Fix ZXing Wi-Fi QR code parsing bug.

ZXing Wi-Fi QR code uses ';' as the delimiter for key/value pairs,
should not treat an escaped "\;" as the delimiter.

This fix also change the parsing result:

  If there is no specified key, the result value is null.
  If specified key exists with empty value, the result value is an empty string.

Bug: 118797380
Test: atest WifiQrCodetest
Change-Id: I786ce7c4fa66dcb31d8a61d7a3251c2f539ccc99

src/com/android/settings/wifi/dpp/WifiQrCode.java

@@ -22,7 +22,8 @@ import android.text.TextUtils;
 import androidx.annotation.Keep;
 import androidx.annotation.VisibleForTesting;
 
-import java.util.regex.Matcher;
+import java.util.Arrays;
+import java.util.List;
 import java.util.regex.Pattern;
 
 /**
@@ -62,7 +63,7 @@ public class WifiQrCode {
     public static final String PREFIX_ZXING_PASSWORD = "P:";
     public static final String PREFIX_ZXING_HIDDEN_SSID = "H:";
 
-    public static final String SUFFIX_QR_CODE = ";";
+    public static final String DELIMITER_QR_CODE = ";";
 
     private String mQrCode;
 
@@ -100,22 +101,27 @@ public class WifiQrCode {
 
     /** Parses Wi-Fi DPP QR code string */
     private void parseWifiDppQrCode(String qrCode) throws IllegalArgumentException {
-        String publicKey = getSubStringOrNull(qrCode, PREFIX_DPP_PUBLIC_KEY, SUFFIX_QR_CODE);
+        List keyValueList = getKeyValueList(qrCode, PREFIX_DPP, DELIMITER_QR_CODE);
+
+        String publicKey = getValueOrNull(keyValueList, PREFIX_DPP_PUBLIC_KEY);
         if (TextUtils.isEmpty(publicKey)) {
             throw new IllegalArgumentException("Invalid format");
         }
         mPublicKey = publicKey;
 
-        mInformation = getSubStringOrNull(qrCode, PREFIX_DPP_INFORMATION, SUFFIX_QR_CODE);
+        mInformation = getValueOrNull(keyValueList, PREFIX_DPP_INFORMATION);
     }
 
     /** Parses ZXing reader library's Wi-Fi Network config format */
     private void parseZxingWifiQrCode(String qrCode) throws IllegalArgumentException {
-        String security = getSubStringOrNull(qrCode, PREFIX_ZXING_SECURITY, SUFFIX_QR_CODE);
+        List keyValueList = getKeyValueList(qrCode, PREFIX_ZXING_WIFI_NETWORK_CONFIG,
-        String ssid = getSubStringOrNull(qrCode, PREFIX_ZXING_SSID, SUFFIX_QR_CODE);
+                DELIMITER_QR_CODE);
-        String password = getSubStringOrNull(qrCode, PREFIX_ZXING_PASSWORD, SUFFIX_QR_CODE);
+
-        String hiddenSsidString = getSubStringOrNull(qrCode, PREFIX_ZXING_HIDDEN_SSID,
+        String security = getValueOrNull(keyValueList, PREFIX_ZXING_SECURITY);
-                SUFFIX_QR_CODE);
+        String ssid = getValueOrNull(keyValueList, PREFIX_ZXING_SSID);
+        String password = getValueOrNull(keyValueList, PREFIX_ZXING_PASSWORD);
+        String hiddenSsidString = getValueOrNull(keyValueList, PREFIX_ZXING_HIDDEN_SSID);
+
         boolean hiddenSsid = "true".equalsIgnoreCase(hiddenSsidString);
 
         //"\", ";", "," and ":" are escaped with a backslash "\", should remove at first
@@ -132,33 +138,37 @@ public class WifiQrCode {
     }
 
     /**
-     * Gets the substring between prefix & suffix from input.
+     * Splits key/value pairs from qrCode
      *
-     * @param prefix the string before the returned substring
+     * @param qrCode the QR code raw string
-     * @param suffix the string after the returned substring
+     * @param prefixQrCode the string before all key/value pairs in qrCode
-     * @return null if not exists, non-null otherwise
+     * @param delimiter the string to split key/value pairs, can't contain a backslash
+     * @return a list contains string of key/value (e.g. K:key1)
      */
-    private static String getSubStringOrNull(String input, String prefix, String suffix) {
+    private List<String> getKeyValueList(String qrCode, String prefixQrCode,
-        StringBuilder sb = new StringBuilder();
+                String delimiter) {
-        String regex = sb.append(prefix).append("(.*?)").append(suffix).toString();
+        String keyValueString = qrCode.substring(prefixQrCode.length());
-        Pattern pattern = Pattern.compile(regex);
-        Matcher matcher = pattern.matcher(input);
 
-        if (!matcher.find()) {
+        // Should not treat \delimiter as a delimiter
-            return null;
+        String regex = "(?<!\\\\)" + Pattern.quote(delimiter);
+
+        List<String> result = Arrays.asList(keyValueString.split(regex));
+        return result;
     }
 
