FFmpeg4/libavformat/smoothstreamingdec.c

/*
 * HTTP Smooth  Streaming based on DASH demuxer
 * Copyright (c) 2017 samsamsam@o2.pl based on HLS demux
 * Copyright (c) 2017 Steven Liu
 *
 * This file is part of FFmpeg.
 *
 * FFmpeg is free software; you can redistribute it and/or
 * modify it under the terms of the GNU Lesser General Public
 * License as published by the Free Software Foundation; either
 * version 2.1 of the License, or (at your option) any later version.
 *
 * FFmpeg is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
 * Lesser General Public License for more details.
 *
 * You should have received a copy of the GNU Lesser General Public
 * License along with FFmpeg; if not, write to the Free Software
 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
 */
#include <libxml/parser.h>
#include "libavutil/intreadwrite.h"
#include "libavutil/opt.h"
#include "libavutil/time.h"
#include "libavutil/parseutils.h"
#include "internal.h"
#include "avio_internal.h"
#include "dash.h"

#define INITIAL_BUFFER_SIZE 32768
#define MAX_MANIFEST_SIZE 50 * 1024
#define DEFAULT_MANIFEST_SIZE 8 * 1024

typedef struct SmoothStreamingContext {
    const AVClass *class;
    char *base_url;
    int is_live;
    AVIOInterruptCB *interrupt_callback;
    char *allowed_extensions;
    AVDictionary *avio_opts;
    int max_url_size;
    char *cenc_decryption_key;

    /* Flags for init section*/
    int is_init_section_common_video;
    int is_init_section_common_audio;

} SmoothStreamingContext;

static int ishttp(char *url)
{
    const char *proto_name = avio_find_protocol_name(url);
    return av_strstart(proto_name, "http", NULL);
}

static int aligned(int val)
{
    return ((val + 0x3F) >> 6) << 6;
}

static int open_url(AVFormatContext *s, AVIOContext **pb, const char *url,
                    AVDictionary **opts, AVDictionary *opts2, int *is_http)
{
    SmoothStreamingContext *c = s->priv_data;
    AVDictionary *tmp = NULL;
    const char *proto_name = NULL;
    int ret;

    if (av_strstart(url, "crypto", NULL)) {
        if (url[6] == '+' || url[6] == ':')
            proto_name = avio_find_protocol_name(url + 7);
    }

    if (!proto_name)
        proto_name = avio_find_protocol_name(url);

    if (!proto_name)
        return AVERROR_INVALIDDATA;

    // only http(s) & file are allowed
    if (av_strstart(proto_name, "file", NULL)) {
        if (strcmp(c->allowed_extensions, "ALL") && !av_match_ext(url, c->allowed_extensions)) {
            av_log(s, AV_LOG_ERROR,
                   "Filename extension of \'%s\' is not a common multimedia extension, blocked for security reasons.\n"
                   "If you wish to override this adjust allowed_extensions, you can set it to \'ALL\' to allow all\n",
                   url);
            return AVERROR_INVALIDDATA;
        }
    } else if (av_strstart(proto_name, "http", NULL)) {
        ;
    } else
        return AVERROR_INVALIDDATA;

    if (!strncmp(proto_name, url, strlen(proto_name)) && url[strlen(proto_name)] == ':')
        ;
    else if (av_strstart(url, "crypto", NULL) && !strncmp(proto_name, url + 7, strlen(proto_name)) && url[7 + strlen(proto_name)] == ':')
        ;
    else if (strcmp(proto_name, "file") || !strncmp(url, "file,", 5))
        return AVERROR_INVALIDDATA;

    av_freep(pb);
    av_dict_copy(&tmp, *opts, 0);
    av_dict_copy(&tmp, opts2, 0);
    ret = avio_open2(pb, url, AVIO_FLAG_READ, c->interrupt_callback, &tmp);
    if (ret >= 0) {
        // update cookies on http response with setcookies.
        char *new_cookies = NULL;

        if (!(s->flags & AVFMT_FLAG_CUSTOM_IO))
            av_opt_get(*pb, "cookies", AV_OPT_SEARCH_CHILDREN, (uint8_t**)&new_cookies);

        if (new_cookies) {
            av_dict_set(opts, "cookies", new_cookies, AV_DICT_DONT_STRDUP_VAL);
        }

    }

    av_dict_free(&tmp);

    if (is_http)
        *is_http = av_strstart(proto_name, "http", NULL);

    return ret;
}

static char *get_content_url(xmlNodePtr *baseurl_nodes,
                             int n_baseurl_nodes,
                             int max_url_size,
                             char *rep_id_val,
                             char *rep_bandwidth_val,
                             char *val)
{
    int i;
    char *text;
    char *url = NULL;
    char *tmp_str = av_mallocz(max_url_size);

    if (!tmp_str)
        return NULL;

    for (i = 0; i < n_baseurl_nodes; ++i) {
        if (baseurl_nodes[i] &&
            baseurl_nodes[i]->children &&
            baseurl_nodes[i]->children->type == XML_TEXT_NODE) {
            text = xmlNodeGetContent(baseurl_nodes[i]->children);
            if (text) {
                memset(tmp_str, 0, max_url_size);
                ff_make_absolute_url(tmp_str, max_url_size, "", text);
                xmlFree(text);
            }
        }
    }

