Network.Pcap

pcap-0.3: A system-independent interface for user-level packet capture

Network.Pcap

Portability	non-portable
Stability	experimental
Maintainer	bos@serpentine.com

Contents

Types
Device opening
Filter handling
Device utilities
Interface control
Link layer utilities
Packet processing
Sending packets
Conversion
Miscellaneous

Description

The Pcap module is a high(ish) level binding to all of the functions in libpcap. See http://www.tcpdump.org for more information.

This module is built on the lower-level Base module, which is slightly more efficient. Don't use Base unless profiling data indicates that you need to.

Only a minimum of marshaling is done on received packets. To convert captured packet data to a ByteString (space efficient, and with O(1) access to every byte in a captured packet), use toBS.

Note that the SockAddr exported here is not the SockAddr from Socket. The SockAddr from Socket corresponds to struct sockaddr_in in BSD terminology. The SockAddr record here is BSD's struct sockaddr. See W.R.Stevens, TCP Illustrated, volume 2, for further elucidation.

This binding should be portable across systems that can use the libpcap from tcpdump.org. It does not yet work with Winpcap, a similar library for Windows, although adapting it should not prove difficult.

Synopsis

data PcapHandle

data DumpHandle

type BpfProgram = ForeignPtr BpfProgramTag

type Callback = PktHdr -> Ptr Word8 -> IO ()

data Direction

= InOut

| In

| Out

data Link

| DLT_PPP

| DLT_RAW

| DLT_REDBACK_SMARTEDGE

| DLT_PPP_SERIAL

| DLT_PPP_ETHER

| DLT_SYMANTEC_FIREWALL

| DLT_ENC

| DLT_IEEE802_11_RADIO

| DLT_ARCNET_LINUX

| DLT_APPLE_IP_OVER_IEEE1394

| DLT_USB

| DLT_BLUETOOTH_HCI_H4

| DLT_MFR

| DLT_IEEE802_16_MAC_CPS

| DLT_USB_LINUX

| DLT_CAN20B

| DLT_IEEE802_15_4_LINUX

| DLT_PPI

| DLT_IEEE802_16_MAC_CPS_RADIO

| DLT_IEEE802_15_4

data Interface = Interface {

ifName :: String

ifDescription :: String

ifAddresses :: [PcapAddr]

ifFlags :: Word32

}

data PcapAddr = PcapAddr {

addrSA :: SockAddr

addrMask :: (Maybe SockAddr)

addrBcast :: (Maybe SockAddr)

addrPeer :: (Maybe SockAddr)

}

data SockAddr = SockAddr {

saFamily :: !Family

saAddr :: !ByteString

}

data Network = Network {

netAddr :: !Word32

netMask :: !Word32

}

data PktHdr = PktHdr {

hdrSeconds :: !Word32

hdrUseconds :: !Word32

hdrCaptureLength :: !Word32

hdrWireLength :: !Word32

}

data Statistics = Statistics {

statReceived :: !Word32

statDropped :: !Word32

statIfaceDropped :: !Word32

}

openOffline :: FilePath -> IO PcapHandle

openLive :: String -> Int -> Bool -> Int64 -> IO PcapHandle

openDead :: Link -> Int -> IO PcapHandle

openDump :: PcapHandle -> FilePath -> IO DumpHandle

setFilter :: PcapHandle -> String -> Bool -> Word32 -> IO ()

compileFilter :: Int -> Link -> String -> Bool -> Word32 -> IO BpfProgram

lookupDev :: IO String

findAllDevs :: IO [Interface]

lookupNet :: String -> IO Network

setNonBlock :: PcapHandle -> Bool -> IO ()

getNonBlock :: PcapHandle -> IO Bool

setDirection :: PcapHandle -> Direction -> IO ()

datalink :: PcapHandle -> IO Link

setDatalink :: PcapHandle -> Link -> IO ()

listDatalinks :: PcapHandle -> IO [Link]

dispatch :: PcapHandle -> Int -> Callback -> IO Int

loop :: PcapHandle -> Int -> Callback -> IO Int

next :: PcapHandle -> IO (PktHdr, Ptr Word8)

dump :: DumpHandle -> Ptr PktHdr -> Ptr Word8 -> IO ()

sendPacket :: PcapHandle -> Ptr Word8 -> Int -> IO ()

sendPacketBS :: PcapHandle -> ByteString -> IO ()

toBS :: (PktHdr, Ptr Word8) -> IO (PktHdr, ByteString)

hdrTime :: PktHdr -> Int64

hdrDiffTime :: PktHdr -> DiffTime

statistics :: PcapHandle -> IO Statistics

version :: PcapHandle -> IO (Int, Int)

isSwapped :: PcapHandle -> IO Bool

snapshotLen :: PcapHandle -> IO Int

Types

data PcapHandle

packet capture handle

data DumpHandle

dump file handle

type BpfProgram = ForeignPtr BpfProgramTag

Compiled Berkeley Packet Filter program

type Callback = PktHdr -> Ptr Word8 -> IO ()

the type of the callback function passed to dispatch or loop.

data Direction

The direction in which packets are to be captured. See setDirection.

