avformat/hlsenc: added HLS encryption

Added HLS encryption with -hls_key_info_file <key_info_file> option. The
first line of key_info_file specifies the key URI written to the
playlist. The key URL is used to access the encryption key during
playback. The second line specifies the path to the key file used to
obtain the key during the encryption process. The key file is read as a
single packed array of 16 octets in binary format. The optional third
line specifies the initialization vector (IV) as a hexadecimal string to
be used instead of the segment sequence number (default) for encryption.
Changes to key_info_file will result in segment encryption with the new
key/IV and an entry in the playlist for the new key URI/IV.

Key info file format:
<key URI>
<key file path>
<IV> (optional)

Example key URIs:
http://server/file.key
/path/to/file.key
file.key

Example key file paths:
file.key
/path/to/file.key

Example IV:
0123456789ABCDEF0123456789ABCDEF

Example:
ffmpeg -f lavfi -i testsrc -c:v h264 -hls_key_info_file file.keyinfo
foo.m3u8

file.keyinfo:
http://server/file.key
/path/to/file.key
0123456789ABCDEF0123456789ABCDEF

Example shell script:
BASE_URL=${1:-'.'}
openssl rand 16 > file.key
echo $BASE_URL/file.key > file.keyinfo
echo file.key >> file.keyinfo
echo $(openssl rand -hex 16) >> file.keyinfo
ffmpeg -f lavfi -re -i testsrc -c:v h264 -hls_flags delete_segments \
  -hls_key_info_file file.keyinfo out.m3u8
--

Signed-off-by: Christian Suloway <csuloway@globaleagleent.com>
Signed-off-by: Dan Dennedy <dan@dennedy.org>
Signed-off-by: Michael Niedermayer <michaelni@gmx.at>

1 files changed, 116 insertions, 2 deletions

diff --git a/libavformat/hlsenc.c b/libavformat/hlsenc.c
index 4d9466c91f..68c6479fe3 100644
--- a/libavformat/hlsenc.c
+++ b/libavformat/hlsenc.c
@@ -37,12 +37,18 @@
 #include "internal.h"
 #include "os_support.h"
 
+#define KEYSIZE 16
+#define LINE_BUFFER_SIZE 1024
+
 typedef struct HLSSegment {
     char filename[1024];
     double duration; /* in seconds */
     int64_t pos;
     int64_t size;
 
+    char key_uri[LINE_BUFFER_SIZE + 1];
+    char iv_string[KEYSIZE*2 + 1];
+
     struct HLSSegment *next;
 } HLSSegment;
 
@@ -89,6 +95,12 @@ typedef struct HLSContext {
     char *baseurl;
     char *format_options_str;
     AVDictionary *format_options;
+
+    char *key_info_file;
+    char key_file[LINE_BUFFER_SIZE + 1];
+    char key_uri[LINE_BUFFER_SIZE + 1];
+    char key_string[KEYSIZE*2 + 1];
+    char iv_string[KEYSIZE*2 + 1];
 } HLSContext;
 
 static int hls_delete_old_segments(HLSContext *hls) {
@@ -156,6 +168,60 @@ fail:
     return ret;
 }
 
+static int hls_encryption_start(AVFormatContext *s)
+{
+    HLSContext *hls = s->priv_data;
+    int ret;
+    AVIOContext *pb;
+    uint8_t key[KEYSIZE];
+
+    if ((ret = avio_open2(&pb, hls->key_info_file, AVIO_FLAG_READ,
+                           &s->interrupt_callback, NULL)) < 0) {
+        av_log(hls, AV_LOG_ERROR,
+                "error opening key info file %s\n", hls->key_info_file);
+        return ret;
+    }
+
+    ff_get_line(pb, hls->key_uri, sizeof(hls->key_uri));
+    hls->key_uri[strcspn(hls->key_uri, "\r\n")] = '\0';
+
+    ff_get_line(pb, hls->key_file, sizeof(hls->key_file));
+    hls->key_file[strcspn(hls->key_file, "\r\n")] = '\0';
+
+    ff_get_line(pb, hls->iv_string, sizeof(hls->iv_string));
+    hls->iv_string[strcspn(hls->iv_string, "\r\n")] = '\0';
+
+    avio_close(pb);
+
+    if (!*hls->key_uri) {
+        av_log(hls, AV_LOG_ERROR, "no key URI specified in key info file\n");
+        return AVERROR(EINVAL);
+    }
+
+    if (!*hls->key_file) {
+        av_log(hls, AV_LOG_ERROR, "no key file specified in key info file\n");
+        return AVERROR(EINVAL);
+    }
+
+    if ((ret = avio_open2(&pb, hls->key_file, AVIO_FLAG_READ,
+                           &s->interrupt_callback, NULL)) < 0) {
+        av_log(hls, AV_LOG_ERROR, "error opening key file %s\n", hls->key_file);
+        return ret;
+    }
+
+    ret = avio_read(pb, key, sizeof(key));
+    avio_close(pb);
+    if (ret != sizeof(key)) {
+        av_log(hls, AV_LOG_ERROR, "error reading key file %s\n", hls->key_file);
+        if (ret >= 0 || ret == AVERROR_EOF)
+            ret = AVERROR(EINVAL);
+        return ret;
+    }
+    ff_data_to_hex(hls->key_string, key, sizeof(key), 0);
+
+    return 0;
+}
+
 static int hls_mux_init(AVFormatContext *s)
 {
     HLSContext *hls = s->priv_data;
@@ -202,6 +268,11 @@ static int hls_append_segment(HLSContext *hls, double duration, int64_t pos,
     en->size     = size;
     en->next     = NULL;
 
