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packet: support extensible, 64 bit clean mmaped ring structure

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The tpacket_hdr is not 64 bit clean due to use of an unsigned long
and can't be extended because the following struct sockaddr_ll needs
to be at a fixed offset.

Add support for a version 2 tpacket protocol that removes these
limitations.

Userspace can query the header size through a new getsockopt option
and change the protocol version through a setsockopt option. The
changes needed to switch to the new protocol version are:

1. replace struct tpacket_hdr by struct tpacket2_hdr
2. query header len and save
3. set protocol version to 2
 - set up ring as usual
4. for getting the sockaddr_ll, use (void *)hdr + TPACKET_ALIGN(hdrlen)
   instead of (void *)hdr + TPACKET_ALIGN(sizeof(struct tpacket_hdr))

Steps 2 and 4 can be omitted if the struct sockaddr_ll isn't needed.

Signed-off-by: Patrick McHardy <kaber@trash.net>
Signed-off-by: David S. Miller <davem@davemloft.net>
This commit is contained in:
Patrick McHardy
2008-07-14 22:50:15 -07:00
committed by David S. Miller
parent bc1d0411b8
commit bbd6ef87c5
2 changed files with 167 additions and 33 deletions
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21
include/linux/if_packet.h
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@ -43,6 +43,8 @@ struct sockaddr_ll
#define PACKET_COPY_THRESH 7
#define PACKET_AUXDATA 8
#define PACKET_ORIGDEV 9
#define PACKET_VERSION 10
#define PACKET_HDRLEN 11
struct tpacket_stats
{
@ -79,6 +81,25 @@ struct tpacket_hdr
#define TPACKET_ALIGN(x) (((x)+TPACKET_ALIGNMENT-1)&~(TPACKET_ALIGNMENT-1))
#define TPACKET_HDRLEN (TPACKET_ALIGN(sizeof(struct tpacket_hdr)) + sizeof(struct sockaddr_ll))
struct tpacket2_hdr
{
__u32 tp_status;
__u32 tp_len;
__u32 tp_snaplen;
__u16 tp_mac;
__u16 tp_net;
__u32 tp_sec;
__u32 tp_nsec;
};
#define TPACKET2_HDRLEN (TPACKET_ALIGN(sizeof(struct tpacket2_hdr)) + sizeof(struct sockaddr_ll))
enum tpacket_versions
{
TPACKET_V1,
TPACKET_V2,
};
/*
Frame structure: