From a310c13bf05d89cb30aaa05289868047bb95638e Mon Sep 17 00:00:00 2001
From: Andy Green <andy@warmcat.com>
Date: Thu, 15 Dec 2016 10:10:23 +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 | 49 ++++++++++++++++++++++++++++++++++++++++++++-
 1 file changed, 48 insertions(+), 1 deletion(-)

diff --git a/lib/libwebsockets.c b/lib/libwebsockets.c
index ca534a50..dbc70920 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;
 
@@ -1595,7 +1603,46 @@ lws_socket_bind(struct lws_vhost *vhost, lws_sockfd_type sockfd, int port,
 		v = (struct sockaddr *)&serv_addr6;
 		n = sizeof(struct sockaddr_in6);
 		bzero((char *) &serv_addr6, sizeof(serv_addr6));
-		serv_addr6.sin6_addr = in6addr_any;
+
+		if (iface &&
+		    interface_to_sa(vhost->context, iface,
+				    (struct sockaddr_in *)v, n) < 0) {
+			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