-        String target = matcher.group(1);
+    private String getValueOrNull(List<String> keyValueList, String prefix) {
-        if (TextUtils.isEmpty(target)) {
+        for (String keyValue : keyValueList) {
-            return null;
+            if (keyValue.startsWith(prefix)) {
+                return  keyValue.substring(prefix.length());
+            }
         }
 
-        return target;
+        return null;
     }
 
     @Keep
     @VisibleForTesting(otherwise = VisibleForTesting.PRIVATE)
-    protected static String removeBackSlash(String input) {
+    protected String removeBackSlash(String input) {
         if (input == null) {
             return null;
         }

tests/unit/src/com/android/settings/wifi/dpp/WifiQrCodeTest.java

@@ -29,7 +29,7 @@ import org.junit.runner.RunWith;
 
 @SmallTest
 @RunWith(AndroidJUnit4.class)
-public class WifiQrCodetest {
+public class WifiQrCodeTest {
     // Valid Wi-Fi DPP QR code & it's parameters
     private static final String VALID_WIFI_DPP_QR_CODE = "DPP:I:SN=4774LH2b4044;M:010203040506;K:"
             + "MDkwEwYHKoZIzj0CAQYIKoZIzj0DAQcDIgADURzxmttZoIRIPWGoQMV00XHWCAQIhXruVWOz0NjlkIA=;;";
@@ -57,6 +57,13 @@ public class WifiQrCodetest {
     private static final String SSID_OF_VALID_ZXING_WIFI_QR_CODE = "mynetwork";
     private static final String PASSWORD_OF_VALID_ZXING_WIFI_QR_CODE = "mypass";
 
+    // Valid ZXing reader library's Wi-Fi Network config format - escaped characters
+    private static final String VALID_ZXING_WIFI_QR_CODE_SPECIAL_CHARACTERS =
+            "WIFI:T:WPA;S:mynetwork;P:m\\;y\\:p\\\\a\\,ss;H:true;;";
+
+    private static final String PASSWORD_OF_VALID_ZXING_WIFI_QR_CODE_SPECIAL_CHARACTERS =
+            "m;y:p\\a,ss";
+
     // Invalid scheme QR code
     private static final String INVALID_SCHEME_QR_CODE = "BT:T:WPA;S:mynetwork;P:mypass;H:true;;";
 
@@ -118,19 +125,35 @@ public class WifiQrCodetest {
 
         assertEquals(WifiQrCode.SCHEME_ZXING_WIFI_NETWORK_CONFIG, wifiQrCode.getScheme());
         assertNotNull(config);
-        assertNull(config.getSecurity());
+        assertEquals("", config.getSecurity());
         assertEquals(SSID_OF_VALID_ZXING_WIFI_QR_CODE, config.getSsid());
-        assertNull(config.getPreSharedKey());
+        assertEquals("", config.getPreSharedKey());
         assertEquals(false, config.getHiddenSsid());
     }
 
+    @Test
+    public void parseValidZxingWifiQrCode_specialCharacters() {
+        WifiQrCode wifiQrCode = new WifiQrCode(VALID_ZXING_WIFI_QR_CODE_SPECIAL_CHARACTERS);
+        WifiNetworkConfig config = wifiQrCode.getWifiNetworkConfig();
+
+        assertEquals(WifiQrCode.SCHEME_ZXING_WIFI_NETWORK_CONFIG, wifiQrCode.getScheme());
+        assertNotNull(config);
+        assertEquals(SECURITY_OF_VALID_ZXING_WIFI_QR_CODE, config.getSecurity());
+        assertEquals(SSID_OF_VALID_ZXING_WIFI_QR_CODE, config.getSsid());
+        assertEquals(PASSWORD_OF_VALID_ZXING_WIFI_QR_CODE_SPECIAL_CHARACTERS,
+                config.getPreSharedKey());
+        assertEquals(true, config.getHiddenSsid());
+    }
+
     @Test
     public void testRemoveBackSlash() {
-        assertEquals("\\", WifiQrCode.removeBackSlash("\\\\"));
+        WifiQrCode wifiQrCode = new WifiQrCode(VALID_WIFI_DPP_QR_CODE);
-        assertEquals("ab", WifiQrCode.removeBackSlash("a\\b"));
+
-        assertEquals("a", WifiQrCode.removeBackSlash("\\a"));
+        assertEquals("\\", wifiQrCode.removeBackSlash("\\\\"));
-        assertEquals("\\b", WifiQrCode.removeBackSlash("\\\\b"));
+        assertEquals("ab", wifiQrCode.removeBackSlash("a\\b"));
-        assertEquals("c\\", WifiQrCode.removeBackSlash("c\\\\"));
+        assertEquals("a", wifiQrCode.removeBackSlash("\\a"));
+        assertEquals("\\b", wifiQrCode.removeBackSlash("\\\\b"));
+        assertEquals("c\\", wifiQrCode.removeBackSlash("c\\\\"));
     }
 
     @Test