977750076d
Add Ancilliary data to better represent loss information I've had a few requests recently to provide more detail regarding frame loss during an AF_PACKET packet capture session. Specifically the requestors want to see where in a packet sequence frames were lost, i.e. they want to see that 40 frames were lost between frames 302 and 303 in a packet capture file. In order to do this we need: 1) The kernel to export this data to user space 2) The applications to make use of it This patch addresses item (1). It does this by doing the following: A) Anytime we drop a frame for which we would increment po->stats.tp_drops, we also no increment a stats called po->stats.tp_gap. B) Every time we successfully enqueue a frame to sk_receive_queue, we record the value of po->stats.tp_gap in skb->mark. skb->cb would nominally be the place to record this, but since all the space there is used up, we're overloading skb->mark. Its safe to do since any enqueued packet is guaranteed to be unshared at this point, and skb->mark isn't used for anything else in the rx path to the application. After we record tp_gap in the skb, we zero po->stats.tp_gap. This allows us to keep a counter of the number of frames lost between any two enqueued packets C) When the application goes to dequeue a frame from the packet socket, we look at skb->mark for that frame. If it is non-zero, we add a cmsg chunk to the msghdr of level SOL_PACKET and type PACKET_GAPDATA. Its a 32 bit integer that represents the number of frames lost between this packet and the last previous frame received. Note there is a chance that if there is frame loss after a receive, and then the socket is closed, some gap data might be lost. This is covered by the use of the PACKET_AUXDATA socket option, which gives total loss data. With a bit of math, the final gap can be determined that way. I've tested this patch myself, and it works well. Signed-off-by: Neil Horman <nhorman@tuxdriver.com> Signed-off-by: Eric Dumazet <eric.dumazet@gmail.com> include/linux/if_packet.h | 2 ++ net/packet/af_packet.c | 33 +++++++++++++++++++++++++++++++++ 2 files changed, 35 insertions(+) Signed-off-by: David S. Miller <davem@davemloft.net>
152 lines
3.4 KiB
C
152 lines
3.4 KiB
C
#ifndef __LINUX_IF_PACKET_H
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#define __LINUX_IF_PACKET_H
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#include <linux/types.h>
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struct sockaddr_pkt
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{
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unsigned short spkt_family;
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unsigned char spkt_device[14];
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__be16 spkt_protocol;
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};
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struct sockaddr_ll
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{
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unsigned short sll_family;
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__be16 sll_protocol;
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int sll_ifindex;
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unsigned short sll_hatype;
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unsigned char sll_pkttype;
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unsigned char sll_halen;
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unsigned char sll_addr[8];
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};
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/* Packet types */
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#define PACKET_HOST 0 /* To us */
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#define PACKET_BROADCAST 1 /* To all */
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#define PACKET_MULTICAST 2 /* To group */
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#define PACKET_OTHERHOST 3 /* To someone else */
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#define PACKET_OUTGOING 4 /* Outgoing of any type */
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/* These ones are invisible by user level */
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#define PACKET_LOOPBACK 5 /* MC/BRD frame looped back */
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#define PACKET_FASTROUTE 6 /* Fastrouted frame */
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/* Packet socket options */
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#define PACKET_ADD_MEMBERSHIP 1
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#define PACKET_DROP_MEMBERSHIP 2
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#define PACKET_RECV_OUTPUT 3
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/* Value 4 is still used by obsolete turbo-packet. */
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#define PACKET_RX_RING 5
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#define PACKET_STATISTICS 6
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#define PACKET_COPY_THRESH 7
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#define PACKET_AUXDATA 8
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#define PACKET_ORIGDEV 9
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#define PACKET_VERSION 10
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#define PACKET_HDRLEN 11
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#define PACKET_RESERVE 12
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#define PACKET_TX_RING 13
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#define PACKET_LOSS 14
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#define PACKET_GAPDATA 15
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struct tpacket_stats
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{
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unsigned int tp_packets;
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unsigned int tp_drops;
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unsigned int tp_gap;
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};
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struct tpacket_auxdata
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{
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__u32 tp_status;
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__u32 tp_len;
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__u32 tp_snaplen;
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__u16 tp_mac;
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__u16 tp_net;
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__u16 tp_vlan_tci;
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};
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/* Rx ring - header status */
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#define TP_STATUS_KERNEL 0x0
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#define TP_STATUS_USER 0x1
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#define TP_STATUS_COPY 0x2
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#define TP_STATUS_LOSING 0x4
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#define TP_STATUS_CSUMNOTREADY 0x8
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/* Tx ring - header status */
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#define TP_STATUS_AVAILABLE 0x0
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#define TP_STATUS_SEND_REQUEST 0x1
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#define TP_STATUS_SENDING 0x2
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#define TP_STATUS_WRONG_FORMAT 0x4
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struct tpacket_hdr
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{
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unsigned long tp_status;
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unsigned int tp_len;
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unsigned int tp_snaplen;
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unsigned short tp_mac;
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unsigned short tp_net;
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unsigned int tp_sec;
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unsigned int tp_usec;
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};
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#define TPACKET_ALIGNMENT 16
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#define TPACKET_ALIGN(x) (((x)+TPACKET_ALIGNMENT-1)&~(TPACKET_ALIGNMENT-1))
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#define TPACKET_HDRLEN (TPACKET_ALIGN(sizeof(struct tpacket_hdr)) + sizeof(struct sockaddr_ll))
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struct tpacket2_hdr
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{
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__u32 tp_status;
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__u32 tp_len;
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__u32 tp_snaplen;
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__u16 tp_mac;
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__u16 tp_net;
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__u32 tp_sec;
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__u32 tp_nsec;
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__u16 tp_vlan_tci;
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};
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#define TPACKET2_HDRLEN (TPACKET_ALIGN(sizeof(struct tpacket2_hdr)) + sizeof(struct sockaddr_ll))
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enum tpacket_versions
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{
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TPACKET_V1,
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TPACKET_V2,
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};
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/*
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Frame structure:
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- Start. Frame must be aligned to TPACKET_ALIGNMENT=16
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- struct tpacket_hdr
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- pad to TPACKET_ALIGNMENT=16
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- struct sockaddr_ll
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- Gap, chosen so that packet data (Start+tp_net) alignes to TPACKET_ALIGNMENT=16
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- Start+tp_mac: [ Optional MAC header ]
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- Start+tp_net: Packet data, aligned to TPACKET_ALIGNMENT=16.
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- Pad to align to TPACKET_ALIGNMENT=16
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*/
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struct tpacket_req
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{
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unsigned int tp_block_size; /* Minimal size of contiguous block */
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unsigned int tp_block_nr; /* Number of blocks */
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unsigned int tp_frame_size; /* Size of frame */
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unsigned int tp_frame_nr; /* Total number of frames */
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};
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struct packet_mreq
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{
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int mr_ifindex;
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unsigned short mr_type;
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unsigned short mr_alen;
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unsigned char mr_address[8];
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};
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#define PACKET_MR_MULTICAST 0
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#define PACKET_MR_PROMISC 1
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#define PACKET_MR_ALLMULTI 2
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#define PACKET_MR_UNICAST 3
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#endif
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