text: #include "defs.h"
  #include <netinet/in.h>
  #include <sys/socket.h>
  #include <arpa/inet.h>
  #include <linux/netlink.h>
  #include <linux/sock_diag.h>
  #include <linux/inet_diag.h>
  #include <linux/unix_diag.h>
  #include <linux/rtnetlink.h>
  
  #include <sys/un.h>
  #ifndef UNIX_PATH_MAX
  # define UNIX_PATH_MAX sizeof(((struct sockaddr_un *) 0)->sun_path)
  #endif
  
  static bool
  inet_send_query(const int fd, const int family, const int proto)
  {
  	struct sockaddr_nl nladdr = {
  		.nl_family = AF_NETLINK
  	};
  	struct {
  		struct nlmsghdr nlh;
  		struct inet_diag_req_v2 idr;
  	} req = {
  		.nlh = {
  			.nlmsg_len = sizeof(req),
  			.nlmsg_type = SOCK_DIAG_BY_FAMILY,
  			.nlmsg_flags = NLM_F_DUMP | NLM_F_REQUEST
  		},
  		.idr = {
  			.sdiag_family = family,
  			.sdiag_protocol = proto,
  			.idiag_states = -1
  		}
  	};
  	struct iovec iov = {
  		.iov_base = &req,
  		.iov_len = sizeof(req)
  	};
  	struct msghdr msg = {
  		.msg_name = (void*)&nladdr,
  		.msg_namelen = sizeof(nladdr),
  		.msg_iov = &iov,
  		.msg_iovlen = 1
  	};
  
  	for (;;) {
  		if (sendmsg(fd, &msg, 0) < 0) {
  			if (errno == EINTR)
  				continue;
  			return false;
  		}
  		return true;
  	}
  }
  
  static bool
  inet_parse_response(const char *proto_name, const void *data, int data_len,
  		    const unsigned long inode)
  {
  	const struct inet_diag_msg *diag_msg = data;
  	static const char zero_addr[sizeof(struct in6_addr)];
  	socklen_t addr_size, text_size;
  
  	if (diag_msg->idiag_inode != inode)
  		return false;
  
  	switch(diag_msg->idiag_family) {
  		case AF_INET:
  			addr_size = sizeof(struct in_addr);
  			text_size = INET_ADDRSTRLEN;
  			break;
  		case AF_INET6:
  			addr_size = sizeof(struct in6_addr);
  			text_size = INET6_ADDRSTRLEN;
  			break;
  		default:
  			return false;
  	}
  
  	char src_buf[text_size];
  
  	if (!inet_ntop(diag_msg->idiag_family, diag_msg->id.idiag_src,
  		       src_buf, text_size))
  		return false;
  
  	if (diag_msg->id.idiag_dport ||
  	    memcmp(zero_addr, diag_msg->id.idiag_dst, addr_size)) {
  		char dst_buf[text_size];
  
  		if (!inet_ntop(diag_msg->idiag_family, diag_msg->id.idiag_dst,
  			       dst_buf, text_size))
  			return false;
  
  		tprintf("%s:[%s:%u->%s:%u]",
  			proto_name,
  			src_buf, ntohs(diag_msg->id.idiag_sport),
  			dst_buf, ntohs(diag_msg->id.idiag_dport));
  	} else {
  		tprintf("%s:[%s:%u]", proto_name, src_buf,
  			ntohs(diag_msg->id.idiag_sport));
  	}
  
  	return true;
  }
  
  static bool
  receive_responses(const int fd, const unsigned long inode,
  		  const char *proto_name,
  		  bool (* parser) (const char *, const void *, int, const unsigned long))
  {
  	static char buf[8192];
  	struct sockaddr_nl nladdr = {
  		.nl_family = AF_NETLINK
  	};
  	struct iovec iov = {
  		.iov_base = buf,
  		.iov_len = sizeof(buf)
  	};
  
  	for (;;) {
  		ssize_t ret;
  		struct nlmsghdr *h;
  		struct msghdr msg = {
  			.msg_name = (void*)&nladdr,
  			.msg_namelen = sizeof(nladdr),
  			.msg_iov = &iov,
  			.msg_iovlen = 1
  		};
  
  		ret = recvmsg(fd, &msg, 0);
  		if (ret < 0) {
  			if (errno == EINTR)
  				continue;
  			return false;
  		}
  		if (!ret)
  			return false;
  		for (h = (struct nlmsghdr*)buf;
  		     NLMSG_OK(h, ret);
  		     h = NLMSG_NEXT(h, ret)) {
  			switch (h->nlmsg_type) {
  				case NLMSG_DONE:
  				case NLMSG_ERROR:
  					return false;
  			}
  			if (parser(proto_name, NLMSG_DATA(h), h->nlmsg_len, inode))
  				return true;
  		}
  	}
  }
  
  static bool
  inet_print(const int fd, const int family, const int protocol,
  	   const unsigned long inode, const char *proto_name)
  {
  	return inet_send_query(fd, family, protocol)
  		&& receive_responses(fd, inode, proto_name, inet_parse_response);
  }
  
