Re: [FFmpeg-devel] [PATCH 1/5] Early version of IPFS protocol support.

[Mark Gaiser <markg85@gmail.com>]

On Mon, Jan 31, 2022 at 5:06 PM James Almer <jamrial@gmail.com> wrote:

>
>
> On 1/31/2022 10:51 AM, Mark Gaiser wrote:
> > Signed-off-by: Mark Gaiser <markg85@gmail.com>
> > ---
> >   configure               |   1 +
> >   doc/protocols.texi      |  30 ++++++
> >   libavformat/Makefile    |   1 +
> >   libavformat/ipfs.c      | 202 ++++++++++++++++++++++++++++++++++++++++
> >   libavformat/protocols.c |   2 +
> >   5 files changed, 236 insertions(+)
> >   create mode 100644 libavformat/ipfs.c
> >
> > diff --git a/configure b/configure
> > index 5b19a35f59..e466f924a3 100755
> > --- a/configure
> > +++ b/configure
> > @@ -3585,6 +3585,7 @@ udp_protocol_select="network"
> >   udplite_protocol_select="network"
> >   unix_protocol_deps="sys_un_h"
> >   unix_protocol_select="network"
> > +ipfs_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..983a77f4f2 100644
> > --- a/libavformat/Makefile
> > +++ b/libavformat/Makefile
> > @@ -656,6 +656,7 @@ 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-$(CONFIG_IPFS_PROTOCOL)             += ipfs.o
> >   TLS-OBJS-$(CONFIG_GNUTLS)                += tls_gnutls.o
> >   TLS-OBJS-$(CONFIG_LIBTLS)                += tls_libtls.o
> >   TLS-OBJS-$(CONFIG_MBEDTLS)               += tls_mbedtls.o
> > diff --git a/libavformat/ipfs.c b/libavformat/ipfs.c
> > new file mode 100644
> > index 0000000000..4cc65750ed
> > --- /dev/null
> > +++ b/libavformat/ipfs.c
> > @@ -0,0 +1,202 @@
> > +/*
> > + * IPFS protocol.
> > + * Copyright (c) 2021 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/avassert.h"
> > +#include "libavutil/avstring.h"
> > +#include "libavutil/internal.h"
> > +#include "libavutil/opt.h"
> > +#include "libavutil/tree.h"
> > +#include "avformat.h"
> > +#include <fcntl.h>
> > +#if HAVE_IO_H
> > +#include <io.h>
> > +#endif
> > +#if HAVE_UNISTD_H
> > +#include <unistd.h>
> > +#endif
> > +#include <sys/stat.h>
> > +#include <stdlib.h>
> > +#include "os_support.h"
> > +#include "url.h"
> > +
> > +typedef struct Context {
> > +    AVClass *class;
> > +    URLContext *inner;
> > +    char *fulluri;
> > +    char *gateway;
> > +} Context;
>
> A more descriptive name would be nice.
>
> > +
> > +static int ipfs_open(URLContext *h, const char *uri, int flags,
> AVDictionary **options)
> > +{
> > +    const char *gatewaysuffix;
> > +    int ret = 0;
> > +    Context *c = h->priv_data;
> > +
> > +    if (!av_strstart(uri, "ipfs://", &gatewaysuffix) &&
> > +        !av_strstart(uri, "ipfs:", &gatewaysuffix)) {
> > +        av_log(h, AV_LOG_ERROR, "Unsupported url %s\n", uri);
> > +        ret = AVERROR(EINVAL);
> > +        goto err;
>
> Just return ret. No need for this goto.
>
> > +    }
> > +
> > +    char* ipfs_gateway = "https://ipfs.io/ipfs/";
>
> const char*
>
> > +
> > +    c->fulluri = malloc(strlen(ipfs_gateway)+strlen(gatewaysuffix) + 1);
>
> av_malloc()
>
> Also, check the return value for allocation failure.
>
> > +
> > +    strcpy(c->fulluri, ipfs_gateway);
> > +    strcat(c->fulluri, gatewaysuffix);
> > +
> > +    if ((ret = ffurl_open_whitelist(&c->inner, c->fulluri, flags,
>
> Is fulluri going to be used after this call? If not, then it should be
> local to this function as there's no need to have it in h->priv_data
> (And for that matter, you're not freeing fulluri anywhere).
>
> > +                                    &h->interrupt_callback, options,
> > +                                    h->protocol_whitelist,
> h->protocol_blacklist, h)) < 0) {
>
> You need to define a whitelist including https in both URLProtocol below.
>
> > +        av_log(h, AV_LOG_ERROR, "Unable to open resource: %s\n",
> c->fulluri);
> > +        goto err;
> > +    }
> > +
> > +err:
> > +    return ret;
> > +}
> > +
> > +static int ipfs_read(URLContext *h, unsigned char *buf, int size)
> > +{
> > +    Context *c = h->priv_data;
> > +    int ret;
> > +
> > +    ret = ffurl_read(c->inner, buf, size);
> > +
> > +    return ret;
> > +}
> > +
> > +static int64_t ipfs_seek(URLContext *h, int64_t pos, int whence)
> > +{
> > +    Context *c = h->priv_data;
> > +    int64_t ret;
> > +
> > +    ret = ffurl_seek(c->inner, pos, whence);
> > +
> > +    return ret;
> > +}
> > +
> > +static int ipfs_close(URLContext *h)
> > +{
> > +    Context *c = h->priv_data;
> > +    int ret;
> > +
> > +    ret = ffurl_closep(&c->inner);
> > +
> > +    return ret;
> > +}
> > +
> > +static int ipns_open(URLContext *h, const char *uri, int flags,
> AVDictionary **options)
> > +{
> > +    const char *gatewaysuffix;
> > +    int ret = 0;
> > +    Context *c = h->priv_data;
> > +
> > +    if (!av_strstart(uri, "ipns://", &gatewaysuffix) &&
> > +        !av_strstart(uri, "ipns:", &gatewaysuffix)) {
> > +        av_log(h, AV_LOG_ERROR, "Unsupported url %s\n", uri);
> > +        ret = AVERROR(EINVAL);
> > +        goto err;
> > +    }
> > +
> > +    char* ipfs_gateway = "https://ipfs.io/ipns/";
> > +
> > +    c->fulluri = malloc(strlen(ipfs_gateway)+strlen(gatewaysuffix) + 1);
> > +
> > +    strcpy(c->fulluri, ipfs_gateway);
> > +    strcat(c->fulluri, gatewaysuffix);
> > +
> > +    if ((ret = ffurl_open_whitelist(&c->inner, c->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",
> c->fulluri);
> > +        goto err;
> > +    }
> > +
> > +err:
> > +    return ret;
>
> Same comments as above apply here.
>

