fix: preserve escaped characters in fork-curl gzip payloads

.changeset/warm-apples-invite.md

@@ -0,0 +1,5 @@
+---
+"posthog-php": patch
+---
+
+Preserve escaped characters in gzip-compressed fork-curl event payloads.

.github/workflows/php.yml

@@ -88,6 +88,7 @@ jobs:
         uses: shivammathur/setup-php@f3e473d116dcccaddc5834248c87452386958240 # v2.37.2
         with:
           php-version: ${{ matrix.php-version }}
+          extensions: zlib
           tools: composer, phpunit
 
       - name: Install Dependencies
@@ -111,7 +112,7 @@ jobs:
         uses: shivammathur/setup-php@f3e473d116dcccaddc5834248c87452386958240 # v2.37.2
         with:
           php-version: 8.4
-          extensions: xdebug
+          extensions: xdebug, zlib
           tools: composer, phpunit
 
       - name: Install Dependencies

CONTRIBUTING.md

@@ -4,7 +4,7 @@ Thanks for your interest in improving the PostHog PHP SDK.
 
 ## Development setup
 
-1. Install [PHP](https://www.php.net/manual/en/install.php) and [Composer](https://getcomposer.org/download/).
+1. Install [PHP](https://www.php.net/manual/en/install.php) and [Composer](https://getcomposer.org/download/). Enable PHP's `zlib` extension for the gzip regression tests. This is a development-only dependency, not an SDK runtime requirement.
 2. Install dependencies using the same command CI uses:
 
    ```bash

composer.json

@@ -22,7 +22,8 @@
 	},
 	"require-dev": {
 		"phpunit/phpunit": "^11.0",
-		"squizlabs/php_codesniffer": "^4.0"
+		"squizlabs/php_codesniffer": "^4.0",
+		"ext-zlib": "*"
 	},
 	"autoload": {
 		"psr-4": {

lib/Consumer/ForkCurl.php

@@ -70,7 +70,7 @@ public function flushBatch($messages)
         if ($this->compress_request) {
             // Compress request to file
             $tmpfname = tempnam("/tmp", "forkcurl_");
-            $cmd2 = "echo " . $payload . " | gzip > " . $tmpfname;
+            $cmd2 = "printf '%s' " . $payload . " | gzip > " . $tmpfname;
             exec($cmd2, $output, $exit);
 
             if (0 == $exit) {

test/ForkCurlCompressionTest.php

@@ -0,0 +1,51 @@
+<?php
+
+namespace PostHog\Test;
+
+use PHPUnit\Framework\Attributes\DataProvider;
+use PHPUnit\Framework\TestCase;
+use PostHog\Consumer\ForkCurl;
+
+class ForkCurlCompressionTest extends TestCase
+{
+    public static function compressionCases(): array
+    {
+        return ['plain JSON' => [false], 'gzip' => [true]];
+    }
+
+    #[DataProvider('compressionCases')]
+    public function testEscapedCharactersSurviveDelivery(bool $compressed): void
+    {
+        $server = new LocalHttpServer();
+        try {
+            $consumer = new ForkCurl('test-key', [
+                'host' => $server->address(),
+                'ssl' => false,
+                'debug' => true,
+                'compress_request' => $compressed,
+            ]);
+            $message = [
+                'event' => 'quoted "event" with an apostrophe\'',
+                'distinct_id' => 'test-user',
+                'properties' => [
+                    'controls' => "line one\nline two\tvalue\rreturn",
+                    'literal_backslashes' => '\\n \\t C:\\path\\file',
+                    'format_string' => '%s %b %n',
+                    'unicode' => 'café 🌍',
+                ],
+            ];
+
+            self::assertTrue($consumer->flushBatch([$message]));
+            $requests = $server->requests();
+            self::assertCount(1, $requests);
+            self::assertSame('POST /batch/ HTTP/1.1', $requests[0]['requestLine']);
+            self::assertSame($compressed ? 'gzip' : null, $requests[0]['headers']['content-encoding'] ?? null);
+            self::assertSame(
+                ['batch' => [$message], 'api_key' => 'test-key'],
+                json_decode($requests[0]['body'], true, 512, JSON_THROW_ON_ERROR)
+            );
+        } finally {
+            $server->stop();
+        }
+    }
+}

