[FFmpeg-devel] [PATCH v10 1/1] avformat: Add IPFS protocol support.
Andreas Rheinhardt
andreas.rheinhardt at outlook.com
Wed Mar 30 15:20:05 EEST 2022
Mark Gaiser:
> This patch adds support for:
> - ffplay ipfs://<cid>
> - ffplay ipns://<cid>
>
> IPFS data can be played from so called "ipfs gateways".
> A gateway is essentially a webserver that gives access to the
> distributed IPFS network.
>
> This protocol support (ipfs and ipns) therefore translates
> ipfs:// and ipns:// to a http:// url. This resulting url is
> then handled by the http protocol. It could also be https
> depending on the gateway provided.
>
> To use this protocol, a gateway must be provided.
> If you do nothing it will try to find it in your
> $HOME/.ipfs/gateway file. The ways to set it manually are:
> 1. Define a -gateway <url> to the gateway.
> 2. Define $IPFS_GATEWAY with the full http link to the gateway.
> 3. Define $IPFS_PATH and point it to the IPFS data path.
> 4. Have IPFS running in your local user folder (under $HOME/.ipfs).
>
> Signed-off-by: Mark Gaiser <markg85 at gmail.com>
> ---
> configure | 2 +
> doc/protocols.texi | 30 ++++
> libavformat/Makefile | 2 +
> libavformat/ipfsgateway.c | 309 ++++++++++++++++++++++++++++++++++++++
> libavformat/protocols.c | 2 +
> 5 files changed, 345 insertions(+)
> create mode 100644 libavformat/ipfsgateway.c
>
> diff --git a/configure b/configure
> index e4d36aa639..55af90957a 100755
> --- a/configure
> +++ b/configure
> @@ -3579,6 +3579,8 @@ udp_protocol_select="network"
> udplite_protocol_select="network"
> unix_protocol_deps="sys_un_h"
> unix_protocol_select="network"
> +ipfs_protocol_select="https_protocol"
> +ipns_protocol_select="https_protocol"
>
> # external library protocols
> libamqp_protocol_deps="librabbitmq"
> diff --git a/doc/protocols.texi b/doc/protocols.texi
> index d207df0b52..7c9c0a4808 100644
> --- a/doc/protocols.texi
> +++ b/doc/protocols.texi
> @@ -2025,5 +2025,35 @@ decoding errors.
>
> @end table
>
> + at section ipfs
> +
> +InterPlanetary File System (IPFS) protocol support. One can access files stored
> +on the IPFS network through so called gateways. Those are http(s) endpoints.
> +This protocol wraps the IPFS native protocols (ipfs:// and ipns://) to be send
> +to such a gateway. Users can (and should) host their own node which means this
> +protocol will use your local machine gateway to access files on the IPFS network.
> +
> +If a user doesn't have a node of their own then the public gateway dweb.link is
> +used by default.
> +
> +You can use this protocol in 2 ways. Using IPFS:
> + at example
> +ffplay ipfs://QmbGtJg23skhvFmu9mJiePVByhfzu5rwo74MEkVDYAmF5T
> + at end example
> +
> +Or the IPNS protocol (IPNS is mutable IPFS):
> + at example
> +ffplay ipns://QmbGtJg23skhvFmu9mJiePVByhfzu5rwo74MEkVDYAmF5T
> + at end example
> +
> +You can also change the gateway to be used:
> +
> + at table @option
> +
> + at item gateway
> +Defines the gateway to use. When nothing is provided the protocol will first try
> +your local gateway. If that fails dweb.link will be used.
