php: Fix that recursion limit is not enforced.

#25067

PiperOrigin-RevId: 856286406

Author: protobuf-github-bot

php/src/Google/Protobuf/Internal/CodedInputStream.php

@@ -337,7 +337,7 @@ public function incrementRecursionDepthAndPushLimit(
         $byte_limit, &$old_limit, &$recursion_budget)
     {
         $old_limit = $this->pushLimit($byte_limit);
-        $recursion_limit = --$this->recursion_limit;
+        $recursion_budget = --$this->recursion_budget;
     }
 
     public function decrementRecursionDepthAndPopLimit($byte_limit)

php/tests/EncodeDecodeTest.php

@@ -603,6 +603,31 @@ public function testDecodeNegativeInt32()
         $this->assertEquals(-1, $m->getOptionalInt32());
     }
 
+    private function makeRecursiveMessage($depth) {
+        $m = new TestMessage();
+        $m->setOptionalInt32(1);
+        if ($depth == 0) {
+            return $m;
+        }
+        $m->setRecursive($this->makeRecursiveMessage($depth - 1));
+        return $m;
+    }
+
+    public function testRecursiveMessage() {
+        $payload = $this->makeRecursiveMessage(99)->serializeToString();
+
+        $m = new TestMessage();
+        $m->mergeFromString($payload);
+    }
+
+    public function testOverlyRecursiveMessage() {
+        $this->expectException(Exception::class);
+        $payload = $this->makeRecursiveMessage(101)->serializeToString();
+
+        $m = new TestMessage();
+        $m->mergeFromString($payload);
+    }
+
     public function testRandomFieldOrder()
     {
         $m = new TestRandomFieldOrder();