fix: add exception when generated thrift string exceeds maximum allowed package siz

src/Jaeger/Thrift/AgentClient.php

@@ -15,6 +15,7 @@
 
 namespace Jaeger\Thrift;
 
+use Exception;
 use Thrift\Transport\TMemoryBuffer;
 use Thrift\Protocol\TCompactProtocol;
 use Thrift\Type\TMessageType;
@@ -26,6 +27,9 @@ class AgentClient
 
     public static $tptl = null;
 
+    /**
+     * @throws Exception
+     */
     public function buildThrift($batch)
     {
         $tran = new TMemoryBuffer();
@@ -42,6 +46,16 @@ public function buildThrift($batch)
         $batchLen = $tran->available();
         $batchThriftStr = $tran->read(Constants\UDP_PACKET_MAX_LENGTH);
 
+        if ($batchLen !== strlen($batchThriftStr)) {
+            throw new Exception(
+                sprintf(
+                    'thrift string was longer than maximum allowed length: %d > %d',
+                    $batchLen,
+                    strlen($batchThriftStr)
+                )
+            );
+        }
+
         return ['len' => $batchLen, 'thriftStr' => $batchThriftStr];
     }
 

tests/Thrift/AgentClientTest.php

@@ -0,0 +1,80 @@
+<?php
+
+namespace tests\Thrift;
+
+use Exception;
+use Jaeger\Thrift\AgentClient;
+use PHPUnit\Framework\TestCase;
+
+class AgentClientTest extends TestCase
+{
+    /**
+     * @param int $spanCount
+     * @dataProvider provideSpanCount
+     * @throws Exception
+     */
+    public function testBuildThriftSuccess($spanCount)
+    {
+        $batch = $this->createBatchWithSpans($spanCount);
+
+        $subject = new AgentClient();
+        $result = $subject->buildThrift($batch);
+        self::assertSame($result['len'], strlen($result['thriftStr']));
+    }
+
+    public function provideSpanCount()
+    {
+        return [
+            [1],
+            [10],
+            [100],
+            [999]
+        ];
+    }
+
+    public function testBuildThriftFailsTooLong()
+    {
+        $batch = $this->createBatchWithSpans(1000);
+
+        $this->expectException(Exception::class);
+        $this->expectExceptionMessageRegExp('/thrift string was longer than maximum allowed length/');
+
+        $subject = new AgentClient();
+        $subject->buildThrift($batch);
+    }
+
+    /**
+     * @param int $spanCount
+     * @return array
+     */
+    private function createBatchWithSpans($spanCount)
+    {
+        $batch = [
+            'thriftProcess' => [
+                'serverName' => 'some server name',
+                'tags' => [
+                    'peer.ipv4' => '0.0.0.0'
+                ]
+            ],
+            'thriftSpans' => []
+        ];
+
+        for ($i = 0; $i < $spanCount; $i++) {
+            $batch['thriftSpans'][] = [
+                'spanId' => '123456789',
+                'operationName' => 'operation name 123456789012',
+                'tags' => [
+                    'span.kind' => 'client'
+                ],
+                'traceIdLow' => '999012393582',
+                'traceIdHigh' => '12338923423',
+                'parentSpanId' => null,
+                'flags' => null,
+                'startTime' => time(),
+                'duration' => 5,
+                'references' => []
+            ];
+        }
+        return $batch;
+    }
+}