libwebsockets/minimal-examples-lowlevel/http-client/minimal-http-client-captive-portal/README.md

lws minimal http client captive portal detect

This demonstrates how to perform captive portal detection integrated with lws_system states.

After reaching the lws_system DHCP state, the application tries to connect through to http://connectivitycheck.android.com/generate_204 over http... if it succeeds, it will get a 204 response and set the captive portal detection state to LWS_CPD_INTERNET_OK and perform a GET from warmcat.com.

If there is a problem detected, the captive portal detection state is set accordingly and the app will respond by exiting without trying the read from warmcat.com.

The captive portal detection scheme is implemented in the user code and can be modified according to the strategy that's desired for captive portal detection.

build

 $ cmake . && make

usage

$ ./bin/lws-minimal-http-client-captive-portal
[2020/03/11 13:07:07:4519] U: LWS minimal http client captive portal detect
[2020/03/11 13:07:07:4519] N: lws_create_context: using ss proxy bind '(null)', port 0, ads '(null)'
[2020/03/11 13:07:07:5022] U: callback_cpd_http: established with resp 204
[2020/03/11 13:07:07:5023] U: app_system_state_nf: OPERATIONAL, cpd 1
[2020/03/11 13:07:07:5896] U: Connected to 46.105.127.147, http response: 200
[2020/03/11 13:07:07:5931] U: RECEIVE_CLIENT_HTTP_READ: read 4087
[2020/03/11 13:07:07:5931] U: RECEIVE_CLIENT_HTTP_READ: read 4096
[2020/03/11 13:07:07:6092] U: RECEIVE_CLIENT_HTTP_READ: read 4087
[2020/03/11 13:07:07:6092] U: RECEIVE_CLIENT_HTTP_READ: read 4096
[2020/03/11 13:07:07:6112] U: RECEIVE_CLIENT_HTTP_READ: read 4087
[2020/03/11 13:07:07:6113] U: RECEIVE_CLIENT_HTTP_READ: read 4096
[2020/03/11 13:07:07:6113] U: RECEIVE_CLIENT_HTTP_READ: read 2657
[2020/03/11 13:07:07:6113] U: LWS_CALLBACK_COMPLETED_CLIENT_HTTP
[2020/03/11 13:07:07:6119] U: main: finished OK