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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_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_bind_node		__sk_common.skc_bind_node
#define sk_prot			__sk_common.skc_prot
#define sk_net			__sk_common.skc_net
  socket_lock_t sk_lock;
  struct sk_buff_head sk_receive_queue;
  struct sk_backlog;
#define sk_rmem_alloc sk_backlog.rmem_alloc
  int sk_forward_alloc;
#ifdef CONFIG_RPS
  __u32 sk_rxhash;
#endif
  atomic_t sk_drops;
  int sk_rcvbuf;
  struct sk_filter __rcu * sk_filter;
  struct socket_wq __rcu * sk_wq;
#ifdef CONFIG_NET_DMA_DUMMY
  struct sk_buff_head sk_async_wait_queue;
#endif
#ifdef CONFIG_XFRM
  struct xfrm_policy * sk_policy[2];
#endif
  unsigned long sk_flags;
  struct dst_entry * sk_dst_cache;
  spinlock_t sk_dst_lock;
  atomic_t sk_wmem_alloc;
  atomic_t sk_omem_alloc;
  int sk_sndbuf;
  struct sk_buff_head sk_write_queue;
  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)~0U)
  int sk_wmem_queued;
  gfp_t sk_allocation;
  int sk_route_caps;
  int sk_route_nocaps;
  int sk_gso_type;
  unsigned int sk_gso_max_size;
  int sk_rcvlowat;
  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 pid * sk_peer_pid;
  const struct cred * sk_peer_cred;
  long sk_rcvtimeo;
  long sk_sndtimeo;
  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;
  u32 sk_classid;
  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_lock
synchronizer
sk_receive_queue
incoming packets
sk_backlog
always used with the per-socket spinlock held
sk_forward_alloc
space allocated forward
sk_rxhash
flow hash received from netif layer
sk_drops
raw/udp drops counter
sk_rcvbuf
size of receive buffer in bytes
sk_filter
socket filtering instructions
sk_wq
sock wait queue and async head
sk_async_wait_queue
DMA copied packets
sk_policy[2]
flow policy
sk_flags
 
SO_LINGER (l_onoff), SO_BROADCAST, SO_KEEPALIVE, SO_OOBINLINE settings, SO_TIMESTAMPING settings
sk_dst_cache
destination cache
sk_dst_lock
destination cache lock
sk_wmem_alloc
transmit queue bytes committed
sk_omem_alloc
"o“ is ”option“ or ”other"
sk_sndbuf
size of send buffer in bytes
sk_write_queue
Packet sending queue
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_wmem_queued
persistent queue size
sk_allocation
allocation mode
sk_route_caps
route capabilities (e.g. NETIF_F_TSO)
sk_route_nocaps
forbidden route capabilities (e.g NETIF_F_GSO_MASK)
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_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_peer_pid
 
struct pid for this socket's peer
sk_peer_cred
 
SO_PEERCRED setting
sk_rcvtimeo
 
SO_RCVTIMEO setting
sk_sndtimeo
 
SO_SNDTIMEO setting
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_classid
this socket's cgroup classid
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

March 2016 Kernel Hackers Manual 3.2.