    if (val)
        ff_make_absolute_url(tmp_str, max_url_size, tmp_str, val);

    if (rep_id_val) {
        url = av_strireplace(tmp_str, "$RepresentationID$", (const char*)rep_id_val);
        if (!url) {
            goto end;
        }
        av_strlcpy(tmp_str, url, max_url_size);
    }
    if (rep_bandwidth_val && tmp_str[0] != '\0') {
        // free any previously assigned url before reassigning
        av_free(url);
        url = av_strireplace(tmp_str, "$Bandwidth$", (const char*)rep_bandwidth_val);
        if (!url) {
            goto end;
        }
    }
end:
    av_free(tmp_str);
    return url;
}

static char *get_val_from_nodes_tab(xmlNodePtr *nodes, const int n_nodes, const char *attrname)
{
    int i;
    char *val;

    for (i = 0; i < n_nodes; ++i) {
        if (nodes[i]) {
            val = xmlGetProp(nodes[i], attrname);
            if (val)
                return val;
        }
    }

    return NULL;
}

static xmlNodePtr find_child_node_by_name(xmlNodePtr rootnode, const char *nodename)
{
    xmlNodePtr node = rootnode;
    if (!node) {
        return NULL;
    }

    node = xmlFirstElementChild(node);
    while (node) {
        if (!av_strcasecmp(node->name, nodename)) {
            return node;
        }
        node = xmlNextElementSibling(node);
    }
    return NULL;
}

static enum AVMediaType get_content_type(xmlNodePtr node)
{
    enum AVMediaType type = AVMEDIA_TYPE_UNKNOWN;
    int i = 0;
    const char *attr;
    char *val = NULL;

    if (node) {
        for (i = 0; i < 2; i++) {
            attr = i ? "mimeType" : "contentType";
            val = xmlGetProp(node, attr);
            if (val) {
                if (av_stristr((const char *)val, "video")) {
                    type = AVMEDIA_TYPE_VIDEO;
                } else if (av_stristr((const char *)val, "audio")) {
                    type = AVMEDIA_TYPE_AUDIO;
                } else if (av_stristr((const char *)val, "text")) {
                    type = AVMEDIA_TYPE_SUBTITLE;
                }
                xmlFree(val);
            }
        }
    }
    return type;
}

static int save_avio_options(AVFormatContext *s)
{
    SmoothStreamingContext *c = s->priv_data;
    const char *opts[] = {
        "headers", "user_agent", "cookies", "http_proxy", "referer", "rw_timeout", "icy", NULL };
    const char **opt = opts;
    uint8_t *buf = NULL;
    int ret = 0;

    while (*opt) {
        if (av_opt_get(s->pb, *opt, AV_OPT_SEARCH_CHILDREN, &buf) >= 0) {
            if (buf[0] != '\0') {
                ret = av_dict_set(&c->avio_opts, *opt, buf, AV_DICT_DONT_STRDUP_VAL);
                if (ret < 0)
                    return ret;
            } else {
                av_freep(&buf);
            }
        }
        opt++;
    }

    return ret;
}

static int nested_io_open(AVFormatContext *s, AVIOContext **pb, const char *url,
                          int flags, AVDictionary **opts)
{
    av_log(s, AV_LOG_ERROR,
           "A SmoothStreaming playlist item '%s' referred to an external file '%s'. "
           "Opening this file was forbidden for security reasons\n",
           s->url, url);
    return AVERROR(EPERM);
}

#define OFFSET(x) offsetof(DASHContext, x)
#define FLAGS AV_OPT_FLAG_DECODING_PARAM
static const AVOption dash_options[] = {
    {"allowed_extensions", "List of file extensions that dash is allowed to access",
        OFFSET(allowed_extensions), AV_OPT_TYPE_STRING,
        {.str = "aac,m4a,m4s,m4v,mov,mp4,webm,ts"},
        INT_MIN, INT_MAX, FLAGS},
    { "cenc_decryption_key", "Media decryption key (hex)", OFFSET(cenc_decryption_key), AV_OPT_TYPE_STRING, {.str = NULL}, INT_MIN, INT_MAX, .flags = FLAGS },
    {NULL}
};

static const AVClass dash_class = {
    .class_name = "dash",
    .item_name  = av_default_item_name,
    .option     = dash_options,
    .version    = LIBAVUTIL_VERSION_INT,
};

AVInputFormat ff_dash_demuxer = {
    .name           = "dash",
    .long_name      = NULL_IF_CONFIG_SMALL("Dynamic Adaptive Streaming over HTTP"),
    .priv_class     = &dash_class,
    .priv_data_size = sizeof(DASHContext),
    .read_probe     = dash_probe,
    .read_header    = dash_read_header,
    .read_packet    = dash_read_packet,
    .read_close     = dash_close,
    .read_seek      = dash_read_seek,
    .flags          = AVFMT_NO_BYTE_SEEK,
};