410 lines
12 KiB
Go
410 lines
12 KiB
Go
/*
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* HTTP tunnel over WebRTC - Server implementation
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* Author: Konstantinos Drakontidis
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* Email: gedra100sh@gmail.com
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*/
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package main
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import (
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"bytes"
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"encoding/gob"
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"encoding/json"
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"fmt"
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"io"
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"net/http"
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"os"
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"github.com/go-yaml/yaml"
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"github.com/google/uuid"
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"github.com/gorilla/websocket"
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"github.com/pion/webrtc/v4"
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)
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var config_t Config
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/*
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* This function gets:
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* dc: pointer to data channel
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* raw: slice of bytes
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* Receives data from dc, decodes it, creates and sends a HTTP request,
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* encodes the HTTP response and sends it back to the dc.
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*/
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func channelHandler(dc *webrtc.DataChannel, raw []byte) {
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// Creating a buffer and store the received
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buf := bytes.NewBuffer(raw)
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// Creating a decoder and decode the data
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dec := gob.NewDecoder(buf)
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var request_t Request
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decode_error := dec.Decode(&request_t)
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if decode_error != nil {
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fmt.Fprintf(os.Stderr, config_t.Messages.GOB.DECODE.ERROR, decode_error)
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return
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} else {
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fmt.Print(config_t.Messages.GOB.DECODE.SUCCESS)
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}
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// Constructing the HTTP request
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req_body := bytes.NewBuffer(request_t.Body)
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req, req_error := http.NewRequest(request_t.Method, config_t.Config.PROXY_SERVER+request_t.Path, req_body)
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if req_error != nil {
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fmt.Fprintf(os.Stderr, config_t.Messages.HTTP.REQUEST.ERROR, req_error)
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return
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} else {
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fmt.Print(config_t.Messages.HTTP.REQUEST.SUCCESS)
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}
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req.Header = request_t.Headers
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// Creating a HTTP client - handles redirect requests as normal requests
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client := &http.Client{
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CheckRedirect: func(req *http.Request, via []*http.Request) error {
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return http.ErrUseLastResponse
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},
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}
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// Submitting the request
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res, send_req_error := client.Do(req)
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if send_req_error != nil {
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fmt.Fprintf(os.Stderr, config_t.Messages.HTTP.SEND_REQUEST.ERROR, send_req_error)
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return
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} else {
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fmt.Print(config_t.Messages.HTTP.SEND_REQUEST.SUCCESS)
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}
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// Constructing the response
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res_body, read_body_error := io.ReadAll(res.Body)
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if read_body_error != nil {
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fmt.Fprintf(os.Stderr, config_t.Messages.HTTP.READ.ERROR, read_body_error)
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return
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} else {
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fmt.Print(config_t.Messages.HTTP.READ.SUCCESS)
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}
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response_t := Response{
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ID: request_t.ID,
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Status: res.StatusCode,
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Headers: res.Header,
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Body: res_body,
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}
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// Encoding and sending the response to the data channel
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var enc_buf bytes.Buffer
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enc := gob.NewEncoder(&enc_buf)
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encode_error := enc.Encode(response_t)
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if encode_error != nil {
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fmt.Fprintf(os.Stderr, config_t.Messages.GOB.ENCODE.ERROR, encode_error)
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return
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} else {
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fmt.Print(config_t.Messages.GOB.ENCODE.SUCCESS)
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}
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data_channel_send_error := dc.Send(enc_buf.Bytes())
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if data_channel_send_error != nil {
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fmt.Fprintf(os.Stderr, config_t.Messages.WEBRTC.SEND_DATA_CHANNEL.ERROR, data_channel_send_error)
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return
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} else {
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fmt.Print(config_t.Messages.WEBRTC.SEND_DATA_CHANNEL.SUCCESS)
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}
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}
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/*
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* This function gets:
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* conn: pointer to the websocket connection
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* peer_connections: pointer to map of tracked peer connections
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* raw: slice of bytes
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* Receives a peer connection offer, creates a new peer connection, sets the
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* listeners for it. Sets the remote descriptions, generates, sets and sends the answer.
