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      1 /*
      2  * Copyright 2012 Daniel Drown <dan-android (at) drown.org>
      3  *
      4  * Licensed under the Apache License, Version 2.0 (the "License");
      5  * you may not use this file except in compliance with the License.
      6  * You may obtain a copy of the License at
      7  *
      8  * http://www.apache.org/licenses/LICENSE-2.0
      9  *
     10  * Unless required by applicable law or agreed to in writing, software
     11  * distributed under the License is distributed on an "AS IS" BASIS,
     12  * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
     13  * See the License for the specific language governing permissions and
     14  * limitations under the License.
     15  *
     16  * setif.c - network interface configuration
     17  */
     18 #include <errno.h>
     19 #include <netinet/in.h>
     20 #include <net/if.h>
     21 
     22 #include <linux/rtnetlink.h>
     23 #include <netlink/handlers.h>
     24 #include <netlink/msg.h>
     25 
     26 #include "netlink_msg.h"
     27 
     28 /* function: add_address
     29  * adds an IP address to/from an interface, returns 0 on success and <0 on failure
     30  * ifname    - name of interface to change
     31  * family    - address family (AF_INET, AF_INET6)
     32  * address   - pointer to a struct in_addr or in6_addr
     33  * prefixlen - bitlength of network (example: 24 for AF_INET's 255.255.255.0)
     34  * broadcast - broadcast address (only for AF_INET, ignored for AF_INET6)
     35  */
     36 int add_address(const char *ifname, int family, const void *address, int prefixlen, const void *broadcast) {
     37   int retval;
     38   size_t addr_size;
     39   struct ifaddrmsg ifa;
     40   struct nl_msg *msg = NULL;
     41 
     42   addr_size = inet_family_size(family);
     43   if(addr_size == 0) {
     44     retval = -EAFNOSUPPORT;
     45     goto cleanup;
     46   }
     47 
     48   memset(&ifa, 0, sizeof(ifa));
     49   if (!(ifa.ifa_index = if_nametoindex(ifname))) {
     50     retval = -ENODEV;
     51     goto cleanup;
     52   }
     53   ifa.ifa_family = family;
     54   ifa.ifa_prefixlen = prefixlen;
     55   ifa.ifa_scope = RT_SCOPE_UNIVERSE;
     56 
     57   msg = nlmsg_alloc_ifaddr(RTM_NEWADDR, NLM_F_ACK | NLM_F_REQUEST | NLM_F_CREATE | NLM_F_REPLACE, &ifa);
     58   if(!msg) {
     59     retval = -ENOMEM;
     60     goto cleanup;
     61   }
     62 
     63   if(nla_put(msg, IFA_LOCAL, addr_size, address) < 0) {
     64     retval = -ENOMEM;
     65     goto cleanup;
     66   }
     67   if(family == AF_INET6) {
     68     // AF_INET6 gets IFA_LOCAL + IFA_ADDRESS
     69     if(nla_put(msg, IFA_ADDRESS, addr_size, address) < 0) {
     70       retval = -ENOMEM;
     71       goto cleanup;
     72     }
     73   } else if(family == AF_INET) {
     74     // AF_INET gets IFA_LOCAL + IFA_BROADCAST
     75     if(nla_put(msg, IFA_BROADCAST, addr_size, broadcast) < 0) {
     76       retval = -ENOMEM;
     77       goto cleanup;
     78     }
     79   } else {
     80     retval = -EAFNOSUPPORT;
     81     goto cleanup;
     82   }
     83 
     84   retval = netlink_sendrecv(msg);
     85 
     86 cleanup:
     87   if(msg)
     88     nlmsg_free(msg);
     89 
     90   return retval;
     91 }
     92 
     93 /* function: if_up
     94  * sets interface link state to up and sets mtu, returns 0 on success and <0 on failure
     95  * ifname - interface name to change
     96  * mtu    - new mtu
     97  */
     98 int if_up(const char *ifname, int mtu) {
     99   int retval = -1;
    100   struct ifinfomsg ifi;
    101   struct nl_msg *msg = NULL;
    102 
    103   memset(&ifi, 0, sizeof(ifi));
    104   if (!(ifi.ifi_index = if_nametoindex(ifname))) {
    105     retval = -ENODEV;
    106     goto cleanup;
    107   }
    108   ifi.ifi_change = IFF_UP;
    109   ifi.ifi_flags = IFF_UP;
    110 
    111   msg = nlmsg_alloc_ifinfo(RTM_SETLINK, NLM_F_ACK | NLM_F_REQUEST | NLM_F_ROOT, &ifi);
    112   if(!msg) {
    113     retval = -ENOMEM;
    114     goto cleanup;
    115   }
    116 
    117   if(nla_put(msg, IFLA_MTU, 4, &mtu) < 0) {
    118     retval = -ENOMEM;
    119     goto cleanup;
    120   }
    121 
    122   retval = netlink_sendrecv(msg);
    123 
    124 cleanup:
    125   if(msg)
    126     nlmsg_free(msg);
    127 
    128   return retval;
    129 }
    130