diff --git a/libavformat/gopher.c b/libavformat/gopher.c
index abd1cc394a3962608c28e11c8c4a8671470d2863..396b358cb12bbcb9ea7499e6a1c99da3a1390691 100644
--- a/libavformat/gopher.c
+++ b/libavformat/gopher.c
@@ -95,7 +95,7 @@ static int gopher_open(URLContext *h, const char *uri, int flags)
     if (port < 0)
         port = 70;
 
-    snprintf(buf, sizeof(buf), "tcp://%s:%d", hostname, port);
+    ff_url_join(buf, sizeof(buf), "tcp", NULL, hostname, port, NULL);
 
     s->hd = NULL;
     err = url_open(&s->hd, buf, URL_RDWR);
diff --git a/libavformat/http.c b/libavformat/http.c
index 0c07592039aea8a307408813cb9a8e3e9fcb576f..da200213ce315e47e40453f14d8bac7af115f528 100644
--- a/libavformat/http.c
+++ b/libavformat/http.c
@@ -71,11 +71,7 @@ static int http_open_cnx(URLContext *h)
     /* needed in any case to build the host string */
     url_split(NULL, 0, auth, sizeof(auth), hostname, sizeof(hostname), &port,
               path1, sizeof(path1), s->location);
-    if (port > 0) {
-        snprintf(hoststr, sizeof(hoststr), "%s:%d", hostname, port);
-    } else {
-        av_strlcpy(hoststr, hostname, sizeof(hoststr));
-    }
+    ff_url_join(hoststr, sizeof(hoststr), NULL, NULL, hostname, port, NULL);
 
     if (use_proxy) {
         url_split(NULL, 0, auth, sizeof(auth), hostname, sizeof(hostname), &port,
@@ -90,7 +86,7 @@ static int http_open_cnx(URLContext *h)
     if (port < 0)
         port = 80;
 
-    snprintf(buf, sizeof(buf), "tcp://%s:%d", hostname, port);
+    ff_url_join(buf, sizeof(buf), "tcp", NULL, hostname, port, NULL);
     err = url_open(&hd, buf, URL_RDWR);
     if (err < 0)
         goto fail;
diff --git a/libavformat/rtmpproto.c b/libavformat/rtmpproto.c
index b5f419cb7ee21afebb8bb370fdf0a3f226b76721..7fd0da81443741e0b83849011934580c1d3e13df 100644
--- a/libavformat/rtmpproto.c
+++ b/libavformat/rtmpproto.c
@@ -113,7 +113,7 @@ static void gen_connect(URLContext *s, RTMPContext *rt, const char *proto,
     ff_rtmp_packet_create(&pkt, RTMP_SYSTEM_CHANNEL, RTMP_PT_INVOKE, 0, 4096);
     p = pkt.data;
 
-    snprintf(tcurl, sizeof(tcurl), "%s://%s:%d/%s", proto, host, port, rt->app);
+    ff_url_join(tcurl, sizeof(tcurl), proto, NULL, host, port, "/%s", rt->app);
     ff_amf_write_string(&p, "connect");
     ff_amf_write_number(&p, 1.0);
     ff_amf_write_object_start(&p);
@@ -817,7 +817,7 @@ static int rtmp_open(URLContext *s, const char *uri, int flags)
 
     if (port < 0)
         port = RTMP_DEFAULT_PORT;
-    snprintf(buf, sizeof(buf), "tcp://%s:%d", hostname, port);
+    ff_url_join(buf, sizeof(buf), "tcp", NULL, hostname, port, NULL);
 
     if (url_open(&rt->stream, buf, URL_RDWR) < 0) {
         av_log(LOG_CONTEXT, AV_LOG_ERROR, "Cannot open connection %s\n", buf);
diff --git a/libavformat/rtpproto.c b/libavformat/rtpproto.c
index 4af97c1822438d3c01904197fbb7905760bcf010..4de905e0b3ab2eaf111db02f620233267436b860 100644
--- a/libavformat/rtpproto.c
+++ b/libavformat/rtpproto.c
@@ -67,10 +67,10 @@ int rtp_set_remote_url(URLContext *h, const char *uri)
     url_split(NULL, 0, NULL, 0, hostname, sizeof(hostname), &port,
               path, sizeof(path), uri);
 
-    snprintf(buf, sizeof(buf), "udp://%s:%d%s", hostname, port, path);
+    ff_url_join(buf, sizeof(buf), "udp", NULL, hostname, port, "%s", path);
     udp_set_remote_url(s->rtp_hd, buf);
 
-    snprintf(buf, sizeof(buf), "udp://%s:%d%s", hostname, port + 1, path);
+    ff_url_join(buf, sizeof(buf), "udp", NULL, hostname, port + 1, "%s", path);
     udp_set_remote_url(s->rtcp_hd, buf);
     return 0;
 }
@@ -101,7 +101,7 @@ static void build_udp_url(char *buf, int buf_size,
                           int local_port, int ttl,
                           int max_packet_size)
 {
-    snprintf(buf, buf_size, "udp://%s:%d", hostname, port);
+    ff_url_join(buf, buf_size, "udp", NULL, hostname, port, NULL);
     if (local_port >= 0)
         url_add_option(buf, buf_size, "localport=%d", local_port);
     if (ttl >= 0)
diff --git a/libavformat/rtsp.c b/libavformat/rtsp.c
index bc0b3b3f42814ed9fb440865fe51244c7cabb076..c7c6fc34222d0ad7ba3186af07ef31c064235d68 100644
--- a/libavformat/rtsp.c
+++ b/libavformat/rtsp.c
@@ -1090,8 +1090,8 @@ static int make_setup_request(AVFormatContext *s, const char *host, int port,
             /* first try in specified port range */
             if (RTSP_RTP_PORT_MIN != 0) {
                 while (j <= RTSP_RTP_PORT_MAX) {
-                    snprintf(buf, sizeof(buf), "rtp://%s?localport=%d",
-                             host, j);
+                    ff_url_join(buf, sizeof(buf), "rtp", NULL, host, -1,
+                                "?localport=%d", j);
                     /* we will use two ports per rtp stream (rtp and rtcp) */
                     j += 2;
                     if (url_open(&rtsp_st->rtp_handle, buf, URL_RDWR) == 0)
@@ -1201,8 +1201,8 @@ static int make_setup_request(AVFormatContext *s, const char *host, int port,
             char url[1024];
 
