1 /* 2 * Copyright (C) 2018 The Android Open Source Project 3 * 4 * Licensed under the Apache License, Version 2.0 (the "License"); 5 * you may not use this file except in compliance with the License. 6 * You may obtain a copy of the License at 7 * 8 * http://www.apache.org/licenses/LICENSE-2.0 9 * 10 * Unless required by applicable law or agreed to in writing, software 11 * distributed under the License is distributed on an "AS IS" BASIS, 12 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. 13 * See the License for the specific language governing permissions and 14 * limitations under the License. 15 */ 16 17 package android.net.captiveportal; 18 19 import static android.net.captiveportal.CaptivePortalProbeResult.PORTAL_CODE; 20 import static android.net.captiveportal.CaptivePortalProbeResult.SUCCESS_CODE; 21 22 import android.text.TextUtils; 23 import android.util.Log; 24 25 import androidx.annotation.NonNull; 26 import androidx.annotation.Nullable; 27 import androidx.annotation.VisibleForTesting; 28 29 import java.net.MalformedURLException; 30 import java.net.URL; 31 import java.text.ParseException; 32 import java.util.ArrayList; 33 import java.util.Collection; 34 import java.util.List; 35 import java.util.regex.Pattern; 36 import java.util.regex.PatternSyntaxException; 37 38 /** @hide */ 39 public abstract class CaptivePortalProbeSpec { 40 private static final String TAG = CaptivePortalProbeSpec.class.getSimpleName(); 41 private static final String REGEX_SEPARATOR = "@@/@@"; 42 private static final String SPEC_SEPARATOR = "@@,@@"; 43 44 private final String mEncodedSpec; 45 private final URL mUrl; 46 CaptivePortalProbeSpec(@onNull String encodedSpec, @NonNull URL url)47 CaptivePortalProbeSpec(@NonNull String encodedSpec, @NonNull URL url) { 48 mEncodedSpec = checkNotNull(encodedSpec); 49 mUrl = checkNotNull(url); 50 } 51 52 /** 53 * Parse a {@link CaptivePortalProbeSpec} from a {@link String}. 54 * 55 * <p>The valid format is a URL followed by two regular expressions, each separated by "@@/@@". 56 * @throws MalformedURLException The URL has invalid format for {@link URL#URL(String)}. 57 * @throws ParseException The string is empty, does not match the above format, or a regular 58 * expression is invalid for {@link Pattern#compile(String)}. 59 * @hide 60 */ 61 @VisibleForTesting 62 @NonNull parseSpec(@onNull String spec)63 public static CaptivePortalProbeSpec parseSpec(@NonNull String spec) throws ParseException, 64 MalformedURLException { 65 if (TextUtils.isEmpty(spec)) { 66 throw new ParseException("Empty probe spec", 0 /* errorOffset */); 67 } 68 69 String[] splits = TextUtils.split(spec, REGEX_SEPARATOR); 70 if (splits.length != 3) { 71 throw new ParseException("Probe spec does not have 3 parts", 0 /* errorOffset */); 72 } 73 74 final int statusRegexPos = splits[0].length() + REGEX_SEPARATOR.length(); 75 final int locationRegexPos = statusRegexPos + splits[1].length() + REGEX_SEPARATOR.length(); 76 final Pattern statusRegex = parsePatternIfNonEmpty(splits[1], statusRegexPos); 77 final Pattern locationRegex = parsePatternIfNonEmpty(splits[2], locationRegexPos); 78 79 return new RegexMatchProbeSpec(spec, new URL(splits[0]), statusRegex, locationRegex); 80 } 81 82 @Nullable parsePatternIfNonEmpty(@ullable String pattern, int pos)83 private static Pattern parsePatternIfNonEmpty(@Nullable String pattern, int pos) 84 throws ParseException { 85 if (TextUtils.isEmpty(pattern)) { 86 return null; 87 } 88 try { 89 return Pattern.compile(pattern); 90 } catch (PatternSyntaxException e) { 91 throw new ParseException( 92 String.format("Invalid status pattern [%s]: %s", pattern, e), 93 pos /* errorOffset */); 94 } 95 } 96 97 /** 98 * Parse a {@link CaptivePortalProbeSpec} from a {@link String}, or return a fallback spec 99 * based on the status code of the provided URL if the spec cannot be parsed. 