Awesome, thank you for your review time!
Will fix all those in V2.

>
> > +}
> > +
> > +static int ipns_read(URLContext *h, unsigned char *buf, int size)
> > +{
> > +    Context *c = h->priv_data;
> > +    int ret;
> > +
> > +    ret = ffurl_read(c->inner, buf, size);
> > +
> > +    return ret;
> > +}
> > +
> > +static int64_t ipns_seek(URLContext *h, int64_t pos, int whence)
> > +{
> > +    Context *c = h->priv_data;
> > +    int64_t ret;
> > +
> > +    ret = ffurl_seek(c->inner, pos, whence);
> > +
> > +    return ret;
> > +}
> > +
> > +static int ipns_close(URLContext *h)
> > +{
> > +    Context *c = h->priv_data;
> > +    int ret;
> > +
> > +    ret = ffurl_closep(&c->inner);
> > +
> > +    return ret;
> > +}
> > +
> > +#define OFFSET(x) offsetof(Context, x)
> > +#define D AV_OPT_FLAG_DECODING_PARAM
> > +
> > +static const AVOption options[] = {
> > +    {"gateway", "The gateway to ask for IPFS data.", OFFSET(gateway),
> AV_OPT_TYPE_BINARY, .flags = D },
> > +    {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           = ipfs_open,
> > +    .url_read            = ipfs_read,
> > +    .url_seek            = ipfs_seek,
> > +    .url_close           = ipfs_close,
> > +    .priv_data_size      = sizeof(Context),
> > +    .priv_data_class     = &ipfs_context_class,
> > +};
> > +
> > +const URLProtocol ff_infs_protocol = {
> > +    .name                = "ipns",
> > +    .url_open2           = ipfs_open,
> > +    .url_read            = ipfs_read,
> > +    .url_seek            = ipfs_seek,
> > +    .url_close           = ipfs_close,
> > +    .priv_data_size      = sizeof(Context),
> > +    .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"
> >
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