xds: Encode the service authority in XdsNameResolver (#10207)

Encode the service authority before passing it into gRPC util in the xDS name resolver to handle xDS requests which might contain multiple slashes. Example: xds:///path/to/service:port.

As currently the underlying Java URI library does not break the encoded authority into host/port correctly simplify the check to just look for '@' as we are only interested in checking for user info to validate the authority for HTTP.

This change also leads to few changes in unit tests that relied on this check for invalid authorities which now will be considered valid.

Just like #9376, depending on Guava packages such as URLEscapers or PercentEscapers leads to internal failures(Ex: Unresolvable reference to com.google.common.escape.Escaper from io.grpc.internal.GrpcUtil). To avoid these issues create an in house version that is heavily inspired by grpc-go/grpc.

core/src/main/java/io/grpc/internal/GrpcUtil.java

@@ -55,9 +55,11 @@ import java.net.SocketAddress;
 import java.net.URI;
 import java.net.URISyntaxException;
 import java.nio.charset.Charset;
+import java.util.Arrays;
 import java.util.Collection;
 import java.util.Collections;
 import java.util.EnumSet;
+import java.util.HashSet;
 import java.util.List;
 import java.util.Locale;
 import java.util.Set;
@@ -526,8 +528,8 @@ public final class GrpcUtil {
    */
   public static String checkAuthority(String authority) {
     URI uri = authorityToUri(authority);
-    checkArgument(uri.getHost() != null, "No host in authority '%s'", authority);
-    checkArgument(uri.getUserInfo() == null,
+    // Verify that the user Info is not provided.
+    checkArgument(uri.getAuthority().indexOf('@') == -1,
         "Userinfo must not be present on authority: '%s'", authority);
     return authority;
   }
@@ -859,5 +861,92 @@ public final class GrpcUtil {
     return false;
   }
 
+  /**
+   * Percent encode the {@code authority} based on
+   * https://datatracker.ietf.org/doc/html/rfc3986#section-3.2.
+   *
+   * <p>When escaping a String, the following rules apply:
+   *
+   * <ul>
+   *   <li>The alphanumeric characters "a" through "z", "A" through "Z" and "0" through "9" remain
+   *       the same.
+   *   <li>The unreserved characters ".", "-", "~", and "_" remain the same.
+   *   <li>The general delimiters for authority, "[", "]", "@" and ":" remain the same.
+   *   <li>The subdelimiters "!", "$", "&amp;", "'", "(", ")", "*", "+", ",", ";", and "=" remain
+   *       the same.
+   *   <li>The space character " " is converted into %20.
+   *   <li>All other characters are converted into one or more bytes using UTF-8 encoding and each
+   *       byte is then represented by the 3-character string "%XY", where "XY" is the two-digit,
+   *       uppercase, hexadecimal representation of the byte value.
+   * </ul>
+   * 
+   * <p>This section does not use URLEscapers from Guava Net as its not Android-friendly thus core
+   *    can't depend on it.
+   */
+  public static class AuthorityEscaper {
+    // Escapers should output upper case hex digits.
+    private static final char[] UPPER_HEX_DIGITS = "0123456789ABCDEF".toCharArray();
+    private static final Set<Character> UNRESERVED_CHARACTERS = Collections
+        .unmodifiableSet(new HashSet<>(Arrays.asList('-', '_', '.', '~')));
+    private static final Set<Character> SUB_DELIMS = Collections
+        .unmodifiableSet(new HashSet<>(
+            Arrays.asList('!', '$', '&', '\'', '(', ')', '*', '+', ',', ';', '=')));
+    private static final Set<Character> AUTHORITY_DELIMS = Collections
+        .unmodifiableSet(new HashSet<>(Arrays.asList(':', '[', ']', '@')));
+
+    private static boolean shouldEscape(char c) {
+      // Only encode ASCII.
+      if (c > 127) {
+        return false;
+      }
+      // Letters don't need an escape.
+      if (((c >= 'a') && (c <= 'z')) || ((c >= 'A') && (c <= 'Z'))) {
+        return false;
+      }
+      // Numbers don't need to be escaped.
+      if ((c >= '0' && c <= '9'))  {
+        return false;
+      }
+      // Don't escape allowed characters.
+      if (UNRESERVED_CHARACTERS.contains(c)
+          || SUB_DELIMS.contains(c)
+          || AUTHORITY_DELIMS.contains(c)) {
+        return false;
+      }
+      return true;
+    }
+
+    public static String encodeAuthority(String authority) {
+      Preconditions.checkNotNull(authority, "authority");
+      int authorityLength = authority.length();
+      int hexCount = 0;
+      // Calculate how many characters actually need escaping.
+      for (int index = 0; index < authorityLength; index++) {
+        char c = authority.charAt(index);
+        if (shouldEscape(c)) {
+          hexCount++;
+        }
+      }
+      // If no char need escaping, just return the original string back.
+      if (hexCount == 0) {
+        return authority;
+      }
+
+      // Allocate enough space as encoded characters need 2 extra chars.
+      StringBuilder encoded_authority = new StringBuilder((2 * hexCount) + authorityLength);
+      for (int index = 0; index < authorityLength; index++) {
+        char c = authority.charAt(index);
+        if (shouldEscape(c)) {
+          encoded_authority.append('%');
+          encoded_authority.append(UPPER_HEX_DIGITS[c >>> 4]);
+          encoded_authority.append(UPPER_HEX_DIGITS[c & 0xF]);
+        } else {
+          encoded_authority.append(c);
+        }
+      }
+      return encoded_authority.toString();
+    }
+  }
+
   private GrpcUtil() {}
 }

core/src/test/java/io/grpc/internal/GrpcUtilTest.java

@@ -163,6 +163,42 @@ public class GrpcUtilTest {
     assertFalse(GrpcUtil.isGrpcContentType("application/bad"));
   }
 
