netsock.c

/*
 * Copyright (C) 2012-2015  B.A.T.M.A.N. contributors:
 *
 * Simon Wunderlich
 *
 * This program is free software; you can redistribute it and/or
 * modify it under the terms of version 2 of the GNU General Public
 * License as published by the Free Software Foundation.
 *
 * This program is distributed in the hope that it will be useful, but
 * WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
 * General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program; if not, write to the Free Software
 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
 * 02110-1301, USA
 *
 */

#include <arpa/inet.h>
#include <errno.h>
#include <fcntl.h>
#include <ifaddrs.h>
#include <net/ethernet.h>
#include <net/if.h>
#include <netinet/in.h>
#include <stddef.h>
#include <stdint.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <sys/ioctl.h>
#include <sys/select.h>
#include <sys/socket.h>
#include <sys/types.h>
#include <sys/un.h>
#include <unistd.h>
#include "netsock.h"
#include "packet.h"
#include "logger.h"

// ff02::1234.1234
struct in6_addr in6addr_localmcast =
{
  {
    {
      0xff, 0x02, 0x00, 0x00,
      0x00, 0x00, 0x00, 0x00,
      0x00, 0x00, 0x00, 0x00,
      0x00, 0x00, 0x12, 0x34
    }
  }
};

struct in6_addr* get_ipv6_linklokal(char* interface) {
  struct ifaddrs *ifaddr, *ifa;
  int n;

  if (getifaddrs(&ifaddr) == -1) {
    ERROR("get_ipv6_linklokal(...): getifaddrs failed\n");
    return NULL;
  }

  for (ifa = ifaddr, n = 0; ifa != NULL; ifa = ifa->ifa_next, n++) {
    if (ifa->ifa_addr == NULL) {
      continue;
    }

    if (strcmp(ifa->ifa_name,interface) == 0) {
      if (ifa->ifa_addr->sa_family == AF_INET6) {
        if(((struct sockaddr_in6*) ifa->ifa_addr)->sin6_scope_id > 0) {
          struct in6_addr* address = malloc(sizeof(struct in6_addr));
          memcpy(address,&((struct sockaddr_in6*) ifa->ifa_addr)->sin6_addr, sizeof(struct in6_addr));
          freeifaddrs(ifaddr);
          return address;
        }
      }
    }
  }

  freeifaddrs(ifaddr);
  return NULL;
}

ATTR_NONNULL_ALL int netsock_unix_socket_open(ddhcp_epoll_data* data) {
  int ctl_sock;
  struct sockaddr_un s_un;
  int ret;

  ctl_sock = socket(AF_UNIX, SOCK_STREAM | SOCK_CLOEXEC, 0);

  memset(&s_un, 0, sizeof(s_un));
  s_un.sun_family = AF_UNIX;

  strncpy(s_un.sun_path, data->interface_name, sizeof(s_un.sun_path));

  unlink(data->interface_name);

  if (bind(ctl_sock, (struct sockaddr*)&s_un, sizeof(s_un)) < 0) {
    perror("can't bind control socket");
    goto err;
  }

  ret = fcntl(ctl_sock, F_GETFL, 0);
  ret = fcntl(ctl_sock, F_SETFL, ret | O_NONBLOCK);

  if (ret < 0) {
    perror("failed to set file status flags");
    goto err;
  }

  if (listen(ctl_sock, 2) < 0) {
    perror("failed to listen");
    goto err;
  }

  data->fd = ctl_sock;
  data->interface_id = 0;
  return 0;

err:
  close(ctl_sock);
  return -1;
}

ATTR_NONNULL_ALL void netsocket_unix_socket_close(ddhcp_config* config) {
  close(config->control_socket);
  remove(config->control_path);
}

ATTR_NONNULL_ALL int netsock_open_socket_v6(ddhcp_epoll_data* data, struct in6_addr* addr, uint16_t port) {
  
  struct sockaddr_in6 sin6 = { 0 };
  
  sin6.sin6_family = AF_INET6;
  memcpy(&sin6.sin6_addr, addr,sizeof(struct in6_addr));
  sin6.sin6_port = htons(port);
  sin6.sin6_scope_id = if_nametoindex(data->interface_name);

  int sock = socket(PF_INET6, SOCK_DGRAM|SOCK_NONBLOCK, IPPROTO_UDP);
  if (sock < 0) {
    FATAL("netsock_open_socket_v6(...): unable to create socket\n");
  }

  if (setsockopt(sock, SOL_SOCKET, SO_BINDTODEVICE, data->interface_name, (socklen_t) strnlen(data->interface_name, IFNAMSIZ))) {
    FATAL("netsock_open_socket_v6(...): setsockopt: can't bind to device '%s'\n", data->interface_name);
    goto error;
  }

