atlas: support unicode escapes in expressions (Netflix#1153)

Update query parsing to support unicode escapes for special
characters like comma.

spectator-reg-atlas/src/main/java/com/netflix/spectator/atlas/impl/Parser.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2014-2019 Netflix, Inc.
+ * Copyright 2014-2024 Netflix, Inc.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -70,7 +70,7 @@ private static Object parse(String expr) {
     String[] parts = expr.split(",");
     Deque<Object> stack = new ArrayDeque<>(parts.length);
     for (String p : parts) {
-      String token = p.trim();
+      String token = unescape(p.trim());
       if (token.isEmpty()) {
         continue;
       }
@@ -238,4 +238,76 @@ private static void pushIn(Deque<Object> stack, String k, List<String> values) {
     else
       stack.push(new Query.In(k, new HashSet<>(values)));
   }
+
+  static boolean isSpecial(int codePoint) {
+    return codePoint == ',' || Character.isWhitespace(codePoint);
+  }
+
+  static void zeroPad(String str, StringBuilder builder) {
+    final int width = 4;
+    final int n = width - str.length();
+    for (int i = 0; i < n; ++i) {
+      builder.append('0');
+    }
+    builder.append(str);
+  }
+
+  private static void escapeCodePoint(int codePoint, StringBuilder builder) {
+    builder.append("\\u");
+    zeroPad(Integer.toHexString(codePoint), builder);
+  }
+
+  /**
+   * Escape special characters in the input string to unicode escape sequences (uXXXX).
+   */
+  @SuppressWarnings("PMD")
+  public static String escape(String str) {
+    final int length = str.length();
+    StringBuilder builder = new StringBuilder(length);
+    for (int i = 0; i < length;) {
+      final int cp = str.codePointAt(i);
+      final int len = Character.charCount(cp);
+      if (isSpecial(cp))
+        escapeCodePoint(cp, builder);
+      else
+        builder.appendCodePoint(cp);
+      i += len;
+    }
+    return builder.toString();
+  }
+
+  /**
+   * Unescape unicode characters in the input string. Ignore any invalid or unrecognized
+   * escape sequences.
+   */
+  @SuppressWarnings("PMD")
+  public static String unescape(String str) {
+    final int length = str.length();
+    StringBuilder builder = new StringBuilder(length);
+    for (int i = 0; i < length; ++i) {
+      final char c = str.charAt(i);
+      if (c == '\\') {
+        // Ensure there is enough space for an encoded character, there must be at
+        // least 5 characters left in the string (uXXXX).
+        if (length - i <= 5) {
+          builder.append(str.substring(i));
+          i = length;
+        } else if (str.charAt(i + 1) == 'u') {
+          try {
+            int cp = Integer.parseInt(str.substring(i + 2, i + 6), 16);
+            builder.appendCodePoint(cp);
+            i += 5;
+          } catch (NumberFormatException e) {
+            builder.append(c);
+          }
+        } else {
+          // Some other escape, copy into buffer and move on
+          builder.append(c);
+        }
+      } else {
+        builder.append(c);
+      }
+    }
+    return builder.toString();
+  }
 }

spectator-reg-atlas/src/main/java/com/netflix/spectator/atlas/impl/Query.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2014-2023 Netflix, Inc.
+ * Copyright 2014-2024 Netflix, Inc.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -27,6 +27,7 @@
 import java.util.Map;
 import java.util.Objects;
 import java.util.Set;
+import java.util.StringJoiner;
 
 /**
  * Query for matching based on tags. For more information see
@@ -497,7 +498,7 @@ final class Has implements KeyQuery {
     }
 
     @Override public String toString() {
-      return k + ",:has";
+      return Parser.escape(k) + ",:has";
     }
 
     @Override public boolean equals(Object obj) {
@@ -542,7 +543,7 @@ public String value() {
     }
 
     @Override public String toString() {
-      return k + "," + v + ",:eq";
+      return Parser.escape(k) + "," + Parser.escape(v) + ",:eq";
     }
 
     @Override public boolean equals(Object obj) {
@@ -609,8 +610,11 @@ public Set<String> values() {
     }
 