Constructors

InOut	incoming and outgoing packets (the default
In	incoming packets
Out	outgoing packets

Instances

Eq Direction

Read Direction

Show Direction

data Link

Datalink types.

This covers all of the datalink types defined in bpf.h. Types defined on your system may vary.

Constructors

DLT_NULL	no link layer encapsulation
DLT_UNKNOWN Int	unknown encapsulation
DLT_EN10MB	10 Mbit per second (or faster) ethernet
DLT_EN3MB	original 3 Mbit per second ethernet
DLT_AX25	amateur radio AX.25
DLT_PRONET	Proteon ProNET Token Ring
DLT_CHAOS	Chaos
DLT_IEEE802	IEEE 802 networks
DLT_ARCNET	ARCNET
DLT_SLIP	Serial line IP
DLT_PPP	Point-to-point protocol
DLT_FDDI	FDDI
DLT_ATM_RFC1483	LLC SNAP encapsulated ATM
DLT_RAW	raw IP
DLT_SLIP_BSDOS	BSD OS serial line IP
DLT_PPP_BSDOS	BSD OS point-to-point protocol
DLT_ATM_CLIP	Linux classical IP over ATM
DLT_REDBACK_SMARTEDGE	Redback SmartEdge 400/800
DLT_PPP_SERIAL	PPP over serial with HDLC encapsulation
DLT_PPP_ETHER	PPP over ethernet
DLT_SYMANTEC_FIREWALL	Symantec Enterprise Firewall
DLT_C_HDLC	Cisco HDLC
DLT_IEEE802_11	IEEE 802.11 wireless
DLT_FRELAY	Frame Relay
DLT_LOOP	OpenBSD loopback device
DLT_ENC	Encapsulated packets for IPsec
DLT_LINUX_SLL	Linux cooked sockets
DLT_LTALK	Apple LocalTalk
DLT_ECONET	Acorn Econet
DLT_IPFILTER	OpenBSD's old ipfilter
DLT_PFLOG	OpenBSD's pflog
DLT_CISCO_IOS	Cisco IOS
DLT_PRISM_HEADER	Intersil Prism II wireless chips
DLT_AIRONET_HEADER	Aironet (Cisco) 802.11 wireless
DLT_HHDLC	Siemens HiPath HDLC
DLT_IP_OVER_FC	RFC 2625 IP-over-Fibre Channel
DLT_SUNATM	Full Frontal ATM on Solaris with SunATM
DLT_IEEE802_11_RADIO	802.11 plus a number of bits of link-layer information
DLT_ARCNET_LINUX	Linux ARCNET header
DLT_APPLE_IP_OVER_IEEE1394	Apple IP-over-IEEE 1394
DLT_MTP2_WITH_PHDR	SS7, C7 MTP2 with pseudo-header
DLT_MTP2	SS7, C7 Message Transfer Part 2 (MPT2)
DLT_MTP3	SS7, C7 Message Transfer Part 3 (MPT3)
DLT_SCCP	SS7, C7 SCCP
DLT_DOCSIS	DOCSIS MAC frame
DLT_LINUX_IRDA	Linux IrDA packet
DLT_USER0	Reserved for private use
DLT_USER1	Reserved for private use
DLT_USER2	Reserved for private use
DLT_USER3	Reserved for private use
DLT_USER4	Reserved for private use
DLT_USER5	Reserved for private use
DLT_USER6	Reserved for private use
DLT_USER7	Reserved for private use
DLT_USER8	Reserved for private use
DLT_USER9	Reserved for private use
DLT_USER10	Reserved for private use
DLT_USER11	Reserved for private use
DLT_USER12	Reserved for private use
DLT_USER13	Reserved for private use
DLT_USER14	Reserved for private use
DLT_USER15	Reserved for private use
DLT_PPP_PPPD	Outgoing packets for ppp daemon
DLT_GPRS_LLC	GPRS LLC
DLT_GPF_T	GPF-T (ITU-T G.7041/Y.1303)
DLT_GPF_F	GPF-F (ITU-T G.7041/Y.1303)
DLT_LINUX_LAPD	Raw LAPD for vISDN (not generic LAPD)
DLT_A429	ARINC 429
DLT_A653_ICM	ARINC 653 Interpartition Communication messages
DLT_USB	USB packet
DLT_BLUETOOTH_HCI_H4	Bluetooth HCI UART transport layer (part H:4)
DLT_MFR	Multi Link Frame Relay (FRF.16)
DLT_IEEE802_16_MAC_CPS	IEEE 802.16 MAC Common Part Sublayer
DLT_USB_LINUX	USB packets, beginning with a Linux USB header
DLT_CAN20B	Controller Area Network (CAN) v2.0B
DLT_IEEE802_15_4_LINUX	IEEE 802.15.4, with address fields padded
DLT_PPI	Per Packet Information encapsulated packets
DLT_IEEE802_16_MAC_CPS_RADIO	802.16 MAC Common Part Sublayer with radiotap radio header
DLT_IEEE802_15_4	IEEE 802.15.4, exactly as in the spec

