GH-22617: avoid null byte truncation of persistent stream keys

Abstract unix domain socket addresses begin with a null byte, but the
persistent stream list is keyed by a NUL-terminated string. The key was
truncated at that null byte, so distinct abstract sockets collapsed onto
the same persistent resource in p(f)sockopen() and stream_socket_client().

Escape null bytes (and backslashes, to stay unambiguous) when building the
persistent hash key so the full address is preserved. The escaping helper
lives in ext/standard rather than the public streams header, since only
p(f)sockopen() and stream_socket_client() need it.

Fix #22617

Author: devnexen

ext/standard/file.h

@@ -44,6 +44,10 @@ PHPAPI void php_fstat(php_stream *stream, zval *return_value);
 PHPAPI void php_flock_common(php_stream *stream, zend_long operation, uint32_t operation_arg_num,
 	zval *wouldblock, zval *return_value);
 
+/* Escapes NUL and backslash bytes so a host containing them cannot truncate or
+ * collide the persistent stream hash key. */
+zend_string *php_stream_escape_persistent_key(const char *host, size_t hostlen);
+
 #define PHP_CSV_NO_ESCAPE EOF
 #define PHP_CSV_ESCAPE_ERROR -500
 

ext/standard/fsock.c

@@ -84,8 +84,9 @@ static void php_fsockopen_stream(INTERNAL_FUNCTION_PARAMETERS, int persistent)
 	}
 
 	if (persistent) {
-		php_fsockopen_format_host_port(&hashkey, "pfsockopen__", strlen("pfsockopen__"), host,
-				host_len, port);
+		zend_string *escaped = php_stream_escape_persistent_key(host, host_len);
+		spprintf(&hashkey, 0, "pfsockopen__%s:"  ZEND_LONG_FMT, ZSTR_VAL(escaped), port);
+		zend_string_release_ex(escaped, false);
 	}
 
 	if (port > 0) {

ext/standard/streamsfuncs.c

@@ -41,6 +41,27 @@ typedef unsigned __int64 php_timeout_ull;
 
 static php_stream_context *decode_context_param(zval *contextresource);
 
+zend_string *php_stream_escape_persistent_key(const char *host, size_t hostlen)
+{
+	zend_string *escaped = zend_string_safe_alloc(hostlen, 2, 0, 0);
+	char *ptr = ZSTR_VAL(escaped);
+	for (size_t i = 0; i < hostlen; i++) {
+		if (host[i] == '\0') {
+			*ptr++ = '\\';
+			*ptr++ = '0';
+		} else if (host[i] == '\\') {
+			*ptr++ = '\\';
+			*ptr++ = '\\';
+		} else {
+			*ptr++ = host[i];
+		}
+	}
+	*ptr = '\0';
+	ZSTR_LEN(escaped) = ptr - ZSTR_VAL(escaped);
+
+	return escaped;
+}
+
 /* Streams based network functions */
 
 #ifdef HAVE_SOCKETPAIR
@@ -130,7 +151,9 @@ PHP_FUNCTION(stream_socket_client)
 	context = php_stream_context_from_zval(zcontext, flags & PHP_FILE_NO_DEFAULT_CONTEXT);
 
 	if (flags & PHP_STREAM_CLIENT_PERSISTENT) {
-		spprintf(&hashkey, 0, "stream_socket_client__%s", ZSTR_VAL(host));
+		zend_string *escaped = php_stream_escape_persistent_key(ZSTR_VAL(host), ZSTR_LEN(host));
+		spprintf(&hashkey, 0, "stream_socket_client__%s", ZSTR_VAL(escaped));
+		zend_string_release_ex(escaped, false);
 	}
 
 	/* prepare the timeout value for use */

ext/standard/tests/streams/gh22617.phpt

@@ -0,0 +1,45 @@
+--TEST--
+GH-22617: Persistent abstract unix domain sockets resolved to wrong resource
+--CREDITS--
+Roysten
+--SKIPIF--
+<?php
+if (PHP_OS_FAMILY !== "Linux") die("skip abstract unix domain sockets are Linux-only");
+if (!function_exists("pfsockopen")) die("skip pfsockopen() not available");
+?>
+--FILE--
+<?php
+// Abstract sockets: the address is prefixed with a null byte.
+$name1 = "gh22617_" . getmypid() . "_1";
+$name2 = "gh22617_" . getmypid() . "_2";
+
+$server1 = stream_socket_server("unix://\0$name1", $errno, $errstr);
+$server2 = stream_socket_server("unix://\0$name2", $errno, $errstr);
+var_dump($server1 !== false, $server2 !== false);
+
+// Connect to the first abstract socket.
+$socket1 = pfsockopen("unix://\0$name1", 0, $errno1, $errstr1);
+var_dump($socket1 !== false);
+var_dump(get_resource_type($socket1));
+
+// Connect to the second abstract socket.
+$socket2 = pfsockopen("unix://\0$name2", 0, $errno2, $errstr2);
+var_dump($socket2 !== false);
+var_dump(get_resource_type($socket2));
+
+// The two distinct abstract sockets must resolve to distinct resources.
+var_dump((int) $socket1 !== (int) $socket2);
+
+fclose($socket1);
+fclose($socket2);
+fclose($server1);
+fclose($server2);
+?>
+--EXPECT--
+bool(true)
+bool(true)
+bool(true)
+string(17) "persistent stream"
+bool(true)
+string(17) "persistent stream"
+bool(true)