diff --git a/share/man/man4/dtrace_tcp.4 b/share/man/man4/dtrace_tcp.4 index 5372b1a858f0..205317819c56 100644 --- a/share/man/man4/dtrace_tcp.4 +++ b/share/man/man4/dtrace_tcp.4 @@ -1,398 +1,532 @@ .\" Copyright (c) 2015 Mark Johnston .\" All rights reserved. .\" .\" Redistribution and use in source and binary forms, with or without .\" modification, are permitted provided that the following conditions .\" are met: .\" 1. Redistributions of source code must retain the above copyright .\" notice, this list of conditions and the following disclaimer. .\" 2. Redistributions in binary form must reproduce the above copyright .\" notice, this list of conditions and the following disclaimer in the .\" documentation and/or other materials provided with the distribution. .\" .\" THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND .\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE .\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE .\" ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE .\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL .\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS .\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) .\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT .\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY .\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF .\" SUCH DAMAGE. .\" .\" $FreeBSD$ .\" -.Dd June 29, 2023 +.Dd July 1, 2023 .Dt DTRACE_TCP 4 .Os .Sh NAME .Nm dtrace_tcp .Nd a DTrace provider for tracing events related to the .Xr tcp 4 protocol .Sh SYNOPSIS .Fn tcp:::accept-established "pktinfo_t *" "csinfo_t *" "ipinfo_t *" \ "tcpsinfo_t *" "tcpinfo_t *" .Fn tcp:::accept-refused "pktinfo_t *" "csinfo_t *" "ipinfo_t *" \ "tcpsinfo_t *" "tcpinfo_t *" .Fn tcp:::connect-established "pktinfo_t *" "csinfo_t *" "ipinfo_t *" \ "tcpsinfo_t *" "tcpinfo_t *" .Fn tcp:::connect-refused "pktinfo_t *" "csinfo_t *" "ipinfo_t *" \ "tcpsinfo_t *" "tcpinfo_t *" .Fn tcp:::connect-request "pktinfo_t *" "csinfo_t *" "ipinfo_t *" \ "tcpsinfo_t *" "tcpinfo_t *" .Fn tcp:::receive "pktinfo_t *" "csinfo_t *" "ipinfo_t *" "tcpsinfo_t *" \ "tcpinfo_t *" .Fn tcp:::send "pktinfo_t *" "csinfo_t *" "ipinfo_t *" "tcpsinfo_t *" \ "tcpinfo_t *" .Fn tcp:::state-change "void *" "csinfo_t *" "void *" "tcpsinfo_t *" "void *" \ "tcplsinfo_t *" +.Fn tcp:::siftr "siftrinfo_t *" .Sh DESCRIPTION The DTrace .Nm tcp provider allows users to trace events in the .Xr tcp 4 protocol implementation. This provider is similar to the .Xr dtrace_ip 4 and .Xr dtrace_udp 4 providers, but additionally contains probes corresponding to protocol events at a level higher than packet reception and transmission. All .Nm tcp probes except for .Fn tcp:::state-change +and +.Fn tcp:::siftr have the same number and type of arguments. The last three arguments are used to describe a TCP segment: the .Vt ipinfo_t argument exposes the version-agnostic fields of the IP header, while the .Vt tcpinfo_t argument exposes the TCP header, and the .Vt tcpsinfo_t argument describes details of the corresponding TCP connection state, if any. Their fields are described in the ARGUMENTS section. .Pp The .Fn tcp:::accept-established probe fires when a remotely-initiated active TCP open succeeds. At this point the new connection is in the ESTABLISHED state, and the probe arguments expose the headers associated with the final ACK of the three-way handshake. The .Fn tcp:::accept-refused probe fires when a SYN arrives on a port without a listening socket. The probe arguments expose the headers associated with the RST to be transmitted to the remote host in response to the SYN segment. .Pp The .Fn tcp:::connect-established , .Fn tcp:::connect-refused , and .Fn tcp:::connect-request probes are similar to the .Ql accept probes, except that they correspond to locally-initiated TCP connections. The .Fn tcp:::connect-established probe fires when the SYN-ACK segment of a three-way handshake is received from the remote host and a final ACK is prepared for transmission. This occurs immediately after the local connection state transitions from SYN-SENT