ftp,sftp: add socks_proxy support for SOCKS5 proxies

Fixes #3558

backend/ftp/ftp.go

@@ -28,6 +28,7 @@ import (
 	"github.com/rclone/rclone/lib/encoder"
 	"github.com/rclone/rclone/lib/env"
 	"github.com/rclone/rclone/lib/pacer"
+	"github.com/rclone/rclone/lib/proxy"
 	"github.com/rclone/rclone/lib/readers"
 )
 
@@ -174,6 +175,18 @@ Enabled by default. Use 0 to disable.`,
 If this is set and no password is supplied then rclone will ask for a password
 `,
 			Advanced: true,
+		}, {
+			Name:    "socks_proxy",
+			Default: "",
+			Help: `Socks 5 proxy host.
+		
+		Supports the format user:pass@host:port, user@host:port, host:port.
+		
+		Example:
+		
+			myUser:myPass@localhost:9005
+		`,
+			Advanced: true,
 		}, {
 			Name:     config.ConfigEncoding,
 			Help:     config.ConfigEncodingHelp,
@@ -218,6 +231,7 @@ type Options struct {
 	ShutTimeout       fs.Duration          `config:"shut_timeout"`
 	AskPassword       bool                 `config:"ask_password"`
 	Enc               encoder.MultiEncoder `config:"encoding"`
+	SocksProxy        string               `config:"socks_proxy"`
 }
 
 // Fs represents a remote FTP server
@@ -359,7 +373,12 @@ func (f *Fs) ftpConnection(ctx context.Context) (c *ftp.ServerConn, err error) {
 		defer func() {
 			fs.Debugf(f, "> dial: conn=%T, err=%v", conn, err)
 		}()
-		conn, err = fshttp.NewDialer(ctx).Dial(network, address)
+		baseDialer := fshttp.NewDialer(ctx)
+		if f.opt.SocksProxy != "" {
+			conn, err = proxy.SOCKS5Dial(network, address, f.opt.SocksProxy, baseDialer)
+		} else {
+			conn, err = baseDialer.Dial(network, address)
+		}
 		if err != nil {
 			return nil, err
 		}

backend/sftp/sftp.go

@@ -416,6 +416,17 @@ An example setting might be:
 Note that when using an external ssh binary rclone makes a new ssh
 connection for every hash it calculates.
 `,
+		}, {
+			Name:    "socks_proxy",
+			Default: "",
+			Help: `Socks 5 proxy host.
+	
+Supports the format user:pass@host:port, user@host:port, host:port.
+
+Example:
+
+	myUser:myPass@localhost:9005
+	`,
 			Advanced: true,
 		}},
 	}
@@ -457,6 +468,7 @@ type Options struct {
 	MACs                    fs.SpaceSepList `config:"macs"`
 	HostKeyAlgorithms       fs.SpaceSepList `config:"host_key_algorithms"`
 	SSH                     fs.SpaceSepList `config:"ssh"`
+	SocksProxy              string          `config:"socks_proxy"`
 }
 
 // Fs stores the interface to the remote SFTP files

backend/sftp/ssh_internal.go

@@ -6,9 +6,11 @@ package sftp
 import (
 	"context"
 	"io"
+	"net"
 
 	"github.com/rclone/rclone/fs"
 	"github.com/rclone/rclone/fs/fshttp"
+	"github.com/rclone/rclone/lib/proxy"
 	"golang.org/x/crypto/ssh"
 )
 
@@ -22,8 +24,17 @@ type sshClientInternal struct {
 // convenience function that connects to the given network address,
 // initiates the SSH handshake, and then sets up a Client.
 func (f *Fs) newSSHClientInternal(ctx context.Context, network, addr string, sshConfig *ssh.ClientConfig) (sshClient, error) {
-	dialer := fshttp.NewDialer(ctx)
-	conn, err := dialer.Dial(network, addr)
+
+	baseDialer := fshttp.NewDialer(ctx)
+	var (
+		conn net.Conn
+		err  error
+	)
+	if f.opt.SocksProxy != "" {
+		conn, err = proxy.SOCKS5Dial(network, addr, f.opt.SocksProxy, baseDialer)
+	} else {
+		conn, err = baseDialer.Dial(network, addr)
+	}
 	if err != nil {
 		return nil, err
 	}

lib/proxy/socks.go

@@ -0,0 +1,41 @@
+package proxy
+
+import (
+	"fmt"
+	"net"
+	"strings"
+
+	"golang.org/x/net/proxy"
+)
+
+// SOCKS5Dial dials a net.Conn using a SOCKS5 proxy server.
+// The socks5Proxy address can be in the form of [user:password@]host:port, [user@]host:port or just host:port if no auth is required.
+// It will optionally take a proxyDialer to dial the SOCKS5 proxy server. If nil is passed, it will use the default net.Dialer.
+func SOCKS5Dial(network, addr, socks5Proxy string, proxyDialer proxy.Dialer) (net.Conn, error) {
+
+	if proxyDialer == nil {
+		proxyDialer = &net.Dialer{}
+	}
+	var (
+		proxyAddress string
+		proxyAuth    *proxy.Auth
+	)
+	if credsAndHost := strings.SplitN(socks5Proxy, "@", 2); len(credsAndHost) == 2 {
+		proxyCreds := strings.SplitN(credsAndHost[0], ":", 2)
+		proxyAuth = &proxy.Auth{
+			User: proxyCreds[0],
+		}
+		if len(proxyCreds) == 2 {
+			proxyAuth.Password = proxyCreds[1]
+		}
+		proxyAddress = credsAndHost[1]
+	} else {
+		proxyAddress = credsAndHost[0]
+	}
+	proxyDialer, err := proxy.SOCKS5("tcp", proxyAddress, proxyAuth, proxyDialer)
+	if err != nil {
+		return nil, fmt.Errorf("failed to create proxy dialer: %w", err)
+	}
+	return proxyDialer.Dial(network, addr)
+
+}