100 */ 101 @Nullable parseSpecOrNull(@ullable String spec)102 public static CaptivePortalProbeSpec parseSpecOrNull(@Nullable String spec) { 103 if (spec != null) { 104 try { 105 return parseSpec(spec); 106 } catch (ParseException | MalformedURLException e) { 107 Log.e(TAG, "Invalid probe spec: " + spec, e); 108 // Fall through 109 } 110 } 111 return null; 112 } 113 114 /** 115 * Parse a config String to build an array of {@link CaptivePortalProbeSpec}. 116 * 117 * <p>Each spec is separated by @@,@@ and follows the format for {@link #parseSpec(String)}. 118 * <p>This method does not throw but ignores any entry that could not be parsed. 119 */ 120 @NonNull parseCaptivePortalProbeSpecs( @onNull String settingsVal)121 public static Collection<CaptivePortalProbeSpec> parseCaptivePortalProbeSpecs( 122 @NonNull String settingsVal) { 123 List<CaptivePortalProbeSpec> specs = new ArrayList<>(); 124 if (settingsVal != null) { 125 for (String spec : TextUtils.split(settingsVal, SPEC_SEPARATOR)) { 126 try { 127 specs.add(parseSpec(spec)); 128 } catch (ParseException | MalformedURLException e) { 129 Log.e(TAG, "Invalid probe spec: " + spec, e); 130 } 131 } 132 } 133 134 if (specs.isEmpty()) { 135 Log.e(TAG, String.format("could not create any validation spec from %s", settingsVal)); 136 } 137 return specs; 138 } 139 140 /** 141 * Get the probe result from HTTP status and location header. 142 */ 143 @NonNull getResult(int status, @Nullable String locationHeader)144 public abstract CaptivePortalProbeResult getResult(int status, @Nullable String locationHeader); 145 146 @NonNull getEncodedSpec()147 public String getEncodedSpec() { 148 return mEncodedSpec; 149 } 150 151 @NonNull getUrl()152 public URL getUrl() { 153 return mUrl; 154 } 155 156 /** 157 * Implementation of {@link CaptivePortalProbeSpec} that is based on configurable regular 158 * expressions for the HTTP status code and location header (if any). Matches indicate that 159 * the page is not a portal. 160 * This probe cannot fail: it always returns SUCCESS_CODE or PORTAL_CODE 161 */ 162 private static class RegexMatchProbeSpec extends CaptivePortalProbeSpec { 163 @Nullable 164 final Pattern mStatusRegex; 165 @Nullable 166 final Pattern mLocationHeaderRegex; 167 RegexMatchProbeSpec( String spec, URL url, Pattern statusRegex, Pattern locationHeaderRegex)168 RegexMatchProbeSpec( 169 String spec, URL url, Pattern statusRegex, Pattern locationHeaderRegex) { 170 super(spec, url); 171 mStatusRegex = statusRegex; 172 mLocationHeaderRegex = locationHeaderRegex; 173 } 174 175 @Override getResult(int status, String locationHeader)176 public CaptivePortalProbeResult getResult(int status, String locationHeader) { 177 final boolean statusMatch = safeMatch(String.valueOf(status), mStatusRegex); 178 final boolean locationMatch = safeMatch(locationHeader, mLocationHeaderRegex); 179 final int returnCode = statusMatch && locationMatch ? SUCCESS_CODE : PORTAL_CODE; 180 return new CaptivePortalProbeResult( 181 returnCode, locationHeader, getUrl().toString(), this); 182 } 183 } 184 safeMatch(@ullable String value, @Nullable Pattern pattern)185 private static boolean safeMatch(@Nullable String value, @Nullable Pattern pattern) { 186 // No value is a match ("no location header" passes the location rule for non-redirects) 187 return pattern == null || TextUtils.isEmpty(value) || pattern.matcher(value).matches(); 188 } 189 190 // Throws NullPointerException if the input is null. checkNotNull(T object)191 private static <T> T checkNotNull(T object) { 192 if (object == null) throw new NullPointerException(); 193 return object; 194 } 195 } 196