On Thu, 21 Dec 2023 17:53:24 +1100
David Gibson <david(a)gibson.dropbear.id.au> wrote:
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(a)gibson.dropbear.id.au>
---
icmp.c | 90 ++++++++++++++++++++++-----------------------------------
icmp.h | 3 +-
passt.c | 4 +--
3 files changed, 37 insertions(+), 60 deletions(-)
diff --git a/icmp.c b/icmp.c
index f6c744a..b26c61f 100644
--- a/icmp.c
+++ b/icmp.c
@@ -57,85 +57,63 @@ 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_map = 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);
-
- /* 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);
+ if (af == AF_INET) {
+ struct icmphdr *ih4 = (struct icmphdr *)buf;
- if (c->mode == MODE_PASTA) {
- if (icmp_id_map[V4][id].seq == seq)
- return;
+ /* 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;
- 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) {
The comment here should be kept -- the kernel behaviour was rather
surprising to me, and I would have otherwise no idea why we return
early here.