+  @Test
+  public void urlAuthorityEscape_ipv6Address() {
+    assertEquals("[::1]", GrpcUtil.AuthorityEscaper.encodeAuthority("[::1]"));
+  }
+
+  @Test
+  public void urlAuthorityEscape_userInAuthority() {
+    assertEquals("user@host", GrpcUtil.AuthorityEscaper.encodeAuthority("user@host"));
+  }
+
+  @Test
+  public void urlAuthorityEscape_slashesAreEncoded() {
+    assertEquals(
+        "project%2F123%2Fnetwork%2Fabc%2Fservice",
+        GrpcUtil.AuthorityEscaper.encodeAuthority("project/123/network/abc/service"));
+  }
+
+  @Test
+  public void urlAuthorityEscape_allowedCharsAreNotEncoded() {
+    assertEquals(
+        "-._~!$&'()*+,;=@:[]", GrpcUtil.AuthorityEscaper.encodeAuthority("-._~!$&'()*+,;=@:[]"));
+  }
+
+  @Test
+  public void urlAuthorityEscape_allLettersAndNumbers() {
+    assertEquals(
+        "abcdefghijklmnopqrstuvwxyz0123456789",
+        GrpcUtil.AuthorityEscaper.encodeAuthority("abcdefghijklmnopqrstuvwxyz0123456789"));
+  }
+
+  @Test
+  public void urlAuthorityEscape_unicodeAreNotEncoded() {
+    assertEquals(
+        "ö®", GrpcUtil.AuthorityEscaper.encodeAuthority("ö®"));
+  }
+
   @Test
   public void checkAuthority_failsOnNull() {
     thrown.expect(NullPointerException.class);
@@ -199,13 +235,6 @@ public class GrpcUtilTest {
     GrpcUtil.checkAuthority("[ : : 1]");
   }
 
-  @Test
-  public void checkAuthority_failsOnInvalidHost() {
-    thrown.expect(IllegalArgumentException.class);
-    thrown.expectMessage("No host in authority");
-
-    GrpcUtil.checkAuthority("bad_host");
-  }
 
   @Test
   public void checkAuthority_userInfoNotAllowed() {

core/src/test/java/io/grpc/internal/ManagedChannelImplBuilderTest.java

@@ -368,7 +368,7 @@ public class ManagedChannelImplBuilderTest {
 
   @Test(expected = IllegalArgumentException.class)
   public void overrideAuthority_invalid() {
-    builder.overrideAuthority("not_allowed");
+    builder.overrideAuthority("user@not_allowed");
   }
 
   @Test

xds/src/main/java/io/grpc/xds/XdsNameResolver.java

@@ -147,7 +147,11 @@ final class XdsNameResolver extends NameResolver {
       XdsClientPoolFactory xdsClientPoolFactory, ThreadSafeRandom random,
       FilterRegistry filterRegistry, @Nullable Map<String, ?> bootstrapOverride) {
     this.targetAuthority = targetAuthority;
-    serviceAuthority = GrpcUtil.checkAuthority(checkNotNull(name, "name"));
+
+    // The name might have multiple slashes so encode it before verifying.
+    String authority = GrpcUtil.AuthorityEscaper.encodeAuthority(checkNotNull(name, "name"));
+    serviceAuthority = GrpcUtil.checkAuthority(authority);
+
     this.overrideAuthority = overrideAuthority;
     this.serviceConfigParser = checkNotNull(serviceConfigParser, "serviceConfigParser");
     this.syncContext = checkNotNull(syncContext, "syncContext");

xds/src/test/java/io/grpc/xds/XdsNameResolverProviderTest.java

@@ -110,14 +110,19 @@ public class XdsNameResolverProviderTest {
   }
 
   @Test
-  public void invalidName_hostnameContainsUnderscore() {
-    URI uri = URI.create("xds:///foo_bar.googleapis.com");
-    try {
-      provider.newNameResolver(uri, args);
-      fail("Expected IllegalArgumentException");
-    } catch (IllegalArgumentException e) {
-      // Expected
-    }
+  public void validName_urlExtractedAuthorityInvalidWithoutEncoding() {
+    XdsNameResolver resolver = 
+        provider.newNameResolver(URI.create("xds:///1234/path/foo.googleapis.com:8080"), args);
+    assertThat(resolver).isNotNull();
+    assertThat(resolver.getServiceAuthority()).isEqualTo("1234%2Fpath%2Ffoo.googleapis.com:8080");
+  }
+
+  @Test
+  public void validName_urlwithTargetAuthorityAndExtractedAuthorityInvalidWithoutEncoding() {
+    XdsNameResolver resolver = provider.newNameResolver(URI.create(
+        "xds://trafficdirector.google.com/1234/path/foo.googleapis.com:8080"), args);
+    assertThat(resolver).isNotNull();
+    assertThat(resolver.getServiceAuthority()).isEqualTo("1234%2Fpath%2Ffoo.googleapis.com:8080");
   }
 
   @Test