Instances

data Interface

The interface structure.

Constructors

Interface

ifName :: String	the interface name
ifDescription :: String	interface description string (if any)
ifAddresses :: [PcapAddr]	address families supported by this interface
ifFlags :: Word32

Instances

Eq Interface

Read Interface

Show Interface

data PcapAddr

The address structure.

Constructors

PcapAddr

addrSA :: SockAddr	interface address
addrMask :: (Maybe SockAddr)	network mask
addrBcast :: (Maybe SockAddr)	broadcast address
addrPeer :: (Maybe SockAddr)	address of peer, of a point-to-point link

Instances

Eq PcapAddr

Read PcapAddr

Show PcapAddr

data SockAddr

The socket address record. Note that this is not the same as SockAddr from Socket. (That is a Haskell version of C's struct sockaddr_in. This is the real struct sockaddr from the BSD network stack.)

Constructors

SockAddr

saFamily :: !Family	an address family exported by Network.Socket
saAddr :: !ByteString

Instances

Eq SockAddr

Read SockAddr

Show SockAddr

data Network

The network address record. Both the address and mask are in network byte order.

Constructors

Network

netAddr :: !Word32	IPv4 network address
netMask :: !Word32	IPv4 netmask

Instances

Eq Network

Read Network

Show Network

data PktHdr

Constructors

PktHdr

hdrSeconds :: !Word32	timestamp (seconds)
hdrUseconds :: !Word32	timestamp (microseconds)
hdrCaptureLength :: !Word32	number of bytes present in capture
hdrWireLength :: !Word32	number of bytes on the wire

Instances

Eq PktHdr

Show PktHdr

data Statistics

Constructors

Statistics

statReceived :: !Word32	packets received
statDropped :: !Word32	packets dropped by `libpcap`
statIfaceDropped :: !Word32	packets dropped by the network interface

Instances

Eq Statistics

Show Statistics

Device opening

openOffline

:: FilePath	name of dump file to read
-> IO PcapHandle
`openOffline` opens a dump file for reading. The file format is the same as used by `tcpdump` and Wireshark. The string `"-"` is a synonym for `stdin`.

openLive

:: String	device name
-> Int	snapshot length
-> Bool	set interface to promiscuous mode?
-> Int64	timeout in microseconds
-> IO PcapHandle
`openLive` is used to get a `PcapHandle` that can be used to look at packets on the network. The arguments are the device name, the snapshot length (in bytes), the promiscuity of the interface (`True` == promiscuous) and a timeout in microseconds. The timeout allows the packet filter to delay while accumulating multiple packets, which is more efficient than reading packets one by one. A timeout of zero will wait indefinitely for "enough" packets to arrive. Using `"any"` as the device name will capture packets from all interfaces. On some systems, reading from the `"any"` device is incompatible with setting the interfaces into promiscuous mode. In that case, only packets whose link layer addresses match those of the interfaces are captured.

openDead

:: Link	datalink type
-> Int	snapshot length
-> IO PcapHandle
`openDead` is used to get a `PcapHandle` without opening a file or device. It is typically used to test packet filter compilation by `setFilter`. The arguments are the link type and the snapshot length.

openDump

:: PcapHandle	packet capture handle
-> FilePath	name of dump file to write to
-> IO DumpHandle
`openDump` opens a dump file for writing. This dump file is written to by the `dump` function.