to ESTABLISHED. The probe arguments describe the headers associated with the received SYN-ACK segment. The .Fn tcp:::connect-refused probe fires when the local host receives a RST segment in response to a SYN segment, indicating that the remote host refused to open a connection. The probe arguments describe the IP and TCP headers associated with the received RST segment. The .Fn tcp:::connect-request probe fires as the kernel prepares to transmit the initial SYN segment of a three-way handshake. .Pp The .Fn tcp:::send and .Fn tcp:::receive probes fire when the host sends or receives a TCP packet, respectively. As with the .Xr dtrace_udp 4 provider, .Nm tcp probes fire only for packets sent by or to the local host; forwarded packets are handled in the IP layer and are only visible to the .Xr dtrace_ip 4 provider. .Pp The .Fn tcp:::state-change probe fires upon local TCP connection state transitions. Its first, third and fifth arguments are currently always .Dv NULL . Its last argument describes the from-state in the transition, and the to-state can be obtained from .Dv args[3]->tcps_state . +.Pp +The +.Fn tcp:::siftr +probe fires when a TCP segment is sent or received by the host. +For a detailed description see +.Xr siftr 4 . +The +.Vt siftrinfo_t +argument provides the information about the TCP connection. .Sh ARGUMENTS The .Vt pktinfo_t argument is currently unimplemented and is included for compatibility with other implementations of this provider. Its fields are: .Bl -tag -width "uinptr_t pkt_addr" -offset indent .It Vt uinptr_t pkt_addr Always set to 0. .El .Pp The .Vt csinfo_t argument is currently unimplemented and is included for compatibility with other implementations of this provider. Its fields are: .Bl -tag -width "uintptr_t cs_addr" -offset indent .It Vt uintptr_t cs_addr Always set to 0. .It Vt uint64_t cs_cid A pointer to the .Vt struct inpcb for this packet, or .Dv NULL . .It Vt pid_t cs_pid Always set to 0. .El .Pp The .Vt ipinfo_t type is a version-agnostic representation of fields from an IP header. Its fields are described in the .Xr dtrace_ip 4 manual page. .Pp The .Vt tcpsinfo_t type is used to provide a stable representation of TCP connection state. Some .Nm tcp probes, such as .Fn tcp:::accept-refused , fire in a context where there is no TCP connection; this argument is .Dv NULL in that case. Its fields are: .Bl -tag -width "uint16_t tcps_lport" -offset indent .It Vt uintptr_t tcps_addr The address of the corresponding TCP control block. This is currently a pointer to a .Vt struct tcpcb . .It Vt int tcps_local A boolean indicating whether the connection is local to the host. Currently unimplemented and always set to -1. .It Vt int tcps_active A boolean indicating whether the connection was initiated by the local host. Currently unimplemented and always set to -1. .It Vt uint16_t tcps_lport Local TCP port. .It Vt uint16_t tcps_rport Remote TCP port. .It Vt string tcps_laddr Local address. .It Vt string tcps_raddr Remote address. .It Vt int32_t tcps_state Current TCP state. The valid TCP state values are given by the constants prefixed with .Ql TCPS_ in .Pa /usr/lib/dtrace/tcp.d . .It Vt uint32_t tcps_iss Initial send sequence number. .It Vt uint32_t tcps_suna Initial sequence number of sent but unacknowledged data. .It Vt uint32_t tcps_snxt Next sequence number for send. .It Vt uint32_t tcps_rack Sequence number of received and acknowledged data. .It Vt uint32_t tcps_rnxt Next expected sequence number for receive. .It Vt u_long tcps_swnd TCP send window size. .It Vt int32_t tcps_snd_ws Window scaling factor for the TCP send window. .It Vt u_long tcps_rwnd TCP receive window size. .It Vt int32_t tcps_rcv_ws Window scaling factor for the TCP receive window. .It Vt u_long tcps_cwnd TCP congestion window size. .It Vt u_long tcps_cwnd_ssthresh Congestion window threshold at which slow start ends and congestion avoidance begins. .It Vt uint32_t tcps_sack_fack Last sequence number selectively acknowledged by the receiver. .It Vt uint32_t tcps_sack_snxt Next selectively acknowledge sequence number at which to