mirror of
https://github.com/warmcat/libwebsockets.git
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minimal examples: ws client demonstrating retry and backoff
Add a simple example to demonstrate the current best approach for connection retry and backoff
This commit is contained in:
Andy Green
parent
414516cad4
commit
0e1b4cf389
5 changed files with 411 additions and 0 deletions
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@ -1,5 +1,6 @@
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|name|demonstrates|
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---|---
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minimal-ws-client|Simple client that connects to libwebsockets.org dumb increment protocol and demonstrates retry and backoff
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minimal-ws-client-echo|Simple client that connects to a ws server and echos anything the server sends
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minimal-ws-client-ping|Ws ping test client
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minimal-ws-client-pmd-bulk|Client that sends bulk multifragment data to the minimal-ws-server-pmd-bulk example
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80
minimal-examples/ws-client/minimal-ws-client/CMakeLists.txt
Normal file
80
minimal-examples/ws-client/minimal-ws-client/CMakeLists.txt
Normal file
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@ -0,0 +1,80 @@
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project(lws-minimal-ws-client-ping)
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cmake_minimum_required(VERSION 2.8)
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include(CheckIncludeFile)
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include(CheckCSourceCompiles)
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set(SAMP lws-minimal-ws-client)
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set(SRCS minimal-ws-client.c)
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# If we are being built as part of lws, confirm current build config supports
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# reqconfig, else skip building ourselves.
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#
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# If we are being built externally, confirm installed lws was configured to
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# support reqconfig, else error out with a helpful message about the problem.
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#
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MACRO(require_lws_config reqconfig _val result)
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if (DEFINED ${reqconfig})
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if (${reqconfig})
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set (rq 1)
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else()
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set (rq 0)
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endif()
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else()
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set(rq 0)
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endif()
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if (${_val} EQUAL ${rq})
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set(SAME 1)
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else()
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set(SAME 0)
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endif()
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if (LWS_WITH_MINIMAL_EXAMPLES AND NOT ${SAME})
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if (${_val})
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message("${SAMP}: skipping as lws being built without ${reqconfig}")
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else()
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message("${SAMP}: skipping as lws built with ${reqconfig}")
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endif()
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set(${result} 0)
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else()
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if (LWS_WITH_MINIMAL_EXAMPLES)
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set(MET ${SAME})
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else()
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CHECK_C_SOURCE_COMPILES("#include <libwebsockets.h>\nint main(void) {\n#if defined(${reqconfig})\n return 0;\n#else\n fail;\n#endif\n return 0;\n}\n" HAS_${reqconfig})
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if (NOT DEFINED HAS_${reqconfig} OR NOT HAS_${reqconfig})
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set(HAS_${reqconfig} 0)
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else()
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set(HAS_${reqconfig} 1)
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endif()
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if ((HAS_${reqconfig} AND ${_val}) OR (NOT HAS_${reqconfig} AND NOT ${_val}))
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set(MET 1)
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else()
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set(MET 0)
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endif()
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endif()
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if (NOT MET)
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if (${_val})
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message(FATAL_ERROR "This project requires lws must have been configured with ${reqconfig}")
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else()
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message(FATAL_ERROR "Lws configuration of ${reqconfig} is incompatible with this project")
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endif()
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endif()
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endif()
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ENDMACRO()
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set(requirements 1)
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require_lws_config(LWS_ROLE_WS 1 requirements)
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require_lws_config(LWS_WITH_CLIENT 1 requirements)
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if (requirements)
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add_executable(${SAMP} ${SRCS})
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if (websockets_shared)
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target_link_libraries(${SAMP} websockets_shared)
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add_dependencies(${SAMP} websockets_shared)
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else()
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target_link_libraries(${SAMP} websockets)
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endif()
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endif()
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58
minimal-examples/ws-client/minimal-ws-client/README.md
Normal file
58
minimal-examples/ws-client/minimal-ws-client/README.md
Normal file
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@ -0,0 +1,58 @@
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# lws minimal ws client
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This connects to libwebsockets.org using the dumb-increment-protocol.
