feat: decode uri path components correctly (#913)

* feat: decode uri path components correctly

The old implementation was incorrecly treating '+' as a space. Now
the only things that get decoded in the path are uri escaped sequences.

Fixes #398

* tweak javadoc

* remove hardcoded string

google-http-client/src/main/java/com/google/api/client/http/GenericUrl.java

@@ -81,10 +81,10 @@ public class GenericUrl extends GenericData {
   private String fragment;
 
   /**
-    * If true, the URL string originally given is used as is (without encoding, decoding and
-    * escaping) whenever referenced; otherwise, part of the URL string may be encoded or decoded as
-    * deemed appropriate or necessary.
-    */
+   * If true, the URL string originally given is used as is (without encoding, decoding and
+   * escaping) whenever referenced; otherwise, part of the URL string may be encoded or decoded as
+   * deemed appropriate or necessary.
+   */
   private boolean verbatim;
 
   public GenericUrl() {}
@@ -112,20 +112,20 @@ public GenericUrl(String encodedUrl) {
   /**
    * Constructs from an encoded URL.
    *
-   * <p>Any known query parameters with pre-defined fields as data keys are parsed based on
-   * their data type. Any unrecognized query parameter are always parsed as a string.
+   * <p>Any known query parameters with pre-defined fields as data keys are parsed based on their
+   * data type. Any unrecognized query parameter are always parsed as a string.
    *
    * <p>Any {@link MalformedURLException} is wrapped in an {@link IllegalArgumentException}.
    *
    * @param encodedUrl encoded URL, including any existing query parameters that should be parsed
-   * @param verbatim flag, to specify if URL should be used as is (without encoding, decoding and escaping)
+   * @param verbatim flag, to specify if URL should be used as is (without encoding, decoding and
+   *     escaping)
    * @throws IllegalArgumentException if URL has a syntax error
    */
   public GenericUrl(String encodedUrl, boolean verbatim) {
     this(parseURL(encodedUrl), verbatim);
   }
 
-
   /**
    * Constructs from a URI.
    *
@@ -140,7 +140,8 @@ public GenericUrl(URI uri) {
    * Constructs from a URI.
    *
    * @param uri URI
-   * @param verbatim flag, to specify if URL should be used as is (without encoding, decoding and escaping)
+   * @param verbatim flag, to specify if URL should be used as is (without encoding, decoding and
+   *     escaping)
    */
   public GenericUrl(URI uri, boolean verbatim) {
     this(
@@ -168,7 +169,8 @@ public GenericUrl(URL url) {
    * Constructs from a URL.
    *
    * @param url URL
-   * @param verbatim flag, to specify if URL should be used as is (without encoding, decoding and escaping)
+   * @param verbatim flag, to specify if URL should be used as is (without encoding, decoding and
+   *     escaping)
    * @since 1.14
    */
   public GenericUrl(URL url, boolean verbatim) {
@@ -209,7 +211,7 @@ private GenericUrl(
         UrlEncodedParser.parse(query, this);
       }
       this.userInfo = userInfo != null ? CharEscapers.decodeUri(userInfo) : null;
-    } 
+    }
   }
 
   @Override
@@ -567,10 +569,11 @@ public static List<String> toPathParts(String encodedPath) {
    *
    * @param encodedPath slash-prefixed encoded path, for example {@code
    *     "/m8/feeds/contacts/default/full"}
-   * @param verbatim flag, to specify if URL should be used as is (without encoding, decoding and escaping)
-   * @return path parts (decoded if not {@code verbatim}), with each part assumed to be preceded by a {@code '/'}, for example
-   *     {@code "", "m8", "feeds", "contacts", "default", "full"}, or {@code null} for {@code null}
-   *     or {@code ""} input
+   * @param verbatim flag, to specify if URL should be used as is (without encoding, decoding and
+   *     escaping)
+   * @return path parts (decoded if not {@code verbatim}), with each part assumed to be preceded by
+   *     a {@code '/'}, for example {@code "", "m8", "feeds", "contacts", "default", "full"}, or
+   *     {@code null} for {@code null} or {@code ""} input
    */
   public static List<String> toPathParts(String encodedPath, boolean verbatim) {
     if (encodedPath == null || encodedPath.length() == 0) {
@@ -588,7 +591,7 @@ public static List<String> toPathParts(String encodedPath, boolean verbatim) {
       } else {
         sub = encodedPath.substring(cur);
       }
-      result.add(verbatim ? sub : CharEscapers.decodeUri(sub));
+      result.add(verbatim ? sub : CharEscapers.decodeUriPath(sub));
       cur = slash + 1;
     }
     return result;
@@ -608,13 +611,17 @@ private void appendRawPathFromParts(StringBuilder buf) {
   }
 
   /** Adds query parameters from the provided entrySet into the buffer. */
-  static void addQueryParams(Set<Entry<String, Object>> entrySet, StringBuilder buf, boolean verbatim) {
+  static void addQueryParams(
+      Set<Entry<String, Object>> entrySet, StringBuilder buf, boolean verbatim) {
     // (similar to UrlEncodedContent)
     boolean first = true;
     for (Map.Entry<String, Object> nameValueEntry : entrySet) {
       Object value = nameValueEntry.getValue();
       if (value != null) {
-        String name =  verbatim ? nameValueEntry.getKey() : CharEscapers.escapeUriQuery(nameValueEntry.getKey());
+        String name =
+            verbatim
+                ? nameValueEntry.getKey()
+                : CharEscapers.escapeUriQuery(nameValueEntry.getKey());
         if (value instanceof Collection<?>) {
           Collection<?> collectionValue = (Collection<?>) value;
           for (Object repeatedValue : collectionValue) {
@@ -627,15 +634,17 @@ static void addQueryParams(Set<Entry<String, Object>> entrySet, StringBuilder bu
     }
   }
 
