X-Git-Url: https://git.saurik.com/apple/xnu.git/blobdiff_plain/de355530ae67247cbd0da700edb3a2a1dae884c2..5eebf7385fedb1517b66b53c28e5aa6bb0a2be50:/bsd/netinet/tcp.h

diff --git a/bsd/netinet/tcp.h b/bsd/netinet/tcp.h
index 39efb3d79..30479bd88 100644
--- a/bsd/netinet/tcp.h
+++ b/bsd/netinet/tcp.h
@@ -123,12 +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,
@@ -155,5 +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