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It demonstrates how to use the connection retry and backoff stuff in lws.
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## build
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```
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$ cmake . && make
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```
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## Commandline Options
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Option|Meaning
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---|---
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-d|Set logging verbosity
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-s|Use a specific server instead of libwebsockets.org, eg `--server localhost`. Implies LCCSCF_ALLOW_SELFSIGNED
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-p|Use a specific port instead of 443, eg `--port 7681`
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-j|Allow selfsigned tls cert
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-k|Allow insecure certs
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-m|Skip server hostname check
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-e|Allow expired certs
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--protocol|Use a specific ws subprotocol rather than dumb-increment-protocol, eg, `--protocol myprotocol`
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## usage
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Just run it, it will connect to libwebsockets.org and spew incrementing numbers
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sent by the server at 20Hz
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```
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$ ./lws-minimal-ws-client
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[2020/01/22 05:38:47:3409] U: LWS minimal ws client
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[2020/01/22 05:38:47:4456] N: Loading client CA for verification ./libwebsockets.org.cer
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[2020/01/22 05:38:48:1649] U: callback_minimal: established
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[2020/01/22 05:38:48:1739] N:
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[2020/01/22 05:38:48:1763] N: 0000: 30 0
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[2020/01/22 05:38:48:1765] N:
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...
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```
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To test against the lws test server instead of libwebsockets.org, run the test
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server as
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```
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$ libwebsockets-test-server -s
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```
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and run this test app with
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```
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$ ./lws-minimal-ws-client -s localhost -p 7681 -j
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```
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You can kill and restart the server to confirm the client connection is re-
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established if done within the backoff period.
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@ -0,0 +1,58 @@
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-----BEGIN CERTIFICATE-----
|
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MIIFWjCCBEKgAwIBAgISA9x0/oj5PLdW46hsmR82/7ytMA0GCSqGSIb3DQEBCwUA
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||||
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||||
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||||
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||||
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||||
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||||
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||||
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||||
