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git.proxmox.com Git - mirror_frr.git/blob - vrrpd/vrrp_packet.c
1 // SPDX-License-Identifier: GPL-2.0-or-later
3 * VRRP packet crafting.
4 * Copyright (C) 2018-2019 Cumulus Networks, Inc.
8 #include <netinet/in.h>
9 #include <netinet/ip.h>
10 #include <netinet/ip6.h>
12 #include "lib/checksum.h"
13 #include "lib/ipaddr.h"
14 #include "lib/memory.h"
17 #include "vrrp_debug.h"
18 #include "vrrp_packet.h"
20 DEFINE_MTYPE_STATIC(VRRPD
, VRRP_PKT
, "VRRP packet");
22 /* clang-format off */
23 static const char *const vrrp_packet_names
[16] = {
25 [VRRP_TYPE_ADVERTISEMENT
] = "ADVERTISEMENT",
44 * Compute the VRRP checksum.
46 * Checksum is not set in the packet, just computed.
49 * VRRP packet, fully filled out except for checksum field.
55 * IP address that pkt will be transmitted from.
58 * VRRP checksum in network byte order.
60 static uint16_t vrrp_pkt_checksum(struct vrrp_pkt
*pkt
, size_t pktsize
,
61 struct ipaddr
*src
, bool ipv4_ph
)
64 bool v6
= (src
->ipa_type
== IPADDR_V6
);
66 uint16_t chksum_pre
= pkt
->hdr
.chksum
;
71 struct ipv6_ph ph
= {};
73 ph
.src
= src
->ipaddr_v6
;
74 inet_pton(AF_INET6
, VRRP_MCASTV6_GROUP_STR
, &ph
.dst
);
75 ph
.ulpl
= htons(pktsize
);
76 ph
.next_hdr
= IPPROTO_VRRP
;
77 chksum
= in_cksum_with_ph6(&ph
, pkt
, pktsize
);
78 } else if (!v6
&& ((pkt
->hdr
.vertype
>> 4) == 3)) {
80 struct ipv4_ph ph
= {};
82 ph
.src
= src
->ipaddr_v4
;
83 inet_pton(AF_INET
, VRRP_MCASTV4_GROUP_STR
, &ph
.dst
);
84 ph
.proto
= IPPROTO_VRRP
;
85 ph
.len
= htons(pktsize
);
86 chksum
= in_cksum_with_ph4(&ph
, pkt
, pktsize
);
88 chksum
= in_cksum(pkt
, pktsize
);
89 } else if (!v6
&& ((pkt
->hdr
.vertype
>> 4) == 2)) {
90 chksum
= in_cksum(pkt
, pktsize
);
92 assert(!"Invalid VRRP protocol version");
95 pkt
->hdr
.chksum
= chksum_pre
;
100 ssize_t
vrrp_pkt_adver_build(struct vrrp_pkt
**pkt
, struct ipaddr
*src
,
101 uint8_t version
, uint8_t vrid
, uint8_t prio
,
102 uint16_t max_adver_int
, uint8_t numip
,
103 struct ipaddr
**ips
, bool ipv4_ph
)
108 assert(version
>= 2 && version
<= 3);
111 v6
= IS_IPADDR_V6(ips
[0]);
112 addrsz
= IPADDRSZ(ips
[0]);
115 assert(!(version
== 2 && v6
));
117 size_t pktsize
= VRRP_PKT_SIZE(v6
? AF_INET6
: AF_INET
, version
, numip
);
119 *pkt
= XCALLOC(MTYPE_VRRP_PKT
, pktsize
);
121 (*pkt
)->hdr
.vertype
|= version
<< 4;
122 (*pkt
)->hdr
.vertype
|= VRRP_TYPE_ADVERTISEMENT
;
123 (*pkt
)->hdr
.vrid
= vrid
;
124 (*pkt
)->hdr
.priority
