| lwIP
    2.0.3
    Lightweight IP stack | 
| Data Fields | |
| struct netconn * | conn | 
| void * | lastdata | 
| u16_t | lastoffset | 
| s16_t | rcvevent | 
| u16_t | sendevent | 
| u16_t | errevent | 
| u8_t | err | 
| u8_t | select_waiting | 
Contains all internal pointers and states used for a socket
| struct netconn* lwip_sock::conn | 
sockets currently are built on netconns, each socket has one netconn
| u8_t lwip_sock::err | 
last error that occurred on this socket (in fact, all our errnos fit into an u8_t)
| u16_t lwip_sock::errevent | 
error happened for this socket, set by event_callback(), tested by select
| void* lwip_sock::lastdata | 
data that was left from the previous read
| u16_t lwip_sock::lastoffset | 
offset in the data that was left from the previous read
| s16_t lwip_sock::rcvevent | 
number of times data was received, set by event_callback(), tested by the receive and select functions
| u8_t lwip_sock::select_waiting | 
counter of how many threads are waiting for this socket using select
| u16_t lwip_sock::sendevent | 
number of times data was ACKed (free send buffer), set by event_callback(), tested by select