> +
> + at end table
>
> @c man end PROTOCOLS
> diff --git a/libavformat/Makefile b/libavformat/Makefile
> index d7182d6bd8..e3233fd7ac 100644
> --- a/libavformat/Makefile
> +++ b/libavformat/Makefile
> @@ -660,6 +660,8 @@ OBJS-$(CONFIG_SRTP_PROTOCOL) += srtpproto.o srtp.o
> OBJS-$(CONFIG_SUBFILE_PROTOCOL) += subfile.o
> OBJS-$(CONFIG_TEE_PROTOCOL) += teeproto.o tee_common.o
> OBJS-$(CONFIG_TCP_PROTOCOL) += tcp.o
> +OBJS-$(CONFIG_IPFS_PROTOCOL) += ipfsgateway.o
> +OBJS-$(CONFIG_IPNS_PROTOCOL) += ipfsgateway.o
> TLS-OBJS-$(CONFIG_GNUTLS) += tls_gnutls.o
> TLS-OBJS-$(CONFIG_LIBTLS) += tls_libtls.o
> TLS-OBJS-$(CONFIG_MBEDTLS) += tls_mbedtls.o
> diff --git a/libavformat/ipfsgateway.c b/libavformat/ipfsgateway.c
> new file mode 100644
> index 0000000000..1a039589c0
> --- /dev/null
> +++ b/libavformat/ipfsgateway.c
> @@ -0,0 +1,309 @@
> +/*
> + * IPFS and IPNS protocol support through IPFS Gateway.
> + * Copyright (c) 2022 Mark Gaiser
> + *
> + * 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 "avformat.h"
> +#include "libavutil/avassert.h"
Unused.
> +#include "libavutil/avstring.h"
> +#include "libavutil/internal.h"
> +#include "libavutil/opt.h"
> +#include "libavutil/tree.h"
?
> +#include <fcntl.h>
> +#if HAVE_IO_H
> +#include <io.h>
> +#endif
> +#if HAVE_UNISTD_H
> +#include <unistd.h>
> +#endif
> +#include "os_support.h"
> +#include "url.h"
> +#include <stdlib.h>
> +#include <sys/stat.h>
> +
> +typedef struct IPFSGatewayContext {
> + AVClass *class;
> + URLContext *inner;
> + // Is filled by the -gateway argument and not changed after.
> + char *gateway;
> + // If the above gateway is non null, it will be copied into this buffer.
> + // Else this buffer will contain the auto detected gateway.
> + // In either case, the gateway to use will be in this buffer.
> + char gateway_buffer[PATH_MAX];
> +} IPFSGatewayContext;
> +
> +// A best-effort way to find the IPFS gateway.
> +// Only the most appropiate gateway is set. It's not actually requested
> +// (http call) to prevent a potential slowdown in startup. A potential timeout
> +// is handled by the HTTP protocol.
> +static int populate_ipfs_gateway(URLContext *h)
> +{
> + IPFSGatewayContext *c = h->priv_data;
> + char ipfs_full_data_folder[PATH_MAX];
> + char ipfs_gateway_file[PATH_MAX];
> + struct stat st;
> + int stat_ret = 0;
> + int ret = AVERROR(EINVAL);
> + FILE *gateway_file = NULL;
> +
> + // Test $IPFS_GATEWAY.
> + if (getenv("IPFS_GATEWAY") != NULL) {
> + if (snprintf(c->gateway_buffer, sizeof(c->gateway_buffer), "%s",
> + getenv("IPFS_GATEWAY")) >= sizeof(c->gateway_buffer)) {
> + av_log(h, AV_LOG_WARNING, "The IPFS_GATEWAY environment variable exceeds the maximum length. We allow a max of %zu characters\n", sizeof(c->gateway_buffer));
> + ret = AVERROR(EINVAL);
> + goto err;
> + }
> +
> + ret = 1;
> + goto err;
> + } else
> + av_log(h, AV_LOG_DEBUG, "$IPFS_GATEWAY is empty.\n");
> +
> + // We need to know the IPFS folder to - eventually - read the contents of
> + // the "gateway" file which would tell us the gateway to use.
> + if (getenv("IPFS_PATH") == NULL) {
> + av_log(h, AV_LOG_DEBUG, "$IPFS_PATH is empty.\n");
> +
> + // Try via the home folder.
> + if (getenv("HOME") == NULL) {
> + av_log(h, AV_LOG_WARNING, "$HOME appears to be empty.\n");
> + ret = AVERROR(EINVAL);
> + goto err;
> + }
> +
> + // Verify the composed path fits.