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|
||||
mVB82B0vd08VJYzU7Nf0pz0PWusAmzRoRn81IXkOfBg9ohlSSEoZhHYS7QIDAQAB
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||||
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||||
BgEFBQcDAjAMBgNVHRMBAf8EAjAAMB0GA1UdDgQWBBRmKKyGjufWgp7pR2x0tWxG
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||||
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||||
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||||
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|
||||
dC5vcmcvMBwGA1UdEQQVMBOCEWxpYndlYnNvY2tldHMub3JnMEwGA1UdIARFMEMw
|
||||
CAYGZ4EMAQIBMDcGCysGAQQBgt8TAQEBMCgwJgYIKwYBBQUHAgEWGmh0dHA6Ly9j
|
||||
cHMubGV0c2VuY3J5cHQub3JnMIIBBAYKKwYBBAHWeQIEAgSB9QSB8gDwAHcAdH7a
|
||||
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|
||||
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|
||||
nmTgWfFyS4TNgLNEPCJYo2s75gB1ACk8UZZUyDlluqpQ/FgH1Ldvv1h6KXLcpMMM
|
||||
9OVFR/R4AAABbQrFil4AAAQDAEYwRAIgNSpvz/1JA2aP6fh6ujGNuYfrAvWjlxXo
|
||||
CJtVGe4XaDYCIGmK1/9tl1uQbVD46P5NswnULq06KQmuOrlI3HO4r86HMA0GCSqG
|
||||
SIb3DQEBCwUAA4IBAQBiAlV7wkCsWE99VmZHBmcbZChWyWUHG3LM1hnaQRQjTSYk
|
||||
CIlauCpWzlUd6weuvra85KqBbCYo+1hxbwITI796uAdgtHmBE8nj0VltHwKeSq2s
|
||||
KKiGXBRT7Z7t0VHYSLOlGOVn1auuQFaWBArc0cQ/m1ZsoHvOiHTlKQvVsA4HnIxA
|
||||
CjGY9OOQoh0c36ecbJZ44XKnU9J/OXtDx00aW6QodaZmgMp/OOCghFQUvufkgTUL
|
||||
LZid873/8dJVWjAaj1VdadO1nSbdAfBbeWXy93+vg1aAoig80RoscrzYCaNlwmR7
|
||||
EO5zWxL3l+xUZogQSJuICgUgNzVB3wjn8HeHGsqt
|
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-----END CERTIFICATE-----
|
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-----BEGIN CERTIFICATE-----
|
||||
MIIEkjCCA3qgAwIBAgIQCgFBQgAAAVOFc2oLheynCDANBgkqhkiG9w0BAQsFADA/
|
||||
MSQwIgYDVQQKExtEaWdpdGFsIFNpZ25hdHVyZSBUcnVzdCBDby4xFzAVBgNVBAMT
|
||||
DkRTVCBSb290IENBIFgzMB4XDTE2MDMxNzE2NDA0NloXDTIxMDMxNzE2NDA0Nlow
|
||||
SjELMAkGA1UEBhMCVVMxFjAUBgNVBAoTDUxldCdzIEVuY3J5cHQxIzAhBgNVBAMT
|
||||
GkxldCdzIEVuY3J5cHQgQXV0aG9yaXR5IFgzMIIBIjANBgkqhkiG9w0BAQEFAAOC
|
||||
AQ8AMIIBCgKCAQEAnNMM8FrlLke3cl03g7NoYzDq1zUmGSXhvb418XCSL7e4S0EF
|
||||
q6meNQhY7LEqxGiHC6PjdeTm86dicbp5gWAf15Gan/PQeGdxyGkOlZHP/uaZ6WA8
|
||||
SMx+yk13EiSdRxta67nsHjcAHJyse6cF6s5K671B5TaYucv9bTyWaN8jKkKQDIZ0
|
||||
Z8h/pZq4UmEUEz9l6YKHy9v6Dlb2honzhT+Xhq+w3Brvaw2VFn3EK6BlspkENnWA
|
||||
a6xK8xuQSXgvopZPKiAlKQTGdMDQMc2PMTiVFrqoM7hD8bEfwzB/onkxEz0tNvjj
|
||||
/PIzark5McWvxI0NHWQWM6r6hCm21AvA2H3DkwIDAQABo4IBfTCCAXkwEgYDVR0T
|
||||
AQH/BAgwBgEB/wIBADAOBgNVHQ8BAf8EBAMCAYYwfwYIKwYBBQUHAQEEczBxMDIG
|
||||
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||||
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|
||||
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|
||||
VAYDVR0gBE0wSzAIBgZngQwBAgEwPwYLKwYBBAGC3xMBAQEwMDAuBggrBgEFBQcC
|
||||
ARYiaHR0cDovL2Nwcy5yb290LXgxLmxldHNlbmNyeXB0Lm9yZzA8BgNVHR8ENTAz
|
||||
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|
||||
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|
||||
AAOCAQEA3TPXEfNjWDjdGBX7CVW+dla5cEilaUcne8IkCJLxWh9KEik3JHRRHGJo
|
||||
uM2VcGfl96S8TihRzZvoroed6ti6WqEBmtzw3Wodatg+VyOeph4EYpr/1wXKtx8/
|
||||
wApIvJSwtmVi4MFU5aMqrSDE6ea73Mj2tcMyo5jMd6jmeWUHK8so/joWUoHOUgwu
|
||||
X4Po1QYz+3dszkDqMp4fklxBwXRsW10KXzPMTZ+sOPAveyxindmjkW8lGy+QsRlG
|
||||
PfZ+G6Z6h7mjem0Y+iWlkYcV4PIWL1iwBi8saCbGS5jN2p8M+X+Q7UNKEkROb3N6
|
||||
KOqkqm57TH2H3eDJAkSnh6/DNFu0Qg==
|
||||
-----END CERTIFICATE-----
|
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214
minimal-examples/ws-client/minimal-ws-client/minimal-ws-client.c
Normal file
214
minimal-examples/ws-client/minimal-ws-client/minimal-ws-client.c
Normal file
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@ -0,0 +1,214 @@
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/*
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* lws-minimal-ws-client
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*
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* Written in 2010-2020 by Andy Green <andy@warmcat.com>
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*
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* This file is made available under the Creative Commons CC0 1.0
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* Universal Public Domain Dedication.
