chore: allow override IV_VER by peer-info for OpenVPN

transport/openvpn/keymethod.go

@@ -174,6 +174,10 @@ func InstallScriptOptionsString(proto, cipher, auth string, compLZO string) stri
 }
 
 func InstallScriptPeerInfo(cipher string, dataCiphers []string, compLZO string, peerInfo map[string]string) string {
+	ivVer := "mihomo-openvpn"
+	if value, ok := peerInfo["IV_VER"]; ok {
+		ivVer = value
+	}
 	lzo := ""
 	if compLZO == CompLzoYes {
 		lzo = "IV_LZO=1\n"
@@ -188,11 +192,19 @@ func InstallScriptPeerInfo(cipher string, dataCiphers []string, compLZO string,
 		}
 		ivCiphers = strings.Join(normalized, ":")
 	}
-	info := fmt.Sprintf("IV_VER=mihomo-openvpn\nIV_PROTO=6\n%sIV_CIPHERS=%s\n", lzo, ivCiphers)
+	info := fmt.Sprintf("IV_VER=%s\nIV_PROTO=6\n%sIV_CIPHERS=%s\n", ivVer, lzo, ivCiphers)
 	// Append user-defined peer-info entries (e.g. IV_HWADDR, UV_*) after the
 	// built-in fields. Keys are sorted so the output is deterministic.
 	keys := make([]string, 0, len(peerInfo))
 	for key := range peerInfo {
+		switch key {
+		case "IV_VER", "IV_PROTO", "IV_CIPHERS":
+			continue
+		case "IV_LZO":
+			if lzo != "" {
+				continue
+			}
+		}
 		keys = append(keys, key)
 	}
 	sort.Strings(keys)

transport/openvpn/keymethod_test.go

@@ -107,6 +107,19 @@ func TestInstallScriptPeerInfo(t *testing.T) {
 	if info != want {
 		t.Fatalf("unexpected peer-info:\n got %q\nwant %q", info, want)
 	}
+
+	// A user-defined IV_VER replaces the built-in value, while other generated
+	// fields are not duplicated by peer-info entries.
+	overridden := InstallScriptPeerInfo(CipherAES128GCM, nil, CompLzoYes, map[string]string{
+		"IV_VER":     "custom-client/1.0",
+		"IV_PROTO":   "999",
+		"IV_LZO":     "0",
+		"IV_CIPHERS": "AES-256-CBC",
+	})
+	want = "IV_VER=custom-client/1.0\nIV_PROTO=6\nIV_LZO=1\nIV_CIPHERS=AES-128-GCM\n"
+	if overridden != want {
+		t.Fatalf("unexpected overridden peer-info:\n got %q\nwant %q", overridden, want)
+	}
 }
 
 func TestParseServerKeyMethod2Record(t *testing.T) {