.TH "udp" 3 "Thu Jan 28 2021" "Version 1.0.5" "libnetfilter_queue" \" -*- nroff -*-
.ad l
.nh
.SH NAME
udp \- UDP helper functions
.SH SYNOPSIS
.br
.PP
.SS "Modules"

.in +1c
.ti -1c
.RI "\fBInternal UDP functions\fP"
.br
.in -1c
.SS "Functions"

.in +1c
.ti -1c
.RI "struct udphdr * \fBnfq_udp_get_hdr\fP (struct pkt_buff *pktb)"
.br
.ti -1c
.RI "void * \fBnfq_udp_get_payload\fP (struct udphdr *udph, struct pkt_buff *pktb)"
.br
.ti -1c
.RI "unsigned int \fBnfq_udp_get_payload_len\fP (struct udphdr *udph, struct pkt_buff *pktb)"
.br
.ti -1c
.RI "int \fBnfq_udp_mangle_ipv4\fP (struct pkt_buff *pktb, unsigned int match_offset, unsigned int match_len, const char *rep_buffer, unsigned int rep_len)"
.br
.ti -1c
.RI "int \fBnfq_udp_mangle_ipv6\fP (struct pkt_buff *pktb, unsigned int match_offset, unsigned int match_len, const char *rep_buffer, unsigned int rep_len)"
.br
.ti -1c
.RI "int \fBnfq_udp_snprintf\fP (char *buf, size_t size, const struct udphdr *udph)"
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.in -1c
.SH "Detailed Description"
.PP 

.SH "Function Documentation"
.PP 
.SS "struct udphdr* nfq_udp_get_hdr (struct pkt_buff * pktb)"
nfq_udp_get_hdr - get the UDP header\&. 
.PP
\fBParameters\fP
.RS 4
\fIpktb\fP Pointer to userspace network packet buffer
.RE
.PP
\fBReturns\fP
.RS 4
validated pointer to the UDP header or NULL if the UDP header was not set or if a minimal length check fails\&. 
.RE
.PP
\fBNote\fP
.RS 4
You have to call \fBnfq_ip_set_transport_header()\fP or \fBnfq_ip6_set_transport_header()\fP first to set the UDP header\&. 
.RE
.PP

.PP
Definition at line 43 of file udp\&.c\&.
.SS "void* nfq_udp_get_payload (struct udphdr * udph, struct pkt_buff * pktb)"
nfq_udp_get_payload - get the UDP packet payload\&. 
.PP
\fBParameters\fP
.RS 4
\fIudph\fP Pointer to UDP header 
.br
\fIpktb\fP Pointer to userspace network packet buffer 
.RE
.PP
\fBReturns\fP
.RS 4
Pointer to the UDP payload, or NULL if malformed UDP packet\&. 
.RE
.PP

.PP
Definition at line 62 of file udp\&.c\&.
.SS "unsigned int nfq_udp_get_payload_len (struct udphdr * udph, struct pkt_buff * pktb)"
nfq_udp_get_payload_len - get the udp packet payload\&. 
.PP
\fBParameters\fP
.RS 4
\fIudph\fP Pointer to UDP header 
.br
\fIpktb\fP Pointer to userspace network packet buffer 
.RE
.PP
\fBReturns\fP
.RS 4
Length of UDP payload (user data) 
.RE
.PP

.PP
Definition at line 84 of file udp\&.c\&.
.SS "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 
.PP
\fBParameters\fP
.RS 4
\fIpktb\fP Pointer to network packet buffer 
.br
\fImatch_offset\fP Offset from start of UDP data of content that you want to mangle 
.br
\fImatch_len\fP Length of the existing content you want to mangle 
.br
\fIrep_buffer\fP Pointer to data you want to use to replace current content 
.br
\fIrep_len\fP Length of data you want to use to replace current content 
.RE
.PP
\fBReturns\fP
.RS 4
1 for success and 0 for failure\&. See \fBpktb_mangle()\fP for failure case 
.RE
.PP
\fBNote\fP
.RS 4
This function updates the IPv4 and UDP lengths and recalculates their checksums for you\&. 
.RE
.PP

.PP
Definition at line 150 of file udp\&.c\&.
.SS "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 
.PP
\fBParameters\fP
.RS 4
\fIpktb\fP Pointer to network packet buffer 
.br
\fImatch_offset\fP Offset from start of UDP data of content that you want to mangle 
.br
\fImatch_len\fP Length of the existing content you want to mangle 
.br
\fIrep_buffer\fP Pointer to data you want to use to replace current content 
.br
\fIrep_len\fP Length of data you want to use to replace current content 
.RE
.PP
\fBReturns\fP
.RS 4
1 for success and 0 for failure\&. See \fBpktb_mangle()\fP for failure case 
.RE
.PP
\fBNote\fP
.RS 4
This function updates the IPv6 and UDP lengths and recalculates the UDP checksum for you\&. 
.RE
.PP

.PP
Definition at line 184 of file udp\&.c\&.
.SS "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 
.PP
\fBParameters\fP
.RS 4
\fIbuf\fP pointer to buffer that is used to print the object 
.br
\fIsize\fP size of the buffer (or remaining room in it)\&. 
.br
\fIudph\fP pointer to a valid udp header\&. 
.RE
.PP
\fBReturns\fP
.RS 4
The number of characters notionally written (excluding trailing NUL) 
.RE
.PP
\fBSee also\fP
.RS 4
\fBsnprintf\fP(3) 
.RE
.PP

.PP
Definition at line 220 of file udp\&.c\&.
.SH "Author"
.PP 
Generated automatically by Doxygen for libnetfilter_queue from the source code\&.