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Redo protocol for proxy--broker messages

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Switch to containing all communication between the proxy and the broker
in the HTTP response body. This will make things easier if we ever use
something other than HTTP communicate between different actors in the
snowflake system.

Other changes to the protocol are as follows:
- requests are accompanied by a version number so the broker can be
backwards compatable if desired in the future
- all responses are 200 OK unless the request was badly formatted
This commit is contained in:
Cecylia Bocovich 2019-10-07 14:02:01 -04:00
parent abefae1587
commit c4ae64905b
6 changed files with 489 additions and 53 deletions
Download patch file Download diff file Expand all files Collapse all files

41
proxy-go/snowflake.go
View file

@ -19,6 +19,7 @@ import (
"sync"
"time"
"git.torproject.org/pluggable-transports/snowflake.git/common/messages"
"git.torproject.org/pluggable-transports/snowflake.git/common/safelog"
"github.com/pion/webrtc"
"golang.org/x/net/websocket"
@ -168,7 +169,12 @@ func pollOffer(sid string) *webrtc.SessionDescription {
timeOfNextPoll = now
}
req, _ := http.NewRequest("POST", broker.String(), bytes.NewBuffer([]byte(sid)))
b, err := messages.EncodePollRequest(sid)
if err != nil {
log.Printf("Error encoding poll message: %s", err.Error())
return nil
}
req, _ := http.NewRequest("POST", broker.String(), bytes.NewBuffer(b))
req.Header.Set("X-Session-ID", sid)
resp, err := client.Do(req)
if err != nil {
@ -182,7 +188,16 @@ func pollOffer(sid string) *webrtc.SessionDescription {
if err != nil {
log.Printf("error reading broker response: %s", err)
} else {
return deserializeSessionDescription(string(body))
offer, err := messages.DecodePollResponse(body)
if err != nil {
log.Printf("error reading broker response: %s", err.Error())
log.Printf("body: %s", body)
return nil
}
if offer != "" {
return deserializeSessionDescription(offer)
}
}
}
}
@ -191,9 +206,12 @@ func pollOffer(sid string) *webrtc.SessionDescription {
func sendAnswer(sid string, pc *webrtc.PeerConnection) error {
broker := brokerURL.ResolveReference(&url.URL{Path: "answer"})
body := bytes.NewBuffer([]byte(serializeSessionDescription(pc.LocalDescription())))
req, _ := http.NewRequest("POST", broker.String(), body)
req.Header.Set("X-Session-ID", sid)
answer := string([]byte(serializeSessionDescription(pc.LocalDescription())))
b, err := messages.EncodeAnswerRequest(answer, sid)
if err != nil {
return err
}
req, _ := http.NewRequest("POST", broker.String(), bytes.NewBuffer(b))
resp, err := client.Do(req)
if err != nil {
return err
@ -201,6 +219,19 @@ func sendAnswer(sid string, pc *webrtc.PeerConnection) error {
if resp.StatusCode != http.StatusOK {
return fmt.Errorf("broker returned %d", resp.StatusCode)
}
body, err := limitedRead(resp.Body, readLimit)
if err != nil {
return fmt.Errorf("error reading broker response: %s", err)
}
success, err := messages.DecodeAnswerResponse(body)
if err != nil {
return err
}
if !success {
return fmt.Errorf("broker returned client timeout")
}
return nil
}