Page MenuHomeFreeBSD
Files F150998178

D506.id1157.diff
No OneTemporary
Actions

D506.id1157.diff
View Options

Index: sys/netinet/tcp_output.c
===================================================================
--- sys/netinet/tcp_output.c
+++ sys/netinet/tcp_output.c
@@ -675,6 +675,12 @@
send:
SOCKBUF_LOCK_ASSERT(&so->so_snd);
+ if (len > 0) {
+ if (len >= tp->t_maxseg)
+ tp->t_pmtud_flags |= PLPMTU_MAXSEGSNT;
+ else
+ tp->t_pmtud_flags &= ~PLPMTU_MAXSEGSNT;
+ }
/*
* Before ESTABLISHED, force sending of initial options
* unless TCP set not to do any options.
@@ -1219,8 +1225,12 @@
*
* NB: Don't set DF on small MTU/MSS to have a safe fallback.
*/
- if (V_path_mtu_discovery && tp->t_maxopd > V_tcp_minmss)
+ if (V_path_mtu_discovery && tp->t_maxopd > V_tcp_minmss) {
ip->ip_off |= htons(IP_DF);
+ tp->t_pmtud_flags |= PLPMTU_PMTUD;
+ } else {
+ tp->t_pmtud_flags &= ~PLPMTU_PMTUD;
+ }
if (tp->t_state == TCPS_SYN_SENT)
TCP_PROBE5(connect__request, NULL, tp, ip, tp, th);
Index: sys/netinet/tcp_timer.c
===================================================================
--- sys/netinet/tcp_timer.c
+++ sys/netinet/tcp_timer.c
@@ -66,6 +66,9 @@
#include <netinet/tcp_fsm.h>
#include <netinet/tcp_timer.h>
#include <netinet/tcp_var.h>
+#ifdef INET6
+#include <netinet6/tcp6_var.h>
+#endif
#include <netinet/tcpip.h>
#ifdef TCPDEBUG
#include <netinet/tcp_debug.h>
@@ -119,7 +122,20 @@
SYSCTL_INT(_net_inet_tcp, OID_AUTO, keepcnt, CTLFLAG_RW, &tcp_keepcnt, 0,
"Number of keepalive probes to send");
+int tcp_pmtud_black_hole_detect = 0 ;
+SYSCTL_INT(_net_inet_tcp, OID_AUTO, pmtud_blackhole_detection, CTLTYPE_INT|CTLFLAG_RW,
+ &tcp_pmtud_black_hole_detect, 0, "Path MTU Discovery Black Hole Detection");
+
+int tcp_pmtud_black_hole_mss = 1200 ;
+SYSCTL_INT(_net_inet_tcp, OID_AUTO, pmtud_blackhole_mss, CTLTYPE_INT|CTLFLAG_RW,
+ &tcp_pmtud_black_hole_mss, 0, "Path MTU Discovery Black Hole Detection lowered MSS");
+ /* max idle probes */
+
+int tcp_v6pmtud_black_hole_mss = 1200 ;
+SYSCTL_INT(_net_inet_tcp, OID_AUTO, v6pmtud_blackhole_mss, CTLTYPE_INT|CTLFLAG_RW,
+ &tcp_v6pmtud_black_hole_mss, 0, "Path MTU Discovery IPv6 Black Hole Detection lowered MSS");
/* max idle probes */
+
int tcp_maxpersistidle;
static int tcp_rexmit_drop_options = 0;
@@ -539,6 +555,9 @@
ostate = tp->t_state;
#endif
+#ifdef INET6
+ int isipv6 = (tp->t_inpcb->inp_vflag & INP_IPV4) == 0;
+#endif /* INET6 */
INP_INFO_RLOCK(&V_tcbinfo);
inp = tp->t_inpcb;
/*
@@ -633,6 +652,7 @@
tp->t_flags |= TF_PREVVALID;
} else
tp->t_flags &= ~TF_PREVVALID;
+
TCPSTAT_INC(tcps_rexmttimeo);
if (tp->t_state == TCPS_SYN_SENT)
rexmt = TCPTV_RTOBASE * tcp_syn_backoff[tp->t_rxtshift];
@@ -640,6 +660,69 @@
rexmt = TCP_REXMTVAL(tp) * tcp_backoff[tp->t_rxtshift];
TCPT_RANGESET(tp->t_rxtcur, rexmt,
tp->t_rttmin, TCPTV_REXMTMAX);
+
+ if (tcp_pmtud_black_hole_detect && (tp->t_state == TCPS_ESTABLISHED)) {
+ int optlen = 0;
+ if (((tp->t_pmtud_flags & (PLPMTU_PMTUD|PLPMTU_MAXSEGSNT)) ==
+ (PLPMTU_PMTUD|PLPMTU_MAXSEGSNT)) &&
+ (tp->t_rxtshift <= 2)) {
+ /*
+ * Enter Path MTU Black-hole Detection mechanism:
+ * - Disable Path MTU Discovery (IP "DF" bit).
