE;
  	else if(!query_read_done) {
  		if(h2_session->is_drop) {
  			/* connection needs to be closed. Return failure to make
  			 * sure no other action are taken anymore on comm point.
  			 * failure will result in reclaiming (and closing)
  			 * of comm point. */
  			verbose(VERB_QUERY, "http2 query dropped in worker cb");
  			h2_session->postpone_drop = 0;
  			return NGHTTP2_ERR_CALLBACK_FAILURE;
  		}
  		/* nothing to submit right now, query added to mesh. */
  		h2_session->postpone_drop = 0;
  		return 0;
  	}
  	if(!http2_submit_dns_response(h2_session)) {
  		sldns_buffer_clear(h2_session->c->buffer);
  		h2_session->c->h2_stream = NULL;
  		return NGHTTP2_ERR_CALLBACK_FAILURE;
  	}
  	verbose(VERB_QUERY, "http2 query submitted to session");
  	sldns_buffer_clear(h2_session->c->buffer);
  	h2_session->c->h2_stream = NULL;
  	return 0;
  }
  
  /** nghttp2 callback. Used to detect start of new streams. */
  static int http2_req_begin_headers_cb(nghttp2_session* session,
  	const nghttp2_frame* frame, void* cb_arg)
  {
  	struct http2_session* h2_session = (struct http2_session*)cb_arg;
  	struct http2_stream* h2_stream;
  	int ret;
  	if(frame->hd.type != NGHTTP2_HEADERS ||
  		frame->headers.cat != NGHTTP2_HCAT_REQUEST) {
  		/* only interrested in request headers */
  		return 0;
  	}
  	if(!(h2_stream = http2_stream_create(frame->hd.stream_id))) {
  		log_err("malloc failure while creating http2 stream");
  		return NGHTTP2_ERR_CALLBACK_FAILURE;
  	}
  	http2_session_add_stream(h2_session, h2_stream);
  	ret = nghttp2_session_set_stream_user_data(session,
  		frame->hd.stream_id, h2_stream);
  	if(ret) {
  		/* stream does not exist */
  		verbose(VERB_QUERY, "http2: set_stream_user_data failed, "
  			"error: %s", nghttp2_strerror(ret));
  		return NGHTTP2_ERR_CALLBACK_FAILURE;
  	}
  
  	return 0;
  }
  
  /**
   * base64url decode, store in qbuffer
   * @param h2_session: http2 session
   * @param h2_stream: http2 stream
   * @param start: start of the base64 string
   * @param length: length of the base64 string
   * @return: 0 on error, 1 otherwise. query will be stored in h2_stream->qbuffer,
   * buffer will be NULL is unparseble.
   */
  static int http2_buffer_uri_query(struct http2_session* h2_session,
  	struct http2_stream* h2_stream, const uint8_t* start, size_t length)
  {
  	size_t expectb64len;
  	int b64len;
  	if(h2_stream->http_method == HTTP_METHOD_POST)
  		return 1;
  	if(length == 0)
  		return 1;
  	if(h2_stream->qbuffer) {
  		verbose(VERB_ALGO, "http2_req_header fail, "
  			"qbuffer already set");
  		return 0;
  	}
  
  	/* calculate size, might be a bit bigger than the real
  	 * decoded buffer size */
  	expectb64len = sldns_b64_pton_calculate_size(length);
  	log_assert(expectb64len > 0);
  	if(expectb64len >
  		h2_session->c->http2_stream_max_qbuffer_size) {
  		h2_stream->query_too_large = 1;
  		return 1;
  	}
  
