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Diffstat (limited to 'vrrpd/vrrp_packet.h')
| -rw-r--r-- | vrrpd/vrrp_packet.h | 203 |
1 files changed, 203 insertions, 0 deletions
diff --git a/vrrpd/vrrp_packet.h b/vrrpd/vrrp_packet.h new file mode 100644 index 0000000..082935f --- /dev/null +++ b/vrrpd/vrrp_packet.h @@ -0,0 +1,203 @@ +/* + * VRRP packet crafting. + * Copyright (C) 2018-2019 Cumulus Networks, Inc. + * Quentin Young + * + * This program is free software; you can redistribute it and/or modify it + * under the terms of the GNU General Public License as published by the Free + * Software Foundation; either version 2 of the License, or (at your option) + * any later version. + * + * This program is distributed in the hope that it will be useful, but WITHOUT + * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or + * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for + * more details. + * + * You should have received a copy of the GNU General Public License along + * with this program; see the file COPYING; if not, write to the Free Software + * Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA + */ +#ifndef __VRRP_PACKET_H__ +#define __VRRP_PACKET_H__ + +#include <zebra.h> + +#include "lib/ipaddr.h" +#include "lib/memory.h" +#include "lib/prefix.h" + +#define VRRP_TYPE_ADVERTISEMENT 1 + +/* + * Shared header for VRRPv2/v3 packets. + */ +struct vrrp_hdr { + /* + * H L H L + * 0000 0000 + * ver type + */ + uint8_t vertype; + uint8_t vrid; + uint8_t priority; + uint8_t naddr; + union { + struct { + uint8_t auth_type; + /* advertisement interval (in sec) */ + uint8_t adver_int; + } v2; + struct { + /* + * advertisement interval (in centiseconds) + * H L H L + * 0000 000000000000 + * rsvd adver_int + */ + uint16_t adver_int; + } v3; + }; + uint16_t chksum; +} __attribute__((packed)); + +#define VRRP_HDR_SIZE sizeof(struct vrrp_hdr) + +struct vrrp_pkt { + struct vrrp_hdr hdr; + /* + * When used, this is actually an array of one or the other, not an + * array of union. If N v4 addresses are stored then + * sizeof(addrs) == N * sizeof(struct in_addr). + * + * Under v2, the last 2 entries in this array are the authentication + * data fields. We don't support auth in v2 so these are always just 8 + * bytes of 0x00. + */ + union { + struct in_addr v4; + struct in6_addr v6; + } addrs[]; +} __attribute__((packed)); + +#define VRRP_PKT_SIZE(_f, _ver, _naddr) \ + ({ \ + size_t _asz = ((_f) == AF_INET) ? sizeof(struct in_addr) \ + : sizeof(struct in6_addr); \ + size_t _auth = 2 * sizeof(uint32_t) * (3 - (_ver)); \ + sizeof(struct vrrp_hdr) + (_asz * (_naddr)) + _auth; \ + }) + +#define VRRP_MIN_PKT_SIZE_V4 VRRP_PKT_SIZE(AF_INET, 3, 1) +#define VRRP_MAX_PKT_SIZE_V4 VRRP_PKT_SIZE(AF_INET, 2, 255) +#define VRRP_MIN_PKT_SIZE_V6 VRRP_PKT_SIZE(AF_INET6, 3, 1) +#define VRRP_MAX_PKT_SIZE_V6 VRRP_PKT_SIZE(AF_INET6, 3, 255) + +#define VRRP_MIN_PKT_SIZE VRRP_MIN_PKT_SIZE_V4 +#define VRRP_MAX_PKT_SIZE VRRP_MAX_PKT_SIZE_V6 + +/* + * Builds a VRRP ADVERTISEMENT packet. + * + * pkt + * Pointer to store pointer to result buffer in + * + * src + * Source address packet will be transmitted from. This is needed to compute + * the VRRP checksum. The returned packet must be sent in an IP datagram with + * the source address equal to this field, or the checksum will be invalid. + * + * version + * VRRP version; must be 2 or 3 + * + * vrid + * Virtual Router Identifier + * + * prio + * Virtual Router Priority + * + * max_adver_int + * time between ADVERTISEMENTs + * + * v6 + * whether 'ips' is an array of v4 or v6 addresses + * + * numip + * number of IPvX addresses in 'ips' + * + * ips + * array of pointer to either struct in_addr (v6 = false) or struct in6_addr + * (v6 = true) + */ +ssize_t vrrp_pkt_adver_build(struct vrrp_pkt **pkt, struct ipaddr *src, + uint8_t version, uint8_t vrid, uint8_t prio, + uint16_t max_adver_int, uint8_t numip, + struct ipaddr **ips); + +/* free memory allocated by vrrp_pkt_adver_build's pkt arg */ +void vrrp_pkt_free(struct vrrp_pkt *pkt); + +/* + * Dumps a VRRP ADVERTISEMENT packet to a string. + * + * Currently only dumps the header. + * + * buf + * Buffer to store string representation + * + * buflen + * Size of buf + * + * pkt + * Packet to dump to a string + * + * Returns: + * # bytes written to buf + */ +size_t vrrp_pkt_adver_dump(char *buf, size_t buflen, struct vrrp_pkt *pkt); + + +/* + * Parses a VRRP packet, checking for illegal or invalid data. + * + * This function parses both VRRPv2 and VRRPv3 packets. Which version is + * expected is determined by the version argument. For example, if version is 3 + * and the received packet has version field 2 it will fail to parse. + * + * Note that this function only checks whether the packet itself is a valid + * VRRP packet. It is up to the caller to validate whether the VRID is correct, + * priority and timer values are correct, etc. + * + * family + * Address family of received packet + * + * version + * VRRP version to use for validation + * + * m + * msghdr containing results of recvmsg() on VRRP router socket + * + * read + * Return value of recvmsg() on VRRP router socket; must be non-negative + * + * src + * Pointer to struct ipaddr to store address of datagram sender + * + * pkt + * Pointer to pointer to set to location of VRRP packet within buf + * + * errmsg + * Buffer to store human-readable error message in case of error; may be + * NULL, in which case no message will be stored + * + * errmsg_len + * Size of errmsg + * + * Returns: + * Size of VRRP packet, or -1 upon error + */ +ssize_t vrrp_pkt_parse_datagram(int family, int version, struct msghdr *m, + size_t read, struct ipaddr *src, + struct vrrp_pkt **pkt, char *errmsg, + size_t errmsg_len); + +#endif /* __VRRP_PACKET_H__ */ |