xnu-517.9.5.tar.gz

[apple/xnu.git] / bsd / netinet / tcp.h

diff --git a/bsd/netinet/tcp.h b/bsd/netinet/tcp.h
index 85ea2021a27c9daa5705085cf121da8b0570e6e8..30479bd881b9eb45bf003b35a67147e1ce7bae83 100644 (file)
--- a/bsd/netinet/tcp.h
+++ b/bsd/netinet/tcp.h
@@ -3,22 +3,19 @@
  *
  * @APPLE_LICENSE_HEADER_START@
  * 
- * Copyright (c) 1999-2003 Apple Computer, Inc.  All Rights Reserved.
+ * The contents of this file constitute Original Code as defined in and
+ * are subject to the Apple Public Source License Version 1.1 (the
+ * "License").  You may not use this file except in compliance with the
+ * License.  Please obtain a copy of the License at
+ * http://www.apple.com/publicsource and read it before using this file.
  * 
- * This file contains Original Code and/or Modifications of Original Code
- * as defined in and that are subject to the Apple Public Source License
- * Version 2.0 (the 'License'). You may not use this file except in
- * compliance with the License. Please obtain a copy of the License at
- * http://www.opensource.apple.com/apsl/ and read it before using this
- * file.
- * 
- * The Original Code and all software distributed under the License are
- * distributed on an 'AS IS' basis, WITHOUT WARRANTY OF ANY KIND, EITHER
+ * This Original Code and all software distributed under the License are
+ * distributed on an "AS IS" basis, WITHOUT WARRANTY OF ANY KIND, EITHER
  * EXPRESS OR IMPLIED, AND APPLE HEREBY DISCLAIMS ALL SUCH WARRANTIES,
  * INCLUDING WITHOUT LIMITATION, ANY WARRANTIES OF MERCHANTABILITY,
- * FITNESS FOR A PARTICULAR PURPOSE, QUIET ENJOYMENT OR NON-INFRINGEMENT.
- * Please see the License for the specific language governing rights and
- * limitations under the License.
+ * FITNESS FOR A PARTICULAR PURPOSE OR NON-INFRINGEMENT.  Please see the
+ * License for the specific language governing rights and limitations
+ * under the License.
  * 
  * @APPLE_LICENSE_HEADER_END@
  */
@@ -126,12 +123,23 @@ struct tcphdr {
 
 /*
  * Default maximum segment size for TCP.
- * With an IP MSS of 576, this is 536,
+ * With an IP MTU of 576, this is 536,
  * but 512 is probably more convenient.
  * This should be defined as MIN(512, IP_MSS - sizeof (struct tcpiphdr)).
  */
 #define        TCP_MSS 512
 
+/*
+ * TCP_MINMSS is defined to be 216 which is fine for the smallest
+ * link MTU (256 bytes, SLIP interface) in the Internet.
+ * However it is very unlikely to come across such low MTU interfaces
+ * these days (anno dato 2004).
+ * Probably it can be set to 512 without ill effects. But we play safe.
+ * See tcp_subr.c tcp_minmss SYSCTL declaration for more comments.
+ * Setting this to "0" disables the minmss check.
+ */
+#define        TCP_MINMSS 216
+
 /*
  * Default maximum segment size for TCP6.
  * With an IP6 MSS of 1280, this is 1220,
@@ -158,5 +166,6 @@ struct tcphdr {
 #define        TCP_MAXSEG      0x02    /* set maximum segment size */
 #define TCP_NOPUSH     0x04    /* don't push last block of write */
 #define TCP_NOOPT      0x08    /* don't use TCP options */
+#define TCP_KEEPALIVE  0x10    /* idle time used when SO_KEEPALIVE is enabled */
 
 #endif