[FFmpeg-devel] [PATCH] Option to prevent probing for HTTP seekability

[Duncan Salerno]

Some HLS servers return 403 when the Range header is present. Add an option to HTTP to control sending the range header (default on). HLS sets this option to disabled.
---
 libavformat/hls.c  |   27 +++++++++++++++++++++------
 libavformat/http.c |    6 ++++--
 2 files changed, 25 insertions(+), 8 deletions(-)

diff --git a/libavformat/hls.c b/libavformat/hls.c
index 00c3cf0..3bd29bc 100644
--- a/libavformat/hls.c
+++ b/libavformat/hls.c
@@ -212,10 +212,16 @@ static int parse_playlist(HLSContext *c, const char *url,
     int close_in = 0;
 
     if (!in) {
+        AVDictionary *opts = NULL;
+        /* Some HLS servers dont like being sent the range header */
+        av_dict_set(&opts, "probe_seek", "0", 0);
         close_in = 1;
         if ((ret = avio_open2(&in, url, AVIO_FLAG_READ,
-                              c->interrupt_callback, NULL)) < 0)
+                              c->interrupt_callback, &opts)) < 0) {
+            av_dict_free(&opts);
             return ret;
+        }
+        av_dict_free(&opts);
     }
 
     read_chomp_line(in, line, sizeof(line));
@@ -325,17 +331,21 @@ fail:
 
 static int open_input(struct variant *var)
 {
+    AVDictionary *opts = NULL;
     struct segment *seg = var->segments[var->cur_seq_no - var->start_seq_no];
+    av_dict_set(&opts, "probe_seek", "0", 0);
     if (seg->key_type == KEY_NONE) {
-        return ffurl_open(&var->input, seg->url, AVIO_FLAG_READ,
-                          &var->parent->interrupt_callback, NULL);
+        int ret = ffurl_open(&var->input, seg->url, AVIO_FLAG_READ,
+                             &var->parent->interrupt_callback, &opts);
+        av_dict_free(&opts);
+        return ret;
     } else if (seg->key_type == KEY_AES_128) {
         char iv[33], key[33], url[MAX_URL_SIZE];
         int ret;
         if (strcmp(seg->key, var->key_url)) {
             URLContext *uc;
             if (ffurl_open(&uc, seg->key, AVIO_FLAG_READ,
-                           &var->parent->interrupt_callback, NULL) == 0) {
+                           &var->parent->interrupt_callback, &opts) == 0) {
                 if (ffurl_read_complete(uc, var->key, sizeof(var->key))
                     != sizeof(var->key)) {
                     av_log(NULL, AV_LOG_ERROR, "Unable to read key file %s\n",
@@ -356,17 +366,22 @@ static int open_input(struct variant *var)
         else
             snprintf(url, sizeof(url), "crypto:%s", seg->url);
         if ((ret = ffurl_alloc(&var->input, url, AVIO_FLAG_READ,
-                               &var->parent->interrupt_callback)) < 0)
+                               &var->parent->interrupt_callback)) < 0) {
+            av_dict_free(&opts);
             return ret;
+        }
         av_opt_set(var->input->priv_data, "key", key, 0);
         av_opt_set(var->input->priv_data, "iv", iv, 0);
-        if ((ret = ffurl_connect(var->input, NULL)) < 0) {
+        if ((ret = ffurl_connect(var->input, &opts)) < 0) {
             ffurl_close(var->input);
             var->input = NULL;
+            av_dict_free(&opts);
             return ret;
         }
+        av_dict_free(&opts);
         return 0;
     }
+    av_dict_free(&opts);
     return AVERROR(ENOSYS);
 }
 
diff --git a/libavformat/http.c b/libavformat/http.c
index ede4e8b..6d47882 100644
--- a/libavformat/http.c
+++ b/libavformat/http.c
@@ -50,6 +50,7 @@ typedef struct {
     HTTPAuthState proxy_auth_state;
     char *headers;
     int willclose;          /**< Set if the server correctly handles Connection: close and will close the connection after feeding us the content. */
+    int probe_seek;
     int chunked_post;
     int end_chunked_post;   /**< A flag which indicates if the end of chunked encoding has been sent. */
     int end_header;         /**< A flag which indicates we have finished to read POST reply. */
@@ -64,6 +65,7 @@ typedef struct {
 #define E AV_OPT_FLAG_ENCODING_PARAM
 #define DEC AV_OPT_FLAG_DECODING_PARAM
 static const AVOption options[] = {
+{"probe_seek", "probe if server supports seeking by sending range header", OFFSET(probe_seek), AV_OPT_TYPE_INT, {.i64 = 1}, 0, 1, D },
 {"chunked_post", "use chunked transfer-encoding for posts", OFFSET(chunked_post), AV_OPT_TYPE_INT, {.i64 = 1}, 0, 1, E },
 {"headers", "custom HTTP headers, can override built in default headers", OFFSET(headers), AV_OPT_TYPE_STRING, { 0 }, 0, 0, D|E },
 {"user-agent", "override User-Agent header", OFFSET(user_agent), AV_OPT_TYPE_STRING, {.str = NULL}, 0, 0, DEC},
@@ -411,10 +413,10 @@ static int http_connect(URLContext *h, const char *path, const char *local_path,
     if (!has_header(s->headers, "\r\nAccept: "))
         len += av_strlcpy(headers + len, "Accept: */*\r\n",
                           sizeof(headers) - len);
-    // Note: we send this on purpose even when s->off is 0,
+    // Note: we send this on purpose even when s->off is 0 and probe_seek set,
     // since it allows us to detect more reliably if a (non-conforming)
     // server supports seeking by analysing the reply headers.
-    if (!has_header(s->headers, "\r\nRange: ") && !post)
+    if (!has_header(s->headers, "\r\nRange: ") && !post && (s->off > 0 || s->probe_seek))
         len += av_strlcatf(headers + len, sizeof(headers) - len,
                            "Range: bytes=%"PRId64"-\r\n", s->off);
 
-- 
1.7.9.5