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.  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_tcp(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>.