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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_tx_queue_mapping	__sk_common.skc_tx_queue_mapping
#define sk_dontcopy_begin	__sk_common.skc_dontcopy_begin
#define sk_dontcopy_end		__sk_common.skc_dontcopy_end
#define sk_hash			__sk_common.skc_hash
#define sk_portpair		__sk_common.skc_portpair
#define sk_num			__sk_common.skc_num
#define sk_dport		__sk_common.skc_dport
#define sk_addrpair		__sk_common.skc_addrpair
#define sk_daddr		__sk_common.skc_daddr
#define sk_rcv_saddr		__sk_common.skc_rcv_saddr
#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_ipv6only		__sk_common.skc_ipv6only
#define sk_net_refcnt		__sk_common.skc_net_refcnt
#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
#define sk_v6_daddr		__sk_common.skc_v6_daddr
#define sk_v6_rcv_saddr	__sk_common.skc_v6_rcv_saddr
#define sk_cookie		__sk_common.skc_cookie
#define sk_incoming_cpu		__sk_common.skc_incoming_cpu
#define sk_flags		__sk_common.skc_flags
#define sk_rxhash		__sk_common.skc_rxhash


  socket_lock_t sk_lock;


  atomic_t sk_drops;


  int sk_rcvlowat;


  struct sk_buff_head sk_error_queue;


  struct sk_buff_head sk_receive_queue;


  struct {unnamed_struct};
#ifdef CONFIG_XFRM


  struct xfrm_policy __rcu * sk_policy[2];
#endif


  struct dst_entry * sk_rx_dst;


  struct dst_entry __rcu * sk_dst_cache;


  atomic_t sk_omem_alloc;


  int sk_sndbuf;


  int sk_wmem_queued;


  atomic_t sk_wmem_alloc;


  struct sk_buff * sk_send_head;


  struct sk_buff_head sk_write_queue;


  __s32 sk_peek_off;


  int sk_write_pending;


  __u32 sk_dst_pending_confirm;


  long sk_sndtimeo;


  struct timer_list sk_timer;


  __u32 sk_priority;


  __u32 sk_mark;


  u32 sk_pacing_rate;


  u32 sk_max_pacing_rate;


  struct page_frag sk_frag;


  netdev_features_t sk_route_caps;


  netdev_features_t sk_route_nocaps;


  int sk_gso_type;


  unsigned int sk_gso_max_size;


  gfp_t sk_allocation;


  __u32 sk_txhash;
#ifdef __BIG_ENDIAN_BITFIELD
#define SK_FL_PROTO_SHIFT  16
#define SK_FL_PROTO_MASK   0x00ff0000
#define SK_FL_TYPE_SHIFT   0
#define SK_FL_TYPE_MASK    0x0000ffff
#else
#define SK_FL_PROTO_SHIFT  8
#define SK_FL_PROTO_MASK   0x0000ff00
#define SK_FL_TYPE_SHIFT   16
#define SK_FL_TYPE_MASK    0xffff0000
#endif


  unsigned int sk_padding:1;


  unsigned int sk_kern_sock:1;


  unsigned int sk_no_check_tx:1;


  unsigned int sk_no_check_rx:1;


  unsigned int sk_userlocks:4;


  unsigned int sk_protocol:8;


  unsigned int sk_type:16;
#define SK_PROTOCOL_MAX U8_MAX


  u16 sk_gso_max_segs;


  unsigned long sk_lingertime;


  struct proto * sk_prot_creator;


  rwlock_t sk_callback_lock;


  int sk_err;


  int sk_err_soft;


  u32 sk_ack_backlog;


  u32 sk_max_ack_backlog;


  struct pid * sk_peer_pid;


  const struct cred * sk_peer_cred;


  long sk_rcvtimeo;


  ktime_t sk_stamp;


  u16 sk_tsflags;


  u8 sk_shutdown;


  u32 sk_tskey;


  struct socket * sk_socket;


  void * sk_user_data;
#ifdef CONFIG_SECURITY


  void * sk_security;
#endif


  struct sock_cgroup_data sk_cgrp_data;


  struct mem_cgroup * sk_memcg;


  void (* sk_state_change) (struct sock *sk);


  void (* sk_data_ready) (struct sock *sk);


  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);


  struct sock_reuseport __rcu * sk_reuseport_cb;


  struct rcu_head sk_rcu;
};

