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vrrpd: cleanup vrrp packet crafting code

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* Prefix all packet functions with 'vrrp_pkt'
* Break out checksum computation into separate function
* Accept version field when building advertisements
* Update doc comments

Signed-off-by: Quentin Young <qlyoung@cumulusnetworks.com>
This commit is contained in:
Quentin Young 2019-02-01 18:49:16 +00:00
parent 72df9d93a5
commit d9e01e1cab
3 changed files with 87 additions and 45 deletions
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20
vrrpd/vrrp.c
View File

@ -424,18 +424,18 @@ static int vrrp_master_down_timer_expire(struct thread *thread);
static void vrrp_send_advertisement(struct vrrp_router *r)
{
struct vrrp_pkt *pkt;
ssize_t pktlen;
ssize_t pktsz;
struct ipaddr *addrs[r->addrs->count];
union sockunion dest;
list_to_array(r->addrs, (void **)addrs, r->addrs->count);
pktlen = vrrp_pkt_build(&pkt, &r->src, r->vr->vrid, r->priority,
r->vr->advertisement_interval, r->addrs->count,
(struct ipaddr **)&addrs);
pktsz = vrrp_pkt_adver_build(&pkt, &r->src, 3, r->vr->vrid, r->priority,
r->vr->advertisement_interval,
r->addrs->count, (struct ipaddr **)&addrs);
if (pktlen > 0)
zlog_hexdump(pkt, (size_t) pktlen);
if (pktsz > 0)
zlog_hexdump(pkt, (size_t) pktsz);
else
zlog_warn("Could not build VRRP packet");
@ -443,7 +443,7 @@ static void vrrp_send_advertisement(struct vrrp_router *r)
r->family == AF_INET ? VRRP_MCASTV4_GROUP_STR : VRRP_MCASTV6_GROUP_STR;
str2sockunion(group, &dest);
ssize_t sent = sendto(r->sock_tx, pkt, (size_t)pktlen, 0, &dest.sa,
ssize_t sent = sendto(r->sock_tx, pkt, (size_t)pktsz, 0, &dest.sa,
sockunion_sizeof(&dest));
XFREE(MTYPE_VRRP_PKT, pkt);
@ -469,7 +469,7 @@ static int vrrp_recv_advertisement(struct vrrp_router *r, struct vrrp_pkt *pkt,
size_t pktsize)
{
char dumpbuf[BUFSIZ];
vrrp_pkt_dump(dumpbuf, sizeof(dumpbuf), pkt);
vrrp_pkt_adver_dump(dumpbuf, sizeof(dumpbuf), pkt);
zlog_debug("Received VRRP Advertisement:\n%s", dumpbuf);
/* Check that VRID matches our configured VRID */
@ -595,8 +595,8 @@ static int vrrp_read(struct thread *thread)
r->vr->vrid, family2str(r->family));
zlog_hexdump(r->ibuf, nbytes);
pktsize = vrrp_parse_datagram(r->family, &m, nbytes, &pkt, errbuf,
sizeof(errbuf));
pktsize = vrrp_pkt_parse_datagram(r->family, &m, nbytes, &pkt, errbuf,
sizeof(errbuf));
if (pktsize < 0) {
zlog_warn(VRRP_LOGPFX VRRP_LOGPFX_VRID

