NAME

dtrace_udplite — a DTrace provider for tracing events related to the UDP-Lite protocol

SYNOPSIS

udplite:::receive(pktinfo_t *, csinfo_t *, ipinfo_t *, udplitesinfo_t *, udpliteinfo_t *);

udplite:::send(pktinfo_t *, csinfo_t *, ipinfo_t *, udplitesinfo_t *, udpliteinfo_t *);

DESCRIPTION

The DTrace udplite provider allows users to trace events in the udplite(4) protocol implementation. The udplite:::send() probe fires whenever the kernel prepares to transmit a UDP-Lite packet, and the 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.

ARGUMENTS

The pktinfo_t argument is currently unimplemented and is included for compatibility with other implementations of this provider. Its fields are:

uintptr_t pkt_addr: Always set to 0.

The csinfo_t argument is currently unimplemented and is included for compatibility with other implementations of this provider. Its fields are:

uintptr_t cs_addr: Always set to 0.
uint64_t cs_cid: A pointer to the struct inpcb for this packet, or NULL.
pid_t cs_pid: Always set to 0.

The ipinfo_t argument contains IP fields common to both IPv4 and IPv6 packets. Its fields are:

uint8_t ip_ver: IP version of the packet, 4 for IPv4 packets and 6 for IPv6 packets.
uint32_t ip_plength: IP payload size. This does not include the size of the IP header or IPv6 option headers.
string ip_saddr: IP source address.
string ip_daddr: IP destination address.

The udplitesinfo_t argument contains the state of the UDP-Lite connection associated with the packet. Its fields are:

uintptr_t udplites_addr: Pointer to the struct inpcb containing the IP state for the associated socket.
uint16_t udplites_lport: Local UDP-Lite port.
uint16_t udplites_rport: Remote UDP-Lite port.
string udplites_laddr: Local IPv4 or IPv6 address.
string udplites_raddr: Remote IPv4 or IPv6 address.

The udpliteinfo_t argument is the raw UDP-Lite header of the packet, with all fields in host order. Its fields are:

uint16_t udplite_sport: Source UDP-Lite port.
uint16_t udplite_dport: Destination UDP-Lite port.
uint16_t udplite_coverage: Checksum coverage of the UDP-Lite header, in bytes, or 0 for full coverage.
uint16_t udplite_checksum: A checksum of the UDP-Lite header and payload, or 0 if no checksum was calculated.
struct udplitehdr *udplite_hdr: A pointer to the raw UDP-Lite header.

FILES

/usr/lib/dtrace/udplite.d: DTrace type and translator definitions for the udplite provider.

EXAMPLES

The following script counts transmitted packets by destination port.

udplite:::send
{
        @num[args[4]->udplite_dport] = count();
}

This script will print some details of each UDP-Lite packet as it is sent or received by the kernel:

#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;
}

HISTORY

The udplite provider first appeared in FreeBSD 12.0.

AUTHORS

This manual page was written by Mark Johnston <markj@FreeBSD.org> and
Michael Tuexen <tuexen@FreeBSD.org>.