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DTRACE_UDP(4) Device Drivers 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. 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>.
April 18, 2015 Linux 4.9.0-9-amd64