对于所有对同一问题感到好奇的人，我终于能够弄清楚如何完成这项任务，而无需 root 手机或使用 VPN 服务。
解决这个问题的关键是在手机上查看以下目录：
/proc/net/（tcp、tcp6、udp、udp6 等）
此外，这里有一些来自开源项目的代码，基本上可以满足我的需求。
/*
* Copyright (C) 2010 The Android Open Source Project
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
package android.net.cts;
import java.io.File;
import java.io.FileNotFoundException;
import java.util.ArrayList;
import java.util.List;
import java.util.Scanner;
import java.util.regex.Pattern;
import junit.framework.AssertionFailedError;
import junit.framework.TestCase;
public class ListeningPortsTest extends TestCase {
/** Address patterns used to check whether we're checking the right column in /proc/net. */
private static final List<String> ADDRESS_PATTERNS = new ArrayList<String>(2);
static {
ADDRESS_PATTERNS.add("[0-9A-F]{8}:[0-9A-F]{4}");
ADDRESS_PATTERNS.add("[0-9A-F]{32}:[0-9A-F]{4}");
}
/** Ports that are allowed to be listening on the emulator. */
private static final List<String> EXCEPTION_PATTERNS = new ArrayList<String>(6);
static {
// IPv4 exceptions
EXCEPTION_PATTERNS.add("00000000:15B3"); // 0.0.0.0:5555 - emulator port
EXCEPTION_PATTERNS.add("0F02000A:15B3"); // 10.0.2.15:5555 - net forwarding for emulator
EXCEPTION_PATTERNS.add("[0-9A-F]{6}7F:[0-9A-F]{4}"); // IPv4 Loopback
// IPv6 exceptions
EXCEPTION_PATTERNS.add("[0]{31}1:[0-9A-F]{4}"); // IPv6 Loopback
EXCEPTION_PATTERNS.add("[0]{16}[0]{4}[0]{4}[0-9A-F]{6}7F:[0-9A-F]{4}"); // IPv4-6 Conversion
EXCEPTION_PATTERNS.add("[0]{16}[F]{4}[0]{4}[0-9A-F]{6}7F:[0-9A-F]{4}"); // IPv4-6 Conversion
}
public void testNoListeningTcpPorts() {
assertNoListeningPorts("/proc/net/tcp", true);
}
public void testNoListeningTcp6Ports() {
assertNoListeningPorts("/proc/net/tcp6", true);
}
public void testNoListeningUdpPorts() throws Exception {
assertNoListeningUdpPorts("/proc/net/udp");
}
public void testNoListeningUdp6Ports() throws Exception {
assertNoListeningUdpPorts("/proc/net/udp6");
}
private static final int RETRIES_MAX = 6;
/**
* UDP tests can be flaky due to DNS lookups. Compensate.
*/
private static void assertNoListeningUdpPorts(String procFilePath) throws Exception {
for (int i = 0; i < RETRIES_MAX; i++) {
try {
assertNoListeningPorts(procFilePath, false);
return;
} catch (ListeningPortsAssertionError e) {
if (i == RETRIES_MAX - 1) {
throw e;
}
Thread.sleep(2 * 1000 * i);
}
}
throw new IllegalStateException("unreachable");
}
private static void assertNoListeningPorts(String procFilePath, boolean isTcp) {
/*
* Sample output of "cat /proc/net/tcp" on emulator:
*
* sl local_address rem_address st tx_queue rx_queue tr tm->when retrnsmt uid ...
* 0: 0100007F:13AD 00000000:0000 0A 00000000:00000000 00:00000000 00000000 0 ...
* 1: 00000000:15B3 00000000:0000 0A 00000000:00000000 00:00000000 00000000 0 ...
* 2: 0F02000A:15B3 0202000A:CE8A 01 00000000:00000000 00:00000000 00000000 0 ...
*
*/
File procFile = new File(procFilePath);
Scanner scanner = null;
try {
scanner = new Scanner(procFile);
while (scanner.hasNextLine()) {
String line = scanner.nextLine().trim();
// Skip column headers
if (line.startsWith("sl")) {
continue;
}
String[] fields = line.split("\\s+");
final int expectedNumColumns = 12;
assertTrue(procFilePath + " should have at least " + expectedNumColumns
+ " columns of output " + fields, fields.length >= expectedNumColumns);
String localAddress = fields[1];
String state = fields[3];
assertTrue(procFilePath + " should have an IP address in the second column",
isAddress(localAddress));
if (!isException(localAddress) && isPortListening(state, isTcp)) {
throw new ListeningPortsAssertionError(
"Found port listening on " + localAddress + " in " + procFilePath);
}
}
} catch (FileNotFoundException notFound) {
fail("Could not open file " + procFilePath + " to check for listening ports.");
} finally {
if (scanner != null) {
scanner.close();
}
}
}
private static boolean isAddress(String localAddress) {
return isPatternMatch(ADDRESS_PATTERNS, localAddress);
}
private static boolean isException(String localAddress) {
return isPatternMatch(EXCEPTION_PATTERNS, localAddress);
}
private static boolean isPatternMatch(List<String> patterns, String input) {
for (String pattern : patterns) {
if (Pattern.matches(pattern, input)) {
return true;
}
}
return false;
}
private static boolean isPortListening(String state, boolean isTcp) {
// 0A = TCP_LISTEN from include/net/tcp_states.h
String listeningState = isTcp ? "0A" : "07";
return listeningState.equals(state);
}
private static class ListeningPortsAssertionError extends AssertionFailedError {
private ListeningPortsAssertionError(String msg) {
super(msg);
}
}
}