Mp4: skip tracks shorter than seek position (ticket #414).

Mp4 module does not check movie and track durations when reading
file.  Instead it generates errors when track metadata is shorter
than seek position.  Now such tracks are skipped and movie duration
check is performed at file read stage.

diff --git a/src/http/modules/ngx_http_mp4_module.c b/src/http/modules/ngx_http_mp4_module.c
index da91fde27041722ce2011f9fcf5e0f04465ea4bc..9fe88eccec2a22d4b5aeabfef71268ecbfc1690f 100644 (file)
--- a/src/http/modules/ngx_http_mp4_module.c
+++ b/src/http/modules/ngx_http_mp4_module.c
@@ -1208,7 +1208,7 @@ ngx_http_mp4_read_mvhd_atom(ngx_http_mp4_file_t *mp4, uint64_t atom_data_size)
     u_char                 *atom_header;
     size_t                  atom_size;
     uint32_t                timescale;
-    uint64_t                duration;
+    uint64_t                duration, start_time;
     ngx_buf_t              *atom;
     ngx_mp4_mvhd_atom_t    *mvhd_atom;
     ngx_mp4_mvhd64_atom_t  *mvhd64_atom;
@@ -1251,7 +1251,16 @@ ngx_http_mp4_read_mvhd_atom(ngx_http_mp4_file_t *mp4, uint64_t atom_data_size)
                    "mvhd timescale:%uD, duration:%uL, time:%.3fs",
                    timescale, duration, (double) duration / timescale);
 
-    duration -= (uint64_t) mp4->start * timescale / 1000;
+    start_time = (uint64_t) mp4->start * timescale / 1000;
+
+    if (duration < start_time) {
+        ngx_log_error(NGX_LOG_ERR, mp4->file.log, 0,
+                      "\"%s\" mp4 start time exceeds file duration",
+                      mp4->file.name.data);
+        return NGX_ERROR;
+    }
+
+    duration -= start_time;
 
     ngx_log_debug2(NGX_LOG_DEBUG_HTTP, mp4->file.log, 0,
                    "mvhd new duration:%uL, time:%.3fs",
@@ -1398,7 +1407,7 @@ ngx_http_mp4_read_tkhd_atom(ngx_http_mp4_file_t *mp4, uint64_t atom_data_size)
 {
     u_char                 *atom_header;
     size_t                  atom_size;
-    uint64_t                duration;
+    uint64_t                duration, start_time;
     ngx_buf_t              *atom;
     ngx_http_mp4_trak_t    *trak;
     ngx_mp4_tkhd_atom_t    *tkhd_atom;
@@ -1438,7 +1447,15 @@ ngx_http_mp4_read_tkhd_atom(ngx_http_mp4_file_t *mp4, uint64_t atom_data_size)
                    "tkhd duration:%uL, time:%.3fs",
                    duration, (double) duration / mp4->timescale);
 
-    duration -= (uint64_t) mp4->start * mp4->timescale / 1000;
+    start_time = (uint64_t) mp4->start * mp4->timescale / 1000;
+
+    if (duration < start_time) {
+        ngx_log_debug0(NGX_LOG_DEBUG_HTTP, mp4->file.log, 0,
+                       "tkhd duration is less than start time");
+        return NGX_DECLINED;
+    }
+
+    duration -= start_time;
 
     ngx_log_debug2(NGX_LOG_DEBUG_HTTP, mp4->file.log, 0,
                    "tkhd new duration:%uL, time:%.3fs",
@@ -1541,7 +1558,7 @@ ngx_http_mp4_read_mdhd_atom(ngx_http_mp4_file_t *mp4, uint64_t atom_data_size)
     u_char                 *atom_header;
     size_t                  atom_size;
     uint32_t                timescale;
-    uint64_t                duration;
+    uint64_t                duration, start_time;
     ngx_buf_t              *atom;
     ngx_http_mp4_trak_t    *trak;
     ngx_mp4_mdhd_atom_t    *mdhd_atom;
@@ -1583,7 +1600,15 @@ ngx_http_mp4_read_mdhd_atom(ngx_http_mp4_file_t *mp4, uint64_t atom_data_size)
                    "mdhd timescale:%uD, duration:%uL, time:%.3fs",
                    timescale, duration, (double) duration / timescale);
 
-    duration -= (uint64_t) mp4->start * timescale / 1000;
+    start_time = (uint64_t) mp4->start * timescale / 1000;
+
+    if (duration < start_time) {
+        ngx_log_debug0(NGX_LOG_DEBUG_HTTP, mp4->file.log, 0,
+                       "mdhd duration is less than start time");
+        return NGX_DECLINED;
+    }
+
+    duration -= start_time;
 
     ngx_log_debug2(NGX_LOG_DEBUG_HTTP, mp4->file.log, 0,
                    "mdhd new duration:%uL, time:%.3fs",