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*
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* This demonstrates a ws client that connects by default to libwebsockets.org
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* dumb increment ws server.
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*/
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#include <libwebsockets.h>
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#include <string.h>
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#include <signal.h>
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#include <pthread.h>
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/*
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* This represents your object that "contains" the client connection and has
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* the client connection bound to it
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*/
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static struct my_conn {
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lws_sorted_usec_list_t sul; /* schedule connection retry */
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struct lws *wsi; /* related wsi if any */
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uint16_t retry_count; /* count of consequetive retries */
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} mco;
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static struct lws_context *context;
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static int interrupted, port = 443, ssl_connection = LCCSCF_USE_SSL;
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static const char *server_address = "libwebsockets.org",
|
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*pro = "dumb-increment-protocol";
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|
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/*
|
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* The retry and backoff policy we want to use for our client connections
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*/
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static const uint32_t backoff_ms[] = { 1000, 2000, 3000, 4000, 5000 };
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static const lws_retry_bo_t retry = {
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.retry_ms_table = backoff_ms,
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.retry_ms_table_count = LWS_ARRAY_SIZE(backoff_ms),
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.conceal_count = LWS_ARRAY_SIZE(backoff_ms),
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.secs_since_valid_ping = 3, /* force PINGs after secs idle */
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.secs_since_valid_hangup = 10, /* hangup after secs idle */
|
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.jitter_percent = 20,
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};
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|
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/*
|
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* Scheduled sul callback that starts the connection attempt
|
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*/
|
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|
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static void
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connect_client(lws_sorted_usec_list_t *sul)
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{
|
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struct my_conn *mco = lws_container_of(sul, struct my_conn, sul);
|
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struct lws_client_connect_info i;
|
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|
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memset(&i, 0, sizeof(i));
|
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|
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i.context = context;
|
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i.port = port;
|
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i.address = server_address;
|
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i.path = "/";
|
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i.host = i.address;
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i.origin = i.address;
|
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i.ssl_connection = ssl_connection;
|
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i.protocol = pro;
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i.local_protocol_name = "lws-minimal-client";
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i.pwsi = &mco->wsi;
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i.retry_and_idle_policy = &retry;
|
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i.userdata = mco;
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|
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if (!lws_client_connect_via_info(&i))
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/*
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* Failed... schedule a retry... we can't use the _retry_wsi()
|
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* convenience wrapper api here because no valid wsi at this
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* point.
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*/
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if (lws_retry_sul_schedule(context, 0, sul, &retry,
|
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connect_client, &mco->retry_count)) {
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lwsl_err("%s: connection attempts exhausted\n", __func__);
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interrupted = 1;
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}
|
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}
|
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|
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static int
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callback_minimal(struct lws *wsi, enum lws_callback_reasons reason,
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void *user, void *in, size_t len)
|
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{
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struct my_conn *mco = (struct my_conn *)user;
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|
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switch (reason) {
|
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case LWS_CALLBACK_CLIENT_CONNECTION_ERROR:
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lwsl_err("CLIENT_CONNECTION_ERROR: %s\n",
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in ? (char *)in : "(null)");
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goto do_retry;
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break;
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case LWS_CALLBACK_CLIENT_RECEIVE:
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lwsl_hexdump_notice(in, len);
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break;
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case LWS_CALLBACK_CLIENT_ESTABLISHED:
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lwsl_user("%s: established\n", __func__);
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break;
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case LWS_CALLBACK_CLIENT_CLOSED:
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goto do_retry;
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default:
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break;
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}
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return lws_callback_http_dummy(wsi, reason, user, in, len);
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|
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do_retry:
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/*
|
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* retry the connection to keep it nailed up
|
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*
|
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* For this example, we try to conceal any problem for one set of
|
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* backoff retries and then exit the app.
