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