[PATCH v4 13/16] icmp: Look up ping flows using flow hash

[David Gibson <david@gibson.dropbear.id.au>]

When we receive a ping packet from the tap interface, we currently locate
the correct flow entry (if present) using an anciliary data structure, the
icmp_id_map[] tables.  However, we can look this up using the flow hash
table - that's what it's for.

Signed-off-by: David Gibson <david@gibson.dropbear.id.au>
---
 icmp.c | 19 +++++++++++++++----
 1 file changed, 15 insertions(+), 4 deletions(-)

diff --git a/icmp.c b/icmp.c
index e29416f..3b8f282 100644
--- a/icmp.c
+++ b/icmp.c
@@ -145,6 +145,7 @@ static void icmp_ping_close(const struct ctx *c,
 
 	epoll_ctl(c->epollfd, EPOLL_CTL_DEL, pingf->sock, NULL);
 	close(pingf->sock);
+	flow_hash_remove(c, FLOW_SIDX(pingf, TAPSIDE));
 
 	if (pingf->f.type == FLOW_PING4)
 		icmp_id_map[V4][id] = NULL;
@@ -213,6 +214,7 @@ static struct icmp_ping_flow *icmp_ping_new(const struct ctx *c,
 
 	flow_dbg(pingf, "new socket %i for echo ID %"PRIu16, pingf->sock, id);
 
+	flow_hash_insert(c, FLOW_SIDX(pingf, TAPSIDE));
 	*id_sock = pingf;
 
 	return pingf;
@@ -243,6 +245,8 @@ int icmp_tap_handler(const struct ctx *c, uint8_t pif, sa_family_t af,
 	union sockaddr_inany sa;
 	size_t dlen, l4len;
 	uint16_t id, seq;
+	union flow *flow;
+	uint8_t proto;
 	socklen_t sl;
 	void *pkt;
 
@@ -260,6 +264,7 @@ int icmp_tap_handler(const struct ctx *c, uint8_t pif, sa_family_t af,
 		if (ih->type != ICMP_ECHO)
 			return 1;
 
+		proto = IPPROTO_ICMP;
 		id = ntohs(ih->un.echo.id);
 		id_sock = &icmp_id_map[V4][id];
 		seq = ntohs(ih->un.echo.sequence);
@@ -275,6 +280,7 @@ int icmp_tap_handler(const struct ctx *c, uint8_t pif, sa_family_t af,
 		if (ih->icmp6_type != ICMPV6_ECHO_REQUEST)
 			return 1;
 
+		proto = IPPROTO_ICMPV6;
 		id = ntohs(ih->icmp6_identifier);
 		id_sock = &icmp_id_map[V6][id];
 		seq = ntohs(ih->icmp6_sequence);
@@ -282,12 +288,17 @@ int icmp_tap_handler(const struct ctx *c, uint8_t pif, sa_family_t af,
 		ASSERT(0);
 	}
 
-	if (!(pingf = *id_sock))
-		if (!(pingf = icmp_ping_new(c, id_sock, af, id,
-					    pif, saddr, daddr)))
-			return 1;
+	flow = flow_at_sidx(flow_hash_lookup(c, proto, PIF_TAP,
+					     af, saddr, daddr, id, id));
+
+	if (flow)
+		pingf = &flow->ping;
+	else if (!(pingf = icmp_ping_new(c, id_sock, af, id, pif, saddr, daddr)))
+		return 1;
 
 	sockside = &pingf->f.side[SOCKSIDE];
+
+	ASSERT(flow_proto[pingf->f.type] == proto);
 	pingf->ts = now->tv_sec;
 
 	sockaddr_from_inany(&sa, &sl, &sockside->eaddr, 0, c->ifi6);
-- 
@@ -145,6 +145,7 @@ static void icmp_ping_close(const struct ctx *c,
 
 	epoll_ctl(c->epollfd, EPOLL_CTL_DEL, pingf->sock, NULL);
 	close(pingf->sock);
+	flow_hash_remove(c, FLOW_SIDX(pingf, TAPSIDE));
 
 	if (pingf->f.type == FLOW_PING4)
 		icmp_id_map[V4][id] = NULL;
@@ -213,6 +214,7 @@ static struct icmp_ping_flow *icmp_ping_new(const struct ctx *c,
 
 	flow_dbg(pingf, "new socket %i for echo ID %"PRIu16, pingf->sock, id);
 
+	flow_hash_insert(c, FLOW_SIDX(pingf, TAPSIDE));
 	*id_sock = pingf;
 
 	return pingf;
@@ -243,6 +245,8 @@ int icmp_tap_handler(const struct ctx *c, uint8_t pif, sa_family_t af,
 	union sockaddr_inany sa;
 	size_t dlen, l4len;
 	uint16_t id, seq;
+	union flow *flow;
+	uint8_t proto;
 	socklen_t sl;
 	void *pkt;
 
@@ -260,6 +264,7 @@ int icmp_tap_handler(const struct ctx *c, uint8_t pif, sa_family_t af,
 		if (ih->type != ICMP_ECHO)
 			return 1;
 
+		proto = IPPROTO_ICMP;
 		id = ntohs(ih->un.echo.id);
 		id_sock = &icmp_id_map[V4][id];
 		seq = ntohs(ih->un.echo.sequence);
@@ -275,6 +280,7 @@ int icmp_tap_handler(const struct ctx *c, uint8_t pif, sa_family_t af,
 		if (ih->icmp6_type != ICMPV6_ECHO_REQUEST)
 			return 1;
 
+		proto = IPPROTO_ICMPV6;
 		id = ntohs(ih->icmp6_identifier);
 		id_sock = &icmp_id_map[V6][id];
 		seq = ntohs(ih->icmp6_sequence);
@@ -282,12 +288,17 @@ int icmp_tap_handler(const struct ctx *c, uint8_t pif, sa_family_t af,
 		ASSERT(0);
 	}
 
-	if (!(pingf = *id_sock))
-		if (!(pingf = icmp_ping_new(c, id_sock, af, id,
-					    pif, saddr, daddr)))
-			return 1;
+	flow = flow_at_sidx(flow_hash_lookup(c, proto, PIF_TAP,
+					     af, saddr, daddr, id, id));
+
+	if (flow)
+		pingf = &flow->ping;
+	else if (!(pingf = icmp_ping_new(c, id_sock, af, id, pif, saddr, daddr)))
+		return 1;
 
 	sockside = &pingf->f.side[SOCKSIDE];
+
+	ASSERT(flow_proto[pingf->f.type] == proto);
 	pingf->ts = now->tv_sec;
 
 	sockaddr_from_inany(&sa, &sl, &sockside->eaddr, 0, c->ifi6);
-- 
2.44.0