  	lock_basic_lock(&http2_query_buffer_count_lock);
  	if(http2_query_buffer_count + expectb64len > http2_query_buffer_max) {
  		lock_basic_unlock(&http2_query_buffer_count_lock);
  		verbose(VERB_ALGO, "reset HTTP2 stream, no space left, "
  			"in http2-query-buffer-size");
  		return http2_submit_rst_stream(h2_session, h2_stream);
  	}
  	http2_query_buffer_count += expectb64len;
  	lock_basic_unlock(&http2_query_buffer_count_lock);
  	if(!(h2_stream->qbuffer = sldns_buffer_new(expectb64len))) {
  		lock_basic_lock(&http2_query_buffer_count_lock);
  		http2_query_buffer_count -= expectb64len;
  		lock_basic_unlock(&http2_query_buffer_count_lock);
  		log_err("http2_req_header fail, qbuffer "
  			"malloc failure");
  		return 0;
  	}
  
  	if(!(b64len = sldns_b64url_pton(
  		(char const *)start, length,
  		sldns_buffer_current(h2_stream->qbuffer),
  		expectb64len)) || b64len < 0) {
  		lock_basic_lock(&http2_query_buffer_count_lock);
  		http2_query_buffer_count -= expectb64len;
  		lock_basic_unlock(&http2_query_buffer_count_lock);
  		sldns_buffer_free(h2_stream->qbuffer);
  		h2_stream->qbuffer = NULL;
  		/* return without error, method can be an
  		 * unknown POST */
  		return 1;
  	}
  	sldns_buffer_skip(h2_stream->qbuffer, (size_t)b64len);
  	return 1;
  }
  
  /** nghttp2 callback. Used to parse headers from HEADER frames. */
  static int http2_req_header_cb(nghttp2_session* session,
  	const nghttp2_frame* frame, const uint8_t* name, size_t namelen,
  	const uint8_t* value, size_t valuelen, uint8_t ATTR_UNUSED(flags),
  	void* cb_arg)
  {
  	struct http2_stream* h2_stream = NULL;
  	struct http2_session* h2_session = (struct http2_session*)cb_arg;
  	/* nghttp2 deals with CONTINUATION frames and provides them as part of
  	 * the HEADER */
  	if(frame->hd.type != NGHTTP2_HEADERS ||
  		frame->headers.cat != NGHTTP2_HCAT_REQUEST) {
  		/* only interrested in request headers */
  		return 0;
  	}
  	if(!(h2_stream = nghttp2_session_get_stream_user_data(session,
  		frame->hd.stream_id)))
  		return 0;
  
  	/* earlier checks already indicate we can stop handling this query */
  	if(h2_stream->http_method == HTTP_METHOD_UNSUPPORTED ||
  		h2_stream->invalid_content_type ||
  		h2_stream->invalid_endpoint)
  		return 0;
  
  
  	/* nghttp2 performs some sanity checks in the headers, including:
  	 * name and value are guaranteed to be null terminated
  	 * name is guaranteed to be lowercase
  	 * content-length value is guaranteed to contain digits
  	 */
  
  	if(!h2_stream->http_method && namelen == 7 &&
  		memcmp(":method", name, namelen) == 0) {
  		/* Case insensitive check on :method value to be on the safe
  		 * side. I failed to find text about case sensitivity in specs.
  		 */
  		if(valuelen == 3 && strcasecmp("GET", (const char*)value) == 0)
  			h2_stream->http_method = HTTP_METHOD_GET;
  		else if(valuelen == 4 &&
  			strcasecmp("POST", (const char*)value) == 0) {
  			h2_stream->http_method = HTTP_METHOD_POST;
  			if(h2_stream->qbuffer) {
  				/* POST method uses query from DATA frames */
  				lock_basic_lock(&http2_query_buffer_count_lock);
  				http2_query_buffer_count -=
  					sldns_buffer_capacity(h2_stream->qbuffer);
  				lock_basic_unlock(&http2_query_buffer_count_lock);
  				sldns_buffer_free(h2_stream->qbuffer);
  				h2_stream->qbuffer = NULL;
  			}
  		} else
  			h2_stream->http_method = HTTP_METHOD_UNSUPPORTED;
  		return 0;
  	}
  	if(namelen == 5 && memcmp(":path", name, namelen) == 0) {
  		/* :path may contain DNS query, depending on method. Method might
  		 * not be known yet here, so check after finishing receiving
  		 * stream. */
  #define	HTTP_QUERY_PARAM "?dns="
  		size_t el = strlen(h2_session->c->http_endpoint);
  		size_t qpl = strlen(HTTP_QUERY_PARAM);
  
