nhrpd/linux.c

   1 /* NHRP daemon Linux specific glue
   2  * Copyright (c) 2014-2015 Timo Teräs
   3  *
   4  * This file is free software: you may copy, redistribute and/or modify
   5  * it under the terms of the GNU General Public License as published by
   6  * the Free Software Foundation, either version 2 of the License, or
   7  * (at your option) any later version.
   8  */
   9
  10 #include "zebra.h"
  11
  12 #include <errno.h>
  13 #include <linux/if_packet.h>
  14
  15 #include "nhrp_protocol.h"
  16 #include "os.h"
  17
  18 #ifndef HAVE_STRLCPY
  19 size_t strlcpy(char *__restrict dest,
  20                const char *__restrict src, size_t destsize);
  21 #endif
  22
  23 static int nhrp_socket_fd = -1;
  24
  25 int os_socket(void)
  26 {
  27         if (nhrp_socket_fd < 0)
  28                 nhrp_socket_fd =
  29                         socket(PF_PACKET, SOCK_DGRAM, htons(ETH_P_NHRP));
  30         return nhrp_socket_fd;
  31 }
  32
  33 int os_sendmsg(const uint8_t *buf, size_t len, int ifindex, const uint8_t *addr,
  34                size_t addrlen, uint16_t protocol)
  35 {
  36         struct sockaddr_ll lladdr;
  37         struct iovec iov = {
  38                 .iov_base = (void *)buf, .iov_len = len,
  39         };
  40         struct msghdr msg = {
  41                 .msg_name = &lladdr,
  42                 .msg_namelen = sizeof(lladdr),
  43                 .msg_iov = &iov,
  44                 .msg_iovlen = 1,
  45         };
  46         int status, fd;
  47
  48         if (addrlen > sizeof(lladdr.sll_addr))
  49                 return -1;
  50
  51         memset(&lladdr, 0, sizeof(lladdr));
  52         lladdr.sll_family = AF_PACKET;
  53         lladdr.sll_protocol = htons(protocol);
  54         lladdr.sll_ifindex = ifindex;
  55         lladdr.sll_halen = addrlen;
  56         memcpy(lladdr.sll_addr, addr, addrlen);
  57
  58         fd = os_socket();
  59         if (fd < 0)
  60                 return -1;
  61
  62         status = sendmsg(fd, &msg, 0);
  63         if (status < 0)
  64                 return -errno;
  65
  66         return status;
  67 }
  68
  69 int os_recvmsg(uint8_t *buf, size_t *len, int *ifindex, uint8_t *addr,
  70                size_t *addrlen)
  71 {
  72         struct sockaddr_ll lladdr;
  73         struct iovec iov = {
  74                 .iov_base = buf, .iov_len = *len,
  75         };
  76         struct msghdr msg = {
  77                 .msg_name = &lladdr,
  78                 .msg_namelen = sizeof(lladdr),
  79                 .msg_iov = &iov,
  80                 .msg_iovlen = 1,
  81         };
  82         int r;
  83
  84         r = recvmsg(nhrp_socket_fd, &msg, MSG_DONTWAIT);
  85         if (r < 0)
  86                 return r;
  87
  88         *len = r;
  89         *ifindex = lladdr.sll_ifindex;
  90
  91         if (*addrlen <= (size_t)lladdr.sll_addr) {
  92                 if (memcmp(lladdr.sll_addr, "\x00\x00\x00\x00", 4) != 0) {
  93                         memcpy(addr, lladdr.sll_addr, lladdr.sll_halen);
  94                         *addrlen = lladdr.sll_halen;
  95                 } else {
  96                         *addrlen = 0;
  97                 }
  98         }
  99
 100         return 0;
 101 }
 102
 103 static int linux_configure_arp(const char *iface, int on)
 104 {
 105         struct ifreq ifr;
 106
 107         strlcpy(ifr.ifr_name, iface, IFNAMSIZ);
 108         if (ioctl(nhrp_socket_fd, SIOCGIFFLAGS, &ifr))
 109                 return -1;
 110
 111         if (on)
 112                 ifr.ifr_flags &= ~IFF_NOARP;
 113         else
 114                 ifr.ifr_flags |= IFF_NOARP;
 115
 116         if (ioctl(nhrp_socket_fd, SIOCSIFFLAGS, &ifr))
 117                 return -1;
 118
 119         return 0;
 120 }
 121
 122 static int linux_icmp_redirect_off(const char *iface)
 123 {
 124         char fname[PATH_MAX];
 125         int fd, ret = -1;
 126
 127         snprintf(fname, sizeof(fname),
 128                  "/proc/sys/net/ipv4/conf/%s/send_redirects", iface);
 129         fd = open(fname, O_WRONLY);
 130         if (fd < 0)
 131                 return -1;
 132         if (write(fd, "0\n", 2) == 2)
 133                 ret = 0;
 134         close(fd);
 135
 136         return ret;
 137 }
 138
 139 int os_configure_dmvpn(unsigned int ifindex, const char *ifname, int af)
 140 {
 141         int ret = 0;
 142
 143         switch (af) {
 144         case AF_INET:
 145                 ret |= linux_icmp_redirect_off("all");
 146                 ret |= linux_icmp_redirect_off(ifname);
 147                 break;
 148         }
 149         ret |= linux_configure_arp(ifname, 1);
 150
 151         return ret;
 152 }