Filter handling

setFilter

:: PcapHandle	handle on which to set filter
-> String	filter string
-> Bool	optimize?
-> Word32	IPv4 network mask
-> IO ()
Set a filter on the specified packet capture handle. Valid filter strings are those accepted by `tcpdump`.

compileFilter

:: Int	snapshot length
-> Link	datalink type
-> String	filter string
-> Bool	optimize?
-> Word32	IPv4 network mask
-> IO BpfProgram
Compile a filter for use by another program using the Berkeley Packet Filter library.

Device utilities

lookupDev :: IO String

lookupDev returns the name of a device suitable for use with openLive and lookupNet. If you only have one interface, it is the function of choice. If not, see findAllDevs.

findAllDevs :: IO [Interface]

findAllDevs returns a list of all the network devices that can be opened by openLive. It returns only those devices that the calling process has sufficient privileges to open, so it may not find every device on the system.

lookupNet

:: String	device name
-> IO Network
Return the network address and mask for the specified interface name. Only valid for IPv4. For other protocols, use `findAllDevs` and search the `Interface` list for the associated network mask.

Interface control

setNonBlock

:: PcapHandle	must have been obtained from `openLive`
-> Bool	set/unset blocking mode
-> IO ()
Set the given `PcapHandle` into non-blocking mode if the second argument is `True`, otherwise put it in blocking mode. Note that the `PcapHandle` must have been obtained from `openLive`.

getNonBlock :: PcapHandle -> IO Bool

Return the blocking status of the PcapHandle. True indicates that the handle is non-blocking. Handles referring to dump files opened by openDump always return False.

setDirection :: PcapHandle -> Direction -> IO ()

Specify the direction in which packets are to be captured. Complete functionality is not necessarily available on all platforms.

Link layer utilities

datalink :: PcapHandle -> IO Link

Returns the datalink type associated with the given handle.

setDatalink :: PcapHandle -> Link -> IO ()

Sets the datalink type for the given handle.

listDatalinks :: PcapHandle -> IO [Link]

List all the datalink types supported by the given handle. Entries from the resulting list are valid arguments to setDatalink.

Packet processing

dispatch

:: PcapHandle
-> Int	number of packets to process
-> Callback	packet processing function
-> IO Int	number of packets read
Collect and process packets. The count is the maximum number of packets to process before returning. A count of -1 means process all of the packets received in one buffer (if a live capture) or all of the packets in a dump file (if offline). The callback function is passed two arguments, a packet header record and a pointer to the packet data (`Ptr Word8`). THe header record contains the number of bytes captured, whcih can be used to marshal the data into a list, array, or `ByteString` (using `toBS`).

loop

:: PcapHandle
-> Int	number of packets to read (-1 == loop forever)
-> Callback	packet processing function
-> IO Int	number of packets read
Similar to `dispatch`, but loop until the number of packets specified by the second argument are read. A negative value loops forever. This function does not return when a live read tiemout occurs. Use `dispatch` instead if you wnat to specify a timeout.

next :: PcapHandle -> IO (PktHdr, Ptr Word8)

Read the next packet (equivalent to calling dispatch with a count of 1).

dump

:: DumpHandle
-> Ptr PktHdr	packet header record
-> Ptr Word8	packet data
-> IO ()
Write the packet data given by the second and third arguments to a dump file opened by `openDead`. `dump` is designed so it can be easily used as a default callback function by `dispatch` or `loop`.

Sending packets

sendPacket

:: PcapHandle
-> Ptr Word8	packet data (including link-level header)
-> Int	packet size
-> IO ()
Send a raw packet through the network interface.

sendPacketBS

:: PcapHandle
-> ByteString	packet data (including link-level header)
-> IO ()
Send a raw packet through the network interface.

Conversion

toBS :: (PktHdr, Ptr Word8) -> IO (PktHdr, ByteString)

Represent a captured packet as a ByteString. Suitable for use as is with the result of next, or use curry toBS inside a Callback with dispatch.

hdrTime :: PktHdr -> Int64

Get the timestamp of a packet as a single quantity, in microseconds.

hdrDiffTime :: PktHdr -> DiffTime

Get the timestamp of a packet as a DiffTime.

Miscellaneous

statistics :: PcapHandle -> IO Statistics

Returns the number of packets received, the number of packets dropped by the packet filter and the number of packets dropped by the interface (before processing by the packet filter).

version :: PcapHandle -> IO (Int, Int)

Version of the library. The returned pair consists of the major and minor version numbers.

isSwapped :: PcapHandle -> IO Bool

isSwapped returns True if the current dump file uses a different byte order than the one native to the system.

snapshotLen :: PcapHandle -> IO Int

The snapshot length that was used in the call to openLive.

Produced by Haddock version 0.8