[snowflake/master] Handle generated errors in server-webrtc - tor-commits

8 Oct 2019

commit 3ec9dd19faa8584dd76ba3b85eb71a03b8ee25c0
Author: Shane Howearth Shane.h.1@gmail.com
Date:   Thu Sep 26 09:19:22 2019 +1000
Handle generated errors in server-webrtc
---
 client/lib/snowflake.go    | 15 +++++++++----
 server-webrtc/http.go      | 11 ++++++++--
 server-webrtc/snowflake.go | 53 ++++++++++++++++++++++++++++++++--------------
 3 files changed, 57 insertions(+), 22 deletions(-)

diff --git a/client/lib/snowflake.go b/client/lib/snowflake.go
index 900af88..4af3d88 100644
--- a/client/lib/snowflake.go
+++ b/client/lib/snowflake.go
@@ -13,7 +13,7 @@ const (
    SnowflakeTimeout = 30
 )
-// When a connection handler starts, +1 is written to this channel; when it
+// HandlerChan - When a connection handler starts, +1 is written to this channel; when it
 // ends, -1 is written.
 var HandlerChan = make(chan int)
@@ -27,7 +27,10 @@ func Handler(socks SocksConnector, snowflakes SnowflakeCollector) error {
    // Obtain an available WebRTC remote. May block.
    snowflake := snowflakes.Pop()
    if nil == snowflake {
-		socks.Reject()
+		if err := socks.Reject(); err != nil {
+			log.Printf("socks.Reject returned error: %v", err)
+		}
+
    	return errors.New("handler: Received invalid Snowflake")
    }
    defer socks.Close()
@@ -57,11 +60,15 @@ func copyLoop(a, b io.ReadWriter) {
    var wg sync.WaitGroup
    wg.Add(2)
    go func() {
-		io.Copy(b, a)
+		if _, err := io.Copy(ORPort, WebRTC); err != nil {
+			log.Printf("copying WebRTC to ORPort resulted in error: %v", err)
+		}
    	wg.Done()
    }()
    go func() {
-		io.Copy(a, b)
+		if _, err := io.Copy(WebRTC, ORPort); err != nil {
+			log.Printf("copying ORPort to WebRTC resulted in error: %v", err)
+		}
    	wg.Done()
    }()
    wg.Wait()
diff --git a/server-webrtc/http.go b/server-webrtc/http.go
index f0ecb88..1232239 100644
--- a/server-webrtc/http.go
+++ b/server-webrtc/http.go
@@ -23,11 +23,14 @@ func (h *httpHandler) ServeHTTP(w http.ResponseWriter, req *http.Request) {
    case "GET":
    	w.Header().Set("Content-Type", "text/plain; charset=utf-8")
    	w.WriteHeader(http.StatusOK)
-		w.Write([]byte(`HTTP signaling channel
+		_, err := w.Write([]byte(`HTTP signaling channel
Send a POST request containing an SDP offer. The response will
 contain an SDP answer.
 `))
+		if err != nil {
+			log.Printf("GET request write failed with error: %v", err)
+		}
    	return
    case "POST":
    	break
@@ -57,7 +60,11 @@ contain an SDP answer.
    log.Println("answering HTTP POST")
w.WriteHeader(http.StatusOK)
-	w.Write([]byte(pc.LocalDescription().Serialize()))
+	_, err = w.Write([]byte(pc.LocalDescription().Serialize()))
+	if err != nil {
+		log.Printf("answering HTTP POST write failed with error %v", err)
+	}
+
 }
func receiveSignalsHTTP(addr string, config *webrtc.Configuration) error {
diff --git a/server-webrtc/snowflake.go b/server-webrtc/snowflake.go
index 5923d6b..cf1c888 100644
--- a/server-webrtc/snowflake.go
+++ b/server-webrtc/snowflake.go
@@ -13,7 +13,7 @@ import (
    "syscall"
    "time"
-	"git.torproject.org/pluggable-transports/goptlib.git"
+	pt "git.torproject.org/pluggable-transports/goptlib.git"
    "github.com/keroserene/go-webrtc"
 )
@@ -25,15 +25,19 @@ var logFile *os.File
 // when it ends, -1 is written.
 var handlerChan = make(chan int)
-func copyLoop(a, b net.Conn) {
+func copyLoop(WebRTC, ORPort net.Conn) {
    var wg sync.WaitGroup
    wg.Add(2)
    go func() {
-		io.Copy(b, a)
+		if _, err := io.Copy(ORPort, WebRTC); err != nil {
+			log.Printf("copy WebRTC to ORPort error in copyLoop: %v", err)
+		}
    	wg.Done()
    }()
    go func() {
-		io.Copy(a, b)
