1STRUCT SOCK(9) Linux Networking STRUCT SOCK(9)
2
6 struct_sock - network layer representation of sockets
7
9 struct sock {
10 struct sock_common __sk_common;
11 #define sk_node __sk_common.skc_node
12 #define sk_nulls_node __sk_common.skc_nulls_node
13 #define sk_refcnt __sk_common.skc_refcnt
14 #define sk_copy_start __sk_common.skc_hash
15 #define sk_hash __sk_common.skc_hash
16 #define sk_family __sk_common.skc_family
17 #define sk_state __sk_common.skc_state
18 #define sk_reuse __sk_common.skc_reuse
19 #define sk_reuseport __sk_common.skc_reuseport
20 #define sk_bound_dev_if __sk_common.skc_bound_dev_if
21 #define sk_bind_node __sk_common.skc_bind_node
22 #define sk_prot __sk_common.skc_prot
23 #define sk_net __sk_common.skc_net
24 unsigned int sk_shutdown:2;
25 unsigned int sk_no_check:2;
26 unsigned int sk_userlocks:4;
27 unsigned int sk_protocol:8;
28 unsigned int sk_type:16;
29 #define SK_PROTOCOL_MAX U8_MAX
30 int sk_rcvbuf;
31 socket_lock_t sk_lock;
32 struct sk_backlog;
33 wait_queue_head_t * sk_sleep;
34 struct dst_entry * sk_dst_cache;
35 #ifdef CONFIG_XFRM
36 struct xfrm_policy * sk_policy[2];
37 #endif
38 rwlock_t sk_dst_lock;
39 atomic_t sk_rmem_alloc;
40 atomic_t sk_wmem_alloc;
41 atomic_t sk_omem_alloc;
42 int sk_sndbuf;
43 struct sk_buff_head sk_receive_queue;
44 struct sk_buff_head sk_write_queue;
45 #ifdef CONFIG_NET_DMA
46 struct sk_buff_head sk_async_wait_queue;
47 #endif
48 int sk_wmem_queued;
49 int sk_forward_alloc;
50 gfp_t sk_allocation;
51 int sk_route_caps;
52 int sk_gso_type;
53 unsigned int sk_gso_max_size;
54 int sk_rcvlowat;
55 unsigned long sk_flags;
56 unsigned long sk_lingertime;
57 struct sk_buff_head sk_error_queue;
58 struct proto * sk_prot_creator;
59 rwlock_t sk_callback_lock;
60 int sk_err;
61 int sk_err_soft;
62 atomic_t sk_drops;
63 unsigned short sk_ack_backlog;
64 unsigned short sk_max_ack_backlog;
65 __u32 sk_priority;
66 struct ucred sk_peercred;
67 long sk_rcvtimeo;
68 long sk_sndtimeo;
69 struct sk_filter * sk_filter;
70 void * sk_protinfo;
71 struct timer_list sk_timer;
72 ktime_t sk_stamp;
73 struct socket * sk_socket;
74 void * sk_user_data;
75 struct page * sk_sndmsg_page;
76 struct sk_buff * sk_send_head;
77 __u32 sk_sndmsg_off;
78 int sk_write_pending;
79 #ifdef CONFIG_SECURITY
80 void * sk_security;
81 #endif
82 __u32 sk_mark;
83 void (* sk_state_change) (struct sock *sk);
84 void (* sk_data_ready) (struct sock *sk, int bytes);
85 void (* sk_write_space) (struct sock *sk);
86 void (* sk_error_report) (struct sock *sk);
87 int (* sk_backlog_rcv) (struct sock *sk,struct sk_buff *skb);
88 void (* sk_destruct) (struct sock *sk);
89 };
90
92 __sk_common
93 shared layout with inet_timewait_sock
94 sk_shutdown
96 mask of SEND_SHUTDOWN and/or RCV_SHUTDOWN
97 sk_no_check
99 SO_NO_CHECK setting, wether or not checkup packets
101 sk_userlocks
103 SO_SNDBUF and SO_RCVBUF settings
105 sk_protocol
107 which protocol this socket belongs in this network family
108 sk_type
110 socket type (SOCK_STREAM, etc)
111 sk_rcvbuf
113 size of receive buffer in bytes
114 sk_lock
116 synchronizer
117 sk_backlog
119 always used with the per-socket spinlock held
120 sk_sleep
122 sock wait queue
123 sk_dst_cache
125 destination cache
126 sk_policy[2]
128 flow policy
129 sk_dst_lock
131 destination cache lock
132 sk_rmem_alloc
134 receive queue bytes committed
135 sk_wmem_alloc
137 transmit queue bytes committed
138 sk_omem_alloc
140 "o“ is ”option“ or ”other"
141 sk_sndbuf
143 size of send buffer in bytes
144 sk_receive_queue
146 incoming packets
147 sk_write_queue
149 Packet sending queue
150 sk_async_wait_queue
152 DMA copied packets
153 sk_wmem_queued
155 persistent queue size
156 sk_forward_alloc
158 space allocated forward
159 sk_allocation
161 allocation mode
162 sk_route_caps
164 route capabilities (e.g. NETIF_F_TSO)
165 sk_gso_type
167 GSO type (e.g. SKB_GSO_TCPV4)
168 sk_gso_max_size
170 Maximum GSO segment size to build
171 sk_rcvlowat
173 SO_RCVLOWAT setting
175 sk_flags
177 SO_LINGER (l_onoff), SO_BROADCAST, SO_KEEPALIVE, SO_OOBINLINE
179 settings, SO_TIMESTAMPING settings
180 sk_lingertime
182 SO_LINGER l_linger setting
184 sk_error_queue
186 rarely used
187 sk_prot_creator
189 sk_prot of original sock creator (see ipv6_setsockopt,
190 IPV6_ADDRFORM for instance)
191 sk_callback_lock
193 used with the callbacks in the end of this struct
194 sk_err
196 last error
197 sk_err_soft
199 errors that don´t cause failure but are the cause of a persistent
200 failure not just ´timed out´
201 sk_drops
203 raw/udp drops counter
204 sk_ack_backlog
206 current listen backlog
207 sk_max_ack_backlog
209 listen backlog set in listen
210 sk_priority
212 SO_PRIORITY setting
214 sk_peercred
216 SO_PEERCRED setting
218 sk_rcvtimeo
220 SO_RCVTIMEO setting
222 sk_sndtimeo
224 SO_SNDTIMEO setting
226 sk_filter
228 socket filtering instructions
229 sk_protinfo
231 private area, net family specific, when not using slab
232 sk_timer
234 sock cleanup timer
235 sk_stamp
237 time stamp of last packet received
238 sk_socket
240 Identd and reporting IO signals
241 sk_user_data
243 RPC layer private data
244 sk_sndmsg_page
246 cached page for sendmsg
247 sk_send_head
249 front of stuff to transmit
250 sk_sndmsg_off
252 cached offset for sendmsg
253 sk_write_pending
255 a write to stream socket waits to start
256 sk_security
258 used by security modules
259 sk_mark
261 generic packet mark
262 sk_state_change
264 callback to indicate change in the state of the sock
265 sk_data_ready
267 callback to indicate there is data to be processed
268 sk_write_space
270 callback to indicate there is bf sending space available
271 sk_error_report
273 callback to indicate errors (e.g. MSG_ERRQUEUE)
274 sk_backlog_rcv
276 callback to process the backlog
277 sk_destruct
279 called at sock freeing time, i.e. when all refcnt == 0
280
282Kernel Hackers Manual 2.6. June 2019 STRUCT SOCK(9)