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/*
* 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, bool ipv4_ph);
/* 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, bool ipv4_ph,
struct msghdr *m, size_t read,
struct ipaddr *src, struct vrrp_pkt **pkt,
char *errmsg, size_t errmsg_len);
#endif /* __VRRP_PACKET_H__ */
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