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Merged
neilalexander merged 1 commit into from
Oct 3, 2025
Merged

Add HTTP proxy support for WebSocket leaf node connections #7242

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92 changes: 92 additions & 0 deletions server/config_check_test.go
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Original file line number Diff line number Diff line change
Expand Up @@ -2398,6 +2398,98 @@ func TestConfigCheck(t *testing.T) {
errorLine: 9,
errorPos: 9,
},
{
name: "leafnode proxy with unsupported scheme",
config: `
leafnodes {
remotes = [
{
url: "ws://127.0.0.1:7422"
proxy {
url: "ftp://proxy.example.com:8080"
}
}
]
}
`,
err: errors.New("proxy URL scheme must be http or https, got: ftp"),
errorLine: 6,
errorPos: 8,
},
{
name: "leafnode proxy with missing host",
config: `
leafnodes {
remotes = [
{
url: "ws://127.0.0.1:7422"
proxy {
url: "http://"
}
}
]
}
`,
err: errors.New("proxy URL must specify a host"),
errorLine: 6,
errorPos: 8,
},
{
name: "leafnode proxy with username but no password",
config: `
leafnodes {
remotes = [
{
url: "ws://127.0.0.1:7422"
proxy {
url: "http://proxy.example.com:8080"
username: "testuser"
}
}
]
}
`,
err: errors.New("proxy username and password must both be specified or both be empty"),
errorLine: 6,
errorPos: 8,
},
{
name: "leafnode proxy with password but no username",
config: `
leafnodes {
remotes = [
{
url: "ws://127.0.0.1:7422"
proxy {
url: "http://proxy.example.com:8080"
password: "testpass"
}
}
]
}
`,
err: errors.New("proxy username and password must both be specified or both be empty"),
errorLine: 6,
errorPos: 8,
},
{
name: "leafnode proxy with WSS URL but no TLS config",
config: `
leafnodes {
remotes = [
{
url: "wss://127.0.0.1:7422"
proxy {
url: "http://proxy.example.com:8080"
}
}
]
}
`,
err: errors.New("proxy is configured but remote URL wss://127.0.0.1:7422 requires TLS and no TLS configuration is provided"),
errorLine: 6,
errorPos: 8,
},
}

checkConfig := func(config string) error {
Expand Down
160 changes: 159 additions & 1 deletion server/leafnode.go
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Original file line number Diff line number Diff line change
Expand Up @@ -285,6 +285,11 @@ func validateLeafNode(o *Options) error {

// If a remote has a websocket scheme, all need to have it.
for _, rcfg := range o.LeafNode.Remotes {
// Validate proxy configuration
if _, err := validateLeafNodeProxyOptions(rcfg); err != nil {
return err
}

if len(rcfg.URLs) >= 2 {
firstIsWS, ok := isWSURL(rcfg.URLs[0]), true
for i := 1; i < len(rcfg.URLs); i++ {
Expand Down Expand Up @@ -369,6 +374,60 @@ func validateLeafNodeAuthOptions(o *Options) error {
return nil
}

func validateLeafNodeProxyOptions(remote *RemoteLeafOpts) ([]string, error) {
var warnings []string

if remote.Proxy.URL == _EMPTY_ {
return warnings, nil
}

proxyURL, err := url.Parse(remote.Proxy.URL)
if err != nil {
return warnings, fmt.Errorf("invalid proxy URL: %v", err)
}

if proxyURL.Scheme != "http" && proxyURL.Scheme != "https" {
return warnings, fmt.Errorf("proxy URL scheme must be http or https, got: %s", proxyURL.Scheme)
}

if proxyURL.Host == _EMPTY_ {
return warnings, fmt.Errorf("proxy URL must specify a host")
}

if remote.Proxy.Timeout < 0 {
return warnings, fmt.Errorf("proxy timeout must be >= 0")
}

if (remote.Proxy.Username == _EMPTY_) != (remote.Proxy.Password == _EMPTY_) {
return warnings, fmt.Errorf("proxy username and password must both be specified or both be empty")
}