  		if(valuelen < el || memcmp(h2_session->c->http_endpoint,
  			value, el) != 0) {
  			h2_stream->invalid_endpoint = 1;
  			return 0;
  		}
  		/* larger than endpoint only allowed if it is for the query
  		 * parameter */
  		if(valuelen <= el+qpl ||
  			memcmp(HTTP_QUERY_PARAM, value+el, qpl) != 0) {
  			if(valuelen != el)
  				h2_stream->invalid_endpoint = 1;
  			return 0;
  		}
  
  		if(!http2_buffer_uri_query(h2_session, h2_stream,
  			value+(el+qpl), valuelen-(el+qpl))) {
  			return NGHTTP2_ERR_CALLBACK_FAILURE;
  		}
  		return 0;
  	}
  	/* Content type is a SHOULD (rfc7231#section-3.1.1.5) when using POST,
  	 * and not needed when using GET. Don't enfore.
  	 * If set only allow lowercase "application/dns-message".
  	 *
  	 * Clients SHOULD (rfc8484#section-4.1) set an accept header, but MUST
  	 * be able to handle "application/dns-message". Since that is the only
  	 * content-type supported we can ignore the accept header.
  	 */
  	if((namelen == 12 && memcmp("content-type", name, namelen) == 0)) {
  		if(valuelen != 23 || memcmp("application/dns-message", value,
  			valuelen) != 0) {
  			h2_stream->invalid_content_type = 1;
  		}
  	}
  
  	/* Only interested in content-lentg for POST (on not yet known) method.
  	 */
  	if((!h2_stream->http_method ||
  		h2_stream->http_method == HTTP_METHOD_POST) &&
  		!h2_stream->content_length && namelen  == 14 &&
  		memcmp("content-length", name, namelen) == 0) {
  		if(valuelen > 5) {
  			h2_stream->query_too_large = 1;
  			return 0;
  		}
  		/* guaranteed to only contian digits and be null terminated */
  		h2_stream->content_length = atoi((const char*)value);
  		if(h2_stream->content_length >
  			h2_session->c->http2_stream_max_qbuffer_size) {
  			h2_stream->query_too_large = 1;
  			return 0;
  		}
  	}
  	return 0;
  }
  
  /** nghttp2 callback. Used to get data from DATA frames, which can contain
   * queries in POST requests. */
  static int http2_req_data_chunk_recv_cb(nghttp2_session* ATTR_UNUSED(session),
  	uint8_t ATTR_UNUSED(flags), int32_t stream_id, const uint8_t* data,
  	size_t len, void* cb_arg)
  {
  	struct http2_session* h2_session = (struct http2_session*)cb_arg;
  	struct http2_stream* h2_stream;
  	size_t qlen = 0;
  
  	if(!(h2_stream = nghttp2_session_get_stream_user_data(
  		h2_session->session, stream_id))) {
  		return 0;
  	}
  
  	if(h2_stream->query_too_large)
  		return 0;
  