-  private static boolean appendParam(boolean first, StringBuilder buf, String name, Object value, boolean verbatim) {
+  private static boolean appendParam(
+      boolean first, StringBuilder buf, String name, Object value, boolean verbatim) {
     if (first) {
       first = false;
       buf.append('?');
     } else {
       buf.append('&');
     }
     buf.append(name);
-    String stringValue = verbatim ? value.toString() : CharEscapers.escapeUriQuery(value.toString());
+    String stringValue =
+        verbatim ? value.toString() : CharEscapers.escapeUriQuery(value.toString());
     if (stringValue.length() != 0) {
       buf.append('=').append(stringValue);
     }

google-http-client/src/main/java/com/google/api/client/util/escape/CharEscapers.java

@@ -16,6 +16,8 @@
 
 import java.io.UnsupportedEncodingException;
 import java.net.URLDecoder;
+import java.nio.ByteBuffer;
+import java.nio.charset.StandardCharsets;
 
 /**
  * Utility functions for dealing with {@code CharEscaper}s, and some commonly used {@code
@@ -83,7 +85,29 @@ public static String escapeUri(String value) {
    */
   public static String decodeUri(String uri) {
     try {
-      return URLDecoder.decode(uri, "UTF-8");
+      return URLDecoder.decode(uri, StandardCharsets.UTF_8.name());
+    } catch (UnsupportedEncodingException e) {
+      // UTF-8 encoding guaranteed to be supported by JVM
+      throw new RuntimeException(e);
+    }
+  }
+
+  /**
+   * Decodes the path component of a URI. This must be done via a method that does not try to
+   * convert + into spaces(the behavior of {@link java.net.URLDecoder#decode(String, String)}). This
+   * method transforms URI encoded values into their decoded symbols.
+   *
+   * <p>i.e: {@code decodePath("%3Co%3E")} would return {@code "<o>"}
+   *
+   * @param path the value to be decoded
+   * @return decoded version of {@code path}
+   */
+  public static String decodeUriPath(String path) {
+    if (path == null) {
+      return null;
+    }
+    try {
+      return URLDecoder.decode(path.replace("+", "%2B"), StandardCharsets.UTF_8.name());
     } catch (UnsupportedEncodingException e) {
       // UTF-8 encoding guaranteed to be supported by JVM
       throw new RuntimeException(e);

google-http-client/src/main/java/com/google/api/client/util/escape/PercentEscaper.java

@@ -62,7 +62,7 @@ public class PercentEscaper extends UnicodeEscaper {
    * specified in RFC 3986. Note that some of these characters do need to be escaped when used in
    * other parts of the URI.
    */
-  public static final String SAFEPATHCHARS_URLENCODER = "-_.!~*'()@:$&,;=";
+  public static final String SAFEPATHCHARS_URLENCODER = "-_.!~*'()@:$&,;=+";
 
   /**
    * Contains the save characters plus all reserved characters. This happens to be the safe path

google-http-client/src/test/java/com/google/api/client/http/GenericUrlTest.java

@@ -480,6 +480,8 @@ public void testToPathParts() {
     subtestToPathParts("/path/to/resource", "", "path", "to", "resource");
     subtestToPathParts("/path/to/resource/", "", "path", "to", "resource", "");
     subtestToPathParts("/Go%3D%23%2F%25%26%20?%3Co%3Egle/2nd", "", "Go=#/%& ?<o>gle", "2nd");
+    subtestToPathParts("/plus+test/resource", "", "plus+test", "resource");
+    subtestToPathParts("/plus%2Btest/resource", "", "plus+test", "resource");
   }
 
   private void subtestToPathParts(String encodedPath, String... expectedDecodedParts) {

google-http-client/src/test/java/com/google/api/client/util/escape/CharEscapersTest.java

@@ -0,0 +1,49 @@
+/*
+ * Copyright 2019 Google LLC
+ *
+ * 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 com.google.api.client.util.escape;
+
+import junit.framework.TestCase;
+
+public class CharEscapersTest extends TestCase {
+
+  public void testDecodeUriPath() {
+    subtestDecodeUriPath(null, null);
+    subtestDecodeUriPath("", "");
+    subtestDecodeUriPath("abc", "abc");
+    subtestDecodeUriPath("a+b%2Bc", "a+b+c");
+    subtestDecodeUriPath("Go%3D%23%2F%25%26%20?%3Co%3Egle", "Go=#/%& ?<o>gle");
+  }
+
+  private void subtestDecodeUriPath(String input, String expected) {
+    String actual = CharEscapers.decodeUriPath(input);
+    assertEquals(expected, actual);
+  }
+
+  public void testDecodeUri_IllegalArgumentException() {
+    subtestDecodeUri_IllegalArgumentException("abc%-1abc");
+    subtestDecodeUri_IllegalArgumentException("%JJ");
+    subtestDecodeUri_IllegalArgumentException("abc%0");
+  }
+
+  private void subtestDecodeUri_IllegalArgumentException(String input) {
+    boolean thrown = false;
+    try {
+      CharEscapers.decodeUriPath(input);
+    } catch (IllegalArgumentException e) {
+      thrown = true;
+    }
+    assertTrue(thrown);
+  }
+}