mirror of https://git.ffmpeg.org/ffmpeg.git
348 lines
12 KiB
C
348 lines
12 KiB
C
/*
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* IPFS and IPNS protocol support through IPFS Gateway.
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* Copyright (c) 2022 Mark Gaiser
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*
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* This file is part of FFmpeg.
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*
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* FFmpeg is free software; you can redistribute it and/or
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* modify it under the terms of the GNU Lesser General Public
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* License as published by the Free Software Foundation; either
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* version 2.1 of the License, or (at your option) any later version.
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*
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* FFmpeg is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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* Lesser General Public License for more details.
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*
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* You should have received a copy of the GNU Lesser General Public
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* License along with FFmpeg; if not, write to the Free Software
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* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
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*/
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#include "libavutil/avstring.h"
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#include "libavutil/opt.h"
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#include <sys/stat.h>
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#include "os_support.h"
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#include "url.h"
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// Define the posix PATH_MAX if not there already.
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// This fixes a compile issue for MSVC.
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#ifndef PATH_MAX
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#define PATH_MAX 4096
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#endif
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typedef struct IPFSGatewayContext {
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AVClass *class;
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URLContext *inner;
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// Is filled by the -gateway argument and not changed after.
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char *gateway;
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// If the above gateway is non null, it will be copied into this buffer.
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// Else this buffer will contain the auto detected gateway.
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// In either case, the gateway to use will be in this buffer.
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char gateway_buffer[PATH_MAX];
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} IPFSGatewayContext;
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// A best-effort way to find the IPFS gateway.
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// Only the most appropiate gateway is set. It's not actually requested
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// (http call) to prevent a potential slowdown in startup. A potential timeout
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// is handled by the HTTP protocol.
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static int populate_ipfs_gateway(URLContext *h)
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{
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IPFSGatewayContext *c = h->priv_data;
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char ipfs_full_data_folder[PATH_MAX];
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char ipfs_gateway_file[PATH_MAX];
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struct stat st;
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int stat_ret = 0;
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int ret = AVERROR(EINVAL);
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FILE *gateway_file = NULL;
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// Test $IPFS_GATEWAY.
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if (getenv("IPFS_GATEWAY") != NULL) {
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if (snprintf(c->gateway_buffer, sizeof(c->gateway_buffer), "%s",
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getenv("IPFS_GATEWAY"))
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>= sizeof(c->gateway_buffer)) {
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av_log(h, AV_LOG_WARNING,
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"The IPFS_GATEWAY environment variable "
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"exceeds the maximum length. "
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"We allow a max of %zu characters\n",
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sizeof(c->gateway_buffer));
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ret = AVERROR(EINVAL);
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goto err;
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}
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ret = 1;
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goto err;
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} else
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av_log(h, AV_LOG_DEBUG, "$IPFS_GATEWAY is empty.\n");
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// We need to know the IPFS folder to - eventually - read the contents of
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// the "gateway" file which would tell us the gateway to use.
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if (getenv("IPFS_PATH") == NULL) {
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av_log(h, AV_LOG_DEBUG, "$IPFS_PATH is empty.\n");
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// Try via the home folder.
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if (getenv("HOME") == NULL) {
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av_log(h, AV_LOG_WARNING, "$HOME appears to be empty.\n");
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ret = AVERROR(EINVAL);
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goto err;
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}
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// Verify the composed path fits.
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if (snprintf(ipfs_full_data_folder, sizeof(ipfs_full_data_folder),
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"%s/.ipfs/", getenv("HOME"))
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>= sizeof(ipfs_full_data_folder)) {
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av_log(h, AV_LOG_WARNING,
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"The IPFS data path exceeds the "
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"max path length (%zu)\n",
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sizeof(ipfs_full_data_folder));
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ret = AVERROR(EINVAL);
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goto err;
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}
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// Stat the folder.
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// It should exist in a default IPFS setup when run as local user.
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stat_ret = stat(ipfs_full_data_folder, &st);
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if (stat_ret < 0) {
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av_log(h, AV_LOG_INFO,
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"Unable to find IPFS folder. We tried:\n"
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"- $IPFS_PATH, which was empty.\n"
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"- $HOME/.ipfs (full uri: %s) which doesn't exist.\n",
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ipfs_full_data_folder);
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ret = AVERROR(ENOENT);
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goto err;
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}
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} else {
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if (snprintf(ipfs_full_data_folder, sizeof(ipfs_full_data_folder), "%s",
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getenv("IPFS_PATH"))
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>= sizeof(ipfs_full_data_folder)) {
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av_log(h, AV_LOG_WARNING,
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"The IPFS_PATH environment variable "
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"exceeds the maximum length. "
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"We allow a max of %zu characters\n",
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sizeof(c->gateway_buffer));
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ret = AVERROR(EINVAL);
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goto err;
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}
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}
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// Copy the fully composed gateway path into ipfs_gateway_file.
