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Member "n2n-3.1.1/src/tuntap_linux.c" (31 Mar 2022, 8509 Bytes) of package /linux/misc/n2n-3.1.1.tar.gz:
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1 /**
2 * (C) 2007-22 - ntop.org and contributors
3 *
4 * This program is free software; you can redistribute it and/or modify
5 * it under the terms of the GNU General Public License as published by
6 * the Free Software Foundation; either version 3 of the License, or
7 * (at your option) any later version.
8 *
9 * This program is distributed in the hope that it will be useful,
10 * but WITHOUT ANY WARRANTY; without even the implied warranty of
11 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
12 * GNU General Public License for more details.
13 *
14 * You should have received a copy of the GNU General Public License
15 * along with this program; if not see see <http://www.gnu.org/licenses/>
16 *
17 */
18
19
20 #ifdef __linux__
21
22
23 #include "n2n.h"
24
25
26 static int setup_ifname (int fd, const char *ifname, const char *ipaddr,
27 const char *netmask, uint8_t *mac, int mtu) {
28
29 struct ifreq ifr;
30
31 memset(&ifr, 0, sizeof(ifr));
32
33 strncpy(ifr.ifr_name, ifname, IFNAMSIZ);
34 ifr.ifr_name[IFNAMSIZ-1] = '\0';
35
36 ifr.ifr_hwaddr.sa_family = ARPHRD_ETHER;
37 memcpy(ifr.ifr_hwaddr.sa_data, mac, 6);
38
39 if(ioctl(fd, SIOCSIFHWADDR, &ifr) == -1) {
40 traceEvent(TRACE_ERROR, "ioctl(SIOCSIFHWADDR) failed [%d]: %s", errno, strerror(errno));
41 return -1;
42 }
43
44 ifr.ifr_addr.sa_family = AF_INET;
45
46 // interface address
47 inet_pton(AF_INET, ipaddr, &((struct sockaddr_in*)&ifr.ifr_addr)->sin_addr);
48 if(ioctl(fd, SIOCSIFADDR, &ifr) == -1) {
49 traceEvent(TRACE_ERROR, "ioctl(SIOCSIFADDR) failed [%d]: %s", errno, strerror(errno));
50 return -2;
51 }
52
53 // netmask
54 if(netmask && (((struct sockaddr_in*)&ifr.ifr_addr)->sin_addr.s_addr != 0)) {
55 inet_pton(AF_INET, netmask, &((struct sockaddr_in*)&ifr.ifr_addr)->sin_addr);
56 if(ioctl(fd, SIOCSIFNETMASK, &ifr) == -1) {
57 traceEvent(TRACE_ERROR, "ioctl(SIOCSIFNETMASK, %s) failed [%d]: %s", netmask, errno, strerror(errno));
58 return -3;
59 }
60 }
61
62 // MTU
63 ifr.ifr_mtu = mtu;
64 if(ioctl(fd, SIOCSIFMTU, &ifr) == -1) {
65 traceEvent(TRACE_ERROR, "ioctl(SIOCSIFMTU) failed [%d]: %s", errno, strerror(errno));
66 return -4;
67 }
68
69 // set up and running
70 if(ioctl(fd, SIOCGIFFLAGS, &ifr) == -1) {
71 traceEvent(TRACE_ERROR, "ioctl(SIOCGIFFLAGS) failed [%d]: %s", errno, strerror(errno));
72 return -5;
73 }
74
75 ifr.ifr_flags |= (IFF_UP | IFF_RUNNING);
76
77 if(ioctl(fd, SIOCSIFFLAGS, &ifr) == -1) {
78 traceEvent(TRACE_ERROR, "ioctl(SIOCSIFFLAGS) failed [%d]: %s", errno, strerror(errno));
79 return -6;
80 }
81
82 return 0;
83 }
84
85
86 /** @brief Open and configure the TAP device for packet read/write.
87 *
88 * This routine creates the interface via the tuntap driver and then
89 * configures it.
90 *
91 * @param device - [inout] a device info holder object
92 * @param dev - user-defined name for the new iface,
93 * if NULL system will assign a name
94 * @param device_ip - address of iface
95 * @param device_mask - netmask for device_ip
96 * @param mtu - MTU for device_ip
97 *
98 * @return - negative value on error
99 * - non-negative file-descriptor on success
100 */
101 int tuntap_open (tuntap_dev *device,
102 char *dev, /* user-definable interface name, eg. edge0 */
103 const char *address_mode, /* static or dhcp */
104 char *device_ip,
105 char *device_mask,
106 const char * device_mac,
107 int mtu) {
108
109 char *tuntap_device = "/dev/net/tun";
110 int ioctl_fd;
111 struct ifreq ifr;
112 int rc;
113 int nl_fd;
114 char nl_buf[8192]; /* >= 8192 to avoid truncation, see "man 7 netlink" */
115 struct iovec iov;
116 struct sockaddr_nl sa;
117 int up_and_running = 0;
118 struct msghdr msg;
119
120 device->fd = open(tuntap_device, O_RDWR);
121 if(device->fd < 0) {
122 traceEvent(TRACE_ERROR, "tuntap open() error: %s[%d]. Is the tun kernel module loaded?\n", strerror(errno), errno);
123 return -1;
124 }
125
126 memset(&ifr, 0, sizeof(ifr));
127
128 // want a TAP device for layer 2 frames
129 ifr.ifr_flags = IFF_TAP|IFF_NO_PI;
130
131 strncpy(ifr.ifr_name, dev, IFNAMSIZ-1);
