UDP helper functions

Functions
struct udphdr *	nfq_udp_get_hdr (struct pkt_buff *pktb)
void *	nfq_udp_get_payload (struct udphdr *udph, struct pkt_buff *pktb)
unsigned int	nfq_udp_get_payload_len (struct udphdr *udph, struct pkt_buff *pktb)
void	nfq_udp_compute_checksum_ipv4 (struct udphdr *udph, struct iphdr *iph)
void	nfq_udp_compute_checksum_ipv6 (struct udphdr *udph, struct ip6_hdr *ip6h)
int	nfq_udp_mangle_ipv4 (struct pkt_buff *pkt, unsigned int match_offset, unsigned int match_len, const char *rep_buffer, unsigned int rep_len)
int	nfq_udp_snprintf (char *buf, size_t size, const struct udphdr *udph)

Detailed Description

Function Documentation

void nfq_udp_compute_checksum_ipv4	(	struct udphdr *	udph,
		struct iphdr *	iph
	)

nfq_udp_set_checksum_ipv4 - computes a IPv4/TCP packet's segment

Parameters

iphdrp	pointer to the ip header
ippayload	payload of the ip packet

Returns

the checksum of the udp segment.

See also

nfq_pkt_compute_ip_checksum

nfq_pkt_compute_udp_checksum

Definition at line 95 of file udp.c.

void nfq_udp_compute_checksum_ipv6	(	struct udphdr *	udph,
		struct ip6_hdr *	ip6h
	)

nfq_udp_set_checksum_ipv6 - computes a IPv6/TCP packet's segment

Parameters

iphdrp	pointer to the ip header
ippayload	payload of the ip packet

Returns

the checksum of the udp segment.

See also

nfq_pkt_compute_ip_checksum

nfq_pkt_compute_udp_checksum

Definition at line 114 of file udp.c.

struct udphdr* nfq_udp_get_hdr

(

struct pkt_buff *

pktb

)

nfq_udp_get_hdr - get the UDP header.

Parameters

head	pointer to the beginning of the packet
tail	pointer to the tail of the packet

This function returns NULL if invalid UDP header is found. On success, it returns the UDP header.

Definition at line 40 of file udp.c.

void* nfq_udp_get_payload	(	struct udphdr *	udph,
		struct pkt_buff *	pktb
	)

nfq_udp_get_payload - get the UDP packet payload.

Parameters

udph	the pointer to the UDP header.
tail	pointer to the tail of the packet

Definition at line 58 of file udp.c.

unsigned int nfq_udp_get_payload_len	(	struct udphdr *	udph,
		struct pkt_buff *	pktb
	)

nfq_udp_get_payload_len - get the udp packet payload.

Parameters

udp	the pointer to the udp header.

Definition at line 78 of file udp.c.

int nfq_udp_mangle_ipv4	(	struct pkt_buff *	pkt,
		unsigned int	match_offset,
		unsigned int	match_len,
		const char *	rep_buffer,
		unsigned int	rep_len
	)

nfq_tcp_mangle_ipv4 - mangle TCP/IPv4 packet buffer

Parameters

pktb	pointer to network packet buffer
match_offset	offset to content that you want to mangle
match_len	length of the existing content you want to mangle
rep_buffer	pointer to data you want to use to replace current content
rep_len	length of data you want to use to replace current content

Note

This function recalculates the IPv4 and TCP checksums for you.

Definition at line 133 of file udp.c.

int nfq_udp_snprintf	(	char *	buf,
		size_t	size,
		const struct udphdr *	udph
	)

nfq_pkt_snprintf_udp_hdr - print udp header into one buffer in a humnan readable way

Parameters

buf	pointer to buffer that is used to print the object
size	size of the buffer (or remaining room in it).
udp	pointer to a valid udp header.

Definition at line 161 of file udp.c.