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refactor(pubsub): base64url for all URL args
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This makes it easier to reason about.
Also added better helptext to each command explaining how the binary
data is encoded on the wire, and how to process it in userland.
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@lidel
lidel committed Oct 6, 2021
1 parent f168552 commit ba52fd4
Showing 1 changed file with 133 additions and 54 deletions.
187 changes: 133 additions & 54 deletions core/commands/pubsub.go
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Original file line number Diff line number Diff line change
Expand Up @@ -25,10 +25,11 @@ var PubsubCmd = &cmds.Command{
ipfs pubsub allows you to publish messages to a given topic, and also to
subscribe to new messages on a given topic.
This is an experimental feature. It is not intended in its current state
to be used in a production environment.
EXPERIMENTAL FEATURE
To use, the daemon must be run with '--enable-pubsub-experiment'.
It is not intended in its current state to be used in a production
environment. To use, the daemon must be run with
'--enable-pubsub-experiment'.
`,
},
Subcommands: map[string]*cmds.Command{
Expand All @@ -39,10 +40,6 @@ To use, the daemon must be run with '--enable-pubsub-experiment'.
},
}

const (
pubsubDiscoverOptionName = "discover"
)

type pubsubMessage struct {
From string `json:"from,omitempty"`
Data string `json:"data,omitempty"`
Expand All @@ -56,37 +53,37 @@ var PubsubSubCmd = &cmds.Command{
ShortDescription: `
ipfs pubsub sub subscribes to messages on a given topic.
This is an experimental feature. It is not intended in its current state
to be used in a production environment.
EXPERIMENTAL FEATURE
To use, the daemon must be run with '--enable-pubsub-experiment'.
`,
LongDescription: `
ipfs pubsub sub subscribes to messages on a given topic.
It is not intended in its current state to be used in a production
environment. To use, the daemon must be run with
'--enable-pubsub-experiment'.
This is an experimental feature. It is not intended in its current state
to be used in a production environment.
TOPIC ENCODING
To use, the daemon must be run with '--enable-pubsub-experiment'.
Topic names are a binary data. To ensure all bytes are transferred
correctly RPC client and server will use multibase encoding behind
the scenes.
This command outputs data in the following encodings:
* "json"
(Specified by the "--encoding" or "--enc" flag)
You can inspect the format by passing --enc=json. ipfs multibase commands
can be used for encoding/decoding multibase strings in the userland.
`,
},
Arguments: []cmds.Argument{
cmds.StringArg("topic", true, false, "String name of topic to subscribe to."),
},
Options: []cmds.Option{
cmds.BoolOption(pubsubDiscoverOptionName, "Deprecated option to instruct pubsub to discovery peers for the topic. Discovery is now built into pubsub."),
cmds.StringArg("topic", true, false, "Name of topic to subscribe to."),
},
PreRun: urlArgsEncoder,
Run: func(req *cmds.Request, res cmds.ResponseEmitter, env cmds.Environment) error {
api, err := cmdenv.GetApi(env, req)
if err != nil {
return err
}
if err := urlArgsDecoder(req, env); err != nil {
return err
}

topic := req.Arguments[0]

sub, err := api.PubSub().Subscribe(req.Context, topic)
if err != nil {
return err
Expand All @@ -105,7 +102,9 @@ This command outputs data in the following encodings:
return err
}

encoder, _ := mbase.EncoderByName("base64")
// encode as base64url so the same string is present in body and URL args
// when sent over HTTP RPC API
encoder, _ := mbase.EncoderByName("base64url")
psm := pubsubMessage{
Data: encoder.Encode(msg.Data()),
From: encoder.Encode([]byte(msg.From())),
Expand All @@ -128,6 +127,7 @@ This command outputs data in the following encodings:
_, err = w.Write(dec)
return err
}),
// --enc=ndpayload is not documented, byt used internally by sharness tests
"ndpayload": cmds.MakeTypedEncoder(func(req *cmds.Request, w io.Writer, psm *pubsubMessage) error {
_, dec, err := mbase.Decode(psm.Data)
if err != nil {
Expand All @@ -137,6 +137,7 @@ This command outputs data in the following encodings:
_, err = w.Write(data)
return err
}),
// ¯\_(ツ)_/¯ – seems unused, can we remove this?
"lenpayload": cmds.MakeTypedEncoder(func(req *cmds.Request, w io.Writer, psm *pubsubMessage) error {
buf := make([]byte, 8, len(psm.Data)+8)

