refactor: smarter channel sleeps, better byte handling

.github/workflows/commit.yaml

@@ -9,7 +9,7 @@ jobs:
   unit-test:
     runs-on: ${{ matrix.os }}
     strategy:
-      max-parallel: 8
+      max-parallel: 10
       matrix:
         os:
           - ubuntu-latest
@@ -19,19 +19,20 @@ jobs:
           - "1.17"
           - "1.18"
           - "1.19"
+          - "1.20"
     steps:
       - name: checkout
         uses: actions/checkout@v3
         with:
-          fetch-depth: 0
+          fetch-depth: 1
       - name: set up go ${{ matrix.go-version }}
         uses: actions/setup-go@v4
         with:
           go-version: ${{ matrix.go-version }}
       - name: lint
         uses: golangci/golangci-lint-action@v3
         with:
-          version: v1.52
+          version: v1.54
           args: --timeout 5m
       - name: install gotestsum
         run: go install gotest.tools/gotestsum@latest
@@ -45,7 +46,7 @@ jobs:
         os:
           - ubuntu-latest
         go-version:
-          - "1.19"
+          - "1.20"
         runtime:
           - "docker"
     needs:
@@ -54,7 +55,7 @@ jobs:
       - name: checkout
         uses: actions/checkout@v3
         with:
-          fetch-depth: 0
+          fetch-depth: 1
       - name: set up go ${{ matrix.go-version }}
         uses: actions/setup-go@v4
         with:

.golangci.yaml

@@ -112,12 +112,12 @@ issues:
       text: "package-comments"
 
 run:
-  go: '1.19'
+  go: '1.20'
   skip-dirs:
     - private
 
 output:
   uniq-by-line: false
 
 service:
-  golangci-lint-version: 1.52.x
+  golangci-lint-version: 1.54.x

channel/channel.go

@@ -17,16 +17,17 @@ const (
 	// DefaultTimeoutOpsSeconds is the default time value for operations -- 60 seconds.
 	DefaultTimeoutOpsSeconds = 60
 	// DefaultReadDelayMicroSeconds is the default value for the delay between reads of the
-	// transport -- 100 microseconds. Going very low is likely to lead to very high cpu and not
+	// transport -- 250 microseconds. Going very low is likely to lead to very high cpu and not
 	// yield any recognizable gains, so be careful changing this!
 	DefaultReadDelayMicroSeconds = 250
 	// DefaultReturnChar is the character used to send an "enter" key to the device, "\n".
 	DefaultReturnChar = "\n"
 	// DefaultPromptSearchDepth -- is the default depth to search for the prompt in the received
 	// bytes.
 	DefaultPromptSearchDepth = 1_000
-	redacted                 = "redacted"
-	readDelayDivisor         = 1_000
+
+	redacted         = "redacted"
+	readDelayDivisor = 1_000
 )
 
 var (
@@ -136,39 +137,41 @@ func (c *Channel) Open() (reterr error) {
 
 	go c.read()
 
-	if !c.AuthBypass {
-		var b []byte
+	if c.AuthBypass {
+		c.l.Debug("auth bypass is enabled, skipping in channel auth check")
+
+		return nil
+	}
 
-		authData := c.t.InChannelAuthData()
+	var b []byte
 
-		switch authData.Type {
-		case transport.InChannelAuthSSH:
-			c.l.Debug("transport requests in channel ssh auth, starting...")
+	authData := c.t.InChannelAuthData()
 
-			b, err = c.AuthenticateSSH(
-				[]byte(authData.Password),
-				[]byte(authData.PrivateKeyPassPhrase),
-			)
-			if err != nil {
-				return err
-			}
-		case transport.InChannelAuthTelnet:
-			c.l.Debug("transport requests in channel telnet auth, starting...")
+	switch authData.Type {
+	case transport.InChannelAuthSSH:
+		c.l.Debug("transport requests in channel ssh auth, starting...")
 