+    if (hls->key_info_file) {
+        av_strlcpy(en->key_uri, hls->key_uri, sizeof(en->key_uri));
+        av_strlcpy(en->iv_string, hls->iv_string, sizeof(en->iv_string));
+    }
+
     if (!hls->segments)
         hls->segments = en;
     else
@@ -239,6 +310,10 @@ static void hls_free_segments(HLSSegment *p)
     }
 }
 
+static void print_encryption_tag(HLSContext *hls, HLSSegment *en)
+{
+}
+
 static int hls_window(AVFormatContext *s, int last)
 {
     HLSContext *hls = s->priv_data;
@@ -252,6 +327,8 @@ static int hls_window(AVFormatContext *s, int last)
     const char *proto = avio_find_protocol_name(s->filename);
     int use_rename = proto && !strcmp(proto, "file");
     static unsigned warned_non_file;
+    char *key_uri = NULL;
+    char *iv_string = NULL;
 
     if (!use_rename && !warned_non_file++)
         av_log(s, AV_LOG_ERROR, "Cannot use rename on non file protocol, this may lead to races and temporarly partial files\n");
@@ -282,6 +359,16 @@ static int hls_window(AVFormatContext *s, int last)
         hls->discontinuity_set = 1;
     }
     for (en = hls->segments; en; en = en->next) {
+        if (hls->key_info_file && (!key_uri || strcmp(en->key_uri, key_uri) ||
+                                    av_strcasecmp(en->iv_string, iv_string))) {
+            avio_printf(out, "#EXT-X-KEY:METHOD=AES-128,URI=\"%s\"", en->key_uri);
+            if (*en->iv_string)
+                avio_printf(out, ",IV=0x%s", en->iv_string);
+            avio_printf(out, "\n");
+            key_uri = en->key_uri;
+            iv_string = en->iv_string;
+        }
+
         if (hls->flags & HLS_ROUND_DURATIONS)
             avio_printf(out, "#EXTINF:%d,\n",  (int)round(en->duration));
         else
@@ -308,6 +395,8 @@ static int hls_start(AVFormatContext *s)
 {
     HLSContext *c = s->priv_data;
     AVFormatContext *oc = c->avf;
+    AVDictionary *options = NULL;
+    char *filename, iv_string[KEYSIZE*2 + 1];
     int err = 0;
 
     if (c->flags & HLS_SINGLE_FILE)
@@ -321,9 +410,33 @@ static int hls_start(AVFormatContext *s)
         }
     c->number++;
 
-    if ((err = avio_open2(&oc->pb, oc->filename, AVIO_FLAG_WRITE,
+    if (c->key_info_file) {
+        if ((err = hls_encryption_start(s)) < 0)
+            return err;
+        if ((err = av_dict_set(&options, "encryption_key", c->key_string, 0))
+                < 0)
+            return err;
+        err = av_strlcpy(iv_string, c->iv_string, sizeof(iv_string));
+        if (!err)
+            snprintf(iv_string, sizeof(iv_string), "%032"PRIx64, c->sequence);
+        if ((err = av_dict_set(&options, "encryption_iv", iv_string, 0)) < 0)
+            return err;
+
+        filename = av_asprintf("crypto:%s", oc->filename);
+        if (!filename) {
+            av_dict_free(&options);
+            return AVERROR(ENOMEM);
+        }
+        err = avio_open2(&oc->pb, filename, AVIO_FLAG_WRITE,
+                         &s->interrupt_callback, &options);
+        av_free(filename);
+        av_dict_free(&options);
+        if (err < 0)
+            return err;
+    } else
+        if ((err = avio_open2(&oc->pb, oc->filename, AVIO_FLAG_WRITE,
                           &s->interrupt_callback, NULL)) < 0)
-        return err;
+            return err;
 
     if (oc->oformat->priv_class && oc->priv_data)
         av_opt_set(oc->priv_data, "mpegts_flags", "resend_headers", 0);
@@ -520,6 +633,7 @@ static const AVOption options[] = {
     {"hls_allow_cache", "explicitly set whether the client MAY (1) or MUST NOT (0) cache media segments", OFFSET(allowcache), AV_OPT_TYPE_INT, {.i64 = -1}, INT_MIN, INT_MAX, E},
     {"hls_base_url",  "url to prepend to each playlist entry",   OFFSET(baseurl), AV_OPT_TYPE_STRING, {.str = NULL},  0, 0,       E},
     {"hls_segment_filename", "filename template for segment files", OFFSET(segment_filename),   AV_OPT_TYPE_STRING, {.str = NULL},            0,       0,         E},
+    {"hls_key_info_file",    "file with key URI and key file path", OFFSET(key_info_file),      AV_OPT_TYPE_STRING, {.str = NULL},            0,       0,         E},
     {"hls_flags",     "set flags affecting HLS playlist and media file generation", OFFSET(flags), AV_OPT_TYPE_FLAGS, {.i64 = 0 }, 0, UINT_MAX, E, "flags"},
     {"single_file",   "generate a single media file indexed with byte ranges", 0, AV_OPT_TYPE_CONST, {.i64 = HLS_SINGLE_FILE }, 0, UINT_MAX,   E, "flags"},
     {"delete_segments", "delete segment files that are no longer part of the playlist", 0, AV_OPT_TYPE_CONST, {.i64 = HLS_DELETE_SEGMENTS }, 0, UINT_MAX,   E, "flags"},