From f7b933f570545def0d654b9408c92b82ac0e54f4 Mon Sep 17 00:00:00 2001
From: Juha Reunanen <juha.reunanen@tomaattinen.com>
Date: Mon, 6 Jul 2015 18:05:31 +0300
Subject: [PATCH] LIBZMQ-195 allow explicitly setting sndbuf and rcvbuf to 0
 (see https://support.microsoft.com/en-us/kb/201213)

---
 src/options.cpp         | 4 ++--
 src/pgm_socket.cpp      | 4 ++--
 src/socks_connecter.cpp | 4 ++--
 src/tcp_connecter.cpp   | 4 ++--
 src/tcp_listener.cpp    | 4 ++--
 5 files changed, 10 insertions(+), 10 deletions(-)

diff --git a/src/options.cpp b/src/options.cpp
index 6742f92e..da86c3fb 100644
--- a/src/options.cpp
+++ b/src/options.cpp
@@ -41,8 +41,8 @@ zmq::options_t::options_t () :
     rate (100),
     recovery_ivl (10000),
     multicast_hops (1),
-    sndbuf (0),
-    rcvbuf (0),
+    sndbuf (-1),
+    rcvbuf (-1),
     tos (0),
     type (-1),
     linger (-1),
diff --git a/src/pgm_socket.cpp b/src/pgm_socket.cpp
index 02655797..2557c668 100644
--- a/src/pgm_socket.cpp
+++ b/src/pgm_socket.cpp
@@ -196,14 +196,14 @@ int zmq::pgm_socket_t::init (bool udp_encapsulation_, const char *network_)
 
     {
 		const int rcvbuf = (int) options.rcvbuf;
-		if (rcvbuf) {
+		if (rcvbuf >= 0) {
 		    if (!pgm_setsockopt (sock, SOL_SOCKET, SO_RCVBUF, &rcvbuf,
 		          sizeof (rcvbuf)))
 		        goto err_abort;
 		}
 
 		const int sndbuf = (int) options.sndbuf;
-		if (sndbuf) {
+		if (sndbuf >= 0) {
 		    if (!pgm_setsockopt (sock, SOL_SOCKET, SO_SNDBUF, &sndbuf,
 		          sizeof (sndbuf)))
 		        goto err_abort;
diff --git a/src/socks_connecter.cpp b/src/socks_connecter.cpp
index bdc435ec..fb69ea7d 100644
--- a/src/socks_connecter.cpp
+++ b/src/socks_connecter.cpp
@@ -340,9 +340,9 @@ int zmq::socks_connecter_t::connect_to_proxy ()
     unblock_socket (s);
 
     //  Set the socket buffer limits for the underlying socket.
-    if (options.sndbuf != 0)
+    if (options.sndbuf >= 0)
         set_tcp_send_buffer (s, options.sndbuf);
-    if (options.rcvbuf != 0)
+    if (options.rcvbuf >= 0)
         set_tcp_receive_buffer (s, options.rcvbuf);
 
     // Set the IP Type-Of-Service for the underlying socket
diff --git a/src/tcp_connecter.cpp b/src/tcp_connecter.cpp
index 17239a74..b328d487 100644
--- a/src/tcp_connecter.cpp
+++ b/src/tcp_connecter.cpp
@@ -258,9 +258,9 @@ int zmq::tcp_connecter_t::open ()
     unblock_socket (s);
 
     //  Set the socket buffer limits for the underlying socket.
-    if (options.sndbuf != 0)
+    if (options.sndbuf >= 0)
         set_tcp_send_buffer (s, options.sndbuf);
-    if (options.rcvbuf != 0)
+    if (options.rcvbuf >= 0)
         set_tcp_receive_buffer (s, options.rcvbuf);
 
     // Set the IP Type-Of-Service for the underlying socket
diff --git a/src/tcp_listener.cpp b/src/tcp_listener.cpp
index 26cc3f0f..1b37a3b5 100644
--- a/src/tcp_listener.cpp
+++ b/src/tcp_listener.cpp
@@ -207,9 +207,9 @@ int zmq::tcp_listener_t::set_address (const char *addr_)
         set_ip_type_of_service (s, options.tos);
 
     //  Set the socket buffer limits for the underlying socket.
-    if (options.sndbuf != 0)
+    if (options.sndbuf >= 0)
         set_tcp_send_buffer (s, options.sndbuf);
-    if (options.rcvbuf != 0)
+    if (options.rcvbuf >= 0)
         set_tcp_receive_buffer (s, options.rcvbuf);
 
     //  Allow reusing of the address.