httpd: fix address family for reverse proxy client socket

When httpd proxies a request to another server, it first creates
an AF_INET socket, then resolves the server name to a sockaddr,
then connects to it. This fails if the server name resolves to
an IPv6 address.

This patch ensures that the socket is created with the correct
address family (AF_INET6 if the server resolves to an IPv6 address
and AF_INET otherwise).

Signed-off-by: Laurent Bercot <ska-dietlibc@skarnet.org>
Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>
diff --git a/networking/httpd.c b/networking/httpd.c
index d301d59..cfcd2a0 100644
--- a/networking/httpd.c
+++ b/networking/httpd.c
@@ -2396,12 +2396,12 @@
 		int proxy_fd;
 		len_and_sockaddr *lsa;
 
-		proxy_fd = socket(AF_INET, SOCK_STREAM, 0);
-		if (proxy_fd < 0)
-			send_headers_and_exit(HTTP_INTERNAL_SERVER_ERROR);
 		lsa = host2sockaddr(proxy_entry->host_port, 80);
 		if (lsa == NULL)
 			send_headers_and_exit(HTTP_INTERNAL_SERVER_ERROR);
+		proxy_fd = socket(lsa->u.sa.sa_family, SOCK_STREAM, 0);
+		if (proxy_fd < 0)
+			send_headers_and_exit(HTTP_INTERNAL_SERVER_ERROR);
 		if (connect(proxy_fd, &lsa->u.sa, lsa->len) < 0)
 			send_headers_and_exit(HTTP_INTERNAL_SERVER_ERROR);
 		fdprintf(proxy_fd, "%s %s%s%s%s HTTP/%c.%c\r\n",