.TH "ipv4" 3 "Thu Jan 28 2021" "Version 1.0.5" "libnetfilter_queue" \" -*- nroff -*-
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.nh
.SH NAME
ipv4 \- IPv4 helper functions
.SH SYNOPSIS
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.PP
.SS "Modules"

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

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.RI "struct iphdr * \fBnfq_ip_get_hdr\fP (struct pkt_buff *pktb)"
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.RI "int \fBnfq_ip_set_transport_header\fP (struct pkt_buff *pktb, struct iphdr *iph)"
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.RI "int \fBnfq_ip_mangle\fP (struct pkt_buff *pktb, unsigned int dataoff, unsigned int match_offset, unsigned int match_len, const char *rep_buffer, unsigned int rep_len)"
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.RI "int \fBnfq_ip_snprintf\fP (char *buf, size_t size, const struct iphdr *iph)"
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.SH "Detailed Description"
.PP 

.SH "Function Documentation"
.PP 
.SS "struct iphdr* nfq_ip_get_hdr (struct pkt_buff * pktb)"
nfq_ip_get_hdr - get the IPv4 header 
.PP
\fBParameters\fP
.RS 4
\fIpktb\fP Pointer to user-space network packet buffer 
.RE
.PP
\fBReturns\fP
.RS 4
validated pointer to the IPv4 header or NULL if IP is malformed or not version 4
.RE
.PP
Many programs will not need to call this function\&. A possible use is to determine the layer 4 protocol\&. The validation is that the buffer is big enough for the declared lengths in the header, i\&.e\&. an extra check for packet truncation\&. 
.PP
Definition at line 40 of file ipv4\&.c\&.
.SS "int nfq_ip_mangle (struct pkt_buff * pktb, unsigned int dataoff, unsigned int match_offset, unsigned int match_len, const char * rep_buffer, unsigned int rep_len)"
nfq_ip_mangle - mangle IPv4 packet buffer 
.PP
\fBParameters\fP
.RS 4
\fIpktb\fP Pointer to user-space network packet buffer 
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\fIdataoff\fP Offset to layer 4 header, or zero to mangle IP header 
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\fImatch_offset\fP Offset to content that you want to mangle 
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\fImatch_len\fP Length of the existing content you want to mangle 
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\fIrep_buffer\fP Pointer to data you want to use to replace current content 
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\fIrep_len\fP Length of data you want to use to replace current content 
.RE
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\fBReturns\fP
.RS 4
1 for success and 0 for failure\&. See \fBpktb_mangle()\fP for failure case 
.RE
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\fBNote\fP
.RS 4
This function updates the IPv4 length if necessary and recalculates the IPv4 checksum\&. 
.RE
.PP

.PP
Definition at line 127 of file ipv4\&.c\&.
.SS "int nfq_ip_set_transport_header (struct pkt_buff * pktb, struct iphdr * iph)"
nfq_ip_set_transport_header - set the \fBtransport_header\fP field in \fBpktb\fP 
.PP
\fBParameters\fP
.RS 4
\fIpktb\fP Pointer to user-space network packet buffer 
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\fIiph\fP Pointer to the IPv4 header 
.RE
.PP
\fBReturns\fP
.RS 4
0 on success or -1 if a minimal validation check fails 
.RE
.PP
\fBNote\fP
.RS 4
Most programs should call \fBnfq_ip_set_transport_header\fP as soon as possible, since most layer 4 helper functions assume the \fBtransport_header\fP field is valid\&. 
.RE
.PP

.PP
Definition at line 73 of file ipv4\&.c\&.
.SS "int nfq_ip_snprintf (char * buf, size_t size, const struct iphdr * iph)"
nfq_pkt_snprintf_ip - print IPv4 header into buffer in iptables LOG format 
.PP
\fBParameters\fP
.RS 4
\fIbuf\fP Pointer to buffer that will be used to print the header 
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\fIsize\fP Size of the buffer (or remaining room in it) 
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\fIiph\fP Pointer to a valid IPv4 header 
.RE
.PP
\fBReturns\fP
.RS 4
same as snprintf 
.RE
.PP
\fBSee also\fP
.RS 4
\fBsnprintf\fP(3) 
.RE
.PP

.PP
Definition at line 153 of file ipv4\&.c\&.
.SH "Author"
.PP 
Generated automatically by Doxygen for libnetfilter_queue from the source code\&.