> + if (snprintf(ipfs_full_data_folder, sizeof(ipfs_full_data_folder),
> + "%s/.ipfs/", getenv("HOME")) >= sizeof(ipfs_full_data_folder)) {
> + av_log(h, AV_LOG_WARNING, "The IPFS data path exceeds the max path length (%zu)\n", sizeof(ipfs_full_data_folder));
> + ret = AVERROR(EINVAL);
> + goto err;
> + }
> +
> + // Stat the folder.
> + // It should exist in a default IPFS setup when run as local user.
> +#ifndef _WIN32
> + stat_ret = stat(ipfs_full_data_folder, &st);
> +#else
> + stat_ret = win32_stat(ipfs_full_data_folder, &st);
> +#endif
> + if (stat_ret < 0) {
> + av_log(h, AV_LOG_INFO, "Unable to find IPFS folder. We tried:\n");
> + av_log(h, AV_LOG_INFO, "- $IPFS_PATH, which was empty.\n");
> + av_log(h, AV_LOG_INFO, "- $HOME/.ipfs (full uri: %s) which doesn't exist.\n", ipfs_full_data_folder);
> + ret = AVERROR(ENOENT);
> + goto err;
> + }
> + } else {
> + if (snprintf(ipfs_full_data_folder, sizeof(ipfs_full_data_folder), "%s",
> + getenv("IPFS_PATH")) >= sizeof(ipfs_full_data_folder)) {
> + av_log(h, AV_LOG_WARNING, "The IPFS_PATH environment variable exceeds the maximum length. We allow a max of %zu characters\n", sizeof(c->gateway_buffer));
> + ret = AVERROR(EINVAL);
> + goto err;
> + }
> +
> + }
> +
> + // Copy the fully composed gateway path into ipfs_gateway_file.
> + if (snprintf(ipfs_gateway_file, sizeof(ipfs_gateway_file), "%sgateway",
> + ipfs_full_data_folder) >= sizeof(ipfs_gateway_file)) {
> + av_log(h, AV_LOG_WARNING, "The IPFS gateway file path exceeds the max path length (%zu)\n", sizeof(ipfs_gateway_file));
> + ret = AVERROR(ENOENT);
> + goto err;
> + }
> +
> + // Get the contents of the gateway file.
> + gateway_file = av_fopen_utf8(ipfs_gateway_file, "r");
> + if (!gateway_file) {
> + av_log(h, AV_LOG_WARNING, "The IPFS gateway file (full uri: %s) doesn't exist. Is the gateway enabled?\n", ipfs_gateway_file);
> + ret = AVERROR(ENOENT);
> + goto err;
> + }
> +
> + // Read a single line (fgets stops at new line mark).
> + fgets(c->gateway_buffer, sizeof(c->gateway_buffer) - 1, gateway_file);
> +
> + // Replace the last char with \0
> + c->gateway_buffer[sizeof(c->gateway_buffer) - 1] = 0;
> +
> + // Replace first occurence of end of line with \0
> + c->gateway_buffer[strcspn(c->gateway_buffer, "\r")] = 0;
> + c->gateway_buffer[strcspn(c->gateway_buffer, "\n")] = 0;
If the buffer contains both \r and \n and the first \n precedes the
first \r, then the above zeroes both the first \r and the first \n. If
it is enough to only zero the first newline, then this can be simplified
to "c->gateway_buffer[strcspn(c->gateway_buffer, "\r\n")] = 0;".
> +
> + // If strlen finds anything longer then 0 characters then we have a
> + // potential gateway url.
> + if (strlen(c->gateway_buffer) < 1) {
if (*c->gateway_buffer == '\0')
> + av_log(h, AV_LOG_WARNING, "The IPFS gateway file (full uri: %s) appears to be empty. Is the gateway started?\n", ipfs_gateway_file);
> + ret = AVERROR(EILSEQ);
> + goto err;
> + } else {
> + // We're done, the c->gateway_buffer has something that looks valid.
