HTTP client failed/timeout to establish connection to airgradient server

[samuelbles07]

Problem

Sometimes when device have bad internet connection, http client failed to connect to airgradient server. That makes these errors occur

[2417017][E][WiFiClientSecure.cpp:144] connect(): start_ssl_client: -1
[ApiClient] Info: GET: https://hw.airgradient.com/sensors/airgradient:aaaaaaaaaa/one/config
[ApiClient] Info: Return code: -1

[887570][E][WiFiGeneric.cpp:1583] hostByName(): DNS Failed for hw.airgradient.com
[ApiClient] Info: GET: https://hw.airgradient.com/sensors/airgradient:aaaaaaaaaaa/one/config
[ApiClient] Info: Return code: -1

Return code indicate connection refused, but it is misleading. After set log level to verbose, it shows the problem:

13:20:22.092 > [321705][V][HTTPClient.cpp:252] beginInternal(): url: https://hw.airgradient.com/sensors/airgradient:aaaaaaa/measures
13:20:22.222 > [321835][D][HTTPClient.cpp:303] beginInternal(): protocol: https, host: hw.airgradient.com port: 443 url: /sensors/airgradient:aaaaaaaa/measures
13:20:22.379 > [321991][D][HTTPClient.cpp:598] sendRequest(): request type: 'POST' redirCount: 0
13:20:22.379 > 
13:20:22.468 > [322080][V][ssl_client.cpp:62] start_ssl_client(): Free internal heap before TLS 184080
13:20:22.560 > [322173][V][ssl_client.cpp:68] start_ssl_client(): Starting socket
13:20:27.633 > [327246][I][ssl_client.cpp:112] start_ssl_client(): select returned due to timeout 5000 ms for fd 49
13:20:27.740 > [327352][E][WiFiClientSecure.cpp:144] connect(): start_ssl_client: -1
13:20:27.814 > [327427][V][ssl_client.cpp:321] stop_ssl_socket(): Cleaning SSL connection.
13:20:27.894 > [327507][D][HTTPClient.cpp:1163] connect(): failed connect to hw.airgradient.com:443
13:20:27.984 > [327597][W][HTTPClient.cpp:1483] returnError(): error(-1): connection refused
13:20:28.067 > [327680][D][HTTPClient.cpp:408] disconnect(): tcp is closed
13:20:28.067 > 
13:20:28.133 > [ApiClient] Info: POST: https://hw.airgradient.com/sensors/airgradient:aaaaaaaa/measures
13:20:28.133 > [ApiClient] Info: Return code: -1
13:20:28.133 > [ApiClient] Error: Post response failed code: -1
13:20:28.133 > [327746][V][ssl_client.cpp:321] stop_ssl_socket(): Cleaning SSL connection.
13:20:28.213 > [327826][V][ssl_client.cpp:321] stop_ssl_socket(): Cleaning SSL connection.

Below there's this log that says select returned due to timeout 5000 ms for fd 49. And after looking through the HTTPClient, timeout occur when attempt connect to the server (connection handshake), not from the actual http data transfer.

Solution

Increase timeout for establishing a connection to the server

[nick-4711]

Great if this helps!

[nick-4711]

Propose to add a comment that explains the difference between the two timeouts.

[samuelbles07]

Added