lwip: fix socket memory leak issue
1. Add socket memory leak debug counter
2. Fix TCP PCB leak issue
Currently ESP32 support maximum 16 TCP PCBs and all TCP PCB are allocated from heap memory. In some scenario, we may
have memory leak issue, for example, the application already created 16 TCP PCB, then it close 5 of them, because the TCP
state machine, the LWIP core may not free all the 5 TCP PCB immediately, maybe some is in TIME_WAIT status, some is in
FIN_WAIT_1 etc. Then the application try to malloc 17th TCP PCB (the application think they just create 12 because they already
close 5), memp_malloc() will return true because the heap is not out of memory, but actually we got 17 TCP PCB. When the
scenario repeat again and again (in our Audio application, it repeat more than 10000 times), more and more TCP PCB will be
created in the system, each TCP PCB require 200B, then memory leak happen (In Audio application, I saw more than 26 TCP PCB
are created, and 10*200=2K memory are leaked).
See merge request !223
LWIP will drop the oldest package at the arp packet cache queue and return "ERR_OK"
We change it that ARP level will drop the current packet and return "ERR_MEM" to tell user that you should send the packet again latter.
LwIP will define O_NONBLOCK in sockets.h if it isn't defined yet.
If sys/fcntl.h is included after socket.h, there will be duplicate definition.
Work around by including sys/fcntl.h into lwipopts.h.
https://github.com/espressif/esp-idf/issues/75
Since the customers need more sockets in their application, support max 16 sockets,
in other words, the total socket number of UDP/TCP/RAW sockets should not exceed 16.
- put contents of a few headers into c++ guard blocks
- fix off-by-one error in do_global_ctors
- remove system_init from startup code (should be called from main)
lwip: add debug code to show udp/tcp pcbs
Add code to show all tcp/udp pcbs, these kind of debug info is helpful for lwip issue debugging.
See merge request !98
Since esp32 has much more memory than esp31B, modify the HEAP_HIGHWAT from
6K to 20K.
Notes: HEAP_HIGHWAT is used for tcp/udp tx flow control, if socket task detects
that the free heap memory is less than HEAP_HIGHWAT, it stops to trasmitting until
the free heap memory is greater than HEAP_HIGHWAT
2. Add struct station_list into tcpip_adapter layer
3. When ap -L cmd is received, get mac address from mac layer first and then search ip address based on mac address on dhcp layer.
