text: /*
   * Copyright 2012 Daniel Drown <dan-android@drown.org>
   *
   * Licensed under the Apache License, Version 2.0 (the "License");
   * you may not use this file except in compliance with the License.
   * You may obtain a copy of the License at
   *
   * http://www.apache.org/licenses/LICENSE-2.0
   *
   * Unless required by applicable law or agreed to in writing, software
   * distributed under the License is distributed on an "AS IS" BASIS,
   * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
   * See the License for the specific language governing permissions and
   * limitations under the License.
   *
   * setif.c - network interface configuration
   */
  #include <errno.h>
  #include <netinet/in.h>
  #include <net/if.h>
  
  #include <linux/rtnetlink.h>
  #include <netlink/handlers.h>
  #include <netlink/msg.h>
  
  #include "logging.h"
  #include "netlink_msg.h"
  
  #define DEBUG_OPTNAME(a) case (a): { optname = #a; break; }
  
  /* function: add_address
   * adds an IP address to/from an interface, returns 0 on success and <0 on failure
   * ifname    - name of interface to change
   * family    - address family (AF_INET, AF_INET6)
   * address   - pointer to a struct in_addr or in6_addr
   * prefixlen - bitlength of network (example: 24 for AF_INET's 255.255.255.0)
   * broadcast - broadcast address (only for AF_INET, ignored for AF_INET6)
   */
  int add_address(const char *ifname, int family, const void *address, int prefixlen, const void *broadcast) {
    int retval;
    size_t addr_size;
    struct ifaddrmsg ifa;
    struct nl_msg *msg = NULL;
  
    addr_size = inet_family_size(family);
    if(addr_size == 0) {
      retval = -EAFNOSUPPORT;
      goto cleanup;
    }
  
    memset(&ifa, 0, sizeof(ifa));
    if (!(ifa.ifa_index = if_nametoindex(ifname))) {
      retval = -ENODEV;
      goto cleanup;
    }
    ifa.ifa_family = family;
    ifa.ifa_prefixlen = prefixlen;
    ifa.ifa_scope = RT_SCOPE_UNIVERSE;
  
    msg = nlmsg_alloc_ifaddr(RTM_NEWADDR, NLM_F_ACK | NLM_F_REQUEST | NLM_F_CREATE | NLM_F_REPLACE, &ifa);
    if(!msg) {
      retval = -ENOMEM;
      goto cleanup;
    }
  
    if(nla_put(msg, IFA_LOCAL, addr_size, address) < 0) {
      retval = -ENOMEM;
      goto cleanup;
    }
    if(family == AF_INET6) {
      // AF_INET6 gets IFA_LOCAL + IFA_ADDRESS
      if(nla_put(msg, IFA_ADDRESS, addr_size, address) < 0) {
        retval = -ENOMEM;
        goto cleanup;
      }
    } else if(family == AF_INET) {
      // AF_INET gets IFA_LOCAL + IFA_BROADCAST
      if(nla_put(msg, IFA_BROADCAST, addr_size, broadcast) < 0) {
        retval = -ENOMEM;
        goto cleanup;
      }
    } else {
      retval = -EAFNOSUPPORT;
      goto cleanup;
    }
  
    retval = netlink_sendrecv(msg);
  
  cleanup:
    if(msg)
      nlmsg_free(msg);
  
    return retval;
  }
  
  /* function: if_up
   * sets interface link state to up and sets mtu, returns 0 on success and <0 on failure
   * ifname - interface name to change
   * mtu    - new mtu
   */
  int if_up(const char *ifname, int mtu) {
    int retval = -1;
    struct ifinfomsg ifi;
    struct nl_msg *msg = NULL;
  
    memset(&ifi, 0, sizeof(ifi));
    if (!(ifi.ifi_index = if_nametoindex(ifname))) {
      retval = -ENODEV;
      goto cleanup;
    }
    ifi.ifi_change = IFF_UP;
    ifi.ifi_flags = IFF_UP;
  
    msg = nlmsg_alloc_ifinfo(RTM_SETLINK, NLM_F_ACK | NLM_F_REQUEST | NLM_F_ROOT, &ifi);
    if(!msg) {
      retval = -ENOMEM;
      goto cleanup;
    }
  
    if(nla_put(msg, IFLA_MTU, 4, &mtu) < 0) {
      retval = -ENOMEM;
      goto cleanup;
    }
  
    retval = netlink_sendrecv(msg);
  
  cleanup:
    if(msg)
      nlmsg_free(msg);
  
    return retval;
  }
  
  static int do_anycast_setsockopt(int sock, int what, struct in6_addr *addr, int ifindex) {
    struct ipv6_mreq mreq = { *addr, ifindex };
    char *optname;
    int ret;
  
    switch (what) {
      DEBUG_OPTNAME(IPV6_JOIN_ANYCAST)
      DEBUG_OPTNAME(IPV6_LEAVE_ANYCAST)
      default:
        optname = "???";
        break;
    }
  
    ret = setsockopt(sock, SOL_IPV6, what, &mreq, sizeof(mreq));
    if (ret) {
      logmsg(ANDROID_LOG_ERROR, "%s: setsockopt(%s): %s", __func__, optname, strerror(errno));
    }
  
    return ret;
  }
  
  /* function: add_anycast_address
   * adds an anycast IPv6 address to an interface, returns 0 on success and <0 on failure
   * sock      - the socket to add the address to
   * addr      - the IP address to add
   * ifname    - name of interface to add the address to
   */
  int add_anycast_address(int sock, struct in6_addr *addr, const char *ifname) {
    int ifindex, s, ret;
  
    ifindex = if_nametoindex(ifname);
    if (!ifindex) {
      logmsg(ANDROID_LOG_ERROR, "%s: unknown ifindex for interface %s", __func__, ifname);
      return -ENODEV;
    }
  
    return do_anycast_setsockopt(sock, IPV6_JOIN_ANYCAST, addr, ifindex);
  }
  
  /* function: del_anycast_address
   * removes an anycast IPv6 address from the system, returns 0 on success and <0 on failure
   * sock      - the socket to remove from, must have had the address added via add_anycast_address
   * addr      - the IP address to remove
   */
  int del_anycast_address(int sock, struct in6_addr *addr) {
    return do_anycast_setsockopt(sock, IPV6_LEAVE_ANYCAST, addr, 0);
  }
  