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5435a2bf | 1 | /* |
63d4bd12 QY |
2 | * VRRP packet crafting. |
3 | * Copyright (C) 2018-2019 Cumulus Networks, Inc. | |
4 | * Quentin Young | |
5435a2bf QY |
5 | * |
6 | * This program is free software; you can redistribute it and/or modify it | |
7 | * under the terms of the GNU General Public License as published by the Free | |
8 | * Software Foundation; either version 2 of the License, or (at your option) | |
9 | * any later version. | |
10 | * | |
11 | * This program is distributed in the hope that it will be useful, but WITHOUT | |
12 | * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or | |
13 | * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for | |
14 | * more details. | |
15 | * | |
16 | * You should have received a copy of the GNU General Public License along | |
17 | * with this program; see the file COPYING; if not, write to the Free Software | |
18 | * Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA | |
19 | */ | |
20 | #include <zebra.h> | |
91188ca6 QY |
21 | #include <netinet/in.h> |
22 | #include <netinet/ip.h> | |
23 | #include <netinet/ip6.h> | |
5435a2bf | 24 | |
3eca3857 | 25 | #include "lib/checksum.h" |
91188ca6 QY |
26 | #include "lib/ipaddr.h" |
27 | #include "lib/memory.h" | |
5435a2bf | 28 | |
8071d5c3 | 29 | #include "vrrp.h" |
5435a2bf QY |
30 | #include "vrrp_packet.h" |
31 | ||
91188ca6 QY |
32 | /* clang-format off */ |
33 | const char *vrrp_packet_names[16] = { | |
34 | [0] = "Unknown", | |
35 | [VRRP_TYPE_ADVERTISEMENT] = "ADVERTISEMENT", | |
36 | [2] = "Unknown", | |
37 | [3] = "Unknown", | |
38 | [4] = "Unknown", | |
39 | [5] = "Unknown", | |
40 | [6] = "Unknown", | |
41 | [7] = "Unknown", | |
42 | [8] = "Unknown", | |
43 | [9] = "Unknown", | |
44 | [10] = "Unknown", | |
45 | [11] = "Unknown", | |
46 | [12] = "Unknown", | |
47 | [13] = "Unknown", | |
48 | [14] = "Unknown", | |
49 | [15] = "Unknown", | |
50 | }; | |
51 | /* clang-format on */ | |
52 | ||
8071d5c3 QY |
53 | ssize_t vrrp_pkt_build(struct vrrp_pkt **pkt, struct ipaddr *src, uint8_t vrid, |
54 | uint8_t prio, uint16_t max_adver_int, uint8_t numip, | |
862f2f37 | 55 | struct ipaddr **ips) |
5435a2bf | 56 | { |
862f2f37 | 57 | bool v6 = IS_IPADDR_V6(ips[0]); |
3eca3857 | 58 | |
5435a2bf | 59 | size_t addrsz = v6 ? sizeof(struct in6_addr) : sizeof(struct in_addr); |
91188ca6 | 60 | size_t pktsize = VRRP_PKT_SIZE(v6 ? AF_INET6 : AF_INET, numip); |
3eca3857 QY |
61 | *pkt = XCALLOC(MTYPE_TMP, pktsize); |
62 | ||
3eca3857 QY |
63 | (*pkt)->hdr.vertype |= VRRP_VERSION << 4; |
64 | (*pkt)->hdr.vertype |= VRRP_TYPE_ADVERTISEMENT; | |
65 | (*pkt)->hdr.vrid = vrid; | |
66 | (*pkt)->hdr.priority = prio; | |
67 | (*pkt)->hdr.naddr = numip; | |
68 | (*pkt)->hdr.v3.adver_int = htons(max_adver_int); | |
69 | ||
862f2f37 QY |
70 | uint8_t *aptr = (void *)(*pkt)->addrs; |
71 | ||
3eca3857 | 72 | for (int i = 0; i < numip; i++) { |
862f2f37 QY |