> + ret = 1;
> + goto err;
> + }
> +
> +err:
> + if (gateway_file)
> + fclose(gateway_file);
> +
> + return ret;
> +}
> +
> +static int translate_ipfs_to_http(URLContext *h, const char *uri,
> + int flags, AVDictionary **options)
> +{
> + const char *ipfs_cid;
> + char *fulluri = NULL;
> + int ret;
> + IPFSGatewayContext *c = h->priv_data;
> +
> + // Test for ipfs://, ipfs:, ipns:// and ipns:. This prefix is stripped from
> + // the string leaving just the CID in ipfs_cid.
> + int is_ipfs = av_stristart(uri, "ipfs://", &ipfs_cid);
> + int is_ipns = av_stristart(uri, "ipns://", &ipfs_cid);
> +
> + // We must have either ipns or ipfs.
> + if (!is_ipfs && !is_ipns) {
> + ret = AVERROR(EINVAL);
> + av_log(h, AV_LOG_WARNING, "Unsupported url %s\n", uri);
> + goto err;
> + }
> +
> + // If the CID has a length greater then 0 then we assume we have a proper working one.
> + // It could still be wrong but in that case the gateway should save us and
> + // ruturn a 403 error. The http protocol handles this.
> + if (strlen(ipfs_cid) < 1) {
> + av_log(h, AV_LOG_WARNING, "A CID must be provided.\n");
> + ret = AVERROR(EILSEQ);
> + goto err;
> + }
> +
> + // Populate c->gateway_buffer with whatever is in c->gateway
> + if (c->gateway != NULL) {
> + if (snprintf(c->gateway_buffer, sizeof(c->gateway_buffer), "%s",
> + c->gateway) >= sizeof(c->gateway_buffer)) {
> + av_log(h, AV_LOG_WARNING, "The -gateway parameter is too long. We allow a max of %zu characters\n", sizeof(c->gateway_buffer));
We typically use SIZE_SPECIFIER instead of z for compatibility with
ancient versions of MSVC.
(I don't know whether there is any supported version of MSVC that
doesn't support z; I don't use MSVC myself.)
> + ret = AVERROR(EINVAL);
> + goto err;
> + }
> + } else {
> + // Populate the IPFS gateway if we have any.
> + // If not, inform the user how to properly set one.
> + ret = populate_ipfs_gateway(h);
> +
> + if (ret < 1) {
> + // We fallback on dweb.link (managed by Protocol Labs).
> + snprintf(c->gateway_buffer, sizeof(c->gateway_buffer), "https://dweb.link");
> +
> + av_log(h, AV_LOG_WARNING, "IPFS does not appear to be running. You’re now using the public gateway at dweb.link.\n");
> + av_log(h, AV_LOG_INFO, "Installing IPFS locally is recommended to improve performance and reliability, and not share all your activity with a single IPFS gateway.\n");
> + av_log(h, AV_LOG_INFO, "There are multiple options to define this gateway.\n");
> + av_log(h, AV_LOG_INFO, "1. Call ffmpeg with a gateway param, without a trailing slash: -gateway <url>.\n");
> + av_log(h, AV_LOG_INFO, "2. Define an $IPFS_GATEWAY environment variable with the full HTTP URL to the gateway without trailing forward slash.\n");
> + av_log(h, AV_LOG_INFO, "3. Define an $IPFS_PATH environment variable and point it to the IPFS data path - this is typically ~/.ipfs\n");
All those AV_LOG_INFO can be combined which has the advantage that the
logs can't be teared apart (which they can now if something else logs at
the same time); furthermore, this would also decrease codesize.
> + }
> + }
> +
> + // Test if the gateway starts with either http:// or https://
> + if (av_stristart(c->gateway_buffer, "http://", NULL) == 0
> + && av_stristart(c->gateway_buffer, "https://", NULL) == 0) {
> + av_log(h, AV_LOG_WARNING, "The gateway URL didn't start with http:// or https:// and is therefore invalid.\n");
> + ret = AVERROR(EILSEQ);
> + goto err;
> + }
> +
> + // Concatenate the url.
