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udp(3) libnetfilter_queue udp(3)

NAME

udp - UDP helper functions

SYNOPSIS

Modules


Internal UDP 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)
int nfq_udp_mangle_ipv4 (struct pkt_buff *pktb, unsigned int match_offset, unsigned int match_len, const char *rep_buffer, unsigned int rep_len)
int nfq_udp_mangle_ipv6 (struct pkt_buff *pktb, 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

struct udphdr* nfq_udp_get_hdr (struct pkt_buff * pktb)

nfq_udp_get_hdr - get the UDP header.

Parameters

pktb Pointer to userspace network packet buffer

Returns

validated pointer to the UDP header or NULL if the UDP header was not set or if a minimal length check fails.

Note

You have to call nfq_ip_set_transport_header() or nfq_ip6_set_transport_header() first to set the UDP header.

Definition at line 43 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 Pointer to UDP header
pktb Pointer to userspace network packet buffer

Returns

Pointer to the UDP payload, or NULL if malformed UDP packet.

Definition at line 62 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

udph Pointer to UDP header
pktb Pointer to userspace network packet buffer

Returns

Length of UDP payload (user data)

Definition at line 84 of file udp.c.

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

nfq_udp_mangle_ipv4 - Mangle UDP/IPv4 packet buffer

Parameters

pktb Pointer to network packet buffer
match_offset Offset from start of UDP data of 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

Returns

1 for success and 0 for failure. See pktb_mangle() for failure case

Note

This function updates the IPv4 and UDP lengths and recalculates their checksums for you.

Definition at line 150 of file udp.c.

int nfq_udp_mangle_ipv6 (struct pkt_buff * pktb, unsigned int match_offset, unsigned int match_len, const char * rep_buffer, unsigned int rep_len)

nfq_udp_mangle_ipv6 - Mangle UDP/IPv6 packet buffer

Parameters

pktb Pointer to network packet buffer
match_offset Offset from start of UDP data of 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

Returns

1 for success and 0 for failure. See pktb_mangle() for failure case

Note

This function updates the IPv6 and UDP lengths and recalculates the UDP checksum for you.

Definition at line 184 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).
udph pointer to a valid udp header.

Returns

The number of characters notionally written (excluding trailing NUL)

See also

snprintf(3)

Definition at line 220 of file udp.c.

Author

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Thu Jan 28 2021 Version 1.0.5