Make CaptivePortalProbeSpec and CaptivePortalProbeResult as a library

These two classes were added to @SystemApi because they are used
both by NetworkMonitor and CaptivePortalLogin. However it turns
out they are not needed in the framework, so having them as a
library sounds better.

Change-Id: Iadf77ec5952b6da8812dc6d006a39bd4e93d2bd9
Fix: 129433264
Test: atest NetworkStackTests FrameworksNetTests

1 files changed, 195 insertions, 0 deletions

diff --git a/common/CaptivePortalProbeSpec.java b/common/CaptivePortalProbeSpec.java
new file mode 100644
index 0000000..bf983a5
--- /dev/null
+++ b/common/CaptivePortalProbeSpec.java
@@ -0,0 +1,195 @@
+/*
+ * Copyright (C) 2018 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.captiveportal;
+
+import static android.net.captiveportal.CaptivePortalProbeResult.PORTAL_CODE;
+import static android.net.captiveportal.CaptivePortalProbeResult.SUCCESS_CODE;
+
+import android.text.TextUtils;
+import android.util.Log;
+
+import androidx.annotation.NonNull;
+import androidx.annotation.Nullable;
+import androidx.annotation.VisibleForTesting;
+
+import java.net.MalformedURLException;
+import java.net.URL;
+import java.text.ParseException;
+import java.util.ArrayList;
+import java.util.Collection;
+import java.util.List;
+import java.util.regex.Pattern;
+import java.util.regex.PatternSyntaxException;
+
+/** @hide */
+public abstract class CaptivePortalProbeSpec {
+    private static final String TAG = CaptivePortalProbeSpec.class.getSimpleName();
+    private static final String REGEX_SEPARATOR = "@@/@@";
+    private static final String SPEC_SEPARATOR = "@@,@@";
+
+    private final String mEncodedSpec;
+    private final URL mUrl;
+
+    CaptivePortalProbeSpec(@NonNull String encodedSpec, @NonNull URL url) {
+        mEncodedSpec = checkNotNull(encodedSpec);
+        mUrl = checkNotNull(url);
+    }
+
+    /**
+     * Parse a {@link CaptivePortalProbeSpec} from a {@link String}.
+     *
+     * <p>The valid format is a URL followed by two regular expressions, each separated by "@@/@@".
+     * @throws MalformedURLException The URL has invalid format for {@link URL#URL(String)}.
+     * @throws ParseException The string is empty, does not match the above format, or a regular
+     * expression is invalid for {@link Pattern#compile(String)}.
+     * @hide
+     */
+    @VisibleForTesting
+    @NonNull
+    public static CaptivePortalProbeSpec parseSpec(@NonNull String spec) throws ParseException,
+            MalformedURLException {
+        if (TextUtils.isEmpty(spec)) {
+            throw new ParseException("Empty probe spec", 0 /* errorOffset */);
+        }
+
+        String[] splits = TextUtils.split(spec, REGEX_SEPARATOR);
+        if (splits.length != 3) {
+            throw new ParseException("Probe spec does not have 3 parts", 0 /* errorOffset */);
+        }
+
+        final int statusRegexPos = splits[0].length() + REGEX_SEPARATOR.length();
+        final int locationRegexPos = statusRegexPos + splits[1].length() + REGEX_SEPARATOR.length();
+        final Pattern statusRegex = parsePatternIfNonEmpty(splits[1], statusRegexPos);
+        final Pattern locationRegex = parsePatternIfNonEmpty(splits[2], locationRegexPos);
+
+        return new RegexMatchProbeSpec(spec, new URL(splits[0]), statusRegex, locationRegex);
+    }
+
+    @Nullable
+    private static Pattern parsePatternIfNonEmpty(@Nullable String pattern, int pos)
+            throws ParseException {
+        if (TextUtils.isEmpty(pattern)) {
+            return null;
+        }
+        try {
+            return Pattern.compile(pattern);
+        } catch (PatternSyntaxException e) {
+            throw new ParseException(
+                    String.format("Invalid status pattern [%s]: %s", pattern, e),
+                    pos /* errorOffset */);
+        }
+    }