begin retransmitting. .It Vt uint32_t tcps_rto Round-trip timeout, in milliseconds. .It Vt uint32_t tcps_mss Maximum segment size. .It Vt int tcps_retransmit A boolean indicating that the local sender is retransmitting data. .It Vt int tcps_srtt Smoothed round-trip time. .El .Pp The .Vt tcpinfo_t type exposes the fields in a TCP segment header in host order. Its fields are: .Bl -tag -width "struct tcphdr *tcp_hdr" -offset indent .It Vt uint16_t tcp_sport Source TCP port. .It Vt uint16_t tcp_dport Destination TCP port. .It Vt uint32_t tcp_seq Sequence number. .It Vt uint32_t tcp_ack Acknowledgement number. .It Vt uint8_t tcp_offset Data offset, in bytes. .It Vt uint8_t tcp_flags TCP flags. .It Vt uint16_t tcp_window TCP window size. .It Vt uint16_t tcp_checksum Checksum. .It Vt uint16_t tcp_urgent Urgent data pointer. .It Vt struct tcphdr *tcp_hdr A pointer to the raw TCP header. .El .Pp The .Vt tcplsinfo_t type is used by the .Fn tcp:::state-change probe to provide the from-state of a transition. Its fields are: .Bl -tag -width "int32_t tcps_state" -offset indent .It Vt int32_t tcps_state A TCP state. The valid TCP state values are given by the constants prefixed with .Ql TCPS_ in .Pa /usr/lib/dtrace/tcp.d . .El +.Pp +The +.Vt siftrinfo_t +type is used by the +.Fn tcp:::siftr +probe to provide the state of the TCP connection. +Its fields are: +.Bl -tag -width "u_int sent_inflight_bytes" -offset indent +.It Vt uint8_t direction +Direction of packet that triggered the log message. +Either +.Qq 0 +for in, or +.Qq 1 +for out. +.It Vt uint8_t ipver +The version of the IP protocol being used. +Either +.Qq 1 +for IPv4, or +.Qq 2 +for IPv6. +.It Vt uint32_t hash +Hash of the packet that triggered the log message. +.It Vt uint16_t tcp_localport +The TCP port that the local host is communicating via. +.It Vt uint16_t tcp_foreignport +The TCP port that the foreign host is communicating via. +.It Vt uint64_t snd_cwnd +The current congestion window (CWND) for the flow, in bytes. +.It Vt u_long snd_wnd +The current sending window for the flow, in bytes. +The post scaled value is reported, except during the initial handshake (first +few packets), during which time the unscaled value is reported. +.It Vt u_long rcv_wnd +The current receive window for the flow, in bytes. +The post scaled value is always reported. +.It Vt u_long snd_bwnd +The current bandwidth-controlled window for the flow, in bytes. +This field is currently unused and reported as zero. +.It Vt u_long snd_ssthresh +The slow start threshold (SSTHRESH) for the flow, in bytes. +.It Vt int conn_state +A TCP state. +The valid TCP state values are given by the constants prefixed with +.Ql TCPS_ +in +.Pa /usr/lib/dtrace/tcp.d . +.It Vt u_int max_seg_size +The maximum segment size for the flow, in bytes. +.It Vt int smoothed_rtt +The current smoothed RTT estimate for the flow, in units of TCP_RTT_SCALE * HZ, +where TCP_RTT_SCALE is a define found in +.Pa /usr/include/netinet/tcp_var.h , +and HZ is the kernel's tick timer. +Divide by TCP_RTT_SCALE * HZ to get the RTT in secs. +.It Vt u_char sack_enabled +SACK enabled indicator. 1 if SACK enabled, 0 otherwise. +.It Vt u_char snd_scale +The current window scaling factor for the sending window. +.It Vt u_char rcv_scale +The current window scaling factor for the receiving window. +.It Vt u_int flags +The current value of the t_flags for the flow. +.It Vt int rxt_length +The current retransmission timeout length for the flow, in units of HZ, where HZ +is the kernel's tick timer. +Divide by HZ to get the timeout length in seconds. +.It Vt u_int snd_buf_hiwater +The current size of the socket send buffer in bytes. +.It Vt u_int snd_buf_cc +The current number of bytes in the socket send buffer. +.It Vt u_int rcv_buf_hiwater +The current size of the socket receive buffer in bytes. +.It Vt u_int rcv_buf_cc +The current number of bytes in the socket receive buffer. +.It Vt u_int sent_inflight_bytes +The current number of unacknowledged bytes in-flight. +Bytes acknowledged via SACK are not excluded from this count. +.It Vt int t_segqlen +The current number