= prio
;
125 (*pkt
)->hdr
.naddr
= numip
;
127 (*pkt
)->hdr
.v3
.adver_int
= htons(max_adver_int
);
128 else if (version
== 2) {
129 (*pkt
)->hdr
.v2
.auth_type
= 0;
130 (*pkt
)->hdr
.v2
.adver_int
= MAX(max_adver_int
/ 100, 1);
133 uint8_t *aptr
= (void *)(*pkt
)->addrs
;
135 for (int i
= 0; i
< numip
; i
++) {
136 memcpy(aptr
, &ips
[i
]->ip
.addr
, addrsz
);
140 (*pkt
)->hdr
.chksum
= vrrp_pkt_checksum(*pkt
, pktsize
, src
, ipv4_ph
);
145 void vrrp_pkt_free(struct vrrp_pkt
*pkt
)
147 XFREE(MTYPE_VRRP_PKT
, pkt
);
150 size_t vrrp_pkt_adver_dump(char *buf
, size_t buflen
, struct vrrp_pkt
*pkt
)
157 struct vrrp_hdr
*hdr
= &pkt
->hdr
;
160 snprintf(tmpbuf
, sizeof(tmpbuf
), "version %u, ", (hdr
->vertype
>> 4));
161 rs
+= strlcat(buf
, tmpbuf
, buflen
);
162 snprintf(tmpbuf
, sizeof(tmpbuf
), "type %u (%s), ",
163 (hdr
->vertype
& 0x0F),
164 vrrp_packet_names
[(hdr
->vertype
& 0x0F)]);
165 rs
+= strlcat(buf
, tmpbuf
, buflen
);
166 snprintf(tmpbuf
, sizeof(tmpbuf
), "vrid %u, ", hdr
->vrid
);
167 rs
+= strlcat(buf
, tmpbuf
, buflen
);
168 snprintf(tmpbuf
, sizeof(tmpbuf
), "priority %u, ", hdr
->priority
);
169 rs
+= strlcat(buf
, tmpbuf
, buflen
);
170 snprintf(tmpbuf
, sizeof(tmpbuf
), "#%u addresses, ", hdr
->naddr
);
171 rs
+= strlcat(buf
, tmpbuf
, buflen
);
172 snprintf(tmpbuf
, sizeof(tmpbuf
), "max adver int %u, ",
173 ntohs(hdr
->v3
.adver_int
));
174 rs
+= strlcat(buf
, tmpbuf
, buflen
);
175 snprintf(tmpbuf
, sizeof(tmpbuf
), "checksum %x", ntohs(hdr
->chksum
));
176 rs
+= strlcat(buf
, tmpbuf
, buflen
);
181 ssize_t
vrrp_pkt_parse_datagram(int family
, int version
, bool ipv4_ph
,
182 struct msghdr
*m
, size_t read
,
183 struct ipaddr
*src
, struct vrrp_pkt
**pkt
,
184 char *errmsg
, size_t errmsg_len
)
186 /* Source (MAC & IP), Dest (MAC & IP) TTL validation done by kernel */
187 size_t addrsz
= (family
== AF_INET
) ? sizeof(struct in_addr
)
188 : sizeof(struct in6_addr
);
191 uint8_t *buf
= m
->msg_iov
->iov_base
;
193 #define VRRP_PKT_VCHECK(cond, _f, ...) \
197 snprintf(errmsg, errmsg_len, (_f), \
203 /* IPvX header check */
205 if (family
== AF_INET
) {
207 read
>= sizeof(struct ip
),
208 "Datagram not large enough to contain IP header");
210 struct ip
*ip
= (struct ip
*)buf
;
212 /* IP total length check */
214 ntohs(ip
->ip_len
) == read
,
215 "IPv4 packet length field does not match # received bytes; %hu!= %zu",
216 ntohs(ip
->ip_len
), read
);
219 VRRP_PKT_VCHECK(ip
->ip_ttl
== 255,
220 "IPv4 TTL is %hhu; should be 255",
