1. Fix 'spurious close' by adding close() in open(). 'spurious close' gets frequent and cannot ignore when send() changes to asynchronous. User can retry open() until 'spurious close' gets true.
2. Allow only one actively sending socket because:
(1) ESP8266 AT packets 'SEND OK'/'SEND FAIL' are not associated with socket ID. No way to tell them.
(2) In original implementation, ESP8266::send() is synchronous, which implies only one actively sending socket.
3. Register 'SEND OK'/'SEND FAIL' oobs, like others in ESP8266::ESP8266 constructor. Don't get involved in oob management with send status because ESP8266 modem possibly doesn't reply these packets on error case.
4. Now that ESP8266::send() changes to asynchronous, drop the code with _parser.recv("SEND OK")/_parser.recv("SEND FAIL"). _parser.recv("SEND OK")/_parser.recv("SEND FAIL") and 'SEND OK'/'SEND FAIL' oobs both consume 'SEND OK'/'SEND FAIL' packets and complicate flow control.
We are now checking if ESP8266 has confirmed receiving data over serial
port with an undocumented (but existing) "Recv x bytes" message. Next we
are explicitly waiting for an official "SEND OK".
All logs now:
- start with a function name (it is not automatically logged by the logger)
- do not contain class name (this can be inferred from log preamble)
- message starts with a capital letter and ends with a full-stop
`ATCmdParser::recv()` should be used when we skim through data trying to look for something and `ATCmdParser::scanf()` is to be used when we know what we are supposed to get- as in `_oob_*` functions, except from `_oob_connection_status()`
Driver must return NSAPI_ERROR_WOULD_BLOCK if a server won't accept
data from the modem and the modem's buffers are full. In case that
socket is closed driver returns NSAPI_ERROR_CONNECTION_LOST.
UDP packets are always received as OOB data. Without checking for
new OOB data with a call to "_process_oob" then recv_udp never blocks.
If a UDP packet is not available then NSAPI_ERROR_WOULD_BLOCK is
returned. This causes mbed-os's DNS handling to always fail when
flow control is enabled.
This patch fixes recv_udp by always calling "_process_oob" regardless
of if flow control is enabled. This ensures that recv_udp follows the
timeout parameter and waits for new data to arrive.
Michal Paszta
Chun-Chieh Li
Antti Yli-Tokola
Martin Kojtal
Anna Bridge
Dominika Maziec
Antti Kauppila
Desmond Chen
Marcin Tomczyk
Kevin Bracey
Cruz Monrreal
Veijo Pesonen
Seppo Takalo
Deepika
Russ Butler