of segments in the reassembly queue. +.It Vt u_int flowid +Flowid for the connection. +A caveat: Zero '0' either represents a valid flowid or a default value when +the flowid is not being set. +.It Vt u_int flowtype +Flow type for the connection. +Flowtype defines which protocol fields are hashed to produce the flowid. +A complete listing is available in +.Pa /usr/include/sys/mbuf.h +under +.Dv M_HASHTYPE_* . +.El .Sh FILES -.Bl -tag -width "/usr/lib/dtrace/tcp.d" -compact +.Bl -tag -width "/usr/lib/dtrace/siftr.d" -compact .It Pa /usr/lib/dtrace/tcp.d +DTrace type and translator definitions for all the probes of the +.Nm tcp +provider except the +.Nm siftr +probe. +.It Pa /usr/lib/dtrace/siftr.d DTrace type and translator definitions for the +.Nm siftr +probe of the .Nm tcp provider. .El .Sh EXAMPLES The following script logs TCP segments in real time: .Bd -literal -offset indent #pragma D option quiet #pragma D option switchrate=10hz dtrace:::BEGIN { printf(" %3s %15s:%-5s %15s:%-5s %6s %s\\n", "CPU", "LADDR", "LPORT", "RADDR", "RPORT", "BYTES", "FLAGS"); } tcp:::send { this->length = args[2]->ip_plength - args[4]->tcp_offset; printf(" %3d %16s:%-5d -> %16s:%-5d %6d (", cpu, args[2]->ip_saddr, args[4]->tcp_sport, args[2]->ip_daddr, args[4]->tcp_dport, this->length); printf("%s", args[4]->tcp_flags & TH_FIN ? "FIN|" : ""); printf("%s", args[4]->tcp_flags & TH_SYN ? "SYN|" : ""); printf("%s", args[4]->tcp_flags & TH_RST ? "RST|" : ""); printf("%s", args[4]->tcp_flags & TH_PUSH ? "PUSH|" : ""); printf("%s", args[4]->tcp_flags & TH_ACK ? "ACK|" : ""); printf("%s", args[4]->tcp_flags & TH_URG ? "URG|" : ""); printf("%s", args[4]->tcp_flags == 0 ? "null " : ""); printf("\\b)\\n"); } tcp:::receive { this->length = args[2]->ip_plength - args[4]->tcp_offset; printf(" %3d %16s:%-5d <- %16s:%-5d %6d (", cpu, args[2]->ip_daddr, args[4]->tcp_dport, args[2]->ip_saddr, args[4]->tcp_sport, this->length); printf("%s", args[4]->tcp_flags & TH_FIN ? "FIN|" : ""); printf("%s", args[4]->tcp_flags & TH_SYN ? "SYN|" : ""); printf("%s", args[4]->tcp_flags & TH_RST ? "RST|" : ""); printf("%s", args[4]->tcp_flags & TH_PUSH ? "PUSH|" : ""); printf("%s", args[4]->tcp_flags & TH_ACK ? "ACK|" : ""); printf("%s", args[4]->tcp_flags & TH_URG ? "URG|" : ""); printf("%s", args[4]->tcp_flags == 0 ? "null " : ""); printf("\\b)\\n"); } .Ed The following script logs TCP connection state changes as they occur: .Bd -literal -offset indent #pragma D option quiet #pragma D option switchrate=25hz int last[int]; dtrace:::BEGIN { printf(" %12s %-20s %-20s %s\\n", "DELTA(us)", "OLD", "NEW", "TIMESTAMP"); } tcp:::state-change { this->elapsed = (timestamp - last[args[1]->cs_cid]) / 1000; printf(" %12d %-20s -> %-20s %d\\n", this->elapsed, tcp_state_string[args[5]->tcps_state], tcp_state_string[args[3]->tcps_state], timestamp); last[args[1]->cs_cid] = timestamp; } tcp:::state-change /last[args[1]->cs_cid] == 0/ { printf(" %12s %-20s -> %-20s %d\\n", "-", tcp_state_string[args[5]->tcps_state], tcp_state_string[args[3]->tcps_state], timestamp); last[args[1]->cs_cid] = timestamp; } .Ed +The following script uses the siftr probe to show the current value of CWND +and SSTHRESH when a packet is sent or received: +.Bd -literal -offset indent +#pragma D option quiet +#pragma D option switchrate=10hz + +dtrace:::BEGIN +{ + printf(" %3s %5s %5s %10s %10s\\n", + "DIR", "LPORT", "RPORT", "CWND", "SSTHRESH"); +} + +tcp:::siftr +{ + printf(" %3s %5d %5d %10d %10d\\n", + siftr_dir_string[args[0]->direction], + args[0]->tcp_localport, args[0]->tcp_foreignport, + args[0]->snd_cwnd, args[0]->snd_ssthresh); +} +.Ed .Sh COMPATIBILITY This provider is compatible with the .Nm tcp provider in Solaris. .Sh SEE ALSO .Xr dtrace 1 , .Xr dtrace_ip 4 , .Xr dtrace_sctp 4 , .Xr dtrace_udp 4 , .Xr dtrace_udplite 4 , +.Xr siftr 4 , .Xr tcp 4 , .Xr SDT 9 .Sh HISTORY The .Nm tcp provider first appeared in .Fx 10.0. .Sh AUTHORS This manual page was written by .An Mark Johnston Aq Mt markj@FreeBSD.org . .Sh BUGS The .Vt tcps_local and .Vt tcps_active fields of .Vt tcpsinfo_t are not filled in by the translator.