ESP8266 Client connexion via a webscoket (no library, only AT commands) - websocket

Question

I am working on websocket implementation on client side using AT commands.
I've taken this as a baseline and read this.
Hardware : ESP8266+arduino uno.
Code :
String cmd = "AT+CIPSTART=\"TCP\",\""; cmd += SERVER_IP; cmd += "\",81"; //Start a TCP connection. to server SERVER_IP on port 81
if (!sendCommand(cmd, "OK", CONTINUE))
return;
delay(2000);
if (!sendCommand("AT+CIPSTATUS", "OK", CONTINUE))// Check for TCP Connection status.
return;
cmd = "GET 192.168.43.228:81 HTTP/1.1\r\n";
cmd += "Host: 192.168.43.228:81\r\n";
cmd += "Upgrade: websocket\r\n";
cmd += "Connection: Upgrade\r\n\r\n";
if (!sendCommand("AT+CIPSEND=" + String(cmd.length()), ">", CONTINUE)) {
sendCommand("AT+CIPCLOSE", "", CONTINUE);
Serial.println("Connection timeout.");
return;
}
sendCommand(cmd, "OK", CONTINUE);// Send data to server.
delay(1000);
readResponseData("");
Log on arduino side :
ESP8266 Demo
AT+RST
OK
bBֆ#⸮Sc⸮⸮⸮ȤS⸮⸮⸮ɥ⸮⸮⸮⸮H⸮
[System Ready
, Vendo:⸮ݹ⸮⸮⸮ɹcom]
AT+GMR
0018000902
OK
AT+CWMODE?
+CWMODE:1
OK
AT+CWMODE=1
no change
AT+CWMODE=1
no change
AT+CIPMUX=0
OK
AT+CWJAP="AndroidAP","xxxx"
OK
Connected to WiFi.
AT+CWJAP="AndroidAP","xxxxx"
OK
AT+CWSAP=?
no this fun
AT+CIFSR
192.168.43.29
OK
Module is ready.
AT+CIPSTART="TCP","192.168.43.228",81
OK
Linked
AT+CIPSTATUS
STATUS:3
+CIPSTATUS:0,"TCP","192.168.43.228",81,0
OK
AT+CIPSEND=100
>
GET 192.168.43.228:81 HTTP/1.1
Host: 192.168.43.228:81
Upgradewrong syntax
ERROR
SEND OK
OK
Unlink
Server side :
WiFi connected
IP address:
192.168.43.228
Server available at ws://192.168.43.228:81
Accepted new web sockets client at index 0
--
...and nothing else from the server which is supposed sending a message as soon as it accepts the websocket.
Please give me some insight :)

Answer 1

I found one solution.
In fact I was not aware about all the details of RFC4566
After a successful handshake, you need to be inline with the frame requirement. It is not just as raw text :)
For a limited use case (i.e. length<125) here is the overview of the solution:
char str[] = "Hello";
char buf[125];
bool toMask = true;
uint8_t extra = toMask ? 6 : 2;
buildFrame(str, buf, WS_OPCODE_TEXT, toMask);
ESP8266SendData(0, buf, str.length() + extra);
I've tested this to get:
void buildFrame(char *str, uint8_t *ret, uint8_t opcode, bool maskon) {
uint8_t mask[4];
int size = strlen(str);
// Opcode; final fragment
ret[0] = opcode | WS_FIN;
ret[1] = (uint8_t) (size) | (maskon == true ? WS_MASK : 0);
if (maskon) {
mask[0] = random(0, 256);
mask[1] = random(0, 256);
mask[2] = random(0, 256);
mask[3] = random(0, 256);
for (int i = 2; i < 4 + 2; ++i) {
ret[i] = mask[i - 2];
}
for (int i = 6; i < size + 6; i++) {
ret[i] = str[i - 6] ^ mask[(i - 6) % 4];
}
}
else {
for (int i = 2; i < size + 2; ++i) {
ret[i] = (uint8_t) str[i - 2];
}
}
}
For frame decoding :
uint8_t extractPayload(String buffer, String& payload) {
// here only payloads whose size < 125
bool FIN = buffer[0] & WS_FIN;
uint8_t opcode = buffer[0] & ~WS_FIN;
bool hasMask = buffer[1] & WS_MASK;
uint8_t len = buffer[1] & ~WS_MASK;
uint8_t mask[4];
if (hasMask) {
mask[0] = buffer[2];
mask[1] = buffer[3];
mask[2] = buffer[4];
mask[3] = buffer[5];
for (int i = 6; i < len + 6; i++) {
payload += (char) (buffer[i] ^ mask[(i - 6) % 4]);
}
}
else {
payload = buffer.substring(2);
}
Serial.print("FIN = "); Serial.println(FIN, HEX);
Serial.print("Opcode = "); Serial.println(opcode, HEX);
Serial.print("Mask = "); Serial.println(hasMask, HEX);
Serial.print("Payload length = "); Serial.println(len, HEX);
return opcode;
}