-			b, err = c.AuthenticateTelnet([]byte(authData.User), []byte(authData.Password))
-			if err != nil {
-				return err
-			}
+		b, err = c.AuthenticateSSH(
+			[]byte(authData.Password),
+			[]byte(authData.PrivateKeyPassPhrase),
+		)
+		if err != nil {
+			return err
 		}
+	case transport.InChannelAuthTelnet:
+		c.l.Debug("transport requests in channel telnet auth, starting...")
 
-		if len(b) > 0 {
-			// requeue any buffer data we get during in channel authentication back onto the
-			// read buffer. mostly this should only be relevant for netconf where we need to
-			// read the server capabilities.
-			c.Q.Requeue(b)
+		b, err = c.AuthenticateTelnet([]byte(authData.User), []byte(authData.Password))
+		if err != nil {
+			return err
 		}
-	} else {
-		c.l.Debug("auth bypass is enabled, skipping in channel auth check")
+	}
+
+	if len(b) > 0 {
+		// requeue any buffer data we get during in channel authentication back onto the
+		// read buffer. mostly this should only be relevant for netconf where we need to
+		// read the server capabilities.
+		c.Q.Requeue(b)
 	}
 
 	return nil

channel/read.go

@@ -33,9 +33,6 @@ func (c *Channel) read() {
 		// afraid to remove it!
 		b = bytes.ReplaceAll(b, []byte("\r"), []byte(""))
 
-		// trim out all the space we padded in the buffer to read into
-		b = bytes.ReplaceAll(b, []byte("\x00"), []byte(""))
-
 		if bytes.Contains(b, []byte("\x1b")) {
 			b = util.StripANSI(b)
 		}
@@ -117,15 +114,11 @@ func (c *Channel) ReadUntilPrompt() ([]byte, error) {
 	var rb []byte
 
 	for {
-		select {
-		case err := <-c.Errs:
+		nb, err := c.Read()
+		if err != nil {
 			return nil, err
-		default:
-			time.Sleep(c.ReadDelay)
 		}
 
-		nb := c.Q.Dequeue()
-
 		if nb == nil {
 			continue
 		}
@@ -137,6 +130,8 @@ func (c *Channel) ReadUntilPrompt() ([]byte, error) {
 
 			return rb, nil
 		}
+
+		time.Sleep(c.ReadDelay)
 	}
 }
 
@@ -146,28 +141,28 @@ func (c *Channel) ReadUntilAnyPrompt(prompts []*regexp.Regexp) ([]byte, error) {
 	var rb []byte
 
 	for {
-		select {
-		case err := <-c.Errs:
+		nb, err := c.Read()
+		if err != nil {
 			return nil, err
-		default:
-			time.Sleep(c.ReadDelay)
 		}
 
-		nb := c.Q.Dequeue()
-
 		if nb == nil {
 			continue
 		}
 
 		rb = append(rb, nb...)
 
+		prb := c.processReadBuf(rb)
+
 		for _, p := range prompts {
-			if p.Match(rb) {
+			if p.Match(prb) {
 				c.l.Debugf("channel read %#v", string(rb))
 
 				return rb, nil
 			}
 		}
+
+		time.Sleep(c.ReadDelay)
 	}
 }
 
@@ -177,25 +172,23 @@ func (c *Channel) ReadUntilExplicit(b []byte) ([]byte, error) {
 	var rb []byte
 
 	for {
-		select {
-		case err := <-c.Errs:
+		nb, err := c.Read()
+		if err != nil {
 			return nil, err
-		default:
-			time.Sleep(c.ReadDelay)
 		}
 
-		nb := c.Q.Dequeue()
-
 		if nb == nil {
 			continue
 		}
 
 		rb = append(rb, nb...)
 