     @Override public String toString() {
-      String values = String.join(",", vs);
-      return k + ",(," + values + ",),:in";
+      StringJoiner joiner = new StringJoiner(",");
+      for (String v : vs) {
+        joiner.add(Parser.escape(v));
+      }
+      return Parser.escape(k) + ",(," + joiner + ",),:in";
     }
 
     @Override public boolean equals(Object obj) {
@@ -654,7 +658,7 @@ final class LessThan implements KeyQuery {
     }
 
     @Override public String toString() {
-      return k + "," + v + ",:lt";
+      return Parser.escape(k) + "," + Parser.escape(v) + ",:lt";
     }
 
     @Override public boolean equals(Object obj) {
@@ -694,7 +698,7 @@ final class LessThanEqual implements KeyQuery {
     }
 
     @Override public String toString() {
-      return k + "," + v + ",:le";
+      return Parser.escape(k) + "," + Parser.escape(v) + ",:le";
     }
 
     @Override public boolean equals(Object obj) {
@@ -734,7 +738,7 @@ final class GreaterThan implements KeyQuery {
     }
 
     @Override public String toString() {
-      return k + "," + v + ",:gt";
+      return Parser.escape(k) + "," + Parser.escape(v) + ",:gt";
     }
 
     @Override public boolean equals(Object obj) {
@@ -774,7 +778,7 @@ final class GreaterThanEqual implements KeyQuery {
     }
 
     @Override public String toString() {
-      return k + "," + v + ",:ge";
+      return Parser.escape(k) + "," + Parser.escape(v) + ",:ge";
     }
 
     @Override public boolean equals(Object obj) {
@@ -841,7 +845,7 @@ public boolean alwaysMatches() {
     }
 
     @Override public String toString() {
-      return k + "," + v + "," + name;
+      return Parser.escape(k) + "," + Parser.escape(v) + "," + name;
     }
 
     @Override public boolean equals(Object obj) {

spectator-reg-atlas/src/test/java/com/netflix/spectator/atlas/impl/ParserTest.java

@@ -0,0 +1,64 @@
+/*
+ * Copyright 2014-2024 Netflix, Inc.
+ *
+ * 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.netflix.spectator.atlas.impl;
+
+import org.junit.jupiter.api.Assertions;
+import org.junit.jupiter.api.Test;
+
+public class ParserTest {
+
+  private static String zeroPad(int i) {
+    StringBuilder builder = new StringBuilder();
+    Parser.zeroPad(Integer.toHexString(i), builder);
+    return builder.toString();
+  }
+
+  @Test
+  public void escape() {
+    for (char i = 0; i < Short.MAX_VALUE; ++i) {
+      String str = Character.toString(i);
+      String expected = Parser.isSpecial(i) ? "\\u" + zeroPad(i) : str;
+      Assertions.assertEquals(expected, Parser.escape(str));
+    }
+  }
+
+  @Test
+  public void unescape() {
+    for (char i = 0; i < Short.MAX_VALUE; ++i) {
+      String str = Character.toString(i);
+      String escaped = "\\u" + zeroPad(i);
+      Assertions.assertEquals(str, Parser.unescape(escaped));
+    }
+  }
+
+  @Test
+  public void unescapeTooShort() {
+    String str = "foo\\u000";
+    Assertions.assertEquals(str, Parser.unescape(str));
+  }
+
+  @Test
+  public void unescapeUnknownType() {
+    String str = "foo\\x0000";
+    Assertions.assertEquals(str, Parser.unescape(str));
+  }
+
+  @Test
+  public void unescapeInvalid() {
+    String str = "foo\\uzyff";
+    Assertions.assertEquals(str, Parser.unescape(str));
+  }
+}

