.\" Copyright (c) 2015 Mark Johnston <markj@FreeBSD.org>
.\" Copyright (c) 2018 Michael Tuexen <tuexen@FreeBSD.org>
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.Dd August 1, 2018
.Dt DTRACE_UDPLITE 4
.Os
.Sh NAME
.Nm dtrace_udplite
.Nd a DTrace provider for tracing events related to the UDP-Lite protocol
.Sh SYNOPSIS
.Fn udplite:::receive "pktinfo_t *" "csinfo_t *" "ipinfo_t *" "udplitesinfo_t *" \
    "udpliteinfo_t *"
.Fn udplite:::send "pktinfo_t *" "csinfo_t *" "ipinfo_t *" "udplitesinfo_t *" \
    "udpliteinfo_t *"
.Sh DESCRIPTION
The DTrace
.Nm udplite
provider allows users to trace events in the
.Xr udplite 4
protocol implementation.
The
.Fn udplite:::send
probe fires whenever the kernel prepares to transmit a UDP-Lite packet, and the
.Fn udplite:::receive
probe fires whenever the kernel receives a UDP-Lite packet, unless
the UDP-Lite header is incomplete,
the destination port is 0,
the length field is invalid,
or the checksum is wrong.
The arguments to these probes can be used to obtain detailed information about
the IP and UDP-Lite headers of the corresponding packet.
.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 "uintptr_t pkt_addr" -offset indent
.It Vt uintptr_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
argument contains IP fields common to both IPv4 and IPv6 packets.
Its fields are:
.Bl -tag -width "uint32_t ip_plength" -offset indent
.It Vt uint8_t ip_ver
IP version of the packet, 4 for IPv4 packets and 6 for IPv6 packets.
.It Vt uint32_t ip_plength
IP payload size.
This does not include the size of the IP header or IPv6 option headers.
.It Vt string ip_saddr
IP source address.
.It Vt string ip_daddr
IP destination address.
.El
.Pp
The
.Vt udplitesinfo_t
argument contains the state of the UDP-Lite connection associated with the packet.
Its fields are:
.Bl -tag -width "uintptr_t udplites_addr" -offset indent
.It Vt uintptr_t udplites_addr
Pointer to the
.Vt struct inpcb
containing the IP state for the associated socket.
.It Vt uint16_t udplites_lport
Local UDP-Lite port.
.It Vt uint16_t udplites_rport
Remote UDP-Lite port.
.It Vt string udplites_laddr
Local IPv4 or IPv6 address.
.It Vt string udplites_raddr
Remote IPv4 or IPv6 address.
.El
.Pp
The
.Vt udpliteinfo_t
argument is the raw UDP-Lite header of the packet, with all fields in host order.
Its fields are:
.Bl -tag -width "struct udplitehdr *udplite_hdr" -offset indent
.It Vt uint16_t udplite_sport
Source UDP-Lite port.
.It Vt uint16_t udplite_dport
Destination UDP-Lite port.
.It Vt uint16_t udplite_coverage
Checksum coverage of the UDP-Lite header, in bytes, or 0 for full coverage.
.It Vt uint16_t udplite_checksum
A checksum of the UDP-Lite header and payload, or 0 if no checksum was calculated.
.It Vt struct udplitehdr *udplite_hdr
A pointer to the raw UDP-Lite header.
.El
.Sh FILES
.Bl -tag -width "/usr/lib/dtrace/udplite.d" -compact
.It Pa /usr/lib/dtrace/udplite.d
DTrace type and translator definitions for the
.Nm udplite
provider.
.El
.Sh EXAMPLES
The following script counts transmitted packets by destination port.
.Bd -literal -offset indent
udplite:::send
{
        @num[args[4]->udplite_dport] = count();
}
.Ed
.Pp
This script will print some details of each UDP-Lite packet as it is sent or received
by the kernel:
.Bd -literal -offset indent
#pragma D option quiet
#pragma D option switchrate=10Hz

dtrace:::BEGIN
{
        printf(" %10s %36s    %-36s %6s\\n", "DELTA(us)", "SOURCE",
            "DEST", "COV");
        last = timestamp;
}

udplite:::send
{
        this->elapsed = (timestamp - last) / 1000;
        self->dest = strjoin(strjoin(args[2]->ip_daddr, ":"),
             lltostr(args[4]->udplite_dport));
        printf(" %10d %30s:%-5d -> %-36s %6d\\n", this->elapsed,
            args[2]->ip_saddr, args[4]->udplite_sport,
            self->dest, args[4]->udplite_coverage);
        last = timestamp;
}

udplite:::receive
{
        this->elapsed = (timestamp - last) / 1000;
        self->dest = strjoin(strjoin(args[2]->ip_saddr, ":"),
             lltostr(args[4]->udplite_sport));
        printf(" %10d %30s:%-5d <- %-36s %6d\\n", this->elapsed,
            args[2]->ip_daddr, args[4]->udplite_dport,
            self->dest, args[4]->udplite_coverage);
        last = timestamp;
}
.Ed
.Sh SEE ALSO
.Xr dtrace 1 ,
.Xr dtrace_ip 4 ,
.Xr dtrace_sctp 4 ,
.Xr dtrace_tcp 4 ,
.Xr dtrace_udp 4 ,
.Xr udplite 4 ,
.Xr SDT 9
.Sh HISTORY
The
.Nm udplite
provider first appeared in
.Fx
12.0.
.Sh AUTHORS
This manual page was written by
.An Mark Johnston Aq Mt markj@FreeBSD.org
and
.An Michael Tuexen Aq Mt tuexen@FreeBSD.org .