-		if bytes.Contains(rb, b) {
+		if bytes.Contains(c.processReadBuf(rb), b) {
 			c.l.Debugf("channel read %#v", string(rb))
 
 			return rb, nil
 		}
+
+		time.Sleep(c.ReadDelay)
 	}
 }

go.mod

@@ -7,6 +7,5 @@ require (
 	github.com/google/go-cmp v0.5.9
 	github.com/sirikothe/gotextfsm v1.0.1-0.20200816110946-6aa2cfd355e4
 	golang.org/x/crypto v0.6.0
-	golang.org/x/term v0.8.0 // indirect
 	gopkg.in/yaml.v3 v3.0.1
 )

go.sum

@@ -21,14 +21,12 @@ golang.org/x/sys v0.0.0-20201119102817-f84b799fce68/go.mod h1:h1NjWce9XRLGQEsW7w
 golang.org/x/sys v0.0.0-20210615035016-665e8c7367d1/go.mod h1:oPkhp1MJrh7nUepCBck5+mAzfO9JrbApNNgaTdGDITg=
 golang.org/x/sys v0.0.0-20220520151302-bc2c85ada10a/go.mod h1:oPkhp1MJrh7nUepCBck5+mAzfO9JrbApNNgaTdGDITg=
 golang.org/x/sys v0.0.0-20220722155257-8c9f86f7a55f/go.mod h1:oPkhp1MJrh7nUepCBck5+mAzfO9JrbApNNgaTdGDITg=
+golang.org/x/sys v0.5.0 h1:MUK/U/4lj1t1oPg0HfuXDN/Z1wv31ZJ/YcPiGccS4DU=
 golang.org/x/sys v0.5.0/go.mod h1:oPkhp1MJrh7nUepCBck5+mAzfO9JrbApNNgaTdGDITg=
-golang.org/x/sys v0.8.0 h1:EBmGv8NaZBZTWvrbjNoL6HVt+IVy3QDQpJs7VRIw3tU=
-golang.org/x/sys v0.8.0/go.mod h1:oPkhp1MJrh7nUepCBck5+mAzfO9JrbApNNgaTdGDITg=
 golang.org/x/term v0.0.0-20201126162022-7de9c90e9dd1/go.mod h1:bj7SfCRtBDWHUb9snDiAeCFNEtKQo2Wmx5Cou7ajbmo=
 golang.org/x/term v0.0.0-20210927222741-03fcf44c2211/go.mod h1:jbD1KX2456YbFQfuXm/mYQcufACuNUgVhRMnK/tPxf8=
+golang.org/x/term v0.5.0 h1:n2a8QNdAb0sZNpU9R1ALUXBbY+w51fCQDN+7EdxNBsY=
 golang.org/x/term v0.5.0/go.mod h1:jMB1sMXY+tzblOD4FWmEbocvup2/aLOaQEp7JmGp78k=
-golang.org/x/term v0.8.0 h1:n5xxQn2i3PC0yLAbjTpNT85q/Kgzcr2gIoX9OrJUols=
-golang.org/x/term v0.8.0/go.mod h1:xPskH00ivmX89bAKVGSKKtLOWNx2+17Eiy94tnKShWo=
 golang.org/x/text v0.3.0/go.mod h1:NqM8EUOU14njkJ3fqMW+pc6Ldnwhi/IjpwHt7yyuwOQ=
 golang.org/x/text v0.3.3/go.mod h1:5Zoc/QRtKVWzQhOtBMvqHzDpF6irO9z98xDceosuGiQ=
 golang.org/x/text v0.3.7/go.mod h1:u+2+/6zg+i71rQMx5EYifcz6MCKuco9NR6JIITiCfzQ=

transport/standard.go

@@ -236,9 +236,12 @@ func (t *Standard) IsAlive() bool {
 func (t *Standard) Read(n int) ([]byte, error) {
 	b := make([]byte, n)
 
-	_, err := t.reader.Read(b)
+	n, err := t.reader.Read(b)
+	if err != nil {
+		return nil, err
+	}
 
-	return b, err
+	return b[0:n], nil
 }
 
 // Write writes bytes b to the transport.

transport/system.go

@@ -216,9 +216,12 @@ func (t *System) IsAlive() bool {
 func (t *System) Read(n int) ([]byte, error) {
 	b := make([]byte, n)
 
-	_, err := t.fd.Read(b)
+	n, err := t.fd.Read(b)
+	if err != nil {
+		return nil, err
+	}
 
-	return b, err
+	return b[0:n], nil
 }
 
 // Write writes bytes b to the transport.