--- name: "struct_sock" section: "9" platform: "linux" package: "linux-manual-4.9" version: "4.9.228-1" release: "Debian 9 (Stretch)" platforms: ["linux"] url: "https://new.carta.tech/struct_sock" --- # struct\_sock(9) network layer representation of sockets ## 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; 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_wmem_alloc; atomic_t sk_omem_alloc; int sk_sndbuf; struct sk_buff_head sk_write_queue; unsigned int sk_padding:2; 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 int sk_wmem_queued; gfp_t sk_allocation; u32 sk_pacing_rate; u32 sk_max_pacing_rate; netdev_features_t sk_route_caps; netdev_features_t sk_route_nocaps; int sk_gso_type; unsigned int sk_gso_max_size; u16 sk_gso_max_segs; 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; u32 sk_ack_backlog; u32 sk_max_ack_backlog; __u32 sk_priority; __u32 sk_mark; struct pid * sk_peer_pid; const struct cred * sk_peer_cred; long sk_rcvtimeo; long sk_sndtimeo; struct timer_list sk_timer; ktime_t sk_stamp; #if BITS_PER_LONG==32 seqlock_t sk_stamp_seq; #endif u16 sk_tsflags; u8 sk_shutdown; u32 sk_tskey; struct socket * sk_socket; void * sk_user_data; struct page_frag sk_frag; struct sk_buff * sk_send_head; __s32 sk_peek_off; int sk_write_pending; #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 \_\_sk\_common shared layout with inet\_timewait\_sock sk\_lock synchronizer sk\_receive\_queue incoming packets {unnamed\_struct} anonymous sk\_policy\[2\] flow policy sk\_rx\_dst receive input route used by early demux sk\_dst\_cache destination cache 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\_padding unused element for alignment sk\_no\_check\_tx **SO\_NO\_CHECK** setting, set checksum in TX packets sk\_no\_check\_rx allow zero checksum in RX 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\_pacing\_rate Pacing rate (if supported by transport/packet scheduler) sk\_max\_pacing\_rate Maximum pacing rate (**SO\_MAX\_PACING\_RATE**) 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\_gso\_max\_segs Maximum number of GSO segments 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\_mark generic packet mark 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\_timer sock cleanup timer sk\_stamp time stamp of last packet received sk\_stamp\_seq lock for accessing sk\_stamp on 32 bit architectures only sk\_tsflags SO\_TIMESTAMPING socket options sk\_shutdown mask of **SEND\_SHUTDOWN** and/or **RCV\_SHUTDOWN** sk\_tskey counter to disambiguate concurrent tstamp requests sk\_socket Identd and reporting IO signals sk\_user\_data RPC layer private data sk\_frag cached page frag sk\_send\_head front of stuff to transmit sk\_peek\_off current peek\_offset value sk\_write\_pending a write to stream socket waits to start sk\_security used by security modules sk\_cgrp\_data cgroup data for this cgroup sk\_memcg this socket's memory cgroup association 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 sk\_reuseport\_cb reuseport group container sk\_rcu used during RCU grace period ## COPYRIGHT