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*
|
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* If you set retry.conceal_count to be larger than the number of
|
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* elements in the backoff table, it will never give up and keep
|
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* retrying at the last backoff delay plus the random jitter amount.
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*/
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if (lws_retry_sul_schedule_retry_wsi(wsi, &mco->sul, connect_client,
|
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&mco->retry_count)) {
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lwsl_err("%s: connection attempts exhausted\n", __func__);
|
||||
interrupted = 1;
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||||
}
|
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|
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return 0;
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}
|
||||
|
||||
static const struct lws_protocols protocols[] = {
|
||||
{ "lws-minimal-client", callback_minimal, 0, 0, },
|
||||
{ NULL, NULL, 0, 0 }
|
||||
};
|
||||
|
||||
static void
|
||||
sigint_handler(int sig)
|
||||
{
|
||||
interrupted = 1;
|
||||
}
|
||||
|
||||
int main(int argc, const char **argv)
|
||||
{
|
||||
struct lws_context_creation_info info;
|
||||
const char *p;
|
||||
int n = 0;
|
||||
|
||||
signal(SIGINT, sigint_handler);
|
||||
memset(&info, 0, sizeof info);
|
||||
lws_cmdline_option_handle_builtin(argc, argv, &info);
|
||||
|
||||
lwsl_user("LWS minimal ws client\n");
|
||||
|
||||
info.options = LWS_SERVER_OPTION_DO_SSL_GLOBAL_INIT;
|
||||
info.port = CONTEXT_PORT_NO_LISTEN; /* we do not run any server */
|
||||
info.protocols = protocols;
|
||||
|
||||
#if defined(LWS_WITH_MBEDTLS)
|
||||
/*
|
||||
* OpenSSL uses the system trust store. mbedTLS has to be told which
|
||||
* CA to trust explicitly.
|
||||
*/
|
||||
info.client_ssl_ca_filepath = "./libwebsockets.org.cer";
|
||||
#endif
|
||||
|
||||
if ((p = lws_cmdline_option(argc, argv, "--protocol")))
|
||||
pro = p;
|
||||
|
||||
if ((p = lws_cmdline_option(argc, argv, "-s")))
|
||||
server_address = p;
|
||||
|
||||
if ((p = lws_cmdline_option(argc, argv, "-p")))
|
||||
port = atoi(p);
|
||||
|
||||
if (lws_cmdline_option(argc, argv, "-j"))
|
||||
ssl_connection |= LCCSCF_ALLOW_SELFSIGNED;
|
||||
|
||||
if (lws_cmdline_option(argc, argv, "-k"))
|
||||
ssl_connection |= LCCSCF_ALLOW_INSECURE;
|
||||
|
||||
if (lws_cmdline_option(argc, argv, "-m"))
|
||||
ssl_connection |= LCCSCF_SKIP_SERVER_CERT_HOSTNAME_CHECK;
|
||||
|
||||
if (lws_cmdline_option(argc, argv, "-e"))
|
||||
ssl_connection |= LCCSCF_ALLOW_EXPIRED;
|
||||
|
||||
info.fd_limit_per_thread = 1 + 1 + 1;
|
||||
|
||||
context = lws_create_context(&info);
|
||||
if (!context) {
|
||||
lwsl_err("lws init failed\n");
|
||||
return 1;
|
||||
}
|
||||
|
||||
/* schedule the first client connection attempt to happen immediately */
|
||||
lws_sul_schedule(context, 0, &mco.sul, connect_client, 1);
|
||||
|
||||
while (n >= 0 && !interrupted)
|
||||
n = lws_service(context, 0);
|
||||
|
||||
lws_context_destroy(context);
|
||||
lwsl_user("Completed\n");
|
||||
|
||||
return 0;
|
||||
}
|
||||
Loading…
Add table
Reference in a new issue