test/LocalHttpServer.php

@@ -0,0 +1,68 @@
+<?php
+
+namespace PostHog\Test;
+
+use RuntimeException;
+
+final class LocalHttpServer
+{
+    private $process;
+    private string $requestsFile;
+    private string $errorsFile;
+    private string $address;
+
+    public function __construct(array $responses = [])
+    {
+        $this->requestsFile = tempnam(sys_get_temp_dir(), 'posthog-requests-');
+        $this->errorsFile = tempnam(sys_get_temp_dir(), 'posthog-server-');
+        $this->process = proc_open(
+            [PHP_BINARY, __DIR__ . '/fixtures/http-server.php', $this->requestsFile, json_encode($responses)],
+            [0 => ['pipe', 'r'], 1 => ['pipe', 'w'], 2 => ['file', $this->errorsFile, 'a']],
+            $pipes
+        );
+        if (!is_resource($this->process)) {
+            $this->stop();
+            throw new RuntimeException('Could not start local HTTP server');
+        }
+        fclose($pipes[0]);
+        stream_set_timeout($pipes[1], 5);
+        $this->address = trim(fgets($pipes[1]) ?: '');
+        fclose($pipes[1]);
+        if ($this->address === '') {
+            $error = file_get_contents($this->errorsFile);
+            $this->stop();
+            throw new RuntimeException('Local HTTP server did not become ready: ' . $error);
+        }
+    }
+
+    public function address(): string
+    {
+        return $this->address;
+    }
+
+    public function requests(): array
+    {
+        return array_map(
+            static fn(string $line): array => json_decode($line, true, 512, JSON_THROW_ON_ERROR),
+            file($this->requestsFile, FILE_IGNORE_NEW_LINES | FILE_SKIP_EMPTY_LINES)
+        );
+    }
+
+    public function stop(): void
+    {
+        if (is_resource($this->process)) {
+            proc_terminate($this->process);
+            proc_close($this->process);
+        }
+        foreach ([$this->requestsFile, $this->errorsFile] as $file) {
+            if (is_file($file)) {
+                unlink($file);
+            }
+        }
+    }
+
+    public function __destruct()
+    {
+        $this->stop();
+    }
+}

test/fixtures/http-server.php

@@ -0,0 +1,57 @@
+<?php
+
+$server = stream_socket_server('tcp://127.0.0.1:0', $errno, $error);
+if ($server === false) {
+    throw new RuntimeException($error, $errno);
+}
+$responses = json_decode($argv[2], true, 512, JSON_THROW_ON_ERROR);
+echo stream_socket_get_name($server, false) . "\n";
+flush();
+
+while ($connection = stream_socket_accept($server, 30)) {
+    stream_set_timeout($connection, 5);
+    $requestLine = trim(fgets($connection));
+    $headers = [];
+    while (($line = fgets($connection)) !== false && trim($line) !== '') {
+        [$name, $value] = explode(':', $line, 2);
+        $headers[strtolower($name)] = trim($value);
+    }
+    if (strtolower($headers['expect'] ?? '') === '100-continue') {
+        fwrite($connection, "HTTP/1.1 100 Continue\r\n\r\n");
+    }
+    $length = (int) ($headers['content-length'] ?? 0);
+    $body = '';
+    while (strlen($body) < $length) {
+        $chunk = fread($connection, $length - strlen($body));
+        if ($chunk === false || $chunk === '') {
+            throw new RuntimeException('Incomplete request body');
+        }
+        $body .= $chunk;
+    }
+    if (($headers['content-encoding'] ?? '') === 'gzip') {
+        $body = gzdecode($body);
+    }
+    file_put_contents($argv[1], json_encode([
+        'requestLine' => $requestLine,
+        'headers' => $headers,
+        'body' => $body,
+    ], JSON_THROW_ON_ERROR) . "\n", FILE_APPEND);
+
+    $response = array_shift($responses) ?? [];
+    $status = $response['status'] ?? 200;
+    $body = $response['body'] ?? '{"status":1}';
+    $headers = '';
+    foreach ($response['headers'] ?? [] as $name => $value) {
+        $headers .= "$name: $value\r\n";
+    }
+    $wire = "HTTP/1.1 $status Response\r\n" . $headers
+        . 'Content-Length: ' . strlen($body) . "\r\nConnection: close\r\n\r\n" . $body;
+    while ($wire !== '') {
+        $written = fwrite($connection, $wire);
+        if ($written === false || $written === 0) {
+            break;
+        }
+        $wire = substr($wire, $written);
+    }
+    fclose($connection);
+}