  	if(!h2_stream->qbuffer) {
  		if(h2_stream->content_length) {
  			if(h2_stream->content_length < len)
  				/* getting more data in DATA frame than
  				 * advertised in content-length header. */
  				return NGHTTP2_ERR_CALLBACK_FAILURE;
  			qlen = h2_stream->content_length;
  		} else if(len <= h2_session->c->http2_stream_max_qbuffer_size) {
  			/* setting this to msg-buffer-size can result in a lot
  			 * of memory consuption. Most queries should fit in a
  			 * single DATA frame, and most POST queries will
  			 * containt content-length which does not impose this
  			 * limit. */
  			qlen = len;
  		}
  	}
  	if(!h2_stream->qbuffer && qlen) {
  		lock_basic_lock(&http2_query_buffer_count_lock);
  		if(http2_query_buffer_count + qlen > http2_query_buffer_max) {
  			lock_basic_unlock(&http2_query_buffer_count_lock);
  			verbose(VERB_ALGO, "reset HTTP2 stream, no space left, "
  				"in http2-query-buffer-size");
  			return http2_submit_rst_stream(h2_session, h2_stream);
  		}
  		http2_query_buffer_count += qlen;
  		lock_basic_unlock(&http2_query_buffer_count_lock);
  		if(!(h2_stream->qbuffer = sldns_buffer_new(qlen))) {
  			lock_basic_lock(&http2_query_buffer_count_lock);
  			http2_query_buffer_count -= qlen;
  			lock_basic_unlock(&http2_query_buffer_count_lock);
  		}
  	}
  
  	if(!h2_stream->qbuffer ||
  		sldns_buffer_remaining(h2_stream->qbuffer) < len) {
  		verbose(VERB_ALGO, "http2 data_chunck_recv failed. Not enough "
  			"buffer space for POST query. Can happen on multi "
  			"frame requests without content-length header");
  		h2_stream->query_too_large = 1;
  		return 0;
  	}
  
  	sldns_buffer_write(h2_stream->qbuffer, data, len);
  
  	return 0;
  }
  
  void http2_req_stream_clear(struct http2_stream* h2_stream)
  {
  	if(h2_stream->qbuffer) {
  		lock_basic_lock(&http2_query_buffer_count_lock);
  		http2_query_buffer_count -=
  			sldns_buffer_capacity(h2_stream->qbuffer);
  		lock_basic_unlock(&http2_query_buffer_count_lock);
  		sldns_buffer_free(h2_stream->qbuffer);
  		h2_stream->qbuffer = NULL;
  	}
  	if(h2_stream->rbuffer) {
  		lock_basic_lock(&http2_response_buffer_count_lock);
  		http2_response_buffer_count -=
  			sldns_buffer_capacity(h2_stream->rbuffer);
  		lock_basic_unlock(&http2_response_buffer_count_lock);
  		sldns_buffer_free(h2_stream->rbuffer);
  		h2_stream->rbuffer = NULL;
  	}
  }
  
  nghttp2_session_callbacks* http2_req_callbacks_create(void)
  {
  	nghttp2_session_callbacks *callbacks;
  	if(nghttp2_session_callbacks_new(&callbacks) == NGHTTP2_ERR_NOMEM) {
  		log_err("failed to initialize nghttp2 callback");
  		return NULL;
  	}
  	/* reception of header block started, used to create h2_stream */
  	nghttp2_session_callbacks_set_on_begin_headers_callback(callbacks,
  		http2_req_begin_headers_cb);
  	/* complete frame received, used to get data from stream if frame
  	 * has end stream flag, and start processing query */
  	nghttp2_session_callbacks_set_on_frame_recv_callback(callbacks,
  		http2_req_frame_recv_cb);
  	/* get request info from headers */
  	nghttp2_session_callbacks_set_on_header_callback(callbacks,
  		http2_req_header_cb);
  	/* get data from DATA frames, containing POST query */
  	nghttp2_session_callbacks_set_on_data_chunk_recv_callback(callbacks,
  		http2_req_data_chunk_recv_cb);
  
  	/* generic HTTP2 callbacks */
  	nghttp2_session_callbacks_set_recv_callback(callbacks, http2_recv_cb);
  	nghttp2_session_callbacks_set_send_callback(callbacks, http2_send_cb);
  	nghttp2_session_callbacks_set_on_stream_close_callback(callbacks,
  		http2_stream_close_cb);
  
  	return callbacks;
  }
  #endif /* HAVE_NGHTTP2 */
  