[FFmpeg-devel] [PATCH v9 1/1] avformat: Add IPFS protocol support.
Mark Gaiser
markg85 at gmail.com
Mon Mar 28 02:31:36 EEST 2022
On Wed, Mar 23, 2022 at 12:24 PM Mark Gaiser <markg85 at gmail.com> wrote:
> On Fri, Mar 18, 2022 at 3:59 PM Mark Gaiser <markg85 at gmail.com> wrote:
>
>> On Fri, Mar 18, 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 | 310 ++++++++++++++++++++++++++++++++++++++
>>> libavformat/protocols.c | 2 +
>>> 5 files changed, 346 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..2b2905d2c2
>>> --- /dev/null
>>> +++ b/libavformat/ipfsgateway.c
>>> @@ -0,0 +1,310 @@
>>> +/*
>>> + * 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 $IPFS_GATEWAY.
>>> + if (getenv("IPFS_GATEWAY") != NULL) {
>>> + if (snprintf(c->gateway_buffer, sizeof(c->gateway_buffer), "%s",
>>> + getenv("IPFS_GATEWAY")) >=
>>> sizeof(c->gateway_buffer)) {
>>> + av_log(h, AV_LOG_WARNING, "The IPFS_GATEWAY environment
>>> variable exceeds the maximum length. We allow a max of %zu characters\n",
>>> sizeof(c->gateway_buffer));
>>> + ret = AVERROR(EINVAL);
>>> + goto err;
>>> + }
>>> +
>>> + ret = 1;
>>> + goto err;
>>> + } else
>>> + av_log(h, AV_LOG_DEBUG, "$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 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_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));
>>> + 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");
>>>
>>
>> Just to make this part clear.
>> I've been holding off sending this patch till I received and OK from
>> Protocol Labs (they maintain this gateway and IPFS).
>> They approve having this fallback gateway in the ffmpeg codebase.
>>
>> This also means that, starting from this patch, "ffplay ipfs://<cid>"
>> will just work on any platform where ffmpeg runs and this protocol is
>> enabled!
>> That's huge!
>>
>> Other than that it's implemented exactly as previously discussed in the
>> V8 series.
>>
>> +
>>> + 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");
>>> + }
>>> + }
>>> +
>>> + // 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);
>>> +
>>> + // 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_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;
>>> + 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
>>>
>>>
> ping...
>
5 days later.
Second ping..
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