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*/
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func offer(conn *websocket.Conn, peer_connections *map[uuid.UUID]*webrtc.PeerConnection, raw []byte) {
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// Constructing the offer
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var offer_t Offer
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message_unmarshal_error := json.Unmarshal(raw, &offer_t)
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if message_unmarshal_error != nil {
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fmt.Fprintf(os.Stderr, config_t.Messages.JSON.UNMARSHAL.ERROR, message_unmarshal_error)
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return
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} else {
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fmt.Print(config_t.Messages.JSON.UNMARSHAL.SUCCESS)
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}
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// Creating the peer configuration
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config := webrtc.Configuration{
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ICEServers: config_t.Config.ICE_SERVERS,
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}
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// Creating peer connection
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var new_peer_error error
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p2p, new_peer_error := webrtc.NewPeerConnection(config)
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if new_peer_error != nil {
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fmt.Fprintf(os.Stderr, config_t.Messages.WEBRTC.NEW.ERROR, new_peer_error)
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return
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} else {
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fmt.Print(config_t.Messages.WEBRTC.NEW.SUCCESS)
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}
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// Setting the peer listeners
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p2p.OnICEConnectionStateChange(func(is webrtc.ICEConnectionState) {
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fmt.Printf("ICE: %s\n", is.String())
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})
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p2p.OnConnectionStateChange(func(pcs webrtc.PeerConnectionState) {
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fmt.Printf("WebRTC: %s\n", pcs.String())
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})
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p2p.OnICECandidate(func(candidate *webrtc.ICECandidate) {
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// Checking if ICE gathering has finished
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if candidate != nil {
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fmt.Print(config_t.Messages.WEBRTC.ON_CANDIDATE)
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// Constructing candidate, encoding to JSON and sending to websocket
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candidate_t := Candidate{
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Type: "candidate",
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Id: offer_t.Id,
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Candidate: (*candidate).ToJSON(),
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}
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// Create JSON string for candidate and send it to the websocket
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candidate_msg, message_marshal_error := json.Marshal(candidate_t)
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if message_marshal_error != nil {
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fmt.Fprintf(os.Stderr, config_t.Messages.JSON.MARSHAL.ERROR, message_marshal_error)
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return
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} else {
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fmt.Print(config_t.Messages.JSON.MARSHAL.SUCCESS)
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}
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ws_write_error := conn.WriteMessage(websocket.TextMessage, candidate_msg)
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if ws_write_error != nil {
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fmt.Fprintf(os.Stderr, config_t.Messages.WS.WRITE.ERROR, ws_write_error)
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return
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} else {
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fmt.Print(config_t.Messages.WS.WRITE.SUCCESS)
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}
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}
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})
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p2p.OnDataChannel(func(dc *webrtc.DataChannel) {
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dc.OnOpen(func() {
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fmt.Print(config_t.Messages.WEBRTC.ON_DATA_CHANNEL)
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})
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dc.OnMessage(func(msg webrtc.DataChannelMessage) {
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fmt.Print(config_t.Messages.WEBRTC.ON_MESSAGE)
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channelHandler(dc, msg.Data)
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})
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})
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// Setting offer as remote description
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set_remote_description_error := p2p.SetRemoteDescription(offer_t.Offer)
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if set_remote_description_error != nil {
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fmt.Fprintf(os.Stderr, config_t.Messages.WEBRTC.REMOTE_DESCRIPTION.ERROR,
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set_remote_description_error)
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return
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} else {
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fmt.Print(config_t.Messages.WEBRTC.REMOTE_DESCRIPTION.SUCCESS)
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}
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// Generating answer
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answer_options := webrtc.AnswerOptions{
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OfferAnswerOptions: webrtc.OfferAnswerOptions{
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VoiceActivityDetection: false,
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},
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}
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answer, create_answer_error := p2p.CreateAnswer(&answer_options)
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if create_answer_error != nil {
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fmt.Fprintf(os.Stderr, config_t.Messages.WEBRTC.ANSWER.ERROR, create_answer_error)
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return
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} else {
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fmt.Print(config_t.Messages.WEBRTC.ANSWER.SUCCESS)
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}
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// Constructing answer, creating JSON from answer and sending it to the websocket
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answer_t := Answer{