MEMBERS

struct sock_common __sk_common

shared layout with inet_timewait_sock

socket_lock_t sk_lock

synchronizer

atomic_t sk_drops

raw/udp drops counter

int sk_rcvlowat

SO_RCVLOWAT setting

struct sk_buff_head sk_error_queue

rarely used

struct sk_buff_head sk_receive_queue

incoming packets

struct {unnamed_struct}

anonymous

struct xfrm_policy __rcu * sk_policy[2]

flow policy

struct dst_entry * sk_rx_dst

receive input route used by early demux

struct dst_entry __rcu * sk_dst_cache

destination cache

atomic_t sk_omem_alloc

"o“ is ”option“ or ”other"

int sk_sndbuf

size of send buffer in bytes

int sk_wmem_queued

persistent queue size

atomic_t sk_wmem_alloc

transmit queue bytes committed

struct sk_buff * sk_send_head

front of stuff to transmit

struct sk_buff_head sk_write_queue

Packet sending queue

__s32 sk_peek_off

current peek_offset value

int sk_write_pending

a write to stream socket waits to start

__u32 sk_dst_pending_confirm

need to confirm neighbour

long sk_sndtimeo

SO_SNDTIMEO setting

struct timer_list sk_timer

sock cleanup timer

__u32 sk_priority

SO_PRIORITY setting

__u32 sk_mark

generic packet mark

u32 sk_pacing_rate

Pacing rate (if supported by transport/packet scheduler)

u32 sk_max_pacing_rate

Maximum pacing rate (SO_MAX_PACING_RATE)

struct page_frag sk_frag

cached page frag

netdev_features_t sk_route_caps

route capabilities (e.g. NETIF_F_TSO)

netdev_features_t sk_route_nocaps

forbidden route capabilities (e.g NETIF_F_GSO_MASK)

int sk_gso_type

GSO type (e.g. SKB_GSO_TCPV4)

unsigned int sk_gso_max_size

Maximum GSO segment size to build

gfp_t sk_allocation

allocation mode

__u32 sk_txhash

computed flow hash for use on transmit

unsigned int:1 sk_padding

unused element for alignment

unsigned int:1 sk_kern_sock

True if sock is using kernel lock classes

unsigned int:1 sk_no_check_tx

SO_NO_CHECK setting, set checksum in TX packets

unsigned int:1 sk_no_check_rx

allow zero checksum in RX packets

unsigned int:4 sk_userlocks

SO_SNDBUF and SO_RCVBUF settings

unsigned int:8 sk_protocol

which protocol this socket belongs in this network family

unsigned int:16 sk_type

socket type (SOCK_STREAM, etc)

u16 sk_gso_max_segs

Maximum number of GSO segments

unsigned long sk_lingertime

SO_LINGER l_linger setting

struct proto * sk_prot_creator

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

rwlock_t sk_callback_lock

used with the callbacks in the end of this struct

int sk_err

last error

int sk_err_soft

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

u32 sk_ack_backlog

current listen backlog

u32 sk_max_ack_backlog

listen backlog set in listen

struct pid * sk_peer_pid

struct pid for this socket's peer

const struct cred * sk_peer_cred

SO_PEERCRED setting

long sk_rcvtimeo

SO_RCVTIMEO setting

ktime_t sk_stamp

time stamp of last packet received

u16 sk_tsflags

SO_TIMESTAMPING socket options

u8 sk_shutdown

mask of SEND_SHUTDOWN and/or RCV_SHUTDOWN

u32 sk_tskey

counter to disambiguate concurrent tstamp requests

struct socket * sk_socket

Identd and reporting IO signals

void * sk_user_data

RPC layer private data

void * sk_security

used by security modules

struct sock_cgroup_data sk_cgrp_data

cgroup data for this cgroup

struct mem_cgroup * sk_memcg

this socket's memory cgroup association

void (*)(struct sock *sk) sk_state_change

callback to indicate change in the state of the sock

void (*)(struct sock *sk) sk_data_ready

callback to indicate there is data to be processed

void (*)(struct sock *sk) sk_write_space

callback to indicate there is bf sending space available

void (*)(struct sock *sk) sk_error_report

callback to indicate errors (e.g. MSG_ERRQUEUE)

int (*)(struct sock *sk,struct sk_buff *skb) sk_backlog_rcv

callback to process the backlog

void (*)(struct sock *sk) sk_destruct

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

struct sock_reuseport __rcu * sk_reuseport_cb

reuseport group container

struct rcu_head sk_rcu

used during RCU grace period

COPYRIGHT

June 2017 Kernel Hackers Manual 4.11