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if (snprintf(ipfs_gateway_file, sizeof(ipfs_gateway_file), "%sgateway",
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ipfs_full_data_folder)
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>= sizeof(ipfs_gateway_file)) {
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av_log(h, AV_LOG_WARNING,
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"The IPFS gateway file path exceeds "
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"the max path length (%zu)\n",
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sizeof(ipfs_gateway_file));
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ret = AVERROR(ENOENT);
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goto err;
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}
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// Get the contents of the gateway file.
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gateway_file = avpriv_fopen_utf8(ipfs_gateway_file, "r");
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if (!gateway_file) {
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av_log(h, AV_LOG_WARNING,
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"The IPFS gateway file (full uri: %s) doesn't exist. "
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"Is the gateway enabled?\n",
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ipfs_gateway_file);
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ret = AVERROR(ENOENT);
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goto err;
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}
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// Read a single line (fgets stops at new line mark).
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if (!fgets(c->gateway_buffer, sizeof(c->gateway_buffer) - 1, gateway_file)) {
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av_log(h, AV_LOG_WARNING, "Unable to read from file (full uri: %s).\n",
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ipfs_gateway_file);
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ret = AVERROR(ENOENT);
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goto err;
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}
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// Replace first occurence of end of line with \0
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c->gateway_buffer[strcspn(c->gateway_buffer, "\r\n")] = 0;
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// If strlen finds anything longer then 0 characters then we have a
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// potential gateway url.
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if (*c->gateway_buffer == '\0') {
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av_log(h, AV_LOG_WARNING,
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"The IPFS gateway file (full uri: %s) appears to be empty. "
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"Is the gateway started?\n",
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ipfs_gateway_file);
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ret = AVERROR(EILSEQ);
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goto err;
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} else {
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// We're done, the c->gateway_buffer has something that looks valid.
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ret = 1;
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goto err;
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}
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err:
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if (gateway_file)
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fclose(gateway_file);
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return ret;
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}
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static int translate_ipfs_to_http(URLContext *h, const char *uri, int flags, AVDictionary **options)
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{
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const char *ipfs_cid;
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char *fulluri = NULL;
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int ret;
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IPFSGatewayContext *c = h->priv_data;
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// Test for ipfs://, ipfs:, ipns:// and ipns:. This prefix is stripped from
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// the string leaving just the CID in ipfs_cid.
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int is_ipfs = av_stristart(uri, "ipfs://", &ipfs_cid);
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int is_ipns = av_stristart(uri, "ipns://", &ipfs_cid);
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// We must have either ipns or ipfs.
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if (!is_ipfs && !is_ipns) {
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ret = AVERROR(EINVAL);
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av_log(h, AV_LOG_WARNING, "Unsupported url %s\n", uri);
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goto err;
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}
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// If the CID has a length greater then 0 then we assume we have a proper working one.
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// It could still be wrong but in that case the gateway should save us and
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// ruturn a 403 error. The http protocol handles this.
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if (strlen(ipfs_cid) < 1) {
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av_log(h, AV_LOG_WARNING, "A CID must be provided.\n");
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ret = AVERROR(EILSEQ);
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goto err;
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}
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// Populate c->gateway_buffer with whatever is in c->gateway
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if (c->gateway != NULL) {
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if (snprintf(c->gateway_buffer, sizeof(c->gateway_buffer), "%s",
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c->gateway)
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>= sizeof(c->gateway_buffer)) {
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av_log(h, AV_LOG_WARNING,
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"The -gateway parameter is too long. "
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"We allow a max of %zu characters\n",
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sizeof(c->gateway_buffer));
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ret = AVERROR(EINVAL);
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goto err;
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}
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} else {
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// Populate the IPFS gateway if we have any.
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// If not, inform the user how to properly set one.
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ret = populate_ipfs_gateway(h);
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if (ret < 1) {
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// We fallback on dweb.link (managed by Protocol Labs).
