1 /* $OpenBSD: packet.c,v 1.17 2021/01/19 16:02:22 claudio Exp $ */
2
3 /*
4 * Copyright (c) 2006 Michele Marchetto <mydecay@openbeer.it>
5 * Copyright (c) 2004, 2005 Esben Norby <norby@openbsd.org>
6 *
7 * Permission to use, copy, modify, and distribute this software for any
8 * purpose with or without fee is hereby granted, provided that the above
9 * copyright notice and this permission notice appear in all copies.
10 *
11 * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
12 * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
13 * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
14 * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
15 * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
16 * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
17 * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
18 */
19
20 #include <sys/types.h>
21 #include <sys/socket.h>
22 #include <sys/uio.h>
23
24 #include <netinet/in.h>
25 #include <netinet/ip.h>
26 #include <netinet/udp.h>
27 #include <arpa/inet.h>
28
29 #include <net/if_dl.h>
30
31 #include <errno.h>
32 #include <event.h>
33 #include <stdlib.h>
34 #include <string.h>
35
36 #include "ripd.h"
37 #include "rip.h"
38 #include "log.h"
39 #include "ripe.h"
40
41 int rip_hdr_sanity_check(struct rip_hdr *);
42 struct iface *find_iface(struct ripd_conf *, unsigned int, struct in_addr);
43
44 static u_int8_t *recv_buf;
45
46 int
gen_rip_hdr(struct ibuf * buf,u_int8_t command)47 gen_rip_hdr(struct ibuf *buf, u_int8_t command)
48 {
49 struct rip_hdr rip_hdr;
50
51 bzero(&rip_hdr, sizeof(rip_hdr));
52 rip_hdr.version = RIP_VERSION;
53 rip_hdr.command = command;
54
55 return (ibuf_add(buf, &rip_hdr, sizeof(rip_hdr)));
56 }
57
58 /* send and receive packets */
59 int
send_packet(struct iface * iface,void * pkt,size_t len,struct sockaddr_in * dst)60 send_packet(struct iface *iface, void *pkt, size_t len, struct sockaddr_in *dst)
61 {
62 /* set outgoing interface for multicast traffic */
63 if (IN_MULTICAST(ntohl(dst->sin_addr.s_addr)))
64 if (if_set_mcast(iface) == -1) {
65 log_warn("send_packet: error setting multicast "
66 "interface, %s", iface->name);
67 return (-1);
68 }
69
70 if (sendto(iface->fd, pkt, len, 0,
71 (struct sockaddr *)dst, sizeof(*dst)) == -1) {
72 log_warn("send_packet: error sending packet on interface %s",
73 iface->name);
74 return (-1);
75 }
76
77 return (0);
78 }
79
80 void
recv_packet(int fd,short event,void * bula)81 recv_packet(int fd, short event, void *bula)
82 {
83 union {
84 struct cmsghdr hdr;
85 char buf[CMSG_SPACE(sizeof(struct sockaddr_dl))];
86 } cmsgbuf;
87 struct sockaddr_in src;
88 struct iovec iov;
89 struct msghdr msg;
90 struct cmsghdr *cmsg;
91 struct sockaddr_dl *dst = NULL;
92 struct nbr_failed *nbr_failed = NULL;
93 struct ripd_conf *xconf = bula;
94 struct iface *iface;
95 struct rip_hdr *rip_hdr;
96 struct nbr *nbr;
97 u_int8_t *buf;
98 ssize_t r;
99 u_int16_t len, srcport;
100 u_int32_t auth_crypt_num = 0;
101
102 if (event != EV_READ)
103 return;
104
105 if (recv_buf == NULL)
106 if ((recv_buf = malloc(READ_BUF_SIZE)) == NULL)
107 fatal(__func__);
108
109 /* setup buffer */
110 bzero(&msg, sizeof(msg));
111 iov.iov_base = buf = recv_buf;
112 iov.iov_len = READ_BUF_SIZE;
113 msg.msg_name = &src;
114 msg.msg_namelen = sizeof(src);
115 msg.msg_iov = &iov;
116 msg.msg_iovlen = 1;
117 msg.msg_control = &cmsgbuf.buf;
118 msg.msg_controllen = sizeof(cmsgbuf.buf);
119
120 if ((r = recvmsg(fd, &msg, 0)) == -1) {