  static bool
  unix_send_query(const int fd, const unsigned long inode)
  {
  	struct sockaddr_nl nladdr = {
  		.nl_family = AF_NETLINK
  	};
  	struct {
  		struct nlmsghdr nlh;
  		struct unix_diag_req udr;
  	} req = {
  		.nlh = {
  			.nlmsg_len = sizeof(req),
  			.nlmsg_type = SOCK_DIAG_BY_FAMILY,
  			.nlmsg_flags = NLM_F_DUMP | NLM_F_REQUEST
  		},
  		.udr = {
  			.sdiag_family = AF_UNIX,
  			.udiag_ino = inode,
  			.udiag_states = -1,
  			.udiag_show = UDIAG_SHOW_NAME | UDIAG_SHOW_PEER
  		}
  	};
  	struct iovec iov = {
  		.iov_base = &req,
  		.iov_len = sizeof(req)
  	};
  	struct msghdr msg = {
  		.msg_name = (void*)&nladdr,
  		.msg_namelen = sizeof(nladdr),
  		.msg_iov = &iov,
  		.msg_iovlen = 1
  	};
  
  	for (;;) {
  		if (sendmsg(fd, &msg, 0) < 0) {
  			if (errno == EINTR)
  				continue;
  			return false;
  		}
  		return true;
  	}
  }
  
  static bool
  unix_parse_response(const char *proto_name, const void *data, int data_len,
  		    const unsigned long inode)
  {
  	const struct unix_diag_msg *diag_msg = data;
  	struct rtattr *attr;
  	int rta_len = data_len - NLMSG_LENGTH(sizeof(*diag_msg));
  	uint32_t peer = 0;
  	size_t path_len = 0;
  	char path[UNIX_PATH_MAX + 1];
  
  	if (diag_msg->udiag_ino != inode)
  		return false;
  	if (diag_msg->udiag_family != AF_UNIX)
  		return false;
  
  	for (attr = (struct rtattr *) (diag_msg + 1);
  	     RTA_OK(attr, rta_len);
  	     attr = RTA_NEXT(attr, rta_len)) {
  		switch (attr->rta_type) {
  		case UNIX_DIAG_NAME:
  			if (!path_len) {
  				path_len = RTA_PAYLOAD(attr);
  				if (path_len > UNIX_PATH_MAX)
  					path_len = UNIX_PATH_MAX;
  				memcpy(path, RTA_DATA(attr), path_len);
  				path[path_len] = '\0';
  			}
  			break;
  		case UNIX_DIAG_PEER:
  			if (RTA_PAYLOAD(attr) >= 4)
  				peer = *(uint32_t *)RTA_DATA(attr);
  			break;
  		}
  	}
  
  	/*
  	 * print obtained information in the following format:
  	 * "UNIX:[" SELF_INODE [ "->" PEER_INODE ][ "," SOCKET_FILE ] "]"
  	 */
  	if (peer || path_len) {
  		tprintf("%s:[%lu", proto_name, inode);
  		if (peer)
  			tprintf("->%u", peer);
  		if (path_len) {
  			if (path[0] == '\0') {
  				char *outstr = alloca(4 * path_len - 1);
  				string_quote(path + 1, outstr, -1, path_len);
  				tprintf(",@%s", outstr);
  			} else {
  				char *outstr = alloca(4 * path_len + 3);
  				string_quote(path, outstr, -1, path_len + 1);
  				tprintf(",%s", outstr);
  			}
  		}
  		tprints("]");
  		return true;
  	}
  	else
  		return false;
  }
  
  static bool
  unix_print(int fd, const unsigned long inode)
  {
  	return unix_send_query(fd, inode)
  		&& receive_responses(fd, inode, "UNIX", unix_parse_response);
  }
  
  /* Given an inode number of a socket, print out the details
   * of the ip address and port. */
  bool
  print_sockaddr_by_inode(const unsigned long inode, const char *proto_name)
  {
  	int fd;
  	bool r = false;
  
  	fd = socket(AF_NETLINK, SOCK_RAW, NETLINK_SOCK_DIAG);
  	if (fd < 0)
  		return false;
  
  	if (proto_name) {
  		if (strcmp(proto_name, "TCP") == 0)
  			r = inet_print(fd, AF_INET, IPPROTO_TCP, inode, "TCP");
  		else if (strcmp(proto_name, "UDP") == 0)
  			r = inet_print(fd, AF_INET, IPPROTO_UDP, inode, "UDP");
  		else if (strcmp(proto_name, "TCPv6") == 0)
  			r = inet_print(fd, AF_INET6, IPPROTO_TCP, inode, "TCPv6");
  		else if (strcmp(proto_name, "UDPv6") == 0)
  			r = inet_print(fd, AF_INET6, IPPROTO_UDP, inode, "UDPv6");
  		else if (strcmp(proto_name, "UNIX") == 0)
  			r = unix_print(fd, inode);
  	} else {
  		const struct {
  			const int family;
  			const int protocol;
  			const char *name;
  		} protocols[] = {
  			{ AF_INET, IPPROTO_TCP, "TCP" },
  			{ AF_INET, IPPROTO_UDP, "UDP" },
  			{ AF_INET6, IPPROTO_TCP, "TCPv6" },
  			{ AF_INET6, IPPROTO_UDP, "UDPv6" }
  		};
  		size_t i;
  
  		for (i = 0; i < ARRAY_SIZE(protocols); ++i) {
  			if ((r = inet_print(fd, protocols[i].family,
  					    protocols[i].protocol, inode,
  					    protocols[i].name)))
  				break;
  		}
  	}
  
  	close(fd);
  	return r;
  }
  