Expand All @@ -155,49 +156,49 @@ var PubsubPubCmd = &cmds.Command{
ShortDescription: `
ipfs pubsub pub publishes a message to a specified topic.
This is an experimental feature. It is not intended in its current state
to be used in a production environment.
EXPERIMENTAL FEATURE
It is not intended in its current state to be used in a production
environment. To use, the daemon must be run with
'--enable-pubsub-experiment'.
TOPIC AND DATA ENCODING
Topic names are a binary data too. To ensure all bytes are transferred
correctly RPC client and server will use multibase encoding behind
the scenes.
To use, the daemon must be run with '--enable-pubsub-experiment'.
You can inspect the format by passing --enc=json. ipfs multibase commands
can be used for encoding/decoding multibase strings in the userland.
`,
},
Arguments: []cmds.Argument{
cmds.StringArg("topic", true, false, "Topic to publish to."),
cmds.StringArg("data", false, true, "Payload of message to publish."),
},
PreRun: func(req *cmds.Request, env cmds.Environment) error {
encoder, _ := mbase.EncoderByName("base64url")
for n, arg := range req.Arguments {
req.Arguments[n] = encoder.Encode([]byte(arg))
}

// when there are no string args, read from stdin.
// when there are no string args with data, read from stdin.
if len(req.Arguments) == 1 {
buf, err := ioutil.ReadAll(os.Stdin)
if err != nil {
return err
}
req.Arguments = append(req.Arguments, encoder.Encode(buf))
req.Arguments = append(req.Arguments, string(buf))
}
return nil
return urlArgsEncoder(req, env)
},
Run: func(req *cmds.Request, res cmds.ResponseEmitter, env cmds.Environment) error {
api, err := cmdenv.GetApi(env, req)
if err != nil {
return err
}

_, topic, err := mbase.Decode(req.Arguments[0])
if err != nil {
return errors.Wrap(err, "pubsub topic must be multibase encoded")
if err := urlArgsDecoder(req, env); err != nil {
return err
}

topic := req.Arguments[0]
for _, data := range req.Arguments[1:] {
_, datab, err := mbase.Decode(data)
if err != nil {
return errors.Wrap(err, "pubsub data must be multibase encoded")
}
if err := api.PubSub().Publish(req.Context, string(topic), datab); err != nil {
if err := api.PubSub().Publish(req.Context, topic, []byte(data)); err != nil {
return err
}
}
Expand All @@ -212,10 +213,20 @@ var PubsubLsCmd = &cmds.Command{
ShortDescription: `
ipfs pubsub ls lists out the names of topics you are currently subscribed to.
This is an experimental feature. It is not intended in its current state
to be used in a production environment.
EXPERIMENTAL FEATURE
To use, the daemon must be run with '--enable-pubsub-experiment'.
It is not intended in its current state to be used in a production
environment. To use, the daemon must be run with
'--enable-pubsub-experiment'.
TOPIC ENCODING
Topic names are a binary data. To ensure all bytes are transferred
correctly RPC client and server will use multibase encoding behind
the scenes.
You can inspect the format by passing --enc=json. ipfs multibase commands
can be used for encoding/decoding multibase strings in the userland.
`,
},
Run: func(req *cmds.Request, res cmds.ResponseEmitter, env cmds.Environment) error {
Expand All @@ -229,14 +240,31 @@ To use, the daemon must be run with '--enable-pubsub-experiment'.
return err
}

