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)
	nfq_tcp_get - get the TCP header More...
	EXPORT_SYMBOL (nfq_tcp_get_hdr)
void *	nfq_tcp_get_payload (struct tcphdr *tcph, struct pkt_buff *pktb)
	nfq_tcp_get_payload - get the TCP packet payload More...
	EXPORT_SYMBOL (nfq_tcp_get_payload)
unsigned int	nfq_tcp_get_payload_len (struct tcphdr *tcph, struct pkt_buff *pktb)
	nfq_tcp_get_payload_len - get the tcp packet payload More...
	EXPORT_SYMBOL (nfq_tcp_get_payload_len)
void	nfq_tcp_compute_checksum_ipv4 (struct tcphdr *tcph, struct iphdr *iph)
	nfq_tcp_set_checksum_ipv4 - computes IPv4/TCP packet checksum More...
	EXPORT_SYMBOL (nfq_tcp_compute_checksum_ipv4)
void	nfq_tcp_compute_checksum_ipv6 (struct tcphdr *tcph, struct ip6_hdr *ip6h)
	nfq_tcp_set_checksum_ipv6 - computes IPv6/TCP packet checksum More...
	EXPORT_SYMBOL (nfq_tcp_compute_checksum_ipv6)
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 More...
	EXPORT_SYMBOL (nfq_tcp_snprintf)
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 More...
	EXPORT_SYMBOL (nfq_tcp_mangle_ipv4)

Detailed Description

Macro Definition Documentation

#define tcp_flag_word

(

tp

)

( ((union tcp_word_hdr *)(tp))->words[3])

Referenced by nfq_tcp_snprintf().

Function Documentation

EXPORT_SYMBOL

(

nfq_tcp_get_hdr

)

EXPORT_SYMBOL

(

nfq_tcp_get_payload

)

EXPORT_SYMBOL

(

nfq_tcp_get_payload_len

)

EXPORT_SYMBOL

(

nfq_tcp_compute_checksum_ipv4

)

EXPORT_SYMBOL

(

nfq_tcp_compute_checksum_ipv6

)

EXPORT_SYMBOL

(

nfq_tcp_snprintf

)

EXPORT_SYMBOL

(

nfq_tcp_mangle_ipv4

)

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

References nfq_checksum_tcpudp_ipv4().

Referenced by nfq_tcp_mangle_ipv4().

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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

References nfq_checksum_tcpudp_ipv6().

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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.

References NULL, pkt_buff::tail, and pkt_buff::transport_header.

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

References len, NULL, pkt_buff::tail, and pkt_buff::transport_header.

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

References pkt_buff::tail, and pkt_buff::transport_header.

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.

References pkt_buff::network_header, nfq_ip_mangle(), and nfq_tcp_compute_checksum_ipv4().

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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.

References len, tcp_flag_word, and TCP_RESERVED_BITS.