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Type: "answer",
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Id: offer_t.Id,
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Answer: answer,
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}
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answer_msg, message_marshal_error := json.Marshal(answer_t)
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if message_marshal_error != nil {
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fmt.Fprintf(os.Stderr, config_t.Messages.JSON.MARSHAL.ERROR, message_marshal_error)
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return
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} else {
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fmt.Print(config_t.Messages.JSON.MARSHAL.SUCCESS)
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}
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ws_write_error := conn.WriteMessage(websocket.TextMessage, answer_msg)
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if ws_write_error != nil {
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fmt.Fprintf(os.Stderr, config_t.Messages.WS.WRITE.ERROR, ws_write_error)
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return
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} else {
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fmt.Print(config_t.Messages.WS.WRITE.SUCCESS)
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}
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// Setting answer as local description
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set_local_description_error := (*p2p).SetLocalDescription(answer)
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if set_local_description_error != nil {
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fmt.Fprintf(os.Stderr, config_t.Messages.WEBRTC.LOCAL_DESCRIPTION.ERROR,
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set_local_description_error)
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return
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} else {
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fmt.Print(config_t.Messages.WEBRTC.LOCAL_DESCRIPTION.SUCCESS)
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}
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// Storing the peer connection to the map
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(*peer_connections)[offer_t.Id] = p2p
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}
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/*
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* This function gets:
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* peer_connections: pointer to map of tracked peer connections
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* raw: slice of bytes
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* Adds ICE candidate received from the signaling server.
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* The function does not return anything.
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*/
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func candidate(peer_connections *map[uuid.UUID]*webrtc.PeerConnection, raw []byte) {
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// Constructing candidate from received data
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var candidate_t Candidate
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message_unmarshal_error := json.Unmarshal(raw, &candidate_t)
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if message_unmarshal_error != nil {
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fmt.Fprintf(os.Stderr, config_t.Messages.JSON.UNMARSHAL.ERROR, message_unmarshal_error)
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return
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} else {
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fmt.Print(config_t.Messages.JSON.UNMARSHAL.SUCCESS)
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}
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// Getting peer instance from map
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p2p := (*peer_connections)[candidate_t.Id]
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// Adding candidate to peer connection
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add_ice_error := p2p.AddICECandidate(candidate_t.Candidate)
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if add_ice_error != nil {
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fmt.Fprintf(os.Stderr, config_t.Messages.WEBRTC.ADD_CANDIDATE.ERROR, add_ice_error)
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return
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} else {
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fmt.Print(config_t.Messages.WEBRTC.ADD_CANDIDATE.SUCCESS)
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}
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}
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/*
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* This function gets:
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* peer_connections: pointer to map of tracked peer connections
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* raw: slice of bytes
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* Terminates a peer connection.
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*/
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func terminate(peer_connections *map[uuid.UUID]*webrtc.PeerConnection, raw []byte) {
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var terminate_t Terminate
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message_unmarshal_error := json.Unmarshal(raw, &terminate_t)
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if message_unmarshal_error != nil {
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fmt.Fprintf(os.Stderr, config_t.Messages.JSON.UNMARSHAL.ERROR, message_unmarshal_error)
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return
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} else {
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fmt.Print(config_t.Messages.JSON.UNMARSHAL.SUCCESS)
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}
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// Getting peer instance from map and closing the connection
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p2p := (*peer_connections)[terminate_t.Id]
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p2p_close_error := p2p.Close()
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if p2p_close_error != nil {
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fmt.Fprintf(os.Stderr, config_t.Messages.WEBRTC.CLOSE.ERROR, p2p_close_error)
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return
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} else {
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fmt.Print(config_t.Messages.WEBRTC.CLOSE.SUCCESS)
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}
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// Remove peer connection entry from map
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delete(*peer_connections, terminate_t.Id)
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}
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func main() {
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// Attempting to read the config file
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raw_config, config_error := os.ReadFile("config.yml")
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if config_error != nil {
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fmt.Fprintf(os.Stderr, "Could not read config file.\n%v\n", config_error)
