icmp: Share more between IPv4 and IPv6 paths in icmp_tap_handler()

Currently icmp_tap_handler() consists of two almost disjoint paths for the
IPv4 and IPv6 cases.  The only thing they share is an error message.
We can use some intermediate variables to refactor this to share some more
code between those paths.

Signed-off-by: David Gibson <david@gibson.dropbear.id.au>
Signed-off-by: Stefano Brivio <sbrivio@redhat.com>

1 files changed, 68 insertions, 68 deletions

diff --git a/icmp.c b/icmp.c
index 757ca61..40edd55 100644
--- a/icmp.c
+++ b/icmp.c
@@ -154,102 +154,102 @@ 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)
 {
+	uint8_t proto = af == AF_INET ? IPPROTO_ICMP : IPPROTO_ICMPV6;
+	const char *const pname = af == AF_INET ? "ICMP" : "ICMPv6";
+	union {
+		struct sockaddr sa;
+		struct sockaddr_in sa4;
+		struct sockaddr_in6 sa6;
+	} sa = { .sa.sa_family = af };
+	const socklen_t sl = af == AF_INET ? sizeof(sa.sa4) : sizeof(sa.sa6);
+	struct icmp_id_sock *id_sock;
+	uint16_t id, seq;
 	size_t plen;
+	void *pkt;
+	int s;
 
 	(void)saddr;
 	(void)pif;
 
 	if (af == AF_INET) {
-		struct sockaddr_in sa = {
-			.sin_family = AF_INET,
-		};
-		union icmp_epoll_ref iref;
 		const struct icmphdr *ih;
-		int id, s;
 
-		ih = packet_get(p, 0, 0, sizeof(*ih), &plen);
-		if (!ih)
+		if (!(pkt = packet_get(p, 0, 0, sizeof(*ih), &plen)))
 			return 1;
 
+		ih =  (struct icmphdr *)pkt;
+		plen += sizeof(*ih);
+
 		if (ih->type != ICMP_ECHO)
 			return 1;
 
-		iref.id = id = ntohs(ih->un.echo.id);
+		id = ntohs(ih->un.echo.id);
+		id_sock = &icmp_id_map[V4][id];
+		seq = ntohs(ih->un.echo.sequence);
+		sa.sa4.sin_addr = *(struct in_addr *)daddr;
+	} else if (af == AF_INET6) {
+		const struct icmp6hdr *ih;
 
-		if ((s = icmp_id_map[V4][id].sock) < 0) {
-			s = sock_l4(c, AF_INET, IPPROTO_ICMP, &c->ip4.addr_out,
-				    c->ip4.ifname_out, 0, iref.u32);
-			if (s < 0)
-				goto fail_sock;
-			if (s > FD_REF_MAX) {
-				close(s);
-				return 1;
-			}
+		if (!(pkt = packet_get(p, 0, 0, sizeof(*ih), &plen)))
+			return 1;
 
-			icmp_id_map[V4][id].sock = s;
+		ih = (struct icmp6hdr *)pkt;
+		plen += sizeof(*ih);
 
-			debug("ICMP: new socket %i for echo ID %i", s, id);
-		}
-		icmp_id_map[V4][id].ts = now->tv_sec;
+		if (ih->icmp6_type != ICMPV6_ECHO_REQUEST)
+			return 1;
+
+		id = ntohs(ih->icmp6_identifier);
+		id_sock = &icmp_id_map[V6][id];
+		seq = ntohs(ih->icmp6_sequence);
+		sa.sa6.sin6_addr = *(struct in6_addr *)daddr;
+		sa.sa6.sin6_scope_id = c->ifi6;
+	} else {
+		ASSERT(0);
+	}
 
-		sa.sin_addr = *(struct in_addr *)daddr;
-		if (sendto(s, ih, sizeof(*ih) + plen, MSG_NOSIGNAL,
-			   (struct sockaddr *)&sa, sizeof(sa)) < 0) {
-			debug("ICMP: failed to relay request to socket");
+	if ((s = id_sock->sock) < 0) {
+		union icmp_epoll_ref iref = { .id = id };
+		const void *bind_addr;
+		const char *bind_if;
+
+		if (af == AF_INET) {
+			bind_addr = &c->ip4.addr_out;
+			bind_if = c->ip4.ifname_out;
 		} else {
-			debug("ICMP: echo request to socket, ID: %i, seq: %i",
-			      id, ntohs(ih->un.echo.sequence));
+			bind_addr = &c->ip6.addr_out;
+			bind_if = c->ip6.ifname_out;
 		}
-	} else if (af == AF_INET6) {
-		struct sockaddr_in6 sa = {
-			.sin6_family = AF_INET6,
-			.sin6_scope_id = c->ifi6,
-		};
-		union icmp_epoll_ref iref;
-		const struct icmp6hdr *ih;
-		int id, s;
 
-		ih = packet_get(p, 0, 0, sizeof(struct icmp6hdr), &plen);
-		if (!ih)
-			return 1;
+		s = sock_l4(c, af, proto, bind_addr, bind_if, 0, iref.u32);
 
-		if (ih->icmp6_type != ICMPV6_ECHO_REQUEST)
+		if (s < 0) {
+			warn("Cannot open \"ping\" socket. You might need to:");
+			warn("  sysctl -w net.ipv4.ping_group_range=\"0 2147483647\"");
+			warn("...echo requests/replies will fail.");
 			return 1;
-
-		iref.id = id = ntohs(ih->icmp6_identifier);
-		if ((s = icmp_id_map[V6][id].sock) < 0) {
-			s = sock_l4(c, AF_INET6, IPPROTO_ICMPV6,
-				    &c->ip6.addr_out,
-				    c->ip6.ifname_out, 0, iref.u32);
-			if (s < 0)
-				goto fail_sock;
-			if (s > FD_REF_MAX) {
-				close(s);
-				return 1;
-			}
-
-			icmp_id_map[V6][id].sock = s;
-
-			debug("ICMPv6: new socket %i for echo ID %i", s, id);
 		}
-		icmp_id_map[V6][id].ts = now->tv_sec;
 
-		sa.sin6_addr = *(struct in6_addr *)daddr;
-		if (sendto(s, ih, sizeof(*ih) + plen, MSG_NOSIGNAL,
-			   (struct sockaddr *)&sa, sizeof(sa)) < 1) {
-			debug("ICMPv6: failed to relay request to socket");
-		} else {
-			debug("ICMPv6: echo request to socket, ID: %i, seq: %i",
-			      id, ntohs(ih->icmp6_sequence));
+		if (s > FD_REF_MAX) {
+			close(s);
+			return 1;
 		}
+
+		id_sock->sock = s;
+
+		debug("%s: new socket %i for echo ID %"PRIu16, pname, s, id);
 	}
 
-	return 1;
+	id_sock->ts = now->tv_sec;
+
+	if (sendto(s, pkt, plen, MSG_NOSIGNAL, &sa.sa, sl) < 0) {
+		debug("%s: failed to relay request to socket: %s",
+		      pname, strerror(errno));
+	} else {
+		debug("%s: echo request to socket, ID: %"PRIu16", seq: %"PRIu16,
+		      pname, id, seq);
+	}
 
-fail_sock:
-	warn("Cannot open \"ping\" socket. You might need to:");
-	warn("  sysctl -w net.ipv4.ping_group_range=\"0 2147483647\"");
-	warn("...echo requests/replies will fail.");
 	return 1;
 }