223 *pkt
= (struct vrrp_pkt
*)(buf
+ (ip
->ip_hl
<< 2));
224 pktsize
= read
- (ip
->ip_hl
<< 2);
226 /* IP empty packet check */
227 VRRP_PKT_VCHECK(pktsize
> 0, "IPv4 packet has no payload");
229 /* Extract source address */
230 struct sockaddr_in
*sa
= m
->msg_name
;
232 src
->ipa_type
= IPADDR_V4
;
233 src
->ipaddr_v4
= sa
->sin_addr
;
234 } else if (family
== AF_INET6
) {
237 for (c
= CMSG_FIRSTHDR(m
); c
!= NULL
; CMSG_NXTHDR(m
, c
)) {
238 if (c
->cmsg_level
== IPPROTO_IPV6
239 && c
->cmsg_type
== IPV6_HOPLIMIT
)
243 VRRP_PKT_VCHECK(!!c
, "IPv6 Hop Limit not received");
245 uint8_t *hoplimit
= CMSG_DATA(c
);
247 VRRP_PKT_VCHECK(*hoplimit
== 255,
248 "IPv6 Hop Limit is %hhu; should be 255",
251 *pkt
= (struct vrrp_pkt
*)buf
;
254 /* Extract source address */
255 struct sockaddr_in6
*sa
= m
->msg_name
;
257 src
->ipa_type
= IPADDR_V6
;
258 memcpy(&src
->ipaddr_v6
, &sa
->sin6_addr
,
259 sizeof(struct in6_addr
));
261 assert(!"Unknown address family");
265 size_t minsize
= (family
== AF_INET
) ? VRRP_MIN_PKT_SIZE_V4
266 : VRRP_MIN_PKT_SIZE_V6
;
267 size_t maxsize
= (family
== AF_INET
) ? VRRP_MAX_PKT_SIZE_V4
268 : VRRP_MAX_PKT_SIZE_V6
;
269 VRRP_PKT_VCHECK(pktsize
>= minsize
,
270 "VRRP packet is undersized (%zu < %zu)", pktsize
,
272 VRRP_PKT_VCHECK(pktsize
<= maxsize
,
273 "VRRP packet is oversized (%zu > %zu)", pktsize
,
277 uint8_t pktver
= (*pkt
)->hdr
.vertype
>> 4;
279 VRRP_PKT_VCHECK(pktver
== version
, "Bad version %u", pktver
);
282 uint16_t chksum
= vrrp_pkt_checksum(*pkt
, pktsize
, src
, ipv4_ph
);
284 VRRP_PKT_VCHECK((*pkt
)->hdr
.chksum
== chksum
,
285 "Bad VRRP checksum %hx; should be %hx",
286 (*pkt
)->hdr
.chksum
, chksum
);
289 VRRP_PKT_VCHECK(((*pkt
)->hdr
.vertype
& 0x0F) == 1, "Bad type %u",
290 (*pkt
)->hdr
.vertype
& 0x0f);
292 /* Exact size check */
293 size_t ves
= VRRP_PKT_SIZE(family
, pktver
, (*pkt
)->hdr
.naddr
);
295 VRRP_PKT_VCHECK(pktsize
== ves
, "Packet has incorrect # addresses%s",
296 pktver
== 2 ? " or missing auth fields" : "");
298 /* auth type check */
300 VRRP_PKT_VCHECK((*pkt
)->hdr
.v2
.auth_type
== 0,
301 "Bad authentication type %hhu",
302 (*pkt
)->hdr
.v2
.auth_type
);
304 /* Addresses check */
305 char vbuf
[INET6_ADDRSTRLEN
];
306 uint8_t *p
= (uint8_t *)(*pkt
)->addrs
;
308 for (uint8_t i
= 0; i
< (*pkt
)->hdr
.naddr
; i
++) {
309 VRRP_PKT_VCHECK(inet_ntop(family
, p
, vbuf
, sizeof(vbuf
)),
310 "Bad IP address, #%hhu", i
);
314 /* Everything checks out */