yafrag.h File Reference

Fragment reassembly interface for YAF. More...

#include <yaf/autoinc.h>
#include <yaf/decode.h>
#include <yaf/yafcore.h>

Go to the source code of this file.

Typedefs
typedef struct yfFragTab_st	yfFragTab_t
	A fragment table.
Functions
yfFragTab_t *	yfFragTabAlloc (uint32_t idle_ms, uint32_t max_frags, uint32_t max_payload)
	Allocate a fragment table.
void	yfFragTabFree (yfFragTab_t *fragtab)
	Free a fragment table.
gboolean	yfDefragPBuf (yfFragTab_t *fragtab, yfIPFragInfo_t *fraginfo, size_t pbuflen, yfPBuf_t *pbuf, const uint8_t *pkt, size_t hdr_len)
	Defragment a fragment returned by yfDecodeToPBuf().
void	yfFragDumpStats (yfFragTab_t *fragtab, uint64_t packetTotal)
	Print fragment reassembler statistics to the log.
void	yfGetFragTabStats (yfFragTab_t *fragtab, uint32_t *dropped, uint32_t *assembled)
	Get Frag Stats to yfWriteStatsFlow for Stats Export.

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Detailed Description

Fragment reassembly interface for YAF.

[TODO - new frontmatter]

This facility is used by the YAF flow generator.

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Typedef Documentation

typedef struct yfFragTab_st yfFragTab_t

A fragment table.

Opaque. Create with yfFragTabAlloc() and free with yfFragTabFree().

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Function Documentation

gboolean yfDefragPBuf	(	yfFragTab_t *	fragtab,
		yfIPFragInfo_t *	fraginfo,
		size_t	pbuflen,
		yfPBuf_t *	pbuf,
		const uint8_t *	pkt,
		size_t	hdr_len
	)

Defragment a fragment returned by yfDecodeToPBuf().

This adds the fragment to the given fragment table. If the fragment completes a fragmented packet, copies the assembled packet into the given pbuf, overwriting it, and returns TRUE. If the packet is not fragmented (that is, if fraginfo->frag is 0), has no effect and returns TRUE.

Parameters:

	fragtab	fragment table to add fragment to
	fraginfo	fragment information structure filled in by yfDecodeToPBuf()
	pbuflen	size of the packet buffer pbuf
	pbuf	packet buffer. On call, contains decoded fragmented packet to add to the fragment table. If this call returns TRUE, on return, contains assembled packet.
	pkt	pkt buffer from libpcap. We need this to reassemble (memcpy) TCP header fragments when payload is not enabled.
	hdr_len	size of the packet buffer pkt

Returns:

TRUE if pbuf is valid and contains an assembled packet, FALSE otherwise.

void yfFragDumpStats	(	yfFragTab_t *	fragtab,
		uint64_t	packetTotal
	)

Print fragment reassembler statistics to the log.

Parameters:

	fragtab	fragment table to dump stats for
	packetTotal	total number of packets observed

yfFragTab_t* yfFragTabAlloc	(	uint32_t	idle_ms,
		uint32_t	max_frags,
		uint32_t	max_payload
	)

Allocate a fragment table.

Parameters:

	idle_ms	idle timeout in milliseconds. A fragmented packet for which no fragments are received over an idle timeout is dropped. Most host IPv4 implementations use 30 seconds (30000); it is recommended to use the same here.
	max_frags	maximum number of unreassembled fragmented packets. Fragmented packets exceeding this limit will be dropped in least-recent order. Used to limit resource usage of a fragment table. A value of 0 disables fragment count limits.
	max_payload	maximum octets of payload to capture per fragmented packet. A value of 0 disables payload reassembly.

Returns:

a new fragment table.

void yfFragTabFree

(

yfFragTab_t *

fragtab

)

Free a fragment table.

Discards any outstanding fragmented packets within.

Parameters:

fragtab

a fragment table.

void yfGetFragTabStats	(	yfFragTab_t *	fragtab,
		uint32_t *	dropped,
		uint32_t *	assembled
	)

Get Frag Stats to yfWriteStatsFlow for Stats Export.

Parameters:

	fragtab	pointer to fragmentation table
	dropped	number of expired fragments
	assembled	number of assembled packets