2 fd_device.c -- Interaction with Android tun fd
3 Copyright (C) 2001-2005 Ivo Timmermans,
4 2001-2016 Guus Sliepen <guus@tinc-vpn.org>
5 2009 Grzegorz Dymarek <gregd72002@googlemail.com>
6 2016-2020 Pacien TRAN-GIRARD <pacien@pacien.net>
8 This program is free software; you can redistribute it and/or modify
9 it under the terms of the GNU General Public License as published by
10 the Free Software Foundation; either version 2 of the License, or
11 (at your option) any later version.
13 This program is distributed in the hope that it will be useful,
14 but WITHOUT ANY WARRANTY; without even the implied warranty of
15 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
16 GNU General Public License for more details.
18 You should have received a copy of the GNU General Public License along
19 with this program; if not, write to the Free Software Foundation, Inc.,
20 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
36 struct unix_socket_addr {
38 struct sockaddr_un addr;
41 static int read_fd(int socket) {
43 struct iovec iov = {0};
44 char cmsgbuf[CMSG_SPACE(sizeof(device_fd))];
45 struct msghdr msg = {0};
47 struct cmsghdr *cmsgptr;
49 iov.iov_base = &iobuf;
53 msg.msg_control = cmsgbuf;
54 msg.msg_controllen = sizeof(cmsgbuf);
56 if((ret = recvmsg(socket, &msg, 0)) < 1) {
57 logger(DEBUG_ALWAYS, LOG_ERR, "Could not read from unix socket (error %d)!", ret);
63 if(msg.msg_flags & (MSG_CTRUNC | MSG_OOB | MSG_ERRQUEUE)) {
66 if(msg.msg_flags & (MSG_CTRUNC | MSG_OOB)) {
68 logger(DEBUG_ALWAYS, LOG_ERR, "Error while receiving message (flags %d)!", msg.msg_flags);
72 cmsgptr = CMSG_FIRSTHDR(&msg);
74 if(cmsgptr->cmsg_level != SOL_SOCKET) {
75 logger(DEBUG_ALWAYS, LOG_ERR, "Wrong CMSG level: %d, expected %d!",
76 cmsgptr->cmsg_level, SOL_SOCKET);
80 if(cmsgptr->cmsg_type != SCM_RIGHTS) {
81 logger(DEBUG_ALWAYS, LOG_ERR, "Wrong CMSG type: %d, expected %d!",
82 cmsgptr->cmsg_type, SCM_RIGHTS);
86 if(cmsgptr->cmsg_len != CMSG_LEN(sizeof(device_fd))) {
87 logger(DEBUG_ALWAYS, LOG_ERR, "Wrong CMSG data length: %lu, expected %lu!",
88 (unsigned long)cmsgptr->cmsg_len, (unsigned long)CMSG_LEN(sizeof(device_fd)));
92 return *(int *) CMSG_DATA(cmsgptr);
95 static int receive_fd(struct unix_socket_addr socket_addr) {
100 if((socketfd = socket(PF_UNIX, SOCK_STREAM, 0)) < 0) {
101 logger(DEBUG_ALWAYS, LOG_ERR, "Could not open stream socket (error %d)!", socketfd);
105 if((ret = connect(socketfd, (struct sockaddr *) &socket_addr.addr, socket_addr.size)) < 0) {
106 logger(DEBUG_ALWAYS, LOG_ERR, "Could not connect to Unix socket (error %d)!", ret);
111 result = read_fd(socketfd);
118 static struct unix_socket_addr parse_socket_addr(const char *path) {
119 struct sockaddr_un socket_addr;
122 if(strlen(path) >= sizeof(socket_addr.sun_path)) {
123 logger(DEBUG_ALWAYS, LOG_ERR, "Unix socket path too long!");
124 return (struct unix_socket_addr) {
129 socket_addr.sun_family = AF_UNIX;
130 strncpy(socket_addr.sun_path, path, sizeof(socket_addr.sun_path));
133 /* abstract namespace socket */
134 socket_addr.sun_path[0] = '\0';
135 path_length = strlen(path);
137 /* filesystem path with NUL terminator */
138 path_length = strlen(path) + 1;
141 return (struct unix_socket_addr) {
142 .size = offsetof(struct sockaddr_un, sun_path) + path_length,
147 static bool setup_device(void) {
148 if(routing_mode == RMODE_SWITCH) {
149 logger(DEBUG_ALWAYS, LOG_ERR, "Switch mode not supported (requires unsupported TAP device)!");
153 if(!get_config_string(lookup_config(config_tree, "Device"), &device)) {
154 logger(DEBUG_ALWAYS, LOG_ERR, "Could not read device from configuration!");
158 /* device is either directly a file descriptor or an unix socket to read it from */
159 if(sscanf(device, "%d", &device_fd) != 1) {
160 logger(DEBUG_ALWAYS, LOG_INFO, "Receiving fd from Unix socket at %s.", device);
161 device_fd = receive_fd(parse_socket_addr(device));
165 logger(DEBUG_ALWAYS, LOG_ERR, "Could not open %s: %s!", device, strerror(errno));
169 logger(DEBUG_ALWAYS, LOG_INFO, "fd/%d adapter set up.", device_fd);
174 static void close_device(void) {
179 static inline uint16_t get_ip_ethertype(vpn_packet_t *packet) {
180 switch(DATA(packet)[ETH_HLEN] >> 4) {
192 static inline void set_etherheader(vpn_packet_t *packet, uint16_t ethertype) {
193 memset(DATA(packet), 0, ETH_HLEN - ETHER_TYPE_LEN);
195 DATA(packet)[ETH_HLEN - ETHER_TYPE_LEN] = (ethertype >> 8) & 0xFF;
196 DATA(packet)[ETH_HLEN - ETHER_TYPE_LEN + 1] = ethertype & 0xFF;
199 static bool read_packet(vpn_packet_t *packet) {
200 int lenin = read(device_fd, DATA(packet) + ETH_HLEN, MTU - ETH_HLEN);
203 logger(DEBUG_ALWAYS, LOG_ERR, "Error while reading from fd/%d: %s!", device_fd, strerror(errno));
207 uint16_t ethertype = get_ip_ethertype(packet);
209 if(ethertype == ETH_P_MAX) {
210 logger(DEBUG_TRAFFIC, LOG_ERR, "Unknown IP version while reading packet from fd/%d!", device_fd);
214 set_etherheader(packet, ethertype);
215 packet->len = lenin + ETH_HLEN;
217 logger(DEBUG_TRAFFIC, LOG_DEBUG, "Read packet of %d bytes from fd/%d.", packet->len, device_fd);
222 static bool write_packet(vpn_packet_t *packet) {
223 logger(DEBUG_TRAFFIC, LOG_DEBUG, "Writing packet of %d bytes to fd/%d.", packet->len, device_fd);
225 if(write(device_fd, DATA(packet) + ETH_HLEN, packet->len - ETH_HLEN) < 0) {
226 logger(DEBUG_ALWAYS, LOG_ERR, "Error while writing to fd/%d: %s!", device_fd, strerror(errno));
233 const devops_t fd_devops = {
234 .setup = setup_device,
235 .close = close_device,
237 .write = write_packet,