icmp: let icmp use mac address from flowside structure

Even ICMP needs to be updated to use the external MAC address instead
of just the own tap address when applicable. We do that here.

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

5 files changed, 25 insertions, 11 deletions

diff --git a/icmp.c b/icmp.c
index 6dffafb..158b98f 100644
--- a/icmp.c
+++ b/icmp.c
@@ -125,17 +125,21 @@ void icmp_sock_handler(const struct ctx *c, union epoll_ref ref)
 	flow_dbg(pingf, "echo reply to tap, ID: %"PRIu16", seq: %"PRIu16,
 		 ini->eport, seq);
 
+	/* Check if neighbour table has a recorded MAC address */
+	if (MAC_IS_UNDEF(pingf->f.tap_omac))
+		fwd_neigh_mac_get(c, &ini->oaddr, pingf->f.tap_omac);
+
 	if (pingf->f.type == FLOW_PING4) {
 		const struct in_addr *saddr = inany_v4(&ini->oaddr);
 		const struct in_addr *daddr = inany_v4(&ini->eaddr);
 
 		ASSERT(saddr && daddr); /* Must have IPv4 addresses */
-		tap_icmp4_send(c, *saddr, *daddr, buf, n);
+		tap_icmp4_send(c, *saddr, *daddr, buf, pingf->f.tap_omac, n);
 	} else if (pingf->f.type == FLOW_PING6) {
 		const struct in6_addr *saddr = &ini->oaddr.a6;
 		const struct in6_addr *daddr = &ini->eaddr.a6;
 
-		tap_icmp6_send(c, saddr, daddr, buf, n);
+		tap_icmp6_send(c, saddr, daddr, buf, pingf->f.tap_omac, n);
 	}
 	return;
 
diff --git a/ndp.c b/ndp.c
index 430d420..a33239d 100644
--- a/ndp.c
+++ b/ndp.c
@@ -184,7 +184,7 @@ static void ndp_send(const struct ctx *c, const struct in6_addr *dst,
 {
 	const struct in6_addr *src = &c->ip6.our_tap_ll;
 
-	tap_icmp6_send(c, src, dst, buf, l4len);
+	tap_icmp6_send(c, src, dst, buf, c->our_tap_mac, l4len);
 }
 
 /**
diff --git a/tap.c b/tap.c
index 8906b24..7d79f95 100644
--- a/tap.c
+++ b/tap.c
@@ -277,13 +277,14 @@ void tap_udp4_send(const struct ctx *c, struct in_addr src, in_port_t sport,
  * @src:	IPv4 source address
  * @dst:	IPv4 destination address
  * @in:		ICMP packet, including ICMP header
+ * @src_mac:	MAC address to be used as source for message
  * @l4len:	ICMP packet length, including ICMP header
  */
 void tap_icmp4_send(const struct ctx *c, struct in_addr src, struct in_addr dst,
-		    const void *in, size_t l4len)
+		    const void *in, const void *src_mac, size_t l4len)
 {
 	char buf[USHRT_MAX];
-	struct iphdr *ip4h = tap_push_l2h(c, buf, c->our_tap_mac, ETH_P_IP);
+	struct iphdr *ip4h = tap_push_l2h(c, buf, src_mac, ETH_P_IP);
 	struct icmphdr *icmp4h = tap_push_ip4h(ip4h, src, dst,
 					       l4len, IPPROTO_ICMP);
 
@@ -384,14 +385,15 @@ void tap_udp6_send(const struct ctx *c,
  * @src:	IPv6 source address
  * @dst:	IPv6 destination address
  * @in:		ICMP packet, including ICMP header
+ * @src_mac:	MAC address to be used as source for message
  * @l4len:	ICMP packet length, including ICMP header
  */
 void tap_icmp6_send(const struct ctx *c,
 		    const struct in6_addr *src, const struct in6_addr *dst,
-		    const void *in, size_t l4len)
+		    const void *in, const void *src_mac, size_t l4len)
 {
 	char buf[USHRT_MAX];
-	struct ipv6hdr *ip6h = tap_push_l2h(c, buf, c->our_tap_mac, ETH_P_IPV6);
+	struct ipv6hdr *ip6h = tap_push_l2h(c, buf, src_mac, ETH_P_IPV6);
 	struct icmp6hdr *icmp6h = tap_push_ip6h(ip6h, src, dst, l4len,
 						IPPROTO_ICMPV6, 0);
 
