Add a function ff_url_join for assembling URLs

Originally committed as revision 22225 to svn://svn.ffmpeg.org/ffmpeg/trunk

libavformat/avformat.h

@@ -1350,6 +1350,30 @@ void url_split(char *proto, int proto_size,
                char *path, int path_size,
                const char *url);
 
+/**
+ * Assembles a URL string from components. This is the reverse operation
+ * of url_split.
+ *
+ * Note, this requires networking to be initialized, so the caller must
+ * ensure ff_network_init has been called.
+ *
+ * @see url_split
+ *
+ * @param str the buffer to fill with the url
+ * @param size the size of the str buffer
+ * @param proto the protocol identifier, if null, the separator
+ *              after the identifier is left out, too
+ * @param authorization an optional authorization string, may be null
+ * @param hostname the host name string
+ * @param port the port number, left out from the string if negative
+ * @param fmt a generic format string for everything to add after the
+ *            host/port, may be null
+ * @return the number of characters written to the destination buffer
+ */
+int ff_url_join(char *str, int size, const char *proto,
+                const char *authorization, const char *hostname,
+                int port, const char *fmt, ...);
+
 #if LIBAVFORMAT_VERSION_MAJOR < 53
 /**
  * @deprecated Use av_match_ext() instead.

libavformat/utils.c

@@ -27,6 +27,10 @@
 #include <sys/time.h>
 #include <time.h>
 #include <strings.h>
+#include <stdarg.h>
+#if CONFIG_NETWORK
+#include "network.h"
+#endif
 
 #undef NDEBUG
 #include <assert.h>
@@ -3446,3 +3450,48 @@ void av_set_pts_info(AVStream *s, int pts_wrap_bits,
     if(!s->time_base.num || !s->time_base.den)
         s->time_base.num= s->time_base.den= 0;
 }
+
+int ff_url_join(char *str, int size, const char *proto,
+                const char *authorization, const char *hostname,
+                int port, const char *fmt, ...)
+{
+#if CONFIG_NETWORK
+    struct addrinfo hints, *ai;
+#endif
+
+    str[0] = '\0';
+    if (proto)
+        av_strlcatf(str, size, "%s://", proto);
+    if (authorization)
+        av_strlcatf(str, size, "%s@", authorization);
+#if CONFIG_NETWORK && defined(AF_INET6)
+    /* Determine if hostname is a numerical IPv6 address,
+     * properly escape it within [] in that case. */
+    memset(&hints, 0, sizeof(hints));
+    hints.ai_flags = AI_NUMERICHOST;
+    if (!getaddrinfo(hostname, NULL, &hints, &ai)) {
+        if (ai->ai_family == AF_INET6) {
+            av_strlcat(str, "[", size);
+            av_strlcat(str, hostname, size);
+            av_strlcat(str, "]", size);
+        } else {
+            av_strlcat(str, hostname, size);
+        }
+        freeaddrinfo(ai);
+    } else
+#endif
+        /* Not an IPv6 address, just output the plain string. */
+        av_strlcat(str, hostname, size);
+
+    if (port >= 0)
+        av_strlcatf(str, size, ":%d", port);
+    if (fmt) {
+        va_list vl;
+        int len = strlen(str);
+
+        va_start(vl, fmt);
+        vsnprintf(str + len, size > len ? size - len : 0, fmt, vl);
+        va_end(vl);
+    }
+    return strlen(str);
+}