Merge pull request #499 from yggdrasil-network/sessionfix

Prevent session leaks or blocking if the listener is busy

go.sum

@@ -22,6 +22,7 @@ github.com/yggdrasil-network/water v0.0.0-20190725073841-250edb919f8a h1:mQ0mPD+
 github.com/yggdrasil-network/water v0.0.0-20190725073841-250edb919f8a/go.mod h1:R0SBCsugm+Sf1katgTb2t7GXMm+nRIv43tM4VDZbaOs=
 github.com/yggdrasil-network/water v0.0.0-20190725123504-a16161896c34 h1:Qh5FE+Q5iGqpmR/FPMYHuoZLN921au/nxAlmKe+Hdbo=
 github.com/yggdrasil-network/water v0.0.0-20190725123504-a16161896c34/go.mod h1:R0SBCsugm+Sf1katgTb2t7GXMm+nRIv43tM4VDZbaOs=
+github.com/yggdrasil-network/water v0.0.0-20190812103929-c83fe40250f8 h1:YY9Pg2BEp0jeUVU60svTOaDr+fs1ySC9RbdC1Qc6wOw=
 github.com/yggdrasil-network/water v0.0.0-20190812103929-c83fe40250f8/go.mod h1:R0SBCsugm+Sf1katgTb2t7GXMm+nRIv43tM4VDZbaOs=
 golang.org/x/crypto v0.0.0-20181203042331-505ab145d0a9 h1:mKdxBk7AujPs8kU4m80U72y/zjbZ3UcXC7dClwKbUI0=
 golang.org/x/crypto v0.0.0-20181203042331-505ab145d0a9/go.mod h1:6SG95UA2DQfeDnfUPMdvaQW0Q7yPrPDi9nlGo2tz2b4=
@@ -45,6 +46,7 @@ golang.org/x/sys v0.0.0-20190712062909-fae7ac547cb7/go.mod h1:h1NjWce9XRLGQEsW7w
 golang.org/x/sys v0.0.0-20190726091711-fc99dfbffb4e/go.mod h1:h1NjWce9XRLGQEsW7wpKNCjG9DtNlClVuFLEZdDNbEs=
 golang.org/x/sys v0.0.0-20190801041406-cbf593c0f2f3 h1:4y9KwBHBgBNwDbtu44R5o1fdOCQUEXhbk/P4A9WmJq0=
 golang.org/x/sys v0.0.0-20190801041406-cbf593c0f2f3/go.mod h1:h1NjWce9XRLGQEsW7wpKNCjG9DtNlClVuFLEZdDNbEs=
+golang.org/x/sys v0.0.0-20190812073006-9eafafc0a87e h1:TsjK5I7fXk8f2FQrgu6NS7i5Qih3knl2FL1htyguLRE=
 golang.org/x/sys v0.0.0-20190812073006-9eafafc0a87e/go.mod h1:h1NjWce9XRLGQEsW7wpKNCjG9DtNlClVuFLEZdDNbEs=
 golang.org/x/text v0.3.0 h1:g61tztE5qeGQ89tm6NTjjM9VPIm088od1l6aSorWRWg=
 golang.org/x/text v0.3.0/go.mod h1:NqM8EUOU14njkJ3fqMW+pc6Ldnwhi/IjpwHt7yyuwOQ=

src/yggdrasil/session.go

@@ -348,31 +348,30 @@ func (ss *sessions) sendPingPong(sinfo *sessionInfo, isPong bool) {
 func (ss *sessions) handlePing(ping *sessionPing) {
 	// Get the corresponding session (or create a new session)
 	sinfo, isIn := ss.getByTheirPerm(&ping.SendPermPub)
-	// Check if the session is allowed
+	switch {
-	// TODO: this check may need to be moved
+	case isIn: // Session already exists
-	if !isIn && !ss.isSessionAllowed(&ping.SendPermPub, false) {
+	case !ss.isSessionAllowed(&ping.SendPermPub, false): // Session is not allowed
-		return
+	case ping.IsPong: // This is a response, not an initial ping, so ignore it.
-	}
+	default:
-	// Create the session if it doesn't already exist
+		ss.listenerMutex.Lock()
-	if !isIn {
+		if ss.listener != nil {
-		ss.createSession(&ping.SendPermPub)
+			// This is a ping from an allowed node for which no session exists, and we have a listener ready to handle sessions.
-		sinfo, isIn = ss.getByTheirPerm(&ping.SendPermPub)
+			// We need to create a session and pass it to the listener.
-		if !isIn {
+			sinfo = ss.createSession(&ping.SendPermPub)
+			if s, _ := ss.getByTheirPerm(&ping.SendPermPub); s != sinfo {
 				panic("This should not happen")
 			}
-		ss.listenerMutex.Lock()
-		// Check and see if there's a Listener waiting to accept connections
-		// TODO: this should not block if nothing is accepting
-		if !ping.IsPong && ss.listener != nil {
 			conn := newConn(ss.core, crypto.GetNodeID(&sinfo.theirPermPub), &crypto.NodeID{}, sinfo)
 			for i := range conn.nodeMask {
 				conn.nodeMask[i] = 0xFF
 			}
 			conn.session.startWorkers()
-			ss.listener.conn <- conn
+			c := ss.listener.conn
+			go func() { c <- conn }()
 		}
 		ss.listenerMutex.Unlock()
 	}
+	if sinfo != nil {
 		sinfo.doFunc(func() {
 			// Update the session
 			if !sinfo.update(ping) { /*panic("Should not happen in testing")*/
@@ -383,6 +382,7 @@ func (ss *sessions) handlePing(ping *sessionPing) {
 			}
 		})
 	}
+}
 
 // Get the MTU of the session.
 // Will be equal to the smaller of this node's MTU or the remote node's MTU.