73 | memcpy(aptr, &ips[i]->ip.addr, addrsz); |
74 | aptr += addrsz; | |
3eca3857 | 75 | } |
8071d5c3 | 76 | |
3eca3857 QY |
77 | (*pkt)->hdr.chksum = 0; |
78 | ||
8071d5c3 QY |
79 | if (v6) { |
80 | struct ipv6_ph ph = {}; | |
81 | ph.src = src->ipaddr_v6; | |
82 | inet_pton(AF_INET6, VRRP_MCASTV6_GROUP_STR, &ph.dst); | |
83 | ph.ulpl = htons(pktsize); | |
84 | ph.next_hdr = 112; | |
85 | (*pkt)->hdr.chksum = in_cksum_with_ph6(&ph, *pkt, pktsize); | |
86 | } else { | |
87 | struct ipv4_ph ph = {}; | |
88 | ph.src = src->ipaddr_v4; | |
89 | inet_pton(AF_INET, VRRP_MCASTV4_GROUP_STR, &ph.dst); | |
90 | ph.proto = 112; | |
91 | ph.len = htons(pktsize); | |
92 | (*pkt)->hdr.chksum = in_cksum_with_ph4(&ph, *pkt, pktsize); | |
93 | } | |
3eca3857 QY |
94 | |
95 | return pktsize; | |
5435a2bf | 96 | } |
91188ca6 QY |
97 | |
98 | size_t vrrp_pkt_dump(char *buf, size_t buflen, struct vrrp_pkt *pkt) | |
99 | { | |
100 | if (buflen < 1) | |
101 | return 0; | |
102 | ||
103 | char tmpbuf[BUFSIZ]; | |
104 | size_t rs = 0; | |
105 | struct vrrp_hdr *hdr = &pkt->hdr; | |
106 | ||
107 | buf[0] = 0x00; | |
108 | snprintf(tmpbuf, sizeof(tmpbuf), "Version: %u\n", (hdr->vertype >> 4)); | |
109 | rs += strlcat(buf, tmpbuf, buflen); | |
110 | snprintf(tmpbuf, sizeof(tmpbuf), "Type: %u (%s)\n", | |
111 | (hdr->vertype & 0x0F), | |
112 | vrrp_packet_names[(hdr->vertype & 0x0F)]); | |
113 | rs += strlcat(buf, tmpbuf, buflen); | |
114 | snprintf(tmpbuf, sizeof(tmpbuf), "VRID: %u\n", hdr->vrid); | |
115 | rs += strlcat(buf, tmpbuf, buflen); | |
116 | snprintf(tmpbuf, sizeof(tmpbuf), "Priority: %u\n", hdr->priority); | |
117 | rs += strlcat(buf, tmpbuf, buflen); | |
118 | snprintf(tmpbuf, sizeof(tmpbuf), "Count IPvX: %u\n", hdr->naddr); | |
119 | rs += strlcat(buf, tmpbuf, buflen); | |
120 | snprintf(tmpbuf, sizeof(tmpbuf), "Max Adver Int: %u\n", | |
121 | ntohs(hdr->v3.adver_int)); | |
122 | rs += strlcat(buf, tmpbuf, buflen); | |
123 | snprintf(tmpbuf, sizeof(tmpbuf), "Checksum: %x\n", ntohs(hdr->chksum)); | |
124 | rs += strlcat(buf, tmpbuf, buflen); | |
125 | ||
126 | return rs; | |
127 | } | |
128 | ||
129 | ssize_t vrrp_parse_datagram(int family, struct msghdr *m, size_t read, | |
130 | struct vrrp_pkt **pkt, char *errmsg, | |
131 | size_t errmsg_len) | |
132 | { | |
133 | /* Source (MAC & IP), Dest (MAC & IP) TTL validation done by kernel */ | |
134 | size_t addrsz = (family == AF_INET) ? sizeof(struct in_addr) | |
135 | : sizeof(struct in6_addr); | |
136 | ||
137 | size_t pktsize; | |
138 | uint8_t *buf = m->msg_iov->iov_base; | |
139 | ||
140 | #define VRRP_PKT_VCHECK(cond, _f, ...) \ | |
141 | do { \ | |
142 | if (!(cond)) { \ | |
143 | if (errmsg) \ | |
144 | snprintf(errmsg, errmsg_len, (_f), \ | |
145 | ##__VA_ARGS__); \ | |
146 | return -1; \ | |
147 | } \ | |
148 | } while (0) | |
149 | ||
150 | /* IPvX header check */ | |
151 | ||
152 | if (family == AF_INET) { | |
153 | VRRP_PKT_VCHECK( | |
154 | read >= sizeof(struct ip), | |
