archives/snowflake
2
0
Fork 0
mirror of https://gitlab.torproject.org/tpo/anti-censorship/pluggable-transports/snowflake.git synced 2025-10-13 20:11:19 -04:00
Code Issues Projects Releases Packages Wiki Activity Actions

Redo protocol for proxy--broker messages

Browse source 
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

66
broker/broker.go
View file

@ -21,6 +21,7 @@ import (
"syscall"
"time"
"git.torproject.org/pluggable-transports/snowflake.git/common/messages"
"git.torproject.org/pluggable-transports/snowflake.git/common/safelog"
"golang.org/x/crypto/acme/autocert"
)
@ -151,15 +152,16 @@ func (ctx *BrokerContext) AddSnowflake(id string) *Snowflake {
For snowflake proxies to request a client from the Broker.
*/
func proxyPolls(ctx *BrokerContext, w http.ResponseWriter, r *http.Request) {
id := r.Header.Get("X-Session-ID")
body, err := ioutil.ReadAll(http.MaxBytesReader(w, r.Body, readLimit))
if nil != err {
if err != nil {
log.Println("Invalid data.")
w.WriteHeader(http.StatusBadRequest)
return
}
if string(body) != id {
log.Println("Mismatched IDs!")
sid, err := messages.DecodePollRequest(body)
if err != nil {
log.Println("Invalid data.")
w.WriteHeader(http.StatusBadRequest)
return
}
@ -173,14 +175,26 @@ func proxyPolls(ctx *BrokerContext, w http.ResponseWriter, r *http.Request) {
}
// Wait for a client to avail an offer to the snowflake, or timeout if nil.
offer := ctx.RequestOffer(id)
offer := ctx.RequestOffer(sid)
var b []byte
if nil == offer {
ctx.metrics.proxyIdleCount++
w.WriteHeader(http.StatusGatewayTimeout)
b, err = messages.EncodePollResponse("", false)
if err != nil {
w.WriteHeader(http.StatusInternalServerError)
return
}
w.Write(b)
return
}
log.Println("Passing client offer to snowflake.")
if _, err := w.Write(offer); err != nil {
b, err = messages.EncodePollResponse(string(offer), true)
if err != nil {
w.WriteHeader(http.StatusInternalServerError)
return
}
if _, err := w.Write(b); err != nil {
log.Printf("proxyPolls unable to write offer with error: %v", err)
}
}
@ -235,14 +249,7 @@ an offer from proxyHandler to respond with an answer in an HTTP POST,
which the broker will pass back to the original client.
*/
func proxyAnswers(ctx *BrokerContext, w http.ResponseWriter, r *http.Request) {
id := r.Header.Get("X-Session-ID")
snowflake, ok := ctx.idToSnowflake[id]
if !ok || nil == snowflake {
// The snowflake took too long to respond with an answer, so its client
// disappeared / the snowflake is no longer recognized by the Broker.
w.WriteHeader(http.StatusGone)
return
}
body, err := ioutil.ReadAll(http.MaxBytesReader(w, r.Body, readLimit))
if nil != err || nil == body || len(body) <= 0 {
log.Println("Invalid data.")
@ -250,7 +257,32 @@ func proxyAnswers(ctx *BrokerContext, w http.ResponseWriter, r *http.Request) {
return
}
snowflake.answerChannel <- body
answer, id, err := messages.DecodeAnswerRequest(body)
if err != nil || answer == "" {
log.Println("Invalid data.")
w.WriteHeader(http.StatusBadRequest)
return
}
var success = true
snowflake, ok := ctx.idToSnowflake[id]
if !ok || nil == snowflake {
// The snowflake took too long to respond with an answer, so its client
// disappeared / the snowflake is no longer recognized by the Broker.
success = false
}
b, err := messages.EncodeAnswerResponse(success)
if err != nil {
log.Printf("Error encoding answer: %s", err.Error())
w.WriteHeader(http.StatusInternalServerError)
return
}
w.Write(b)
if success {
snowflake.answerChannel <- []byte(answer)
}
}
func debugHandler(ctx *BrokerContext, w http.ResponseWriter, r *http.Request) {