+		if _, err := io.Copy(WebRTC, ORPort); err != nil {
+			log.Printf("copy ORPort to WebRTC error in copyLoop: %v", err)
+		}
    	wg.Done()
    }()
    wg.Wait()
@@ -79,14 +83,17 @@ func (c *webRTCConn) RemoteAddr() net.Addr {
 }
func (c *webRTCConn) SetDeadline(t time.Time) error {
+	// nolint:golint
    return fmt.Errorf("SetDeadline not implemented")
 }
func (c *webRTCConn) SetReadDeadline(t time.Time) error {
+	// nolint:golint
    return fmt.Errorf("SetReadDeadline not implemented")
 }
func (c *webRTCConn) SetWriteDeadline(t time.Time) error {
+	// nolint:golint
    return fmt.Errorf("SetWriteDeadline not implemented")
 }
@@ -139,9 +146,12 @@ func makePeerConnectionFromOffer(sdp *webrtc.SessionDescription, config *webrtc.
    	}
    	dc.OnMessage = func(msg []byte) {
    		log.Printf("OnMessage <--- %d bytes", len(msg))
-			n, err := pw.Write(msg)
+			var n int
+			n, err = pw.Write(msg)
    		if err != nil {
-				pw.CloseWithError(err)
+				if inerr := pw.CloseWithError(err); inerr != nil {
+					log.Printf("close with error returned error: %v", inerr)
+				}
    		}
    		if n != len(msg) {
    			panic("short write")
@@ -153,7 +163,9 @@ func makePeerConnectionFromOffer(sdp *webrtc.SessionDescription, config *webrtc.
err = pc.SetRemoteDescription(sdp)
    if err != nil {
-		pc.Destroy()
+		if err = pc.Destroy(); err != nil {
+			log.Printf("pc.Destroy returned an error: %v", err)
+		}
    	return nil, fmt.Errorf("accept: SetRemoteDescription: %s", err)
    }
    log.Println("sdp offer successfully received.")
@@ -161,18 +173,24 @@ func makePeerConnectionFromOffer(sdp *webrtc.SessionDescription, config *webrtc.
    log.Println("Generating answer...")
    answer, err := pc.CreateAnswer()
    if err != nil {
-		pc.Destroy()
+		if err = pc.Destroy(); err != nil {
+			log.Printf("pc.Destroy returned an error: %v", err)
+		}
    	return nil, err
    }
if answer == nil {
-		pc.Destroy()
-		return nil, fmt.Errorf("Failed gathering ICE candidates.")
+		if err = pc.Destroy(); err != nil {
+			log.Printf("pc.Destroy returned an error: %v", err)
+		}
+		return nil, fmt.Errorf("failed gathering ICE candidates")
    }
err = pc.SetLocalDescription(answer)
    if err != nil {
-		pc.Destroy()
+		if err = pc.Destroy(); err != nil {
+			log.Printf("pc.Destroy returned an error: %v", err)
+		}
    	return nil, err
    }
@@ -180,7 +198,6 @@ func makePeerConnectionFromOffer(sdp *webrtc.SessionDescription, config *webrtc.
 }
func main() {
-	var err error
    var httpAddr string
    var logFilename string
@@ -200,7 +217,7 @@ func main() {
log.Println("starting")
    webrtc.SetLoggingVerbosity(1)
-
+	var err error
    ptInfo, err = pt.ServerSetup(nil)
    if err != nil {
    	log.Fatal(err)
@@ -222,12 +239,14 @@ func main() {
    		bindaddr.Addr.Port = 12345 // lies!!!
    		pt.Smethod(bindaddr.MethodName, bindaddr.Addr)
    	default:
-			pt.SmethodError(bindaddr.MethodName, "no such method")
+			if err := pt.SmethodError(bindaddr.MethodName, "no such method"); err != nil {
+				log.Printf("SmethodError returned error: %v", err)
+			}
    	}
    }
    pt.SmethodsDone()
-	var numHandlers int = 0
+	var numHandlers int
    var sig os.Signal
    sigChan := make(chan os.Signal, 1)
    signal.Notify(sigChan, syscall.SIGTERM)
@@ -236,7 +255,9 @@ func main() {
    	// This environment variable means we should treat EOF on stdin
    	// just like SIGTERM: https://bugs.torproject.org/15435.
    	go func() {
-			io.Copy(ioutil.Discard, os.Stdin)
+			if _, err := io.Copy(ioutil.Discard, os.Stdin); err != nil {
+				log.Printf("error copying os.Stdin to ioutil.Discard: %v", err)
+			}
    		log.Printf("synthesizing SIGTERM because of stdin close")
    		sigChan <- syscall.SIGTERM
    	}()

    