ext/sockets: adding Linux's TCP_SYNCNT constant.

Useful to control how many SYN packets the client will send to the
server before giving up establishing a connection if the server does
not respond (usually 5 or 6 by default).

Close GH-13816

NEWS

@@ -180,6 +180,8 @@ PHP                                                                        NEWS
 
 - Sockets:
   . Added multicast group support for ipv4 on FreeBSD. (jonathan@tangential.ca)
+  . Added the TCP_SYNCNT constant for Linux to set number of attempts to send
+    SYN packets from the client. (David Carlier)
 
 - SNMP:
   . Removed the deprecated inet_ntoa call support. (David Carlier)

UPGRADING

@@ -556,6 +556,7 @@ PHP 8.4 UPGRADE NOTES
   . SO_EXCLUSIVEADDRUSE (Windows only).
   . SOCK_CONN_DGRAM (NetBSD only).
   . SOCK_DCCP (NetBSD only).
+  . TCP_SYNCNT (Linux only).
 
 - Sodium:
   . SODIUM_CRYPTO_AEAD_AEGIS128L_KEYBYTES

ext/sockets/sockets.stub.php

@@ -544,6 +544,13 @@ const SKF_AD_MAX = UNKNOWN;
  */
 const TCP_CONGESTION = UNKNOWN;
 #endif
+#ifdef TCP_SYNCNT
+/**
+ * @var int
+ * @cvalue TCP_SYNCNT
+ */
+const TCP_SYNCNT = UNKNOWN;
+#endif
 #ifdef SO_ZEROCOPY
 /**
  * @var int

ext/sockets/sockets_arginfo.h

@@ -1,5 +1,5 @@
 /* This is a generated file, edit the .stub.php file instead.
- * Stub hash: a99144c7c83a3f06e54a01bc21c0d30c9a21be29 */
+ * Stub hash: c761db0839535812316a42200f68c7db22639d81 */
 
 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)
@@ -535,6 +535,9 @@ static void register_sockets_symbols(int module_number)
 #if defined(TCP_CONGESTION)
 	REGISTER_LONG_CONSTANT("TCP_CONGESTION", TCP_CONGESTION, CONST_PERSISTENT);
 #endif
+#if defined(TCP_SYNCNT)
+	REGISTER_LONG_CONSTANT("TCP_SYNCNT", TCP_SYNCNT, CONST_PERSISTENT);
+#endif
 #if defined(SO_ZEROCOPY)
 	REGISTER_LONG_CONSTANT("SO_ZEROCOPY", SO_ZEROCOPY, CONST_PERSISTENT);
 #endif