TCP helper functions

Data Structures
union	tcp_word_hdr

Macros
#define	tcp_flag_word(tp)   ( ((union tcp_word_hdr *)(tp))->words[3])

Functions
struct tcphdr *	nfq_tcp_get_hdr (struct pkt_buff *pktb)
void *	nfq_tcp_get_payload (struct tcphdr *tcph, struct pkt_buff *pktb)
unsigned int	nfq_tcp_get_payload_len (struct tcphdr *tcph, struct pkt_buff *pktb)
void	nfq_tcp_compute_checksum_ipv4 (struct tcphdr *tcph, struct iphdr *iph)
void	nfq_tcp_compute_checksum_ipv6 (struct tcphdr *tcph, struct ip6_hdr *ip6h)
int	nfq_tcp_snprintf (char *buf, size_t size, const struct tcphdr *tcph)
int	nfq_tcp_mangle_ipv4 (struct pkt_buff *pkt, unsigned int match_offset, unsigned int match_len, const char *rep_buffer, unsigned int rep_len)

Detailed Description

Function Documentation

void nfq_tcp_compute_checksum_ipv4	(	struct tcphdr *	tcph,
		struct iphdr *	iph
	)

nfq_tcp_set_checksum_ipv4 - computes IPv4/TCP packet checksum

Parameters

tcph	pointer to the TCP header
iph	pointer to the IPv4 header

Definition at line 95 of file tcp.c.

void nfq_tcp_compute_checksum_ipv6	(	struct tcphdr *	tcph,
		struct ip6_hdr *	ip6h
	)

nfq_tcp_set_checksum_ipv6 - computes IPv6/TCP packet checksum

Parameters

tcph	pointer to the TCP header
iph	pointer to the IPv6 header

Definition at line 109 of file tcp.c.

struct tcphdr* nfq_tcp_get_hdr

(

struct pkt_buff *

pktb

)

nfq_tcp_get - get the TCP header

Parameters

pktb	pointer to user-space network packet buffer

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

Note

You have to call nfq_ip_set_transport_header or nfq_ip6_set_transport_header first to access the TCP header.

Definition at line 43 of file tcp.c.

void* nfq_tcp_get_payload	(	struct tcphdr *	tcph,
		struct pkt_buff *	pktb
	)

nfq_tcp_get_payload - get the TCP packet payload

Parameters

tcph	pointer to the TCP header
pktb	pointer to user-space network packet buffer

Definition at line 61 of file tcp.c.

unsigned int nfq_tcp_get_payload_len	(	struct tcphdr *	tcph,
		struct pkt_buff *	pktb
	)

nfq_tcp_get_payload_len - get the tcp packet payload

Parameters

tcph	pointer to the TCP header
pktb	pointer to user-space network packet buffer

Definition at line 83 of file tcp.c.

int nfq_tcp_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 193 of file tcp.c.

int nfq_tcp_snprintf	(	char *	buf,
		size_t	size,
		const struct tcphdr *	tcph
	)

nfq_pkt_snprintf_tcp_hdr - print tcp 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).
tcp	pointer to a valid tcp header.

Definition at line 137 of file tcp.c.