[FFmpeg-devel] [PATCH v8 1/1] avformat: Add IPFS protocol support.
Mark Gaiser
markg85 at gmail.com
Thu Feb 17 16:57:03 EET 2022
On Thu, Feb 17, 2022 at 3:50 PM Mark Gaiser <markg85 at gmail.com> wrote:
> 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 5b19a35f59..6ff09e7974 100755
> --- a/configure
> +++ b/configure
> @@ -3585,6 +3585,8 @@ 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 3dc6a479cc..4edce8420f 100644
> --- a/libavformat/Makefile
> +++ b/libavformat/Makefile
> @@ -656,6 +656,8 @@ 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..7dfa56871d
> --- /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"
> +#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 $IPFS_GATEWAY.
> + if (getenv("IPFS_GATEWAY") != NULL) {
> + if (snprintf(c->gateway_buffer, sizeof(c->gateway_buffer), "%s",
> + getenv("IPFS_GATEWAY")) >=
> sizeof(c->gateway_buffer)) {
> + av_log(h, AV_LOG_ERROR, "The IPFS_GATEWAY environment
> variable exceeds the maximum length. We allow a max of %zu characters\n",
> sizeof(c->gateway_buffer));
> + ret = AVERROR(EINVAL);
> + goto err;
> + }
> +
> + ret = 1;
> + goto err;
> + } else
> + av_log(h, AV_LOG_DEBUG, "$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, "$IPFS_PATH is empty.\n");
> +
> + // Try via the home folder.
> + if (getenv("HOME") == NULL) {
> + av_log(h, AV_LOG_ERROR, "$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_ERROR, "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_ERROR, "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_ERROR, "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_ERROR, "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 strlen finds anything longer then 0 characters then we have a
> + // potential gateway url.
> + if (strlen(c->gateway_buffer) < 1) {
> + av_log(h, AV_LOG_ERROR, "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_ERROR, "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_ERROR, "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_ERROR, "The -gateway parameter is too long.
> We allow a max of %zu characters\n", sizeof(c->gateway_buffer));
> + 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) {
> + av_log(h, AV_LOG_ERROR, "No IPFS gateway was set. Make sure a
> local IPFS instance is running.\n");
> + av_log(h, AV_LOG_INFO, "There are multiple options to define
> this gateway. The below options are in order of precedence:\n");
> + av_log(h, AV_LOG_INFO, "1. Define a -gateway <url> to the
> gateway without trailing forward slash.\n");
> + av_log(h, AV_LOG_INFO, "2. Define $IPFS_GATEWAY with the full
> http link to the gateway without trailing forward slash.\n");
> + av_log(h, AV_LOG_INFO, "3. Define $IPFS_PATH and point it to
> the IPFS data path.\n");
> + av_log(h, AV_LOG_INFO, "4. Have IPFS running in your local
> user folder (under $HOME/.ipfs).\n");
> + av_log(h, AV_LOG_INFO, "In all path cases, a file named
> gateway is expected. See https://github.com/ipfs/specs/issues/261 for
> more information.\n");
> + goto err;
> + }
> + }
> +
> + // 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_ERROR, "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);
> +
> + // 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) {
> + av_log(h, AV_LOG_ERROR, "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;
> + av_free(c->gateway);
> + 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 948fae411f..675b684bd3 100644
> --- a/libavformat/protocols.c
> +++ b/libavformat/protocols.c
> @@ -73,6 +73,8 @@ 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"
>
> --
> 2.35.1
>
>
There we go, V8. Would this be the final one? I hope so! :)
Just in case this is the magic final version that is allowed to be merged.
How do I proceed in that case? I don't have merge powers...
A small note on the log lines.
I do prefer to keep them on one line. This seems to be in line with other
ffmpeg code files (i only looked at a couple other protocols like crypto,
http and avio).
Splitting them looks - imho - quite ugly.
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