From 90f091abf3be398641446cc6d7c6656d8100f877 Mon Sep 17 00:00:00 2001
From: Luca Boccassi <luca.boccassi@gmail.com>
Date: Mon, 14 Nov 2016 11:59:32 +0000
Subject: [PATCH] Problem: IPV6_TCLASS setsockopt fails on IPv4 socket

Solution: if setsockopt errors out and errno is set to ENOPROTOOPT
(or EINVAL on OSX) ignore it and carry on.
---
 src/ip.cpp | 12 ++++++++++--
 1 file changed, 10 insertions(+), 2 deletions(-)

diff --git a/src/ip.cpp b/src/ip.cpp
index 81607656..7a8d12c4 100644
--- a/src/ip.cpp
+++ b/src/ip.cpp
@@ -180,9 +180,17 @@ void zmq::set_ip_type_of_service (fd_t s_, int iptos)
         reinterpret_cast<const char*>(&iptos),
         sizeof(iptos));
 
+    //  If IPv6 is not enabled ENOPROTOOPT will be returned on Windows and
+    //  Linux, and EINVAL on OSX
 #ifdef ZMQ_HAVE_WINDOWS
-    wsa_assert (rc != SOCKET_ERROR);
+    if (rc == SOCKET_ERROR) {
+        const int last_error = WSAGetLastError();
+        wsa_assert (last_error == WSAENOPROTOOPT);
+    }
 #else
-    errno_assert (rc == 0);
+    if (rc == -1) {
+        errno_assert (errno == ENOPROTOOPT ||
+                      errno == EINVAL);
+    }
 #endif
 }