diff --git a/tap.h b/tap.h
index 02f7761..1864173 100644
--- a/tap.h
+++ b/tap.h
@@ -91,7 +91,7 @@ void tap_udp4_send(const struct ctx *c, struct in_addr src, in_port_t sport,
 		   struct in_addr dst, in_port_t dport,
 		   const void *in, size_t dlen);
 void tap_icmp4_send(const struct ctx *c, struct in_addr src, struct in_addr dst,
-		    const void *in, size_t l4len);
+		    const void *in, const void *src_mac, size_t l4len);
 const struct in6_addr *tap_ip6_daddr(const struct ctx *c,
 				     const struct in6_addr *src);
 void *tap_push_ip6h(struct ipv6hdr *ip6h,
@@ -103,7 +103,7 @@ void tap_udp6_send(const struct ctx *c,
 		   uint32_t flow, void *in, size_t dlen);
 void tap_icmp6_send(const struct ctx *c,
 		    const struct in6_addr *src, const struct in6_addr *dst,
-		    const void *in, size_t l4len);
+		    const void *in, const void *src_mac, size_t l4len);
 void tap_send_single(const struct ctx *c, const void *data, size_t l2len);
 size_t tap_send_frames(const struct ctx *c, const struct iovec *iov,
 		       size_t bufs_per_frame, size_t nframes);
diff --git a/udp.c b/udp.c
index 3acc401..3981e9b 100644
--- a/udp.c
+++ b/udp.c
@@ -400,6 +400,8 @@ static void udp_send_tap_icmp4(const struct ctx *c,
 	struct in_addr eaddr = toside->eaddr.v4mapped.a4;
 	in_port_t eport = toside->eport;
 	in_port_t oport = toside->oport;
+	union inany_addr saddr_any;
+	uint8_t tap_omac[ETH_ALEN];
 	struct {
 		struct icmphdr icmp4h;
 		struct iphdr ip4h;
@@ -421,7 +423,10 @@ static void udp_send_tap_icmp4(const struct ctx *c,
 	tap_push_uh4(&msg.uh, eaddr, eport, oaddr, oport, in, dlen);
 	memcpy(&msg.data, in, dlen);
 
-	tap_icmp4_send(c, saddr, eaddr, &msg, msglen);
+	/* Try to obtain the MAC address of the generating node */
+	saddr_any = inany_from_v4(saddr);
+	fwd_neigh_mac_get(c, &saddr_any, tap_omac);
+	tap_icmp4_send(c, saddr, eaddr, &msg, tap_omac, msglen);
 }
 
 
@@ -445,6 +450,7 @@ static void udp_send_tap_icmp6(const struct ctx *c,
 	const struct in6_addr *eaddr = &toside->eaddr.a6;
 	in_port_t eport = toside->eport;
 	in_port_t oport = toside->oport;
+	uint8_t tap_omac[ETH_ALEN];
 	struct {
 		struct icmp6_hdr icmp6h;
 		struct ipv6hdr ip6h;
@@ -466,7 +472,9 @@ static void udp_send_tap_icmp6(const struct ctx *c,
 	tap_push_uh6(&msg.uh, eaddr, eport, oaddr, oport, in, dlen);
 	memcpy(&msg.data, in, dlen);
 
-	tap_icmp6_send(c, saddr, eaddr, &msg, msglen);
+	/* Try to obtain the MAC address of the generating node */
+	fwd_neigh_mac_get(c, (union inany_addr *) saddr, tap_omac);
+	tap_icmp6_send(c, saddr, eaddr, &msg, tap_omac, msglen);
 }
 
 /**