On Thu, Feb 17, 2022 at 3:57 PM Mark Gaiser <mark...@gmail.com> wrote:
> On Thu, Feb 17, 2022 at 3:50 PM Mark Gaiser <mark...@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 <mark...@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
>>
>> +@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:
>> +@example
>> +ffplay ipfs://QmbGtJg23skhvFmu9mJiePVByhfzu5rwo74MEkVDYAmF5T
>> +@end example
>> +
>> +Or the IPNS protocol (IPNS is mutable IPFS):
>> +@example
>> +ffplay ipns://QmbGtJg23skhvFmu9mJiePVByhfzu5rwo74MEkVDYAmF5T
>> +@end example
>> +
>> +You can also change the gateway to be used:
>> +
>> +@table @option
>> +
>> +@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.
>> +
>> +@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.
>
ping
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