allow proxying connection (#283)

go.mod

@@ -22,7 +22,7 @@ require (
 	github.com/stretchr/testify v1.4.0
 	github.com/tscholl2/siec v0.0.0-20191122224205-8da93652b094
 	golang.org/x/crypto v0.0.0-20200820211705-5c72a883971a
-	golang.org/x/net v0.0.0-20200904194848-62affa334b73 // indirect
+	golang.org/x/net v0.0.0-20200904194848-62affa334b73
 	golang.org/x/sys v0.0.0-20200916084744-dbad9cb7cb7a // indirect
 	golang.org/x/text v0.3.3 // indirect
 	gopkg.in/check.v1 v1.0.0-20190902080502-41f04d3bba15 // indirect

src/cli/cli.go

@@ -14,6 +14,7 @@ import (
 	"time"
 
 	"github.com/schollz/cli/v2"
+	"github.com/schollz/croc/v8/src/comm"
 	"github.com/schollz/croc/v8/src/croc"
 	"github.com/schollz/croc/v8/src/models"
 	"github.com/schollz/croc/v8/src/tcp"
@@ -84,6 +85,7 @@ func Run() (err error) {
 		&cli.StringFlag{Name: "relay6", Value: models.DEFAULT_RELAY6, Usage: "ipv6 address of the relay", EnvVars: []string{"CROC_RELAY6"}},
 		&cli.StringFlag{Name: "out", Value: ".", Usage: "specify an output folder to receive the file"},
 		&cli.StringFlag{Name: "pass", Value: "pass123", Usage: "password for the relay", EnvVars: []string{"CROC_PASS"}},
+		&cli.StringFlag{Name: "socks5", Value: "", Usage: "add a socks5 proxy", EnvVars: []string{"http_proxy"}},
 	}
 	app.EnableBashCompletion = true
 	app.HideHelp = false
@@ -92,10 +94,10 @@ func Run() (err error) {
 		allStringsAreFiles := func(strs []string) bool {
 			for _, str := range strs {
 				if !utils.Exists(str) {
-					return false;
+					return false
 				}
 			}
-			return true;
+			return true
 		}
 
 		// if trying to send but forgot send, let the user know
@@ -103,7 +105,7 @@ func Run() (err error) {
 			fnames := []string{}
 			for _, fpath := range c.Args().Slice() {
 				_, basename := filepath.Split(fpath)
-				fnames = append(fnames, "'" + basename + "'")
+				fnames = append(fnames, "'"+basename+"'")
 			}
 			yn := utils.GetInput(fmt.Sprintf("Did you mean to send %s? (y/n) ", strings.Join(fnames, ", ")))
 			if strings.ToLower(yn) == "y" {
@@ -159,6 +161,7 @@ func determinePass(c *cli.Context) (pass string) {
 
 func send(c *cli.Context) (err error) {
 	setDebugLevel(c)
+	comm.Socks5Proxy = c.String("socks5")
 	crocOptions := croc.Options{
 		SharedSecret:   c.String("code"),
 		IsSender:       true,
@@ -356,6 +359,7 @@ func saveConfig(c *cli.Context, crocOptions croc.Options) {
 }
 
 func receive(c *cli.Context) (err error) {
+	comm.Socks5Proxy = c.String("socks5")
 	crocOptions := croc.Options{
 		SharedSecret:  c.String("code"),
 		IsSender:      false,

src/comm/comm.go

@@ -8,9 +8,13 @@ import (
 	"net"
 	"time"
 
+	"github.com/schollz/croc/v8/src/utils"
 	log "github.com/schollz/logger"
+	"golang.org/x/net/proxy"
 )
 
+var Socks5Proxy = ""
+
 const MAXBYTES = 4000000
 
 // Comm is some basic TCP communication
@@ -24,7 +28,18 @@ func NewConnection(address string, timelimit ...time.Duration) (c *Comm, err err
 	if len(timelimit) > 0 {
 		tlimit = timelimit[0]
 	}
-	connection, err := net.DialTimeout("tcp", address, tlimit)
+	var connection net.Conn
+	if Socks5Proxy != "" && !utils.IsLocalIP(address) {
+		var dialer proxy.Dialer
+		dialer, err = proxy.SOCKS5("tcp", Socks5Proxy, nil, proxy.Direct)
+		if err != nil {
+			err = fmt.Errorf("proxy failed: %w", err)
+			return
+		}
+		connection, err = dialer.Dial("tcp", address)
+	} else {
+		connection, err = net.DialTimeout("tcp", address, tlimit)
+	}
 	if err != nil {
 		err = fmt.Errorf("comm.NewConnection failed: %w", err)
 		return

src/utils/utils.go

@@ -261,3 +261,43 @@ func FindOpenPorts(host string, portNumStart, numPorts int) (openPorts []int) {
 	}
 	return
 }
+
+// local ip determination
+// https://stackoverflow.com/questions/41240761/check-if-ip-address-is-in-private-network-space
+var privateIPBlocks []*net.IPNet
+
+func init() {
+	for _, cidr := range []string{
+		"127.0.0.0/8",    // IPv4 loopback
+		"10.0.0.0/8",     // RFC1918
+		"172.16.0.0/12",  // RFC1918
+		"192.168.0.0/16", // RFC1918
+		"169.254.0.0/16", // RFC3927 link-local
+		"::1/128",        // IPv6 loopback
+		"fe80::/10",      // IPv6 link-local
+		"fc00::/7",       // IPv6 unique local addr
+	} {
+		_, block, err := net.ParseCIDR(cidr)
+		if err != nil {
+			panic(fmt.Errorf("parse error on %q: %v", cidr, err))
+		}
+		privateIPBlocks = append(privateIPBlocks, block)
+	}
+}
+
+func IsLocalIP(ipaddress string) bool {
+	if strings.Contains(ipaddress, "localhost") {
+		return true
+	}
+	host, _, _ := net.SplitHostPort(ipaddress)
+	ip := net.ParseIP(host)
+	if ip.IsLoopback() || ip.IsLinkLocalUnicast() || ip.IsLinkLocalMulticast() {
+		return true
+	}
+	for _, block := range privateIPBlocks {
+		if block.Contains(ip) {
+			return true
+		}
+	}
+	return false
+}

src/utils/utils_test.go

@@ -191,3 +191,7 @@ func TestFindOpenPorts(t *testing.T) {
 	openPorts := FindOpenPorts("localhost", 9009, 4)
 	assert.Equal(t, []int{9009, 9010, 9011, 9012}, openPorts)
 }
+
+func TestIsLocalIP(t *testing.T) {
+	assert.True(t, IsLocalIP("192.168.0.14:9009"))
+}