DTRACE_UDP(4)          FreeBSD Kernel Interfaces Manual          DTRACE_UDP(4)

NAME
     dtrace_udp - a DTrace provider for tracing events related to the UDP
     protocol

SYNOPSIS
     udp:::receive(pktinfo_t *, csinfo_t *, ipinfo_t *, udpsinfo_t *,
         udpinfo_t *);

     udp:::send(pktinfo_t *, csinfo_t *, ipinfo_t *, udpsinfo_t *,
         udpinfo_t *);

DESCRIPTION
     The DTrace udp provider allows users to trace events in the udp(4)
     protocol implementation.  The udp:::send() probe fires whenever the
     kernel prepares to transmit a UDP packet, and the udp:::receive() probe
     fires whenever the kernel receives a UDP packet, unless the UDP 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 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 udpsinfo_t argument contains the state of the UDP connection
     associated with the packet.  Its fields are:

           uintptr_t udps_addr  Pointer to the struct inpcb containing the IP
                                state for the associated socket.

           uint16_t udps_lport  Local UDP port.

           uint16_t udps_rport  Remote UDP port.

           string udps_laddr    Local IPv4 or IPv6 address.

           string udps_raddr    Remote IPv4 or IPv6 address.

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

           uint16_t udp_sport      Source UDP port.

           uint16_t udp_dport      Destination UDP port.

           uint16_t udp_length     Length of the UDP header and payload, in
                                   bytes.

           uint16_t udp_checksum   A checksum of the UDP header and payload,
                                   or 0 if no checksum was calculated.

           struct udphdr *udp_hdr  A pointer to the raw UDP header.

FILES
     /usr/lib/dtrace/udp.d  DTrace type and translator definitions for the udp
                            provider.

EXAMPLES
     The following script counts transmitted packets by destination port.

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

     This script will print some details of each UDP 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", "BYTES");
                   last = timestamp;
           }

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

           udp:::receive
           {
                   this->elapsed = (timestamp - last) / 1000;
                   self->dest = strjoin(strjoin(args[2]->ip_saddr, ":"),
                        lltostr(args[4]->udp_sport));
                   printf(" %10d %30s:%-5d <- %-36s %6d\n", this->elapsed,
                       args[2]->ip_daddr, args[4]->udp_dport,
                       self->dest, args[4]->udp_length);
                   last = timestamp;
           }

COMPATIBILITY
     This provider is compatible with the udp provider in Solaris.

SEE ALSO
     dtrace(1), dtrace_ip(4), dtrace_sctp(4), dtrace_tcp(4),
     dtrace_udplite(4), udp(4), SDT(9)

HISTORY
     The udp provider first appeared in FreeBSD 10.0.

AUTHORS
     This manual page was written by Mark Johnston <markj@FreeBSD.org>.

FreeBSD 13.1-RELEASE-p6         August 1, 2018         FreeBSD 13.1-RELEASE-p6