if len(remote.URLs) > 0 {
hasWebSocketURL := false
hasNonWebSocketURL := false

for _, remoteURL := range remote.URLs {
if remoteURL.Scheme == wsSchemePrefix || remoteURL.Scheme == wsSchemePrefixTLS {
hasWebSocketURL = true
if (remoteURL.Scheme == wsSchemePrefixTLS) &&
remote.TLSConfig == nil && !remote.TLS {
return warnings, fmt.Errorf("proxy is configured but remote URL %s requires TLS and no TLS configuration is provided. When using proxy with TLS endpoints, ensure TLS is properly configured for the leafnode remote", remoteURL.String())
}
} else {
hasNonWebSocketURL = true
}
}

if !hasWebSocketURL {
warnings = append(warnings, "proxy configuration will be ignored: proxy settings only apply to WebSocket connections (ws:// or wss://), but all configured URLs use TCP connections (nats://)")
} else if hasNonWebSocketURL {
warnings = append(warnings, "proxy configuration will only be used for WebSocket URLs: proxy settings do not apply to TCP connections (nats://)")
}
}

return warnings, nil
}

// Update remote LeafNode TLS configurations after a config reload.
func (s *Server) updateRemoteLeafNodesTLSConfig(opts *Options) {
max := len(opts.LeafNode.Remotes)
Expand Down Expand Up @@ -502,6 +561,67 @@ func (s *Server) setLeafNodeNonExportedOptions() {

const sharedSysAccDelay = 250 * time.Millisecond

// establishHTTPProxyTunnel establishes an HTTP CONNECT tunnel through a proxy server
func establishHTTPProxyTunnel(proxyURL, targetHost string, timeout time.Duration, username, password string) (net.Conn, error) {
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@neilalexander neilalexander Oct 2, 2025

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I think I would really rather us not build and parse HTTP requests/responses by hand here when the Go standard library has the ability to do this for us, i.e. something like this:

	conn, err := natsDialTimeout("tcp", proxyAddr.Host, timeout)
	if err != nil {
		return nil, fmt.Errorf("failed to connect to proxy: %w", err)
	}

	req := &http.Request{
		Method: http.MethodConnect,
		URL:    &url.URL{Opaque: targetHost}, // Opaque is required here
		Host:   targetHost,
		Header: make(http.Header),
	}
 	// do we need auth here?
	req.Header.Set("Proxy-Authorization", "Basic " + ...)

	if err := req.Write(conn); err != nil {
		conn.Close()
		return nil, fmt.Errorf("req.Write: %w", err)
	}

	resp, err := http.ReadResponse(bufio.NewReader(conn), req)
	if err != nil {
		conn.Close()
		return nil, fmt.Errorf("http.ReadResponse: %w", err)
	}
	if resp.StatusCode != http.StatusOK {
		conn.Close()
		return nil, fmt.Errorf("status code: %s", resp.Status)
	}

	// now use "conn"

We already have net/http imported so this is fine to use.

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@danbailey1000 danbailey1000 Oct 2, 2025

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@neilalexander I have changed this to now use the standard http library. Thx

proxyAddr, err := url.Parse(proxyURL)
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if err != nil {
// This should not happen since proxy URL is validated during configuration parsing
return nil, fmt.Errorf("unexpected proxy URL parse error (URL was pre-validated): %v", err)
}

// Connect to the proxy server
conn, err := natsDialTimeout("tcp", proxyAddr.Host, timeout)
if err != nil {
return nil, fmt.Errorf("failed to connect to proxy: %v", err)
}

// Set deadline for the entire proxy handshake
if err := conn.SetDeadline(time.Now().Add(timeout)); err != nil {
conn.Close()
return nil, fmt.Errorf("failed to set deadline: %v", err)
}

req := &http.Request{
Method: http.MethodConnect,
URL: &url.URL{Opaque: targetHost}, // Opaque is required for CONNECT
Host: targetHost,
Header: make(http.Header),
}

