xnu-517.12.7.tar.gz

[apple/xnu.git] / bsd / netinet / tcp_subr.c

diff --git a/bsd/netinet/tcp_subr.c b/bsd/netinet/tcp_subr.c
index 0ce5d476fb94221a4187ad495852da41c53e1672..cb7bda6538acd562dccfb2219e89779aa3036d9d 100644 (file)
--- a/bsd/netinet/tcp_subr.c
+++ b/bsd/netinet/tcp_subr.c
@@ -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@
  */
@@ -140,6 +137,18 @@ SYSCTL_INT(_net_inet_tcp, TCPCTL_V6MSSDFLT, v6mssdflt,
        "Default TCP Maximum Segment Size for IPv6");
 #endif
 
+/*
+ * Minimum MSS we accept and use. This prevents DoS attacks where
+ * we are forced to a ridiculous low MSS like 20 and send hundreds
+ * of packets instead of one. The effect scales with the available
+ * bandwidth and quickly saturates the CPU and network interface
+ * with packet generation and sending. Set to zero to disable MINMSS
+ * checking. This setting prevents us from sending too small packets.
+ */
+int    tcp_minmss = TCP_MINMSS;
+SYSCTL_INT(_net_inet_tcp, OID_AUTO, minmss, CTLFLAG_RW,
+    &tcp_minmss , 0, "Minmum TCP Maximum Segment Size");
+
 static int     tcp_do_rfc1323 = 1;
 SYSCTL_INT(_net_inet_tcp, TCPCTL_DO_RFC1323, rfc1323, CTLFLAG_RW, 
     &tcp_do_rfc1323 , 0, "Enable rfc1323 (high performance TCP) extensions");
@@ -275,6 +284,13 @@ tcp_init()
        tcbinfo.ipi_zone = zinit("tcpcb", sizeof(struct inp_tp), maxsockets,
                                 ZONE_INTERRUPT, 0);
 #endif
+
+       tcp_reass_maxseg = nmbclusters / 16;
+#ifndef __APPLE__
+       TUNABLE_INT_FETCH("net.inet.tcp.reass.maxsegments",
+           &tcp_reass_maxseg);
+#endif
+
 #if INET6
 #define TCP_MINPROTOHDR (sizeof(struct ip6_hdr) + sizeof(struct tcphdr))
 #else /* INET6 */
@@ -693,6 +709,9 @@ tcp_close(tp)
        register struct rtentry *rt;
        int dosavessthresh;
 
+       if ( inp->inp_ppcb == NULL) /* tcp_close was called previously, bail */
+               return;
+
 #ifndef __APPLE__
        /*
         * Make sure that all of our timers are stopped before we
@@ -712,6 +731,7 @@ tcp_close(tp)
                }
        }
 #endif
+       
 
        KERNEL_DEBUG(DBG_FNC_TCP_CLOSE | DBG_FUNC_START, tp,0,0,0,0);
        switch (tp->t_state) 
@@ -879,6 +899,7 @@ tcp_freeq(tp)
                LIST_REMOVE(q, tqe_q);
                m_freem(q->tqe_m);
                FREE(q, M_TSEGQ);
+               tcp_reass_qsize--;
                rv = 1;
        }
        return (rv);
@@ -909,6 +930,7 @@ tcp_drain()
                                        LIST_REMOVE(te, tqe_q);
                                        m_freem(te->tqe_m);
                                        FREE(te, M_TSEGQ);
+                                       tcp_reass_qsize--;
                                }
                        }
                }