             /* XXX: also use address if specified */
-            snprintf(url, sizeof(url), "rtp://%s:%d",
-                     host, reply->transports[0].server_port_min);
+            ff_url_join(url, sizeof(url), "rtp", NULL, host,
+                        reply->transports[0].server_port_min, NULL);
             if (!(rt->server_type == RTSP_SERVER_WMS && i > 1) &&
                 rtp_set_remote_url(rtsp_st->rtp_handle, url) < 0) {
                 err = AVERROR_INVALIDDATA;
@@ -1230,8 +1230,8 @@ static int make_setup_request(AVFormatContext *s, const char *host, int port,
                 port      = rtsp_st->sdp_port;
                 ttl       = rtsp_st->sdp_ttl;
             }
-            snprintf(url, sizeof(url), "rtp://%s:%d?ttl=%d",
-                     inet_ntoa(in), port, ttl);
+            ff_url_join(url, sizeof(url), "rtp", NULL, inet_ntoa(in),
+                        port, "?ttl=%d", ttl);
             if (url_open(&rtsp_st->rtp_handle, url, URL_RDWR) < 0) {
                 err = AVERROR_INVALIDDATA;
                 goto fail;
@@ -1388,6 +1388,9 @@ int ff_rtsp_connect(AVFormatContext *s)
     RTSPMessageHeader reply1, *reply = &reply1;
     int lower_transport_mask = 0;
     char real_challenge[64];
+
+    if (!ff_network_init())
+        return AVERROR(EIO);
 redirect:
     /* extract hostname and port */
     url_split(NULL, 0, auth, sizeof(auth),
@@ -1447,7 +1450,7 @@ redirect:
     }
 
     /* open the tcp connexion */
-    snprintf(tcpname, sizeof(tcpname), "tcp://%s:%d", host, port);
+    ff_url_join(tcpname, sizeof(tcpname), "tcp", NULL, host, port, NULL);
     if (url_open(&rtsp_hd, tcpname, URL_RDWR) < 0) {
         err = AVERROR(EIO);
         goto fail;
@@ -1531,6 +1534,7 @@ redirect:
                s->filename);
         goto redirect;
     }
+    ff_network_close();
     return err;
 }
 #endif
@@ -1886,6 +1890,7 @@ static int rtsp_read_close(AVFormatContext *s)
 
     ff_rtsp_close_streams(s);
     url_close(rt->rtsp_hd);
+    ff_network_close();
     return 0;
 }
 
@@ -1933,6 +1938,9 @@ static int sdp_read_header(AVFormatContext *s, AVFormatParameters *ap)
     char *content;
     char url[1024];
 
+    if (!ff_network_init())
+        return AVERROR(EIO);
+
     /* read the whole sdp file */
     /* XXX: better loading */
     content = av_malloc(SDP_MAX_SIZE);
@@ -1950,11 +1958,10 @@ static int sdp_read_header(AVFormatContext *s, AVFormatParameters *ap)
     for (i = 0; i < rt->nb_rtsp_streams; i++) {
         rtsp_st = rt->rtsp_streams[i];
 
-        snprintf(url, sizeof(url), "rtp://%s:%d?localport=%d&ttl=%d",
-                 inet_ntoa(rtsp_st->sdp_ip),
-                 rtsp_st->sdp_port,
-                 rtsp_st->sdp_port,
-                 rtsp_st->sdp_ttl);
+        ff_url_join(url, sizeof(url), "rtp", NULL,
+                    inet_ntoa(rtsp_st->sdp_ip), rtsp_st->sdp_port,
+                    "?localport=%d&ttl=%d", rtsp_st->sdp_port,
+                    rtsp_st->sdp_ttl);
         if (url_open(&rtsp_st->rtp_handle, url, URL_RDWR) < 0) {
             err = AVERROR_INVALIDDATA;
             goto fail;
@@ -1965,12 +1972,14 @@ static int sdp_read_header(AVFormatContext *s, AVFormatParameters *ap)
     return 0;
 fail:
     ff_rtsp_close_streams(s);
+    ff_network_close();
     return err;
 }
 
 static int sdp_read_close(AVFormatContext *s)
 {
     ff_rtsp_close_streams(s);
+    ff_network_close();
     return 0;
 }
 
diff --git a/libavformat/rtspenc.c b/libavformat/rtspenc.c
index c655e70a98b3a6411bac5e650d559bf9db01cc13..5f893916f1304420333055d984842f46ad37c635 100644
--- a/libavformat/rtspenc.c
+++ b/libavformat/rtspenc.c
@@ -116,6 +116,7 @@ static int rtsp_write_close(AVFormatContext *s)
 
     ff_rtsp_close_streams(s);
     url_close(rt->rtsp_hd);
+    ff_network_close();
     return 0;
 }