struct sock
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## Name

struct sock — network layer representation of sockets

## Synopsis

    struct sock {
      struct sock_common __sk_common;
    #define sk_family		__sk_common.skc_family
    #define sk_state		__sk_common.skc_state
    #define sk_reuse		__sk_common.skc_reuse
    #define sk_bound_dev_if		__sk_common.skc_bound_dev_if
    #define sk_node			__sk_common.skc_node
    #define sk_bind_node		__sk_common.skc_bind_node
    #define sk_refcnt		__sk_common.skc_refcnt
    #define sk_hash			__sk_common.skc_hash
    #define sk_prot			__sk_common.skc_prot
      unsigned char sk_shutdown:2;
      unsigned char sk_no_check:2;
      unsigned char sk_userlocks:4;
      unsigned char sk_protocol;
      unsigned short sk_type;
      int sk_rcvbuf;
      socket_lock_t sk_lock;
      struct sk_backlog;
      wait_queue_head_t * sk_sleep;
      struct dst_entry * sk_dst_cache;
      struct xfrm_policy * sk_policy[2];
      rwlock_t sk_dst_lock;
      atomic_t sk_rmem_alloc;
      atomic_t sk_wmem_alloc;
      atomic_t sk_omem_alloc;
      int sk_sndbuf;
      struct sk_buff_head sk_receive_queue;
      struct sk_buff_head sk_write_queue;
      struct sk_buff_head sk_async_wait_queue;
      int sk_wmem_queued;
      int sk_forward_alloc;
      gfp_t sk_allocation;
      int sk_route_caps;
      int sk_gso_type;
      int sk_rcvlowat;
      unsigned long sk_flags;
      unsigned long sk_lingertime;
      struct sk_buff_head sk_error_queue;
      struct proto * sk_prot_creator;
      rwlock_t sk_callback_lock;
      int sk_err;
      int sk_err_soft;
      unsigned short sk_ack_backlog;
      unsigned short sk_max_ack_backlog;
      __u32 sk_priority;
      struct ucred sk_peercred;
      long sk_rcvtimeo;
      long sk_sndtimeo;
      struct sk_filter * sk_filter;
      void * sk_protinfo;
      struct timer_list sk_timer;
      ktime_t sk_stamp;
      struct socket * sk_socket;
      void * sk_user_data;
      struct page * sk_sndmsg_page;
      struct sk_buff * sk_send_head;
      __u32 sk_sndmsg_off;
      int sk_write_pending;
      void * sk_security;
      void (* sk_state_change) (struct sock *sk);
      void (* sk_data_ready) (struct sock *sk, int bytes);
      void (* sk_write_space) (struct sock *sk);
      void (* sk_error_report) (struct sock *sk);
      int (* sk_backlog_rcv) (struct sock *sk,struct sk_buff *skb);
      void (* sk_destruct) (struct sock *sk);
    };

## Members

__sk_common

  shared layout with inet_timewait_sock

sk_shutdown

  mask of `SEND_SHUTDOWN` and/or `RCV_SHUTDOWN`

sk_no_check

  `SO_NO_CHECK` setting, wether or not checkup packets

sk_userlocks

  `SO_SNDBUF` and `SO_RCVBUF` settings

sk_protocol

  which protocol this socket belongs in this network family

sk_type

  socket type (`SOCK_STREAM`, etc)

sk_rcvbuf

  size of receive buffer in bytes

sk_lock

  synchronizer

sk_backlog

  always used with the per-socket spinlock held

sk_sleep

  sock wait queue

sk_dst_cache

  destination cache

sk_policy[2]

  flow policy

sk_dst_lock

  destination cache lock

sk_rmem_alloc

  receive queue bytes committed

sk_wmem_alloc

  transmit queue bytes committed

sk_omem_alloc

  "o“ is ”option“ or ”other"

sk_sndbuf

  size of send buffer in bytes

sk_receive_queue

  incoming packets

sk_write_queue

  Packet sending queue

sk_async_wait_queue

  DMA copied packets

sk_wmem_queued

  persistent queue size

sk_forward_alloc

  space allocated forward

sk_allocation

  allocation mode

sk_route_caps

  route capabilities (e.g. `NETIF_F_TSO`)

sk_gso_type

  GSO type (e.g. `SKB_GSO_TCPV4`)

sk_rcvlowat

  `SO_RCVLOWAT` setting

sk_flags

  `SO_LINGER` (l_onoff), `SO_BROADCAST`, `SO_KEEPALIVE`, `SO_OOBINLINE` settings

sk_lingertime

  `SO_LINGER` l_linger setting

sk_error_queue

  rarely used

sk_prot_creator

  sk_prot of original sock creator (see ipv6_setsockopt, IPV6_ADDRFORM for instance)

sk_callback_lock

  used with the callbacks in the end of this struct

sk_err

  last error

sk_err_soft

  errors that don't cause failure but are the cause of a persistent failure not just 'timed out'

sk_ack_backlog

  current listen backlog

sk_max_ack_backlog

  listen backlog set in `listen`

sk_priority

  `SO_PRIORITY` setting

sk_peercred

  `SO_PEERCRED` setting

sk_rcvtimeo

  `SO_RCVTIMEO` setting

sk_sndtimeo

  `SO_SNDTIMEO` setting

sk_filter

  socket filtering instructions

sk_protinfo

  private area, net family specific, when not using slab

sk_timer

  sock cleanup timer

sk_stamp

  time stamp of last packet received

sk_socket

  Identd and reporting IO signals

sk_user_data

  RPC layer private data

sk_sndmsg_page

  cached page for sendmsg

sk_send_head

  front of stuff to transmit

sk_sndmsg_off

  cached offset for sendmsg

sk_write_pending

  a write to stream socket waits to start

sk_security

  used by security modules

sk_state_change

  callback to indicate change in the state of the sock

sk_data_ready

  callback to indicate there is data to be processed

sk_write_space

  callback to indicate there is bf sending space available

sk_error_report

  callback to indicate errors (e.g. `MSG_ERRQUEUE`)

sk_backlog_rcv

  callback to process the backlog

sk_destruct

  called at sock freeing time, i.e. when all refcnt == 0

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