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os.Exit(-1)
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}
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// Loading config file to config struct
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config_error = yaml.Unmarshal(raw_config, &config_t)
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if config_error != nil {
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fmt.Fprintf(os.Stderr, "Could not load config file.\n%v\n", config_error)
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os.Exit(-1)
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}
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// Starting program
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fmt.Print(config_t.Messages.START)
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peer_connections := make(map[uuid.UUID]*webrtc.PeerConnection)
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// Attempting to connect to the signaling server via WebSocket
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conn, _, dial_error := websocket.DefaultDialer.Dial(config_t.Config.SIGNALING_SERVER, nil)
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if dial_error != nil {
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fmt.Fprintf(os.Stderr, config_t.Messages.WS.CONNECT.ERROR, dial_error)
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os.Exit(-1)
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} else {
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fmt.Print(config_t.Messages.WS.CONNECT.SUCCESS)
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}
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defer func() {
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ws_close_error := conn.Close()
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if ws_close_error != nil {
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fmt.Fprintf(os.Stderr, config_t.Messages.WS.CLOSE.ERROR, ws_close_error)
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} else {
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fmt.Print(config_t.Messages.WS.CLOSE.SUCCESS)
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}
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}()
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// Constructing the register message
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register_t := Register{
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Type: "register",
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Username: config_t.Config.AUTHENTICATION.USERNAME,
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Password: config_t.Config.AUTHENTICATION.PASSWORD,
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}
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// Encoding register struct to JSON
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register_msg, register_marshal_error := json.Marshal(register_t)
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if register_marshal_error != nil {
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fmt.Fprintf(os.Stderr, config_t.Messages.JSON.MARSHAL.ERROR, register_marshal_error)
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return
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} else {
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fmt.Print(config_t.Messages.JSON.MARSHAL.SUCCESS)
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}
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// Registering to the signaling server as normal user
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ws_write_error := conn.WriteMessage(websocket.TextMessage, register_msg)
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if ws_write_error != nil {
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fmt.Fprintf(os.Stderr, config_t.Messages.WS.REGISTER.ERROR, ws_write_error)
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return
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} else {
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fmt.Print(config_t.Messages.WS.REGISTER.SUCCESS)
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}
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for {
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// Reading message
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_, ws_msg, ws_read_error := conn.ReadMessage()
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if ws_read_error != nil {
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fmt.Fprintf(os.Stderr, config_t.Messages.WS.READ.ERROR, ws_read_error)
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os.Exit(-1)
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} else {
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fmt.Print(config_t.Messages.WS.READ.SUCCESS)
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}
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// Decoding as any-format JSON
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var parsed map[string]any
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message_unmarshal_error := json.Unmarshal(ws_msg, &parsed)
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if message_unmarshal_error != nil {
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fmt.Fprintf(os.Stderr, config_t.Messages.JSON.UNMARSHAL.ERROR, message_unmarshal_error)
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continue
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} else {
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fmt.Print(config_t.Messages.JSON.UNMARSHAL.SUCCESS)
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}
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// Parsing message type
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msg_type, exists := parsed["type"].(string)
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if !exists {
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fmt.Fprint(os.Stderr, config_t.Messages.JSON.FORMAT.ERROR)
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continue
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} else {
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fmt.Printf(config_t.Messages.JSON.FORMAT.SUCCESS, msg_type)
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}
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// Setting handler function for each message type
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switch msg_type {
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case "offer":
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fmt.Printf(config_t.Messages.JSON.TYPE.SUCCESS, msg_type)
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offer(conn, &peer_connections, ws_msg)
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case "candidate":
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fmt.Printf(config_t.Messages.JSON.TYPE.SUCCESS, msg_type)
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candidate(&peer_connections, ws_msg)
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case "terminate":
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fmt.Printf(config_t.Messages.JSON.TYPE.SUCCESS, msg_type)
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terminate(&peer_connections, ws_msg)
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default:
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fmt.Fprintf(os.Stderr, config_t.Messages.JSON.TYPE.ERROR, msg_type)
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continue
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}
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}
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}
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