spectator-reg-atlas/src/test/java/com/netflix/spectator/atlas/impl/QueryTest.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2014-2021 Netflix, Inc.
+ * Copyright 2014-2024 Netflix, Inc.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -625,4 +625,117 @@ public void simplifyFalse() {
     Query q = Parser.parseQuery(":false");
     Assertions.assertSame(q, q.simplify(tags("nf.cluster", "foo")));
   }
+
+  @Test
+  public void keysAndValuesWithSpecialChars() {
+    String[] ops = {"eq", "lt", "le", "gt", "ge"};
+    for (String op : ops) {
+      String k = "foo\\u002cbar";
+      String v = "a\\u002cb\\u002cc";
+      String expr = k + "," + v + ",:" + op;
+      Query q = Parser.parseQuery(expr);
+      Assertions.assertEquals(expr, q.toString());
+
+      Query.KeyQuery kq = (Query.KeyQuery) q;
+      Assertions.assertEquals("foo,bar", kq.key());
+      if ("lt".equals(op)) {
+        Assertions.assertTrue(kq.matches("a,b,b"));
+      } else if ("gt".equals(op)) {
+        Assertions.assertTrue(kq.matches("a,b,d"));
+      } else {
+        Assertions.assertTrue(kq.matches("a,b,c"));
+      }
+    }
+  }
+
+  @Test
+  public void inClauseWithSpecialChars() {
+    String k = "foo\\u002cbar";
+    String vs = "(,a\\u002cb\\u002cc,d,)";
+    String expr = k + "," + vs + ",:in";
+    Query q = Parser.parseQuery(expr);
+    Assertions.assertEquals(expr, q.toString());
+
+    Query.In in = (Query.In) q;
+    Assertions.assertEquals("foo,bar", in.key());
+    Assertions.assertTrue(in.matches("a,b,c"));
+    Assertions.assertTrue(in.matches("d"));
+  }
+
+  @Test
+  public void hasWithSpecialChars() {
+    String k = "foo\\u002cbar";
+    String expr = k + ",:has";
+    Query q = Parser.parseQuery(expr);
+    Assertions.assertEquals(expr, q.toString());
+
+    Query.Has has = (Query.Has) q;
+    Assertions.assertEquals("foo,bar", has.key());
+  }
+
+  @Test
+  public void reWithSpecialChars() {
+    String k = "foo\\u002cbar";
+    String v = "a\\u002cb\\u002cc";
+    String expr = k + "," + v + ",:re";
+    Query q = Parser.parseQuery(expr);
+    Assertions.assertEquals(expr, q.toString());
+
+    Query.Regex re = (Query.Regex) q;
+    Assertions.assertEquals("foo,bar", re.key());
+    Assertions.assertTrue(re.matches("a,b,c"));
+  }
+
+  @Test
+  public void reicWithSpecialChars() {
+    String k = "foo\\u002cbar";
+    String v = "a\\u002cb\\u002cc";
+    String expr = k + "," + v + ",:reic";
+    Query q = Parser.parseQuery(expr);
+    Assertions.assertEquals(expr, q.toString());
+
+    Query.Regex re = (Query.Regex) q;
+    Assertions.assertEquals("foo,bar", re.key());
+    Assertions.assertTrue(re.matches("a,b,c"));
+    Assertions.assertTrue(re.matches("a,B,c"));
+  }
+
+  @Test
+  public void startsWithSpecialChars() {
+    String k = "foo\\u002cbar";
+    String v = "a\\u002cb\\u002cc";
+    String expr = k + "," + v + ",:starts";
+    Query q = Parser.parseQuery(expr);
+    Assertions.assertEquals(k + "," + v + ",:re", q.toString());
+
+    Query.Regex re = (Query.Regex) q;
+    Assertions.assertEquals("foo,bar", re.key());
+    Assertions.assertTrue(re.matches("a,b,c"));
+  }
+
+  @Test
+  public void endsWithSpecialChars() {
+    String k = "foo\\u002cbar";
+    String v = "a\\u002cb\\u002cc";
+    String expr = k + "," + v + ",:ends";
+    Query q = Parser.parseQuery(expr);
+    Assertions.assertEquals(k + ",.*" + v + "$,:re", q.toString());
+
+    Query.Regex re = (Query.Regex) q;
+    Assertions.assertEquals("foo,bar", re.key());
+    Assertions.assertTrue(re.matches("a,b,c"));
+  }
+
+  @Test
+  public void containsWithSpecialChars() {
+    String k = "foo\\u002cbar";
+    String v = "a\\u002cb\\u002cc";
+    String expr = k + "," + v + ",:contains";
+    Query q = Parser.parseQuery(expr);
+    Assertions.assertEquals(k + ",.*" + v + ",:re", q.toString());
+
+    Query.Regex re = (Query.Regex) q;
+    Assertions.assertEquals("foo,bar", re.key());
+    Assertions.assertTrue(re.matches("a,b,c"));
+  }
 }