From 9ab84e60546d94be9ad726fb291fc92d9702c82b Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Florian=20M=C3=A4rkl?= <info@florianmaerkl.de>
Date: Sun, 10 Jan 2021 16:01:37 +0100
Subject: [PATCH] Prefer fixed local Port for Discovery

---
 lib/include/chiaki/discovery.h |  2 ++
 lib/src/discovery.c            | 49 ++++++++++++++++++++++++----------
 lib/src/discoveryservice.c     |  4 +--
 3 files changed, 39 insertions(+), 16 deletions(-)

diff --git a/lib/include/chiaki/discovery.h b/lib/include/chiaki/discovery.h
index c9881b5..f26200b 100644
--- a/lib/include/chiaki/discovery.h
+++ b/lib/include/chiaki/discovery.h
@@ -25,6 +25,8 @@ extern "C" {
 #define CHIAKI_DISCOVERY_PROTOCOL_VERSION_PS4 "00020020"
 #define CHIAKI_DISCOVERY_PORT_PS5 9302
 #define CHIAKI_DISCOVERY_PROTOCOL_VERSION_PS5 "00030010"
+#define CHIAKI_DISCOVERY_PORT_LOCAL_MIN 9303
+#define CHIAKI_DISCOVERY_PORT_LOCAL_MAX 9319
 
 typedef enum chiaki_discovery_cmd_t
 {
diff --git a/lib/src/discovery.c b/lib/src/discovery.c
index 0658c87..f207a54 100644
--- a/lib/src/discovery.c
+++ b/lib/src/discovery.c
@@ -152,27 +152,48 @@ CHIAKI_EXPORT ChiakiErrorCode chiaki_discovery_init(ChiakiDiscovery *discovery,
 		return CHIAKI_ERR_NETWORK;
 	}
 
-	memset(&discovery->local_addr, 0, sizeof(discovery->local_addr));
-	discovery->local_addr.sa_family = family;
-	if(family == AF_INET6)
+	// First try CHIAKI_DISCOVERY_PORT_LOCAL_MIN..<MAX, then 0 (random)
+	uint16_t port = CHIAKI_DISCOVERY_PORT_LOCAL_MIN;
+	int r;
+	while(true)
 	{
+		memset(&discovery->local_addr, 0, sizeof(discovery->local_addr));
+		discovery->local_addr.sa_family = family;
+		if(family == AF_INET6)
+		{
 #ifndef __SWITCH__
-		struct in6_addr anyaddr = IN6ADDR_ANY_INIT;
+			struct in6_addr anyaddr = IN6ADDR_ANY_INIT;
 #endif
-		struct sockaddr_in6 *addr = (struct sockaddr_in6 *)&discovery->local_addr;
+			struct sockaddr_in6 *addr = (struct sockaddr_in6 *)&discovery->local_addr;
 #ifndef __SWITCH__
-		addr->sin6_addr = anyaddr;
+			addr->sin6_addr = anyaddr;
 #endif
-		addr->sin6_port = htons(0);
-	}
-	else // AF_INET
-	{
-		struct sockaddr_in *addr = (struct sockaddr_in *)&discovery->local_addr;
-		addr->sin_addr.s_addr = htonl(INADDR_ANY);
-		addr->sin_port = htons(0);
+			addr->sin6_port = htons(port);
+		}
+		else // AF_INET
+		{
+			struct sockaddr_in *addr = (struct sockaddr_in *)&discovery->local_addr;
+			addr->sin_addr.s_addr = htonl(INADDR_ANY);
+			addr->sin_port = htons(port);
+		}
+
+		r = bind(discovery->socket, &discovery->local_addr, sizeof(discovery->local_addr));
+		if(r >= 0 || !port)
+			break;
+		if(port == CHIAKI_DISCOVERY_PORT_LOCAL_MAX)
+		{
+			port = 0;
+			CHIAKI_LOGI(discovery->log, "Discovery failed to bind port %u, trying random",
+					(unsigned int)port);
+		}
+		else
+		{
+			port++;
+			CHIAKI_LOGI(discovery->log, "Discovery failed to bind port %u, trying one higher",
+					(unsigned int)port);
+		}
 	}
 
-	int r = bind(discovery->socket, &discovery->local_addr, sizeof(discovery->local_addr));
 	if(r < 0)
 	{
 		CHIAKI_LOGE(discovery->log, "Discovery failed to bind");
diff --git a/lib/src/discoveryservice.c b/lib/src/discoveryservice.c
index 09f31ef..f163092 100644
--- a/lib/src/discoveryservice.c
+++ b/lib/src/discoveryservice.c
@@ -238,7 +238,7 @@ static void discovery_service_host_received(ChiakiDiscoveryHost *host, void *use
 		if(service->hosts_count == service->options.hosts_max)
 		{
 			CHIAKI_LOGE(service->log, "Discovery Service received new host, but no space available");
-			goto r2con;
+			goto rzcon;
 		}
 
 		CHIAKI_LOGI(service->log, "Discovery Service detected new host with id %s", host->host_id);
@@ -279,7 +279,7 @@ static void discovery_service_host_received(ChiakiDiscoveryHost *host, void *use
 	if(change)
 		discovery_service_report_state(service);
 
-r2con:
+rzcon:
 	chiaki_mutex_unlock(&service->state_mutex);
 }