+ * - Reduce MTU to lower value than what we
+ * negociated with peer.
+ */
+ /* Disable Path MTU Discovery for now */
+ tp->t_pmtud_flags &= ~PLPMTU_PMTUD;
+ /* Record that we may have found a black hole */
+ tp->t_pmtud_flags |= PLPMTU_BLACKHOLE;
+ optlen = tp->t_maxopd - tp->t_maxseg;
+ /* Keep track of previous MSS */
+ tp->t_pmtud_saved_maxopd = tp->t_maxopd;
+ /* Reduce the MSS to intermediary value */
+ if (tp->t_maxopd > tcp_pmtud_black_hole_mss) {
+ tp->t_maxopd = /* use the global sysctl tuneable blackhole MSS */
+#ifdef INET6
+ isipv6 ? tcp_v6pmtud_black_hole_mss :
+#endif /* INET6 */
+ tcp_pmtud_black_hole_mss;
+ } else {
+ tp->t_maxopd = /* use the default MSS */
+#ifdef INET6
+ isipv6 ? V_tcp_v6mssdflt :
+#endif /* INET6 */
+ tcp_mssdflt;
+ }
+ tp->t_maxseg = tp->t_maxopd - optlen;
+ /*
+ * Reset the slow-start flight size
+ * as it may depend on the new MSS
+ */
+ if (CC_ALGO(tp)->conn_init != NULL)
+ CC_ALGO(tp)->conn_init(tp->ccv);
+ }
+ /*
+ * If further retransmissions are still unsuccessful with a lowered MTU,
+ * maybe this isn't a Black Hole and we restore the previous MSS and
+ * blackhole detection flags.
+ */
+ else {
+ if ((tp->t_pmtud_flags & PLPMTU_BLACKHOLE) && (tp->t_rxtshift > 4)) {
+ tp->t_pmtud_flags |= PLPMTU_PMTUD;
+ tp->t_pmtud_flags &= ~PLPMTU_BLACKHOLE;
+ optlen = tp->t_maxopd - tp->t_maxseg;
+ tp->t_maxopd = tp->t_pmtud_saved_maxopd;
+ tp->t_maxseg = tp->t_maxopd - optlen;
+ /*
+ * Reset the slow-start flight size as it
+ * may depend on the new MSS
+ */
+ if (CC_ALGO(tp)->conn_init != NULL)
+ CC_ALGO(tp)->conn_init(tp->ccv);
+ }
+ }
+ }
+
/*
* Disable RFC1323 and SACK if we haven't got any response to
* our third SYN to work-around some broken terminal servers
Index: sys/netinet/tcp_var.h
===================================================================
--- sys/netinet/tcp_var.h
+++ sys/netinet/tcp_var.h
@@ -200,8 +200,10 @@
u_int t_keepcnt; /* number of keepalives before close */
u_int t_tsomax; /* tso burst length limit */
+ u_int t_pmtud_saved_maxopd; /* MSS saved before performing PMTU-D BlackHole detection */
+ u_int t_pmtud_flags; /* PLPMTU flags for handling changes to MSS */
- uint32_t t_ispare[8]; /* 5 UTO, 3 TBD */
+ uint32_t t_ispare[6]; /* 5 UTO, 1 TBD */
void *t_pspare2[4]; /* 1 TCP_SIGNATURE, 3 TBD */
uint64_t _pad[6]; /* 6 TBD (1-2 CC/RTT?) */
};
@@ -275,6 +277,13 @@
#endif /* TCP_SIGNATURE */
/*
+ * Flags for PLPMTU handling, t_pmtu_flags
+ */
+#define PLPMTU_BLACKHOLE 0x00000001 /* Path MTU Discovery Black Hole detection */
+#define PLPMTU_PMTUD 0x00000002 /* Perform Path MTU Discovery for this connection */
+#define PLPMTU_MAXSEGSNT 0x00000004 /* last segment sent was a full segment */
+
+/*
* Structure to hold TCP options that are only used during segment
* processing (in tcp_input), but not held in the tcpcb.
* It's basically used to reduce the number of parameters

File Metadata

Mime Type
text/plain
Expires
Mon, Apr 6, 9:22 AM (4 h, 45 m)
Storage Engine
blob
Storage Format
Raw Data
Storage Handle
30955276
Default Alt Text
D506.id1157.diff (6 KB)

Event Timeline