mirror of
https://gitlab.torproject.org/tpo/anti-censorship/pluggable-transports/snowflake.git
synced 2025-10-14 05:11:19 -04:00
e0b36d2f33
This is just enough to be compatible with the HTTP signaling in the server, and doesn't do domain fronting or anything like that. It's just an interim replacement for the copy-paste FIFO signaling while we continue to develop the other pieces that'll be dropped in the middle.
100 lines
2.8 KiB
Go
100 lines
2.8 KiB
Go
// Exchange WebRTC SessionDescriptions over meek.
|
||
// Much of this source is extracted from meek-client.go.
|
||
package main
|
||
|
||
import (
|
||
"bytes"
|
||
"io/ioutil"
|
||
"net/http"
|
||
"net/url"
|
||
|
||
"github.com/keroserene/go-webrtc"
|
||
)
|
||
|
||
// RequestInfo encapsulates all the configuration used for a request–response
|
||
// roundtrip, including variables that may come from SOCKS args or from the
|
||
// command line.
|
||
type RequestInfo struct {
|
||
// What to put in the X-Session-ID header.
|
||
// SessionID string
|
||
// The URL to request.
|
||
URL *url.URL
|
||
// The Host header to put in the HTTP request (optional and may be
|
||
// different from the host name in URL).
|
||
Host string
|
||
}
|
||
|
||
func NewRequestInfo(meekUrl string, front string) *RequestInfo {
|
||
info := new(RequestInfo)
|
||
requestUrl, err := url.Parse(meekUrl)
|
||
if nil != err {
|
||
return nil
|
||
}
|
||
info.URL = requestUrl
|
||
info.Host = info.URL.Host
|
||
info.URL.Host = front
|
||
return info
|
||
}
|
||
|
||
// Meek Signalling Channel
|
||
type MeekChannel struct {
|
||
info *RequestInfo
|
||
// Used to make all requests.
|
||
transport http.Transport
|
||
}
|
||
|
||
func NewMeekChannel(info *RequestInfo) *MeekChannel {
|
||
m := new(MeekChannel)
|
||
// We make a copy of DefaultTransport because we want the default Dial
|
||
// and TLSHandshakeTimeout settings. But we want to disable the default
|
||
// ProxyFromEnvironment setting. Proxy is overridden below if
|
||
// options.ProxyURL is set.
|
||
m.transport = *http.DefaultTransport.(*http.Transport)
|
||
m.transport.Proxy = nil
|
||
m.info = info
|
||
return m
|
||
}
|
||
|
||
// Do an HTTP roundtrip using the payload data in buf.
|
||
func (m *MeekChannel) roundTripHTTP(buf []byte) (*http.Response, error) {
|
||
req, err := http.NewRequest("POST", m.info.URL.String(), bytes.NewReader(buf))
|
||
if nil != err {
|
||
return nil, err
|
||
}
|
||
if "" != m.info.Host {
|
||
req.Host = m.info.Host
|
||
}
|
||
// req.Header.Set("X-Session-Id", m.info.SessionID)
|
||
return m.transport.RoundTrip(req)
|
||
}
|
||
|
||
// Send an SDP offer to the meek facilitator, and wait for an SDP answer from
|
||
// the assigned proxy in the response.
|
||
func (m *MeekChannel) Negotiate(offer *webrtc.SessionDescription) (
|
||
*webrtc.SessionDescription, error) {
|
||
buf := []byte(offer.Serialize())
|
||
resp, err := m.roundTripHTTP(buf)
|
||
if nil != err {
|
||
return nil, err
|
||
}
|
||
defer resp.Body.Close()
|
||
body, err := ioutil.ReadAll(resp.Body)
|
||
answer := webrtc.DeserializeSessionDescription(string(body))
|
||
return answer, nil
|
||
}
|
||
|
||
// Simple interim non-fronting HTTP POST negotiation, to be removed when more
|
||
// general fronting is present.
|
||
func sendOfferHTTP(url string, offer *webrtc.SessionDescription) (*webrtc.SessionDescription, error) {
|
||
resp, err := http.Post(url, "", bytes.NewBuffer([]byte(offer.Serialize())))
|
||
if err != nil {
|
||
return nil, err
|
||
}
|
||
defer resp.Body.Close()
|
||
body, err := ioutil.ReadAll(resp.Body)
|
||
if err != nil {
|
||
return nil, err
|
||
}
|
||
answer := webrtc.DeserializeSessionDescription(string(body))
|
||
return answer, nil
|
||
}
|