// emit topics encoded in multibase
encoder, _ := mbase.EncoderByName("base64url")
for n, topic := range l {
l[n] = encoder.Encode([]byte(topic))
}

return cmds.EmitOnce(res, stringList{l})
},
Type: stringList{},
Encoders: cmds.EncoderMap{
cmds.Text: cmds.MakeTypedEncoder(stringListEncoder),
cmds.Text: cmds.MakeTypedEncoder(multibaseDecodedStringListEncoder),
},
}

func multibaseDecodedStringListEncoder(req *cmds.Request, w io.Writer, list *stringList) error {
for n, mb := range list.Strings {
_, data, err := mbase.Decode(mb)
if err != nil {
return err
}
list.Strings[n] = string(data)
}
return stringListEncoder(req, w, list)
}

func stringListEncoder(req *cmds.Request, w io.Writer, list *stringList) error {
for _, str := range list.Strings {
_, err := fmt.Fprintf(w, "%s\n", cmdenv.EscNonPrint(str))
Expand All @@ -252,23 +280,37 @@ var PubsubPeersCmd = &cmds.Command{
Tagline: "List peers we are currently pubsubbing with.",
ShortDescription: `
ipfs pubsub peers with no arguments lists out the pubsub peers you are
currently connected to. If given a topic, it will list connected
peers who are subscribed to the named topic.
currently connected to. If given a topic, it will list connected peers who are
subscribed to the named topic.
This is an experimental feature. It is not intended in its current state
to be used in a production environment.
EXPERIMENTAL FEATURE
To use, the daemon must be run with '--enable-pubsub-experiment'.
It is not intended in its current state to be used in a production
environment. To use, the daemon must be run with
'--enable-pubsub-experiment'.
TOPIC AND DATA ENCODING
Topic names are a binary data. To ensure all bytes are transferred
correctly RPC client and server will use multibase encoding behind
the scenes.
You can inspect the format by passing --enc=json. ipfs multibase commands
can be used for encoding/decoding multibase strings in the userland.
`,
},
Arguments: []cmds.Argument{
cmds.StringArg("topic", false, false, "topic to list connected peers of"),
cmds.StringArg("topic", false, false, "Topic to list connected peers of."),
},
PreRun: urlArgsEncoder,
Run: func(req *cmds.Request, res cmds.ResponseEmitter, env cmds.Environment) error {
api, err := cmdenv.GetApi(env, req)
if err != nil {
return err
}
if err := urlArgsDecoder(req, env); err != nil {
return err
}

var topic string
if len(req.Arguments) == 1 {
Expand All @@ -293,3 +335,40 @@ To use, the daemon must be run with '--enable-pubsub-experiment'.
cmds.Text: cmds.MakeTypedEncoder(stringListEncoder),
},
}

// Encode binary data to be passed as multibase string in URL arguments.
// (avoiding issues described in https://github.com/ipfs/go-ipfs/issues/7939)
func urlArgsEncoder(req *cmds.Request, env cmds.Environment) error {
encoder, _ := mbase.EncoderByName("base64url")
for n, arg := range req.Arguments {
req.Arguments[n] = encoder.Encode([]byte(arg))
}
return nil
}

// Decode binary data passed as multibase string in URL arguments.
// (avoiding issues described in https://github.com/ipfs/go-ipfs/issues/7939)
func urlArgsDecoder(req *cmds.Request, env cmds.Environment) error {
err := req.ParseBodyArgs()
if err != nil {
return err
}
for n, arg := range req.Arguments {
encoding, data, err := mbase.Decode(arg)
if err != nil {
return errors.Wrap(err, "URL arg must be multibase encoded")
}

// Enforce URL-safe encoding is used for data passed via URL arguments
// - without this we get data corruption similar to https://github.com/ipfs/go-ipfs/issues/7939
// - we can't just deny base64, because there may be other bases that
// are not URL-safe – better to force base64url which is known to be
// safe in URL context
if encoding != mbase.Base64url {
return errors.New("URL arg must be base64url encoded")
}

req.Arguments[n] = string(data)
}
return nil
}

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