From 7ac5aa48ed6e3940eff1b0f84a9ba4f22e971f0e Mon Sep 17 00:00:00 2001
From: Lukas Joswiak <lukas.joswiak@snowflake.com>
Date: Tue, 8 Dec 2020 17:38:32 +0000
Subject: [PATCH] Fix UDP simulation bug with duplicate ports

Occasionally, a second UDP socket would be created with a randomly generated
port equal to the randomly generated port of an earlier socket.
---
 fdbrpc/sim2.actor.cpp | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/fdbrpc/sim2.actor.cpp b/fdbrpc/sim2.actor.cpp
index 1dd1202a12..84bbd15c7b 100644
--- a/fdbrpc/sim2.actor.cpp
+++ b/fdbrpc/sim2.actor.cpp
@@ -1796,6 +1796,7 @@ public:
 	  : id(deterministicRandom()->randomUniqueID()), process(g_simulator.getCurrentProcess()), peerAddress(peerAddress),
 	    actors(false), _localAddress(localAddress) {
 		g_sim2.addressMap.emplace(_localAddress, process);
+		ASSERT(process->boundUDPSockets.find(localAddress) == process->boundUDPSockets.end());
 		process->boundUDPSockets.emplace(localAddress, this);
 	}
 	~UDPSimSocket() {
@@ -1909,6 +1910,9 @@ Future<Reference<IUDPSocket>> Sim2::createUDPSocket(NetworkAddress toAddr) {
 		localAddress.ip = IPAddress(process->address.ip.toV4() + deterministicRandom()->randomInt(0, 256));
 	}
 	localAddress.port = deterministicRandom()->randomInt(40000, 60000);
+	while (process->boundUDPSockets.find(localAddress) != process->boundUDPSockets.end()) {
+		localAddress.port = deterministicRandom()->randomInt(40000, 60000);
+	}
 	return Reference<IUDPSocket>(new UDPSimSocket(localAddress, toAddr));
 }