Adding socket reuse to bssl server.

This allows a server to be restarted immediately with the same port
without having to wait for socket timeout on crash/failure.

Change-Id: Ifcf58d46067f157dd504946f71b0b99d7fbad10c
Reviewed-on: https://boringssl-review.googlesource.com/13044
Reviewed-by: David Benjamin <davidben@google.com>
Commit-Queue: David Benjamin <davidben@google.com>
CQ-Verified: CQ bot account: commit-bot@chromium.org <commit-bot@chromium.org>

tool/transport_common.cc

diff --git a/tool/transport_common.cc b/tool/transport_common.cc
index 9b8715d..5017315 100644
--- a/tool/transport_common.cc
+++ b/tool/transport_common.cc
@@ -159,6 +159,7 @@
   addr.sin6_port = htons(atoi(port.c_str()));
 
   bool ok = false;
+  const char enable = 1;
   int server_sock = -1;
 
   server_sock =
@@ -168,6 +169,12 @@
     goto out;
   }
 
+  if (setsockopt(server_sock, SOL_SOCKET, SO_REUSEADDR, &enable,
+                 sizeof(enable)) < 0) {
+    perror("setsockopt");
+    goto out;
+  }
+
   if (bind(server_sock, (struct sockaddr*)&addr, sizeof(addr)) != 0) {
     perror("connect");
     goto out;