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 <fcntl.h>
  11 #include <stdio.h>
  12 #include <unistd.h>
  13 #include <string.h>
  14 #include <sys/ioctl.h>
  15 #include <sys/socket.h>
  16 #include <sys/types.h>
  17 #include <asm/types.h>
  18 #include <arpa/inet.h>
  19 #include <linux/netlink.h>
  20 #include <linux/rtnetlink.h>
  21 #include <linux/ip.h>
  22 #include <linux/if_arp.h>
  23 #include <linux/if_tunnel.h>
  24
  25 #include "nhrp_protocol.h"
  26 #include "os.h"
  27 #include "netlink.h"
  28
  29 static int nhrp_socket_fd = -1;
  30
  31 int os_socket(void)
  32 {
  33         if (nhrp_socket_fd < 0)
  34                 nhrp_socket_fd = socket(PF_PACKET, SOCK_DGRAM, htons(ETH_P_NHRP));
  35         return nhrp_socket_fd;
  36 }
  37
  38 int os_sendmsg(const uint8_t *buf, size_t len, int ifindex, const uint8_t *addr, size_t addrlen)
  39 {
  40         struct sockaddr_ll lladdr;
  41         struct iovec iov = {
  42                 .iov_base = (void*) buf,
  43                 .iov_len = len,
  44         };
  45         struct msghdr msg = {
  46                 .msg_name = &lladdr,
  47                 .msg_namelen = sizeof(lladdr),
  48                 .msg_iov = &iov,
  49                 .msg_iovlen = 1,
  50         };
  51         int status;
  52
  53         if (addrlen > sizeof(lladdr.sll_addr))
  54                 return -1;
  55
  56         memset(&lladdr, 0, sizeof(lladdr));
  57         lladdr.sll_family = AF_PACKET;
  58         lladdr.sll_protocol = htons(ETH_P_NHRP);
  59         lladdr.sll_ifindex = ifindex;
  60         lladdr.sll_halen = addrlen;
  61         memcpy(lladdr.sll_addr, addr, addrlen);
  62
  63         status = sendmsg(nhrp_socket_fd, &msg, 0);
  64         if (status < 0)
  65                 return -1;
  66
  67         return 0;
  68 }
  69
  70 int os_recvmsg(uint8_t *buf, size_t *len, int *ifindex, uint8_t *addr, size_t *addrlen)
  71 {
  72         struct sockaddr_ll lladdr;
  73         struct iovec iov = {
  74                 .iov_base = buf,
  75                 .iov_len = *len,
  76         };
  77         struct msghdr msg = {
  78                 .msg_name = &lladdr,
  79                 .msg_namelen = sizeof(lladdr),
  80                 .msg_iov = &iov,
  81                 .msg_iovlen = 1,
  82         };
  83         int r;
  84
  85         r = recvmsg(nhrp_socket_fd, &msg, MSG_DONTWAIT);
  86         if (r < 0)
  87                 return r;
  88
  89         *len = r;
  90         *ifindex = lladdr.sll_ifindex;
  91
  92         if (*addrlen <= (size_t) lladdr.sll_addr) {
  93                 if (memcmp(lladdr.sll_addr, "\x00\x00\x00\x00", 4) != 0) {
  94                         memcpy(addr, lladdr.sll_addr, lladdr.sll_halen);
  95                         *addrlen = lladdr.sll_halen;
  96                 } else {
  97                         *addrlen = 0;
  98                 }
  99         }
 100
 101         return 0;
 102 }
 103
 104 static int linux_configure_arp(const char *iface, int on)
 105 {
 106         struct ifreq ifr;
 107
 108         strncpy(ifr.ifr_name, iface, IFNAMSIZ - 1);
 109         if (ioctl(nhrp_socket_fd, SIOCGIFFLAGS, &ifr))
 110                 return -1;
 111
 112         if (on)
 113                 ifr.ifr_flags &= ~IFF_NOARP;
 114         else
 115                 ifr.ifr_flags |= IFF_NOARP;
 116
 117         if (ioctl(nhrp_socket_fd, SIOCSIFFLAGS, &ifr))
 118                 return -1;
 119
 120         return 0;
 121 }
 122
 123 static int linux_icmp_redirect_off(const char *iface)
 124 {
 125         char fname[256];
 126         int fd, ret = -1;
 127
 128         sprintf(fname, "/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         ret |= netlink_configure_arp(ifindex, af);
 151
 152         return ret;
 153 }