Parse target strings with IPv6 support and strict validation

Add parseTargetString() for listenPort:host:targetPort using net.SplitHostPort/JoinHostPort. Replace manual split in updateTargets; fix err shadowing on remove. Validate listen port 1–65535 and reject empty host/port; use %w for errors. Add tests for IPv4, IPv6, hostnames, and invalid cases.
2026-03-26 12:36:45 +00:00 · 2026-03-05 15:12:47 +00:00
parent da9825d030
commit 768415f90b
2 changed files with 262 additions and 16 deletions
--- a/common_test.go
+++ b/common_test.go
@@ -0,0 +1,212 @@
+package main
+
+import (
+	"net"
+	"testing"
+)
+
+func TestParseTargetString(t *testing.T) {
+	tests := []struct {
+		name           string
+		input          string
+		wantListenPort int
+		wantTargetAddr string
+		wantErr        bool
+	}{
+		// IPv4 test cases
+		{
+			name:           "valid IPv4 basic",
+			input:          "3001:192.168.1.1:80",
+			wantListenPort: 3001,
+			wantTargetAddr: "192.168.1.1:80",
+			wantErr:        false,
+		},
+		{
+			name:           "valid IPv4 localhost",
+			input:          "8080:127.0.0.1:3000",
+			wantListenPort: 8080,
+			wantTargetAddr: "127.0.0.1:3000",
+			wantErr:        false,
+		},
+		{
+			name:           "valid IPv4 same ports",
+			input:          "443:10.0.0.1:443",
+			wantListenPort: 443,
+			wantTargetAddr: "10.0.0.1:443",
+			wantErr:        false,
+		},
+
+		// IPv6 test cases
+		{
+			name:           "valid IPv6 loopback",
+			input:          "3001:[::1]:8080",
+			wantListenPort: 3001,
+			wantTargetAddr: "[::1]:8080",
+			wantErr:        false,
+		},
+		{
+			name:           "valid IPv6 full address",
+			input:          "80:[fd70:1452:b736:4dd5:caca:7db9:c588:f5b3]:8080",
+			wantListenPort: 80,
+			wantTargetAddr: "[fd70:1452:b736:4dd5:caca:7db9:c588:f5b3]:8080",
+			wantErr:        false,
+		},
+		{
+			name:           "valid IPv6 link-local",
+			input:          "443:[fe80::1]:443",
+			wantListenPort: 443,
+			wantTargetAddr: "[fe80::1]:443",
+			wantErr:        false,
+		},
+		{
+			name:           "valid IPv6 all zeros compressed",
+			input:          "8000:[::]:9000",
+			wantListenPort: 8000,
+			wantTargetAddr: "[::]:9000",
+			wantErr:        false,
+		},
+		{
+			name:           "valid IPv6 mixed notation",
+			input:          "5000:[::ffff:192.168.1.1]:6000",
+			wantListenPort: 5000,
+			wantTargetAddr: "[::ffff:192.168.1.1]:6000",
+			wantErr:        false,
+		},
+
+		// Hostname test cases
+		{
+			name:           "valid hostname",
+			input:          "8080:example.com:80",
+			wantListenPort: 8080,
+			wantTargetAddr: "example.com:80",
+			wantErr:        false,
+		},
+		{
+			name:           "valid hostname with subdomain",
+			input:          "443:api.example.com:8443",
+			wantListenPort: 443,
+			wantTargetAddr: "api.example.com:8443",
+			wantErr:        false,
+		},
+		{
+			name:           "valid localhost hostname",
+			input:          "3000:localhost:3000",
+			wantListenPort: 3000,
+			wantTargetAddr: "localhost:3000",
+			wantErr:        false,
+		},
+
+		// Error cases
+		{
+			name:    "invalid - no colons",
+			input:   "invalid",
+			wantErr: true,
+		},
+		{
+			name:    "invalid - empty string",
+			input:   "",
+			wantErr: true,
+		},
+		{
+			name:    "invalid - non-numeric listen port",
+			input:   "abc:192.168.1.1:80",
+			wantErr: true,
+		},
+		{
+			name:    "invalid - missing target port",
+			input:   "3001:192.168.1.1",
+			wantErr: true,
+		},
+		{
+			name:    "invalid - IPv6 without brackets",
+			input:   "3001:fd70:1452:b736:4dd5:caca:7db9:c588:f5b3:80",
+			wantErr: true,
+		},
+		{
+			name:    "invalid - only listen port",
+			input:   "3001:",
+			wantErr: true,
+		},
+		{
+			name:    "invalid - missing host",
+			input:   "3001::80",
+			wantErr: true,
+		},
+		{
+			name:    "invalid - IPv6 unclosed bracket",
+			input:   "3001:[::1:80",
+			wantErr: true,
+		},
+		{
+			name:    "invalid - listen port zero",
+			input:   "0:192.168.1.1:80",
+			wantErr: true,
+		},
+		{
+			name:    "invalid - listen port negative",
+			input:   "-1:192.168.1.1:80",
+			wantErr: true,
+		},
+		{
+			name:    "invalid - listen port out of range",
+			input:   "70000:192.168.1.1:80",
+			wantErr: true,
+		},
+		{
+			name:    "invalid - empty target port",
+			input:   "3001:192.168.1.1:",
+			wantErr: true,
+		},
+	}
+
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			listenPort, targetAddr, err := parseTargetString(tt.input)
+
+			if (err != nil) != tt.wantErr {
+				t.Errorf("parseTargetString(%q) error = %v, wantErr %v", tt.input, err, tt.wantErr)
+				return
+			}
+
+			if tt.wantErr {
+				return // Don't check other values if we expected an error
+			}
+
+			if listenPort != tt.wantListenPort {
+				t.Errorf("parseTargetString(%q) listenPort = %d, want %d", tt.input, listenPort, tt.wantListenPort)
+			}
+
+			if targetAddr != tt.wantTargetAddr {
+				t.Errorf("parseTargetString(%q) targetAddr = %q, want %q", tt.input, targetAddr, tt.wantTargetAddr)
+			}
+		})
+	}
+}
+
+// TestParseTargetStringNetDialCompatibility verifies that the output is compatible with net.Dial
+func TestParseTargetStringNetDialCompatibility(t *testing.T) {
+	tests := []struct {
+		name  string
+		input string
+	}{
+		{"IPv4", "8080:127.0.0.1:80"},
+		{"IPv6 loopback", "8080:[::1]:80"},
+		{"IPv6 full", "8080:[2001:db8::1]:80"},
+	}
+
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			_, targetAddr, err := parseTargetString(tt.input)
+			if err != nil {
+				t.Fatalf("parseTargetString(%q) unexpected error: %v", tt.input, err)
+			}
+
+			// Verify the format is valid for net.Dial by checking it can be split back
+			// This doesn't actually dial, just validates the format
+			_, _, err = net.SplitHostPort(targetAddr)
+			if err != nil {
+				t.Errorf("parseTargetString(%q) produced invalid net.Dial format %q: %v", tt.input, targetAddr, err)
+			}
+		})
+	}
+}