ext/sockets: UDP_SEGMENT support.

UDP segmentation offload is an optimisation attempt by sending multiple
large enough datagrams over UDP which reduces syscalls as by default,
they have to be broke down in small UDP packets, it is better if the
hardware supports it, other handed down to the software implementation.

close GH-18213

NEWS

@@ -208,6 +208,8 @@ PHP                                                                        NEWS
     (David Carlier)
   . Added IP_BINDANY for a socket to bind to any address. (David Carlier)
   . Added SO_BUSY_POOL to reduce packets poll latency. (David Carlier)
+  - Added UDP_SEGMENT support to optimise multiple large datagrams over UDP
+    if the kernel and hardware supports it. (David Carlier)
 
 - Sodium:
   . Fix overall theorical overflows on zend_string buffer allocations.

UPGRADING

@@ -440,6 +440,7 @@ PHP 8.5 UPGRADE NOTES
   . AF_PACKET (Linux only).
   . IP_BINDANY (FreeBSD/NetBSD/OpenBSD only).
   . SO_BUSY_POLL (Linux only).
+  . UDP_SEGMENT (Linux only).
 
 ========================================
 11. Changes to INI File Handling

ext/sockets/config.m4

@@ -5,7 +5,7 @@ PHP_ARG_ENABLE([sockets],
 
 if test "$PHP_SOCKETS" != "no"; then
   AC_CHECK_FUNCS([hstrerror if_nametoindex if_indextoname sockatmark])
-  AC_CHECK_HEADERS([sys/sockio.h linux/filter.h linux/if_packet.h linux/if_ether.h])
+  AC_CHECK_HEADERS([sys/sockio.h linux/filter.h linux/if_packet.h linux/if_ether.h linux/udp.h])
   AC_DEFINE([HAVE_SOCKETS], [1],
     [Define to 1 if the PHP extension 'sockets' is available.])
 

ext/sockets/sockets.c

@@ -70,6 +70,9 @@
 # if defined(HAVE_LINUX_IF_ETHER_H)
 #  include <linux/if_ether.h>
 # endif
+# if defined(HAVE_LINUX_UDP_H)
+#  include <linux/udp.h>
+# endif
 #endif
 
 #include <stddef.h>
@@ -2301,6 +2304,22 @@ PHP_FUNCTION(socket_set_option)
 		}
 #endif
 
+#if defined(UDP_SEGMENT)
+		case UDP_SEGMENT: {
+			ov = zval_get_long(arg4);
+
+			// UDP segmentation offload maximum size or 0 to disable it
+			if (ov < 0 || ov > USHRT_MAX) {
+				zend_argument_value_error(4, "must be of between 0 and %u", USHRT_MAX);
+				RETURN_FALSE;
+			}
+
+			optlen = sizeof(ov);
+			opt_ptr = &ov;
+			break;
+		}
+#endif
+
 		default:
 default_case:
 			ov = zval_get_long(arg4);

ext/sockets/sockets.stub.php

@@ -2022,6 +2022,14 @@ const ETH_P_LOOP = UNKNOWN;
 const ETH_P_ALL = UNKNOWN;
 #endif
 
+#ifdef UDP_SEGMENT
+/**
+ * @var int
+ * @cvalue UDP_SEGMENT
+ */
+const UDP_SEGMENT = UNKNOWN;
+#endif
+
 /**
  * @strict-properties
  * @not-serializable

ext/sockets/sockets_arginfo.h

@@ -1,5 +1,5 @@
 /* This is a generated file, edit the .stub.php file instead.
- * Stub hash: 42d486d2666d23569e70860e2b1ef203161792b3 */
+ * Stub hash: 0ff66adfea41b603b9d58f1f0a82a950f4034cc4 */
 
 ZEND_BEGIN_ARG_WITH_RETURN_TYPE_MASK_EX(arginfo_socket_select, 0, 4, MAY_BE_LONG|MAY_BE_FALSE)
 	ZEND_ARG_TYPE_INFO(1, read, IS_ARRAY, 1)
@@ -1108,6 +1108,9 @@ static void register_sockets_symbols(int module_number)
 #if defined(ETH_P_ALL)
 	REGISTER_LONG_CONSTANT("ETH_P_ALL", ETH_P_ALL, CONST_PERSISTENT);
 #endif
+#if defined(UDP_SEGMENT)
+	REGISTER_LONG_CONSTANT("UDP_SEGMENT", UDP_SEGMENT, CONST_PERSISTENT);
+#endif
 }
 
 static zend_class_entry *register_class_Socket(void)

ext/sockets/tests/socket_cmsg_udp_segment.phpt

@@ -0,0 +1,26 @@
+--TEST--
+UDP_SEGMENT setsockopt(), can't really test is as the kernel support might not be enabled.
+--EXTENSIONS--
+sockets
+--SKIPIF--
+<?php
+if (!defined('UDP_SEGMENT')) { die('skip UDP_SEGMENT is not defined'); }
+?>
+--FILE--
+<?php
+$src = socket_create(AF_UNIX, SOCK_DGRAM, 0);
+
+try {
+	socket_setopt($src, SOL_UDP, UDP_SEGMENT, -1);
+} catch (\ValueError $e) {
+	echo $e->getMessage(), PHP_EOL;
+}
+try {
+	socket_setopt($src, SOL_UDP, UDP_SEGMENT, 65536);
+} catch (\ValueError $e) {
+	echo $e->getMessage(), PHP_EOL;
+}
+?>
+--EXPECT--
+socket_setopt(): Argument #4 ($value) must be of between 0 and 65535
+socket_setopt(): Argument #4 ($value) must be of between 0 and 65535