> + // This ends up with something like: http://localhost:8080/ipfs/Qm.....
> + // The format of "%s%s%s%s" is the following:
> + // 1st %s = The gateway.
> + // 2nd %s = If the gateway didn't end in a slash, add a "/". Otherwise it's an empty string
> + // 3rd %s = Either ipns/ or ipfs/.
> + // 4th %s = The IPFS CID (Qm..., bafy..., ...).
> + fulluri = av_asprintf("%s%s%s%s",
> + c->gateway_buffer,
> + (c->gateway_buffer[strlen(c->gateway_buffer) - 1] == '/') ? "" : "/",
> + (is_ipns) ? "ipns/" : "ipfs/",
> + ipfs_cid);
Missing allocation check.
> +
> + // Pass the URL back to FFMpeg's protocol handler.
> + if ((ret = ffurl_open_whitelist(&c->inner, fulluri, flags,
> + &h->interrupt_callback, options,
> + h->protocol_whitelist,
> + h->protocol_blacklist, h))
> + < 0) {
Weird formatting; why don't you just use
ret = ffurl_open_whitelist(...);
if (ret < 0) {
> + av_log(h, AV_LOG_WARNING, "Unable to open resource: %s\n", fulluri);
> + goto err;
> + }
> +
> +err:
> + av_free(fulluri);
> + return ret;
> +}
> +
> +static int ipfs_read(URLContext *h, unsigned char *buf, int size)
> +{
> + IPFSGatewayContext *c = h->priv_data;
> + return ffurl_read(c->inner, buf, size);
> +}
> +
> +static int64_t ipfs_seek(URLContext *h, int64_t pos, int whence)
> +{
> + IPFSGatewayContext *c = h->priv_data;
> + return ffurl_seek(c->inner, pos, whence);
> +}
> +
> +static int ipfs_close(URLContext *h)
> +{
> + IPFSGatewayContext *c = h->priv_data;
> + return ffurl_closep(&c->inner);
> +}
> +
> +#define OFFSET(x) offsetof(IPFSGatewayContext, x)
> +
> +static const AVOption options[] = {
> + {"gateway", "The gateway to ask for IPFS data.", OFFSET(gateway), AV_OPT_TYPE_STRING, {.str = NULL}, 0, 0, AV_OPT_FLAG_DECODING_PARAM},
> + {NULL},
> +};
> +
> +static const AVClass ipfs_context_class = {
> + .class_name = "IPFS",
> + .item_name = av_default_item_name,
> + .option = options,
> + .version = LIBAVUTIL_VERSION_INT,
> +};
> +
> +const URLProtocol ff_ipfs_protocol = {
> + .name = "ipfs",
> + .url_open2 = translate_ipfs_to_http,
> + .url_read = ipfs_read,
> + .url_seek = ipfs_seek,
> + .url_close = ipfs_close,
> + .priv_data_size = sizeof(IPFSGatewayContext),
> + .priv_data_class = &ipfs_context_class,
> +};
> +
> +const URLProtocol ff_ipns_protocol = {
> + .name = "ipns",
> + .url_open2 = translate_ipfs_to_http,
> + .url_read = ipfs_read,
> + .url_seek = ipfs_seek,
> + .url_close = ipfs_close,
> + .priv_data_size = sizeof(IPFSGatewayContext),
> + .priv_data_class = &ipfs_context_class,
> +};
> diff --git a/libavformat/protocols.c b/libavformat/protocols.c
> index d07563cd0c..6ee62a598a 100644
> --- a/libavformat/protocols.c
> +++ b/libavformat/protocols.c
> @@ -71,6 +71,8 @@ extern const URLProtocol ff_libsrt_protocol;
> extern const URLProtocol ff_libssh_protocol;
> extern const URLProtocol ff_libsmbclient_protocol;
> extern const URLProtocol ff_libzmq_protocol;
> +extern const URLProtocol ff_ipfs_protocol;
> +extern const URLProtocol ff_ipns_protocol;
>
> #include "libavformat/protocol_list.c"
>
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