155 | "Datagram not large enough to contain IP header"); | |
156 | ||
157 | struct ip *ip = (struct ip *)buf; | |
158 | ||
159 | /* IP total length check */ | |
160 | VRRP_PKT_VCHECK( | |
161 | ntohs(ip->ip_len) == read, | |
162 | "IPv4 packet length field does not match # received bytes; %u != %lu", | |
163 | ntohs(ip->ip_len), read); | |
164 | ||
165 | /* TTL check */ | |
dad18a2f QY |
166 | VRRP_PKT_VCHECK(ip->ip_ttl == 255, |
167 | "IPv4 TTL is %" PRIu8 "; should be 255", | |
168 | ip->ip_ttl); | |
91188ca6 QY |
169 | |
170 | *pkt = (struct vrrp_pkt *)(buf + (ip->ip_hl << 2)); | |
171 | pktsize = read - (ip->ip_hl << 2); | |
172 | ||
173 | /* IP empty packet check */ | |
174 | VRRP_PKT_VCHECK(pktsize > 0, "IPv4 packet has no payload"); | |
175 | } else if (family == AF_INET6) { | |
176 | struct cmsghdr *c; | |
177 | for (c = CMSG_FIRSTHDR(m); c != NULL; CMSG_NXTHDR(m, c)) { | |
178 | if (c->cmsg_level == IPPROTO_IPV6 | |
179 | && c->cmsg_type == IPV6_HOPLIMIT) | |
180 | break; | |
181 | } | |
182 | ||
183 | VRRP_PKT_VCHECK(!!c, "IPv6 Hop Limit not received"); | |
184 | ||
185 | uint8_t *hoplimit = CMSG_DATA(c); | |
dad18a2f QY |
186 | VRRP_PKT_VCHECK(*hoplimit == 255, |
187 | "IPv6 Hop Limit is %" PRIu8 "; should be 255", | |
188 | *hoplimit); | |
91188ca6 QY |
189 | |
190 | *pkt = (struct vrrp_pkt *)buf; | |
191 | pktsize = read; | |
192 | } else { | |
193 | assert(!"Unknown address family"); | |
194 | } | |
195 | ||
196 | /* Size check */ | |
197 | size_t minsize = (family == AF_INET) ? VRRP_MIN_PKT_SIZE_V4 | |
198 | : VRRP_MIN_PKT_SIZE_V6; | |
199 | size_t maxsize = (family == AF_INET) ? VRRP_MAX_PKT_SIZE_V4 | |
200 | : VRRP_MAX_PKT_SIZE_V6; | |
201 | VRRP_PKT_VCHECK(pktsize >= minsize, | |
202 | "VRRP packet is undersized (%lu < %lu)", pktsize, | |
203 | VRRP_MIN_PKT_SIZE); | |
204 | VRRP_PKT_VCHECK(pktsize <= maxsize, | |
205 | "VRRP packet is oversized (%lu > %lu)", pktsize, | |
206 | VRRP_MAX_PKT_SIZE); | |
207 | /* Version check */ | |
208 | VRRP_PKT_VCHECK(((*pkt)->hdr.vertype >> 4) != 2, "VRPPv2 unsupported"); | |
209 | VRRP_PKT_VCHECK(((*pkt)->hdr.vertype >> 4) == 3, "Bad version %u", | |
210 | (*pkt)->hdr.vertype >> 4); | |
211 | /* Type check */ | |
212 | VRRP_PKT_VCHECK(((*pkt)->hdr.vertype & 0x0F) == 1, "Bad type %u", | |
213 | (*pkt)->hdr.vertype & 0x0f); | |
91188ca6 QY |
214 | /* # addresses check */ |
215 | size_t ves = VRRP_PKT_SIZE(family, (*pkt)->hdr.naddr); | |
216 | VRRP_PKT_VCHECK(pktsize == ves, "Packet has incorrect # addresses"); | |
217 | /* FIXME: checksum check */ | |
218 | /* ... */ | |
219 | ||
220 | /* Addresses check */ | |
221 | char vbuf[INET6_ADDRSTRLEN]; | |
222 | uint8_t *p = (uint8_t *)(*pkt)->addrs; | |
223 | for (uint8_t i = 0; i < (*pkt)->hdr.naddr; i++) { | |
224 | VRRP_PKT_VCHECK(inet_ntop(family, p, vbuf, sizeof(vbuf)), | |
225 | "Bad IP address, #%u", i); | |
226 | p += addrsz; | |
227 | } | |
228 | ||
229 | /* Everything checks out */ | |
230 | return pktsize; | |
231 | } |