121 if (errno != EINTR && errno != EAGAIN)
122 log_debug("recv_packet: read error: %s",
123 strerror(errno));
124 return;
125 }
126
127 for (cmsg = CMSG_FIRSTHDR(&msg); cmsg != NULL;
128 cmsg = CMSG_NXTHDR(&msg, cmsg)) {
129 if (cmsg->cmsg_level == IPPROTO_IP &&
130 cmsg->cmsg_type == IP_RECVIF) {
131 dst = (struct sockaddr_dl *)CMSG_DATA(cmsg);
132 break;
133 }
134 }
135
136 if (dst == NULL)
137 return;
138
139 len = (u_int16_t)r;
140
141 /* Check the packet is not from one of the local interfaces */
142 LIST_FOREACH(iface, &xconf->iface_list, entry) {
143 if (iface->addr.s_addr == src.sin_addr.s_addr)
144 return;
145 }
146
147 /* find a matching interface */
148 if ((iface = find_iface(xconf, dst->sdl_index, src.sin_addr)) == NULL) {
149 log_debug("recv_packet: cannot find a matching interface");
150 return;
151 }
152
153 srcport = ntohs(src.sin_port);
154
155 /* RIP header sanity checks */
156 if (len < RIP_HDR_LEN) {
157 log_debug("recv_packet: bad packet size");
158 return;
159 }
160 rip_hdr = (struct rip_hdr *)buf;
161
162 if (rip_hdr_sanity_check(rip_hdr) == -1)
163 return;
164
165 nbr = nbr_find_ip(iface, src.sin_addr.s_addr);
166
167 if (nbr == NULL && iface->auth_type == AUTH_CRYPT)
168 nbr_failed = nbr_failed_find(iface, src.sin_addr.s_addr);
169
170 /* switch RIP command */
171 switch (rip_hdr->command) {
172 case COMMAND_REQUEST:
173 /* Requests don't create a real neighbor, just a temporary
174 * one to build the response.
175 */
176 if ((msg.msg_flags & MSG_MCAST) == 0 && srcport == RIP_PORT)
177 return;
178
179 if (nbr == NULL) {
180 nbr = nbr_new(src.sin_addr.s_addr, iface);
181 nbr->addr = src.sin_addr;
182 }
183 nbr->port = srcport;
184 nbr_fsm(nbr, NBR_EVT_REQUEST_RCVD);
185
186 buf += RIP_HDR_LEN;
187 len -= RIP_HDR_LEN;
188
189 recv_request(iface, nbr, buf, len);
190 break;
191 case COMMAND_RESPONSE:
192 if (srcport != RIP_PORT)
193 return;
194
195 if (auth_validate(&buf, &len, iface, nbr, nbr_failed,
196 &auth_crypt_num)) {
197 log_warnx("recv_packet: authentication error, "
198 "interface %s", iface->name);
199 return;
200 }
201
202 if (nbr == NULL) {
203 nbr = nbr_new(src.sin_addr.s_addr, iface);
204 if (nbr_failed != NULL)
205 nbr_failed_delete(nbr_failed);
206 nbr->addr = src.sin_addr;
207 }
208 nbr->auth_seq_num = auth_crypt_num;
209 nbr_fsm(nbr, NBR_EVT_RESPONSE_RCVD);
210
211 recv_response(iface, nbr, buf, len);
212 break;
213 default:
214 log_debug("recv_packet: unknown RIP command, interface %s",
215 iface->name);
216 }
217 }
218
219 int
rip_hdr_sanity_check(struct rip_hdr * rip_hdr)220 rip_hdr_sanity_check(struct rip_hdr *rip_hdr)
221 {
222 if (rip_hdr->version != RIP_VERSION) {
223 log_debug("rip_hdr_sanity_check: invalid RIP version %d",
224 rip_hdr->version);
225 return (-1);
226 }
227
228 return (0);
229 }
230
231 struct iface *
find_iface(struct ripd_conf * xconf,unsigned int ifindex,struct in_addr src)232 find_iface(struct ripd_conf *xconf, unsigned int ifindex, struct in_addr src)
233 {
234 struct iface *iface = NULL;
235
236 /* returned interface needs to be active */
237 LIST_FOREACH(iface, &xconf->iface_list, entry) {
238 if (ifindex == 0 || ifindex != iface->ifindex)
239 continue;
240
241 if (iface->passive)
242 continue;
243
244 if ((iface->addr.s_addr & iface->mask.s_addr) ==
245 (src.s_addr & iface->mask.s_addr))
246 return (iface);
247
248 if (iface->dst.s_addr && iface->dst.s_addr == src.s_addr)
249 return (iface);
250 }
251
252 return (NULL);
253 }
254