From e0bed8da33566695c6f780559679e10372ce3bd6 Mon Sep 17 00:00:00 2001
From: Andy Green <andy@warmcat.com>
Date: Thu, 15 Dec 2016 09:58:20 +0800
Subject: [PATCH] ipv6-allow-binding-to-ipv6-address-in-iface

ipv4 and ipv6 binding to a named interface works OK.  ipv4 binding to an IP also
works, but we need some extra ipv6 magic to identify the ipv6 interface from an
ipv6 address.

This patch based on code from "user3546716" at
http://stackoverflow.com/questions/13504934/binding-sockets-to-ipv6-addresses

adds the necessary magic.

https://github.com/warmcat/libwebsockets/issues/717
---
 lib/libwebsockets.c | 41 +++++++++++++++++++++++++++++++++++++++++
 1 file changed, 41 insertions(+)

diff --git a/lib/libwebsockets.c b/lib/libwebsockets.c
index f8c879a3..36fb4711 100755
--- a/lib/libwebsockets.c
+++ b/lib/libwebsockets.c
@@ -30,6 +30,14 @@
 #include <sys/wait.h>
 #endif
 
+#ifdef LWS_USE_IPV6
+#if defined(WIN32) || defined(_WIN32)
+#include <Iphlpapi.h>
+#else
+#include <net/if.h>
+#endif
+#endif
+
 int log_level = LLL_ERR | LLL_WARN | LLL_NOTICE;
 static void (*lwsl_emit)(int level, const char *line) = lwsl_emit_stderr;
 
@@ -1517,6 +1525,39 @@ lws_socket_bind(struct lws_vhost *vhost, lws_sockfd_type sockfd, int port,
 			lwsl_err("Unable to find interface %s\n", iface);
 			return -1;
 		}
+
+		if (iface) {
+			struct ifaddrs *addrs, *addr;
+			char ip[NI_MAXHOST];
+			unsigned int i;
+
+			getifaddrs(&addrs);
+			for (addr = addrs; addr; addr = addr->ifa_next) {
+				if (!addr->ifa_addr ||
+				    addr->ifa_addr->sa_family != AF_INET6)
+					continue;
+
+				getnameinfo(addr->ifa_addr,
+					    sizeof(struct sockaddr_in6),
+					    ip, sizeof(ip),
+					    NULL, 0, NI_NUMERICHOST);
+
+				i = 0;
+				while (ip[i])
+					if (ip[i++] == '%') {
+						ip[i - 1] = '\0';
+						break;
+					}
+
+				if (!strcmp(ip, iface)) {
+					serv_addr6.sin6_scope_id =
+						if_nametoindex(addr->ifa_name);
+					break;
+				}
+			}
+			freeifaddrs(addrs);
+		}
+
 		serv_addr6.sin6_family = AF_INET6;
 		serv_addr6.sin6_port = htons(port);
 	} else