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snprintf(c->gateway_buffer, sizeof(c->gateway_buffer), "https://dweb.link");
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av_log(h, AV_LOG_WARNING,
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"IPFS does not appear to be running. "
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"You’re now using the public gateway at dweb.link.\n");
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av_log(h, AV_LOG_INFO,
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"Installing IPFS locally is recommended to "
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"improve performance and reliability, "
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"and not share all your activity with a single IPFS gateway.\n"
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"There are multiple options to define this gateway.\n"
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"1. Call ffmpeg with a gateway param, "
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"without a trailing slash: -gateway <url>.\n"
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"2. Define an $IPFS_GATEWAY environment variable with the "
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"full HTTP URL to the gateway "
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"without trailing forward slash.\n"
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"3. Define an $IPFS_PATH environment variable "
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"and point it to the IPFS data path "
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"- this is typically ~/.ipfs\n");
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}
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}
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// Test if the gateway starts with either http:// or https://
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if (av_stristart(c->gateway_buffer, "http://", NULL) == 0
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&& av_stristart(c->gateway_buffer, "https://", NULL) == 0) {
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av_log(h, AV_LOG_WARNING,
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"The gateway URL didn't start with http:// or "
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"https:// and is therefore invalid.\n");
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ret = AVERROR(EILSEQ);
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goto err;
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}
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// Concatenate the url.
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// This ends up with something like: http://localhost:8080/ipfs/Qm.....
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// The format of "%s%s%s%s" is the following:
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// 1st %s = The gateway.
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// 2nd %s = If the gateway didn't end in a slash, add a "/". Otherwise it's an empty string
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// 3rd %s = Either ipns/ or ipfs/.
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// 4th %s = The IPFS CID (Qm..., bafy..., ...).
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fulluri = av_asprintf("%s%s%s%s",
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c->gateway_buffer,
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(c->gateway_buffer[strlen(c->gateway_buffer) - 1] == '/') ? "" : "/",
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(is_ipns) ? "ipns/" : "ipfs/",
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ipfs_cid);
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if (!fulluri) {
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av_log(h, AV_LOG_ERROR, "Failed to compose the URL\n");
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ret = AVERROR(ENOMEM);
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goto err;
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}
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// Pass the URL back to FFMpeg's protocol handler.
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ret = ffurl_open_whitelist(&c->inner, fulluri, flags,
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&h->interrupt_callback, options,
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h->protocol_whitelist,
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h->protocol_blacklist, h);
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if (ret < 0) {
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av_log(h, AV_LOG_WARNING, "Unable to open resource: %s\n", fulluri);
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goto err;
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}
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err:
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av_free(fulluri);
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return ret;
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}
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static int ipfs_read(URLContext *h, unsigned char *buf, int size)
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{
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IPFSGatewayContext *c = h->priv_data;
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return ffurl_read(c->inner, buf, size);
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}
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static int64_t ipfs_seek(URLContext *h, int64_t pos, int whence)
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{
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IPFSGatewayContext *c = h->priv_data;
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return ffurl_seek(c->inner, pos, whence);
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}
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static int ipfs_close(URLContext *h)
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{
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IPFSGatewayContext *c = h->priv_data;
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return ffurl_closep(&c->inner);
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}
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#define OFFSET(x) offsetof(IPFSGatewayContext, x)
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static const AVOption options[] = {
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{"gateway", "The gateway to ask for IPFS data.", OFFSET(gateway), AV_OPT_TYPE_STRING, {.str = NULL}, 0, 0, AV_OPT_FLAG_DECODING_PARAM},
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{NULL},
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};
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static const AVClass ipfs_context_class = {
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.class_name = "IPFS",
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.item_name = av_default_item_name,
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.option = options,
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.version = LIBAVUTIL_VERSION_INT,
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};
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const URLProtocol ff_ipfs_protocol = {
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.name = "ipfs",
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.url_open2 = translate_ipfs_to_http,
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.url_read = ipfs_read,
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.url_seek = ipfs_seek,
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.url_close = ipfs_close,
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.priv_data_size = sizeof(IPFSGatewayContext),
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.priv_data_class = &ipfs_context_class,
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};
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const URLProtocol ff_ipns_protocol = {
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.name = "ipns",
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.url_open2 = translate_ipfs_to_http,
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.url_read = ipfs_read,
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.url_seek = ipfs_seek,
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.url_close = ipfs_close,
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.priv_data_size = sizeof(IPFSGatewayContext),
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.priv_data_class = &ipfs_context_class,
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};
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