From b0a169a1465a75592f0083a3e4e17c307878fc73 Mon Sep 17 00:00:00 2001
From: Matthias Schiffer <mschiffer@universe-factory.net>
Date: Thu, 7 Jun 2012 00:56:47 +0200
Subject: Limit handshake frequency where possible

---
 src/config.c                  |  1 +
 src/fastd.c                   | 12 ++++++++++--
 src/fastd.h                   |  1 +
 src/peer.c                    |  8 ++++++++
 src/peer.h                    |  6 ++++++
 src/protocol_ec25519_fhmqvc.c | 10 +++++++++-
 6 files changed, 35 insertions(+), 3 deletions(-)

diff --git a/src/config.c b/src/config.c
index 64903cb..4613295 100644
--- a/src/config.c
+++ b/src/config.c
@@ -63,6 +63,7 @@ static void default_config(fastd_config *conf) {
 	conf->reorder_count = 64;
 	conf->reorder_time = 10;
 
+	conf->min_handshake_interval = 15;
 	conf->min_resolve_interval = 15;
 
 	conf->ifname = NULL;
diff --git a/src/fastd.c b/src/fastd.c
index 406cb53..457a488 100644
--- a/src/fastd.c
+++ b/src/fastd.c
@@ -403,8 +403,16 @@ static inline void update_time(fastd_context *ctx) {
 
 static inline void send_handshake(fastd_context *ctx, fastd_peer *peer) {
 	if (peer->address.sa.sa_family != AF_UNSPEC) {
-		pr_debug(ctx, "sending handshake to %P...", peer);
-		ctx->conf->protocol->handshake_init(ctx, &peer->address, peer->config);
+		if (timespec_diff(&ctx->now, &peer->last_handshake) < ctx->conf->min_handshake_interval*1000
+		    && fastd_peer_address_equal(&peer->address, &peer->last_handshake_address)) {
+			pr_debug(ctx, "not sending a handshake to %P as we sent one a short time ago", peer);
+		}
+		else {
+			pr_debug(ctx, "sending handshake to %P...", peer);
+			peer->last_handshake = ctx->now;
+			peer->last_handshake_address = peer->address;
+			ctx->conf->protocol->handshake_init(ctx, &peer->address, peer->config);
+		}
 	}
 
 	fastd_task_schedule_handshake(ctx, peer, fastd_rand(ctx, 17500, 22500));
diff --git a/src/fastd.h b/src/fastd.h
index add22f2..8a0fcce 100644
--- a/src/fastd.h
+++ b/src/fastd.h
@@ -136,6 +136,7 @@ struct _fastd_config {
 	unsigned reorder_count;
 	unsigned reorder_time;
 
+	unsigned min_handshake_interval;
 	unsigned min_resolve_interval;
 
 	char *ifname;
diff --git a/src/peer.c b/src/peer.c
index 078bfdc..f412836 100644
--- a/src/peer.c
+++ b/src/peer.c
@@ -176,9 +176,17 @@ static inline void setup_peer(fastd_context *ctx, fastd_peer *peer) {
 		peer->address = peer->config->address;
 
 	peer->established = false;
+
 	peer->last_resolve = (struct timespec){0, 0};
 	peer->last_resolve_return = (struct timespec){0, 0};
 	peer->seen = (struct timespec){0, 0};
+
+	peer->last_handshake = (struct timespec){0, 0};
+	peer->last_handshake_address.sa.sa_family = AF_UNSPEC;
+
+	peer->last_handshake_response = (struct timespec){0, 0};
+	peer->last_handshake_response_address.sa.sa_family = AF_UNSPEC;
+
 	peer->protocol_state = NULL;
 
 	if (!fastd_peer_is_floating(peer))
diff --git a/src/peer.h b/src/peer.h
index 15a5769..007eefd 100644
--- a/src/peer.h
+++ b/src/peer.h
@@ -43,6 +43,12 @@ struct _fastd_peer {
 	struct timespec last_resolve_return;
 	struct timespec seen;
 
+	struct timespec last_handshake;
+	fastd_peer_address last_handshake_address;
+
+	struct timespec last_handshake_response;
+	fastd_peer_address last_handshake_response_address;
+
 	fastd_protocol_peer_state *protocol_state;
 };
 
diff --git a/src/protocol_ec25519_fhmqvc.c b/src/protocol_ec25519_fhmqvc.c
index 75360b7..96f0847 100644
--- a/src/protocol_ec25519_fhmqvc.c
+++ b/src/protocol_ec25519_fhmqvc.c
@@ -577,12 +577,20 @@ static void protocol_handshake_handle(fastd_context *ctx, const fastd_peer_addre
 
 	switch(handshake->type) {
 	case 1:
+		if (timespec_diff(&ctx->now, &peer->last_handshake_response) < ctx->conf->min_handshake_interval*1000
+		    && fastd_peer_address_equal(address, &peer->last_handshake_response_address)) {
+			pr_debug(ctx, "not responding repeated handshake from %P[%I]", peer, address);
+			return;
+		}
+
 		if (handshake->records[RECORD_VERSION_NAME].data)
 			peer_version_name = strndup(handshake->records[RECORD_VERSION_NAME].data, handshake->records[RECORD_VERSION_NAME].length);
-		
+
 		pr_verbose(ctx, "received handshake from %P[%I] using fastd %s", peer, address, peer_version_name);
 		free(peer_version_name);
 
+		peer->last_handshake_response = ctx->now;
+		peer->last_handshake_response_address = *address;
 		respond_handshake(ctx, address, peer, &ctx->protocol_state->handshake_key, handshake->records[RECORD_SENDER_HANDSHAKE_KEY].data, handshake);
 		break;
 
-- 
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