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STRUCT SOCK(9) Linux Networking STRUCT SOCK(9)

NAME

struct_sock - network layer representation of sockets

SYNOPSIS

struct sock {


  struct sock_common __sk_common;
#define sk_node			__sk_common.skc_node
#define sk_nulls_node		__sk_common.skc_nulls_node
#define sk_refcnt		__sk_common.skc_refcnt
#define sk_copy_start		__sk_common.skc_hash
#define sk_hash			__sk_common.skc_hash
#define sk_family		__sk_common.skc_family
#define sk_state		__sk_common.skc_state
#define sk_reuse		__sk_common.skc_reuse
#define sk_reuseport		__sk_common.skc_reuseport
#define sk_bound_dev_if		__sk_common.skc_bound_dev_if
#define sk_bind_node		__sk_common.skc_bind_node
#define sk_prot			__sk_common.skc_prot
#define sk_net			__sk_common.skc_net


  unsigned int sk_shutdown:2;


  unsigned int sk_no_check:2;


  unsigned int sk_userlocks:4;


  unsigned int sk_protocol:8;


  unsigned int sk_type:16;
#define SK_PROTOCOL_MAX U8_MAX


  int sk_rcvbuf;


  socket_lock_t sk_lock;


  struct sk_backlog;


  wait_queue_head_t * sk_sleep;


  struct dst_entry * sk_dst_cache;
#ifdef CONFIG_XFRM


  struct xfrm_policy * sk_policy[2];
#endif


  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;
#ifdef CONFIG_NET_DMA


  struct sk_buff_head sk_async_wait_queue;
#endif


  int sk_wmem_queued;


  int sk_forward_alloc;


  gfp_t sk_allocation;


  int sk_route_caps;


  int sk_gso_type;


  unsigned int sk_gso_max_size;


  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;


  atomic_t sk_drops;


  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;
#ifdef CONFIG_SECURITY


  void * sk_security;
#endif


  __u32 sk_mark;


  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_gso_max_size

Maximum GSO segment size to build

sk_rcvlowat

SO_RCVLOWAT setting

sk_flags

SO_LINGER (l_onoff), SO_BROADCAST, SO_KEEPALIVE, SO_OOBINLINE settings, SO_TIMESTAMPING 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_drops

raw/udp drops counter

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_mark

generic packet mark

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

COPYRIGHT

April 2023 Kernel Hackers Manual 2.6.