[FFmpeg-devel] [PATCH v12 1/1] avformat: Add IPFS protocol support.
Mark Gaiser
markg85 at gmail.com
Mon Apr 4 01:38:25 EEST 2022
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 | 326 ++++++++++++++++++++++++++++++++++++++
libavformat/protocols.c | 2 +
5 files changed, 362 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..e01eb2f9a3
--- /dev/null
+++ b/libavformat/ipfsgateway.c
@@ -0,0 +1,326 @@
+/*
+ * 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 "libavutil/avstring.h"
+#include "libavutil/opt.h"
+#include <sys/stat.h>
+#include "os_support.h"
+#include "url.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.
+ stat_ret = stat(ipfs_full_data_folder, &st);
+
+ 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).
+ if (!fgets(c->gateway_buffer, sizeof(c->gateway_buffer) - 1, gateway_file)) {
+ av_log(h, AV_LOG_WARNING, "Unable to read from file (full uri: %s).\n",
+ ipfs_gateway_file);
+ ret = AVERROR(ENOENT);
+ goto err;
+ }
+
+ // Replace first occurence of end of line with \0
+ 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 (*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));
+ 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"
+ "There are multiple options to define this gateway.\n"
+ "1. Call ffmpeg with a gateway param, "
+ "without a trailing slash: -gateway <url>.\n"
+ "2. Define an $IPFS_GATEWAY environment variable with the "
+ "full HTTP URL to the gateway "
+ "without trailing forward slash.\n"
+ "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);
+
+ if (!fulluri) {
+ av_log(h, AV_LOG_ERROR, "Failed to compose the URL\n");
+ ret = AVERROR(ENOMEM);
+ goto err;
+ }
+
+ // Pass the URL back to FFMpeg's protocol handler.
+ ret = ffurl_open_whitelist(&c->inner, fulluri, flags,
+ &h->interrupt_callback, options,
+ h->protocol_whitelist,
+ h->protocol_blacklist, h);
+ 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"
--
2.35.1
More information about the ffmpeg-devel
mailing list