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icmp: Consolidate icmp_sock_handler() with icmpv6_sock_handler()

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Currently we have separate handlers for ICMP and ICMPv6 ping replies.
Although there are a number of points of difference, with some creative
refactoring we can combine these together sensibly.  Although it doesn't
save a vast amount of code, it does make it clearer that we're performing
basically the same steps for each case.

Signed-off-by: David Gibson <david@gibson.dropbear.id.au>
Signed-off-by: Stefano Brivio <sbrivio@redhat.com>
This commit is contained in:
David Gibson 2024-01-16 16:16:15 +11:00 committed by Stefano Brivio
parent 70d43f9c05
commit a325121759
3 changed files with 37 additions and 59 deletions
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89
icmp.c
View file

@ -57,85 +57,64 @@ struct icmp_id_sock {
static struct icmp_id_sock icmp_id_map[IP_VERSIONS][ICMP_NUM_IDS];
/**
* icmp_sock_handler() - Handle new data from IPv4 ICMP socket
* icmp_sock_handler() - Handle new data from ICMP or ICMPv6 socket
* @c: Execution context
* @af: Address family (AF_INET or AF_INET6)
* @ref: epoll reference
*/
void icmp_sock_handler(const struct ctx *c, union epoll_ref ref)
void icmp_sock_handler(const struct ctx *c, int af, union epoll_ref ref)
{
struct icmp_id_sock *const id_sock = af == AF_INET
? &icmp_id_map[V4][ref.icmp.id] : &icmp_id_map[V6][ref.icmp.id];
const char *const pname = af == AF_INET ? "ICMP" : "ICMPv6";
char buf[USHRT_MAX];
struct icmphdr *ih = (struct icmphdr *)buf;
struct sockaddr_in sr;
union {
struct sockaddr sa;
struct sockaddr_in sa4;
struct sockaddr_in6 sa6;
} sr;
socklen_t sl = sizeof(sr);
uint16_t seq, id;
uint16_t seq;
ssize_t n;
if (c->no_icmp)
return;
n = recvfrom(ref.fd, buf, sizeof(buf), 0, (struct sockaddr *)&sr, &sl);
n = recvfrom(ref.fd, buf, sizeof(buf), 0, &sr.sa, &sl);
if (n < 0)
return;
seq = ntohs(ih->un.echo.sequence);
if (af == AF_INET) {
struct icmphdr *ih4 = (struct icmphdr *)buf;
/* Adjust the packet to have the ID the guest was using, rather than the
* host chosen value */
id = ref.icmp.id;
ih->un.echo.id = htons(id);
/* Adjust packet back to guest-side ID */
ih4->un.echo.id = htons(ref.icmp.id);
seq = ntohs(ih4->un.echo.sequence);
} else if (af == AF_INET6) {
struct icmp6hdr *ih6 = (struct icmp6hdr *)buf;
if (c->mode == MODE_PASTA) {
if (icmp_id_map[V4][id].seq == seq)
return;
icmp_id_map[V4][id].seq = seq;
/* Adjust packet back to guest-side ID */
ih6->icmp6_identifier = htons(ref.icmp.id);
seq = ntohs(ih6->icmp6_sequence);
} else {
ASSERT(0);
}
debug("ICMP: echo reply to tap, ID: %i, seq: %i", id, seq);
tap_icmp4_send(c, sr.sin_addr, tap_ip4_daddr(c), buf, n);
}
/**
* icmpv6_sock_handler() - Handle new data from ICMPv6 socket
* @c: Execution context
* @ref: epoll reference
*/
void icmpv6_sock_handler(const struct ctx *c, union epoll_ref ref)
{
char buf[USHRT_MAX];
struct icmp6hdr *ih = (struct icmp6hdr *)buf;
struct sockaddr_in6 sr;
socklen_t sl = sizeof(sr);
uint16_t seq, id;
ssize_t n;
if (c->no_icmp)
return;
n = recvfrom(ref.fd, buf, sizeof(buf), 0, (struct sockaddr *)&sr, &sl);
if (n < 0)
return;
seq = ntohs(ih->icmp6_sequence);
/* Adjust the packet to have the ID the guest was using, rather than the
* host chosen value */
id = ref.icmp.id;
ih->icmp6_identifier = htons(id);
/* In PASTA mode, we'll get any reply we send, discard them. */
if (c->mode == MODE_PASTA) {
if (icmp_id_map[V6][id].seq == seq)
if (id_sock->seq == seq)
return;
icmp_id_map[V6][id].seq = seq;
id_sock->seq = seq;
}
debug("ICMPv6: echo reply to tap, ID: %i, seq: %i", id, seq);
tap_icmp6_send(c, &sr.sin6_addr,
tap_ip6_daddr(c, &sr.sin6_addr), buf, n);
debug("%s: echo reply to tap, ID: %"PRIu16", seq: %"PRIu16, pname,
ref.icmp.id, seq);
if (af == AF_INET)
tap_icmp4_send(c, sr.sa4.sin_addr, tap_ip4_daddr(c), buf, n);
else if (af == AF_INET6)
tap_icmp6_send(c, &sr.sa6.sin6_addr,
tap_ip6_daddr(c, &sr.sa6.sin6_addr), buf, n);
}
/**

3
icmp.h
View file

@ -10,8 +10,7 @@
struct ctx;
void icmp_sock_handler(const struct ctx *c, union epoll_ref ref);
void icmpv6_sock_handler(const struct ctx *c, union epoll_ref ref);
void icmp_sock_handler(const struct ctx *c, int af, union epoll_ref ref);
int icmp_tap_handler(const struct ctx *c, uint8_t pif, int af,
const void *saddr, const void *daddr,
const struct pool *p, const struct timespec *now);

4
passt.c
View file

@ -392,10 +392,10 @@ loop:
udp_sock_handler(&c, ref, eventmask, &now);
break;
case EPOLL_TYPE_ICMP:
icmp_sock_handler(&c, ref);
icmp_sock_handler(&c, AF_INET, ref);
break;
case EPOLL_TYPE_ICMPV6:
icmpv6_sock_handler(&c, ref);
icmp_sock_handler(&c, AF_INET6, ref);
break;
default:
/* Can't happen */