+
+    /**
+     * Parse a {@link CaptivePortalProbeSpec} from a {@link String}, or return a fallback spec
+     * based on the status code of the provided URL if the spec cannot be parsed.
+     */
+    @Nullable
+    public static CaptivePortalProbeSpec parseSpecOrNull(@Nullable String spec) {
+        if (spec != null) {
+            try {
+                return parseSpec(spec);
+            } catch (ParseException | MalformedURLException e) {
+                Log.e(TAG, "Invalid probe spec: " + spec, e);
+                // Fall through
+            }
+        }
+        return null;
+    }
+
+    /**
+     * Parse a config String to build an array of {@link CaptivePortalProbeSpec}.
+     *
+     * <p>Each spec is separated by @@,@@ and follows the format for {@link #parseSpec(String)}.
+     * <p>This method does not throw but ignores any entry that could not be parsed.
+     */
+    @NonNull
+    public static Collection<CaptivePortalProbeSpec> parseCaptivePortalProbeSpecs(
+            @NonNull String settingsVal) {
+        List<CaptivePortalProbeSpec> specs = new ArrayList<>();
+        if (settingsVal != null) {
+            for (String spec : TextUtils.split(settingsVal, SPEC_SEPARATOR)) {
+                try {
+                    specs.add(parseSpec(spec));
+                } catch (ParseException | MalformedURLException e) {
+                    Log.e(TAG, "Invalid probe spec: " + spec, e);
+                }
+            }
+        }
+
+        if (specs.isEmpty()) {
+            Log.e(TAG, String.format("could not create any validation spec from %s", settingsVal));
+        }
+        return specs;
+    }
+
+    /**
+     * Get the probe result from HTTP status and location header.
+     */
+    @NonNull
+    public abstract CaptivePortalProbeResult getResult(int status, @Nullable String locationHeader);
+
+    @NonNull
+    public String getEncodedSpec() {
+        return mEncodedSpec;
+    }
+
+    @NonNull
+    public URL getUrl() {
+        return mUrl;
+    }
+
+    /**
+     * Implementation of {@link CaptivePortalProbeSpec} that is based on configurable regular
+     * expressions for the HTTP status code and location header (if any). Matches indicate that
+     * the page is not a portal.
+     * This probe cannot fail: it always returns SUCCESS_CODE or PORTAL_CODE
+     */
+    private static class RegexMatchProbeSpec extends CaptivePortalProbeSpec {
+        @Nullable
+        final Pattern mStatusRegex;
+        @Nullable
+        final Pattern mLocationHeaderRegex;
+
+        RegexMatchProbeSpec(
+                String spec, URL url, Pattern statusRegex, Pattern locationHeaderRegex) {
+            super(spec, url);
+            mStatusRegex = statusRegex;
+            mLocationHeaderRegex = locationHeaderRegex;
+        }
+
+        @Override
+        public CaptivePortalProbeResult getResult(int status, String locationHeader) {
+            final boolean statusMatch = safeMatch(String.valueOf(status), mStatusRegex);
+            final boolean locationMatch = safeMatch(locationHeader, mLocationHeaderRegex);
+            final int returnCode = statusMatch && locationMatch ? SUCCESS_CODE : PORTAL_CODE;
+            return new CaptivePortalProbeResult(
+                    returnCode, locationHeader, getUrl().toString(), this);
+        }
+    }
+
+    private static boolean safeMatch(@Nullable String value, @Nullable Pattern pattern) {
+        // No value is a match ("no location header" passes the location rule for non-redirects)
+        return pattern == null || TextUtils.isEmpty(value) || pattern.matcher(value).matches();
+    }
+
+    // Throws NullPointerException if the input is null.
+    private static <T> T checkNotNull(T object) {
+        if (object == null) throw new NullPointerException();
+        return object;
+    }
+}