// Add proxy authentication if provided
if username != "" && password != "" {
req.Header.Set("Proxy-Authorization", "Basic "+base64.StdEncoding.EncodeToString([]byte(username+":"+password)))
}

if err := req.Write(conn); err != nil {
conn.Close()
return nil, fmt.Errorf("failed to write CONNECT request: %v", err)
}

resp, err := http.ReadResponse(bufio.NewReader(conn), req)
if err != nil {
conn.Close()
return nil, fmt.Errorf("failed to read proxy response: %v", err)
}

if resp.StatusCode != http.StatusOK {
resp.Body.Close()
conn.Close()
return nil, fmt.Errorf("proxy CONNECT failed: %s", resp.Status)
}

// Close the response body
resp.Body.Close()

// Clear the deadline now that we've finished the proxy handshake
if err := conn.SetDeadline(time.Time{}); err != nil {
conn.Close()
return nil, fmt.Errorf("failed to clear deadline: %v", err)
}

return conn, nil
}

func (s *Server) connectToRemoteLeafNode(remote *leafNodeCfg, firstConnect bool) {
defer s.grWG.Done()

Expand Down Expand Up @@ -541,6 +661,19 @@ func (s *Server) connectToRemoteLeafNode(remote *leafNodeCfg, firstConnect bool)

const connErrFmt = "Error trying to connect as leafnode to remote server %q (attempt %v): %v"

// Capture proxy configuration once before the loop with proper locking
remote.RLock()
proxyURL := remote.Proxy.URL
proxyUsername := remote.Proxy.Username
proxyPassword := remote.Proxy.Password
proxyTimeout := remote.Proxy.Timeout
remote.RUnlock()

// Set default proxy timeout if not specified
if proxyTimeout == 0 {
proxyTimeout = dialTimeout
}

attempts := 0

for s.isRunning() && s.remoteLeafNodeStillValid(remote) {
Expand All @@ -557,7 +690,25 @@ func (s *Server) connectToRemoteLeafNode(remote *leafNodeCfg, firstConnect bool)
err = ErrLeafNodeDisabled
} else {
s.Debugf("Trying to connect as leafnode to remote server on %q%s", rURL.Host, ipStr)
conn, err = natsDialTimeout("tcp", url, dialTimeout)

// Check if proxy is configured first, then check if URL supports it
if proxyURL != _EMPTY_ && isWSURL(rURL) {
// Use proxy for WebSocket connections - use original hostname, resolved IP for connection
targetHost := rURL.Host
// If URL doesn't include port, add the default port for the scheme
if rURL.Port() == _EMPTY_ {
defaultPort := "80"
if rURL.Scheme == wsSchemePrefixTLS {
defaultPort = "443"
}
targetHost = net.JoinHostPort(rURL.Hostname(), defaultPort)
}

conn, err = establishHTTPProxyTunnel(proxyURL, targetHost, proxyTimeout, proxyUsername, proxyPassword)
} else {
// Direct connection
conn, err = natsDialTimeout("tcp", url, dialTimeout)
}
}
}
if err != nil {
Expand Down Expand Up @@ -1287,6 +1438,13 @@ func (c *client) processLeafnodeInfo(info *Info) {
// otherwise if there is no TLS configuration block for the remote,
// the solicit side will not attempt to perform the TLS handshake.
if firstINFO && info.TLSRequired {
// Check for TLS/proxy configuration mismatch
if remote.Proxy.URL != _EMPTY_ && !remote.TLS && remote.TLSConfig == nil {
c.mu.Unlock()
c.Errorf("TLS configuration mismatch: Hub requires TLS but leafnode remote is not configured for TLS. When using a proxy, ensure TLS leafnode configuration matches the Hub requirements.")
c.closeConnection(TLSHandshakeError)
return
}
remote.TLS = true
}
if _, err := c.leafClientHandshakeIfNeeded(remote, opts); err != nil {
Expand Down
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