84
vrrpd/vrrp_packet.c
View File

@ -51,17 +51,67 @@ const char *vrrp_packet_names[16] = {
};
/* clang-format on */
ssize_t vrrp_pkt_build(struct vrrp_pkt **pkt, struct ipaddr *src, uint8_t vrid,
uint8_t prio, uint16_t max_adver_int, uint8_t numip,
struct ipaddr **ips)
/*
* Compute the VRRP checksum.
*
* Checksum is not set in the packet, just computed.
*
* pkt
* VRRP packet, fully filled out except for checksum field.
*
* pktsize
* sizeof(*pkt)
*
* src
* IP address that pkt will be transmitted from.
*
* Returns:
* VRRP checksum in network byte order.
*/
static uint16_t vrrp_pkt_checksum(struct vrrp_pkt *pkt, size_t pktsize,
struct ipaddr *src)
{
uint16_t chksum;
bool v6 = (src->ipa_type == IPADDR_V6);
uint16_t chksum_pre = pkt->hdr.chksum;
pkt->hdr.chksum = 0;
if (v6) {
struct ipv6_ph ph = {};
ph.src = src->ipaddr_v6;
inet_pton(AF_INET6, VRRP_MCASTV6_GROUP_STR, &ph.dst);
ph.ulpl = htons(pktsize);
ph.next_hdr = 112;
chksum = in_cksum_with_ph6(&ph, pkt, pktsize);
} else {
struct ipv4_ph ph = {};
ph.src = src->ipaddr_v4;
inet_pton(AF_INET, VRRP_MCASTV4_GROUP_STR, &ph.dst);
ph.proto = 112;
ph.len = htons(pktsize);
chksum = in_cksum_with_ph4(&ph, pkt, pktsize);
}
pkt->hdr.chksum = chksum_pre;
return chksum;
}
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)
{
assert(version >= 2 && version <= 3);
bool v6 = IS_IPADDR_V6(ips[0]);
size_t addrsz = v6 ? sizeof(struct in6_addr) : sizeof(struct in_addr);
size_t pktsize = VRRP_PKT_SIZE(v6 ? AF_INET6 : AF_INET, numip);
*pkt = XCALLOC(MTYPE_VRRP_PKT, pktsize);
(*pkt)->hdr.vertype |= VRRP_VERSION << 4;
(*pkt)->hdr.vertype |= version << 4;
(*pkt)->hdr.vertype |= VRRP_TYPE_ADVERTISEMENT;
(*pkt)->hdr.vrid = vrid;
(*pkt)->hdr.priority = prio;
@ -75,28 +125,12 @@ ssize_t vrrp_pkt_build(struct vrrp_pkt **pkt, struct ipaddr *src, uint8_t vrid,
aptr += addrsz;
}
(*pkt)->hdr.chksum = 0;
if (v6) {
struct ipv6_ph ph = {};
ph.src = src->ipaddr_v6;
inet_pton(AF_INET6, VRRP_MCASTV6_GROUP_STR, &ph.dst);
ph.ulpl = htons(pktsize);
ph.next_hdr = 112;
(*pkt)->hdr.chksum = in_cksum_with_ph6(&ph, *pkt, pktsize);
} else {
struct ipv4_ph ph = {};
ph.src = src->ipaddr_v4;
inet_pton(AF_INET, VRRP_MCASTV4_GROUP_STR, &ph.dst);
ph.proto = 112;
ph.len = htons(pktsize);
(*pkt)->hdr.chksum = in_cksum_with_ph4(&ph, *pkt, pktsize);
}
(*pkt)->hdr.chksum = vrrp_pkt_checksum(*pkt, pktsize, src);
return pktsize;
}
size_t vrrp_pkt_dump(char *buf, size_t buflen, struct vrrp_pkt *pkt)
size_t vrrp_pkt_adver_dump(char *buf, size_t buflen, struct vrrp_pkt *pkt)
{
if (buflen < 1)
return 0;
@ -127,9 +161,9 @@ size_t vrrp_pkt_dump(char *buf, size_t buflen, struct vrrp_pkt *pkt)
return rs;
}
ssize_t vrrp_parse_datagram(int family, struct msghdr *m, size_t read,
struct vrrp_pkt **pkt, char *errmsg,
size_t errmsg_len)
ssize_t vrrp_pkt_parse_datagram(int family, struct msghdr *m, size_t read,
struct vrrp_pkt **pkt, char *errmsg,
size_t errmsg_len)
{
/* Source (MAC & IP), Dest (MAC & IP) TTL validation done by kernel */
size_t addrsz = (family == AF_INET) ? sizeof(struct in_addr)

28
vrrpd/vrrp_packet.h
View File

@ -26,7 +26,6 @@
#include "lib/memory.h"
#include "lib/prefix.h"
#define VRRP_VERSION 3
#define VRRP_TYPE_ADVERTISEMENT 1
extern const char *vrrp_packet_names[16];
@ -94,11 +93,19 @@ struct vrrp_pkt {
#define VRRP_MAX_PKT_SIZE VRRP_MAX_PKT_SIZE_V6
/*
* Builds a VRRP packet.
* 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
*
@ -118,12 +125,13 @@ struct vrrp_pkt {
* array of pointer to either struct in_addr (v6 = false) or struct in6_addr
* (v6 = true)
*/
ssize_t vrrp_pkt_build(struct vrrp_pkt **pkt, struct ipaddr *src, uint8_t vrid,
uint8_t prio, uint16_t max_adver_int, uint8_t numip,
struct ipaddr **ips);
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);
/*
* Dumps a VRRP packet to a string.
* Dumps a VRRP ADVERTISEMENT packet to a string.
*
* Currently only dumps the header.
*
@ -139,7 +147,7 @@ ssize_t vrrp_pkt_build(struct vrrp_pkt **pkt, struct ipaddr *src, uint8_t vrid,
* Returns:
* # bytes written to buf
*/
size_t vrrp_pkt_dump(char *buf, size_t buflen, struct vrrp_pkt *pkt);
size_t vrrp_pkt_adver_dump(char *buf, size_t buflen, struct vrrp_pkt *pkt);
/*
@ -170,8 +178,8 @@ size_t vrrp_pkt_dump(char *buf, size_t buflen, struct vrrp_pkt *pkt);
* Returns:
* Size of VRRP packet, or -1 upon error
*/
ssize_t vrrp_parse_datagram(int family, struct msghdr *m, size_t read,
struct vrrp_pkt **pkt, char *errmsg,
size_t errmsg_len);
ssize_t vrrp_pkt_parse_datagram(int family, struct msghdr *m, size_t read,
struct vrrp_pkt **pkt, char *errmsg,
size_t errmsg_len);
#endif /* __VRRP_PACKET_H__ */