132 ifr.ifr_name[IFNAMSIZ-1] = '\0';
133 rc = ioctl(device->fd, TUNSETIFF, (void *)&ifr);
134
135 if(rc < 0) {
136 traceEvent(TRACE_ERROR, "tuntap ioctl(TUNSETIFF, IFF_TAP) error: %s[%d]\n", strerror(errno), rc);
137 close(device->fd);
138 return -1;
139 }
140
141 // store the device name for later reuse
142 strncpy(device->dev_name, ifr.ifr_name, MIN(IFNAMSIZ, N2N_IFNAMSIZ));
143
144 if(device_mac && device_mac[0]) {
145 // use the user-provided MAC
146 str2mac(device->mac_addr, device_mac);
147 } else {
148 // set an explicit random MAC to know the exact MAC in use, manually
149 // reading the MAC address is not safe as it may change internally
150 // also after the TAP interface UP status has been notified
151
152 memrnd(device->mac_addr, N2N_MAC_SIZE);
153
154 // clear multicast bit
155 device->mac_addr[0] &= ~0x01;
156
157 // set locally-assigned bit
158 device->mac_addr[0] |= 0x02;
159 }
160
161 // initialize netlink socket
162 if((nl_fd = socket(AF_NETLINK, SOCK_RAW, NETLINK_ROUTE)) == -1) {
163 traceEvent(TRACE_ERROR, "netlink socket creation failed [%d]: %s", errno, strerror(errno));
164 return -1;
165 }
166
167 iov.iov_base = nl_buf;
168 iov.iov_len = sizeof(nl_buf);
169
170 memset(&sa, 0, sizeof(sa));
171 sa.nl_family = PF_NETLINK;
172 sa.nl_groups = RTMGRP_LINK;
173 sa.nl_pid = getpid();
174
175 memset(&msg, 0, sizeof(msg));
176 msg.msg_name = &sa;
177 msg.msg_namelen = sizeof(sa);
178 msg.msg_iov = &iov;
179 msg.msg_iovlen = 1;
180
181 // subscribe to interface events
182 if(bind(nl_fd, (struct sockaddr*)&sa, sizeof(sa)) == -1) {
183 traceEvent(TRACE_ERROR, "netlink socket bind failed [%d]: %s", errno, strerror(errno));
184 return -1;
185 }
186
187 if((ioctl_fd = socket(PF_INET, SOCK_DGRAM, IPPROTO_IP)) < 0) {
188 traceEvent(TRACE_ERROR, "socket creation failed [%d]: %s", errno, strerror(errno));
189 close(nl_fd);
190 return -1;
191 }
192
193 if(setup_ifname(ioctl_fd, device->dev_name, device_ip, device_mask, device->mac_addr, mtu) < 0) {
194 close(nl_fd);
195 close(ioctl_fd);
196 close(device->fd);
197 return -1;
198 }
199
200 close(ioctl_fd);
201
202 // wait for the up and running notification
203 traceEvent(TRACE_INFO, "Waiting for TAP interface to be up and running...");
204
205 while(!up_and_running) {
206 ssize_t len = recvmsg(nl_fd, &msg, 0);
207 struct nlmsghdr *nh;
208
209 for(nh = (struct nlmsghdr *)nl_buf; NLMSG_OK(nh, len); nh = NLMSG_NEXT(nh, len)) {
210 if(nh->nlmsg_type == NLMSG_ERROR) {
211 traceEvent(TRACE_DEBUG, "nh->nlmsg_type == NLMSG_ERROR");
212 break;
213 }
214
215 if(nh->nlmsg_type == NLMSG_DONE)
216 break;
217
218 if(nh->nlmsg_type == NETLINK_GENERIC) {
219 struct ifinfomsg *ifi = NLMSG_DATA(nh);
220
221 // NOTE: skipping interface name check, assuming it's our TAP
222 if((ifi->ifi_flags & IFF_UP) && (ifi->ifi_flags & IFF_RUNNING)) {
223 up_and_running = 1;
224 traceEvent(TRACE_INFO, "Interface is up and running");
225 break;
226 }
227 }
228 }
229 }
230
231 close(nl_fd);
232
233 device->ip_addr = inet_addr(device_ip);
234 device->device_mask = inet_addr(device_mask);
235 device->if_idx = if_nametoindex(dev);
236
237 return device->fd;
238 }
239
240
241 int tuntap_read (struct tuntap_dev *tuntap, unsigned char *buf, int len) {
242
243 return read(tuntap->fd, buf, len);
244 }
245
246
247 int tuntap_write (struct tuntap_dev *tuntap, unsigned char *buf, int len) {
248
249 return write(tuntap->fd, buf, len);
250 }
251
252
253 void tuntap_close (struct tuntap_dev *tuntap) {
254
255 close(tuntap->fd);
256 }
257
258
259 // fill out the ip_addr value from the interface, called to pick up dynamic address changes
260 void tuntap_get_address (struct tuntap_dev *tuntap) {
261
262 struct ifreq ifr;
263 int fd;
264
265 if((fd = socket(PF_INET, SOCK_DGRAM, IPPROTO_IP)) < 0) {
266 traceEvent(TRACE_ERROR, "socket creation failed [%d]: %s", errno, strerror(errno));
267 return;
268 }
269
270 ifr.ifr_addr.sa_family = AF_INET;
271 strncpy(ifr.ifr_name, tuntap->dev_name, IFNAMSIZ);
272 ifr.ifr_name[IFNAMSIZ-1] = '\0';
273
274 if(ioctl(fd, SIOCGIFADDR, &ifr) != -1)
275 tuntap->ip_addr = ((struct sockaddr_in *)&ifr.ifr_addr)->sin_addr.s_addr;
276
277 close(fd);
278 }
279
280
281 #endif /* #ifdef __linux__ */