ipdg.h File Reference

IP datagram parsing functions. More...

Go to the source code of this file.

Data Structures
struct	nmsg_ipdg
	Parsed IP datagram. More...

Functions
nmsg_res	nmsg_ipdg_parse (struct nmsg_ipdg *dg, unsigned etype, size_t len, const u_char *pkt)
	Parse IP packets from the network layer, discarding fragments.
nmsg_res	nmsg_ipdg_parse_pcap (struct nmsg_ipdg *dg, nmsg_pcap_t pcap, struct pcap_pkthdr *pkt_hdr, const u_char *pkt)
	Parse IP datagrams from the data link layer, performing reassembly if necessary.
nmsg_res	nmsg_ipdg_parse_pcap_raw (struct nmsg_ipdg *dg, int datalink, const uint8_t *pkt, size_t len)
	Like nmsg_ipdg_parse_pcap(), but performs no fragment handling.

Detailed Description

IP datagram parsing functions.

These functions parse network packets or ethernet frames and return IP datagrams, performing reassembly if requested. Non-IP packets are discarded.

Definition in file ipdg.h.

Function Documentation

nmsg_ipdg_parse()

nmsg_res nmsg_ipdg_parse	(	struct nmsg_ipdg *	dg,
		unsigned	etype,
		size_t	len,
		const u_char *	pkt
	)

Parse IP packets from the network layer, discarding fragments.

Populate a struct nmsg_ipdg indicating where the network, transport, and payload sections of the packet are and the length of the remaining packet at each of those sections.

This function operates on datagrams from the network layer.

Broken and fragmented datagrams are discarded.

Parameters

[out]	dg	caller-allocated struct nmsg_ipdg which will be populated after a successful call.
[in]	etype	ETHERTYPE_* value. The only supported values are ETHERTYPE_IP and ETHERTYPE_IPV6.
[in]	len	length of the packet.
[in]	pkt	pointer to the packet.

Returns

nmsg_res_success

nmsg_res_again

nmsg_ipdg_parse_pcap()

nmsg_res nmsg_ipdg_parse_pcap	(	struct nmsg_ipdg *	dg,
		nmsg_pcap_t	pcap,
		struct pcap_pkthdr *	pkt_hdr,
		const u_char *	pkt
	)

Parse IP datagrams from the data link layer, performing reassembly if necessary.

Populate a struct nmsg_ipdg indicating where the network, transport, and payload sections of the datagram are and the length of the remaining packet at each of those sections.

This function operates on raw frames returned by libpcap from the data link layer. The packet beginning at 'pkt' must match the datalink type associated with 'pcap' and must be pkt_hdr->caplen octets long.

libpcap data link types DLT_EN10MB, DLT_RAW, and DLT_LINUX_SLL are supported.

Broken packets are discarded. All but the final fragment of a fragmented datagram are stored internally and nmsg_res_again is returned.

Parameters

[out]	dg	caller-allocated struct nmsg_ipdg which will be populated after a successful call.
[in]	pcap	caller-initialized nmsg_pcap object from whose pcap handle the packet 'pkt' was received.
[in]	pkt_hdr	pointer to the pcap packet header corresponding to 'pkt'.
[in]	pkt	pointer to the packet.

Returns

nmsg_res_success

nmsg_res_again

nmsg_ipdg_parse_pcap_raw()

nmsg_res nmsg_ipdg_parse_pcap_raw	(	struct nmsg_ipdg *	dg,
		int	datalink,
		const uint8_t *	pkt,
		size_t	len
	)

Like nmsg_ipdg_parse_pcap(), but performs no fragment handling.

Parameters

[out]	dg	caller-allocated struct nmsg_ipdg which will be populated after a successful call.
[in]	datalink	libpcap data link type.
[in]	pkt	pointer to the packet.
[in]	len	length of the packet.