fix #10 race conditions issue

Author: mehrdadrad

client.go

@@ -115,7 +115,7 @@ func (c *clientAttr) run(q *query) {
 	)
 
 	if c.client == nil {
-		c.setErr(errNotConn)
+		setErr(c, errNotConn)
 		q.errResp(c.addr, errNotConn)
 		return
 	}
@@ -129,21 +129,21 @@ func (c *clientAttr) run(q *query) {
 
 	session, err := c.newSession()
 	if err != nil {
-		c.setErr(err)
+		setErr(c, err)
 		q.errResp(c.addr, err)
 		return
 	}
 
 	writer, err := session.StdinPipe()
 	if err != nil {
-		c.setErr(err)
+		setErr(c, err)
 		q.errResp(c.addr, err)
 		return
 	}
 
 	scanOut, scanErr, err := c.getScanners(session, q.limitReadOut, q.limitReadErr)
 	if err != nil {
-		c.setErr(err)
+		setErr(c, err)
 		q.errResp(c.addr, err)
 		return
 	}
@@ -370,6 +370,7 @@ func (c *clientAttr) connect() {
 	c.client = ssh.NewClient(sshConn, chans, req)
 	c.lastUpdate = time.Now()
 	c.err = nil
+	c.stats.errRecent = 0
 }
 
 func (c *clientAttr) close() {
@@ -576,3 +577,10 @@ func (s *Stream) Input(in io.Reader) {
 	buf.ReadFrom(in)
 	s.r.inChan <- buf.Bytes()
 }
+
+// setErr is a helper func to update error with mutex
+func setErr(c *clientAttr, err error) {
+	c.Lock()
+	defer c.Unlock()
+	c.setErr(err)
+}

query.go

@@ -72,7 +72,9 @@ func (q *query) run(v *VSSH) {
 			}
 
 			if client.getErr() != nil {
+				client.RLock()
 				q.respChan <- &Response{id: client.addr, err: client.err}
+				client.RUnlock()
 				return
 			}
 

vssh.go

@@ -366,6 +366,7 @@ func (v *VSSH) reConnect(ctx context.Context) {
 		select {
 		case <-ticker.C:
 			for client := range v.clients.enum() {
+				client.Lock()
 				if client.err != nil && client.stats.errRecent < maxErrRecent {
 					if client.client != nil {
 						client.client.Close()
@@ -374,6 +375,7 @@ func (v *VSSH) reConnect(ctx context.Context) {
 				} else if time.Since(client.lastUpdate) > resetErrRecentDur {
 					client.stats.errRecent = 0
 				}
+				client.Unlock()
 			}
 		case <-ctx.Done():
 			return