  if (bind(sock, (struct sockaddr*) &sin6, sizeof(struct sockaddr_in6)) < 0) {
    FATAL("netsock_open_socket_v6(...): unable to bind %s\n",data->interface_name);
    perror("bind");
    goto error;
  }

  data->fd = sock;
  data->interface_id = sin6.sin6_scope_id;

  return 1;
error:
  close(sock);
  return -1;
}

ATTR_NONNULL_ALL int netsock_multicast_join(ddhcp_epoll_data* data, struct in6_addr* addr) {
  unsigned int zero = 0;
  struct ipv6_mreq mreq = { 0 };
  
  memcpy(&mreq.ipv6mr_multiaddr, addr,sizeof(struct in6_addr));
  mreq.ipv6mr_interface = data->interface_id;

  if (setsockopt(data->fd, IPPROTO_IPV6, IPV6_ADD_MEMBERSHIP, &mreq, sizeof(struct ipv6_mreq))) {
    perror("can't add multicast membership");
    goto error;
  }

  if (setsockopt(data->fd, IPPROTO_IPV6, IPV6_MULTICAST_LOOP, &zero, sizeof(unsigned int))) {
    perror("can't unset multicast loop");
    goto error;
  }

  return 1;

error:
  close(data->fd);
  return -1;
}

ATTR_NONNULL_ALL int netsock_open_dhcp(ddhcp_epoll_data* data,uint16_t port) {
  int sock;
  struct sockaddr_in sin;
  struct in_addr address_client;
  unsigned int broadcast = 1;

  sock = socket(PF_INET, SOCK_DGRAM|SOCK_NONBLOCK, IPPROTO_UDP);

  if (sock  < 0) {
    perror("can't open broadcast socket");
    return -1;
  }

  memset(&sin, 0, sizeof(sin));
  sin.sin_port = htons(port);
  sin.sin_family = AF_INET;

  inet_aton("0.0.0.0", &address_client);
  memcpy(&sin.sin_addr, &address_client, sizeof(sin.sin_addr));

  if (setsockopt(sock, SOL_SOCKET, SO_BINDTODEVICE, data->interface_name,
                 (socklen_t) strnlen(data->interface_name, IFNAMSIZ))) {
    perror("can't bind to broadcast device");
    close(sock);
    return -1;
  }

  if (bind(sock, (struct sockaddr*)&sin, sizeof(sin)) < 0) {
    perror("can't bind broadcast socket");
    close(sock);
    return -1;
  }

  if (setsockopt(sock, SOL_SOCKET, SO_BROADCAST, &broadcast, sizeof(unsigned int))) {
    perror("can't set broadcast on client socket");
    close(sock);
    return -1;
  }

  data->fd = sock;
  data->interface_id = if_nametoindex(data->interface_name);

  return sock;
}

// DDHCPD_SOCKET_INIT_T for all the different socket types we handle

ATTR_NONNULL_ALL int netsock_multicast_init(epoll_data_t data,ddhcp_config* config) {
  ddhcp_epoll_data* ptr = (ddhcp_epoll_data*) data.ptr;
  if ((netsock_open_socket_v6(ptr,&in6addr_localmcast,DDHCP_MULTICAST_PORT)) < 0) {
    FATAL("netsock_init(...): Unable to open multicast socket\n");
    return -1;
  }

  if (netsock_multicast_join(ptr,&in6addr_localmcast) < 0) {
    FATAL("netsock_init(...): Unable to join multicast group\n");
    close(ptr->fd);
    return -1;
  }
  UNUSED(config);
  return 0;
}

ATTR_NONNULL_ALL int netsock_server_init(epoll_data_t data,ddhcp_config* config) {
  ddhcp_epoll_data* ptr = (ddhcp_epoll_data*) data.ptr;
  if ((netsock_open_socket_v6(ptr,(struct in6_addr*) &in6addr_any,DDHCP_UNICAST_PORT)) < 0) {
    FATAL("netsock_init(...): Unable to open server socket\n");
    return -1;
  }
  UNUSED(config);
  return 0;
}

ATTR_NONNULL_ALL int netsock_dhcp_init(epoll_data_t data,ddhcp_config* config) {
  ddhcp_epoll_data* ptr = (ddhcp_epoll_data*) data.ptr;
  if ((netsock_open_dhcp(ptr,config->dhcp_port)) < 0) {
    FATAL("netsock_init(...): Unable to open dhcp socket\n");
    return -1;
  }
  UNUSED(config);
  return 0;
}

ATTR_NONNULL_ALL int netsock_control_init(epoll_data_t data,ddhcp_config* config) {
  ddhcp_epoll_data* ptr = (ddhcp_epoll_data*) data.ptr;
  if((netsock_unix_socket_open(ptr)) < 0) {
    FATAL("netsock_init(...): Unable to open control socket\n");
    return -1;
  }
  UNUSED(config);
  return 0;
}