Tcl

WebSocket Connect through HTTP Proxy

See more WebSocket Examples

This example shows how to establish a WebSocket connection through an HTTP proxy server. Tcl

load ./chilkat.dll

set success 0

# This example requires the Chilkat API to have been previously unlocked.
# See Global Unlock Sample for sample code.

# --------------------------------------------------
# This example borrows the code from the REST using HTTP Proxy example.
# We first use the Chilkat Socket object to establish a connection to the WebSocket server through an HTTP proxy.
# Next, the Rest object uses the Socket object for its connection.
# Finally, the WebSocket object uses the Rest object for its connection.  
# 

set rest [new_CkRest]

set socket [new_CkSocket]

# Set the HTTP proxy domain or IP address, and port.
CkSocket_put_HttpProxyHostname $socket "192.168.1.79"
CkSocket_put_HttpProxyPort $socket 808

# Provide authentication to the HTTP proxy, if needed.
CkSocket_put_HttpProxyUsername $socket "HTTP_PROXY_LOGIN"
CkSocket_put_HttpProxyPassword $socket "HTTP_PROXY_PASSWORD"
CkSocket_put_HttpProxyAuthMethod $socket "Basic"

# Indicate that HTTP requests (i.e. the WebSocket opening handshake) will be sent over the socket.
# This is important for how the HTTP proxy connection is established.
CkSocket_put_HttpProxyForHttp $socket 1

# Connect to the websocket server through the HTTP proxy.
set bTls 0
set port 80
set maxWaitMs 5000
set success [CkSocket_Connect $socket "some-websocket-server.com" $port $bTls $maxWaitMs]
if {$success != 1} then {
    puts "Connect Failure Error Code: [CkSocket_get_ConnectFailReason $socket]"
    puts [CkSocket_lastErrorText $socket]
    delete_CkRest $rest
    delete_CkSocket $socket
    exit
}

# Tell the Rest object to use the connected socket.
set success [CkRest_UseConnection $rest $socket 1]
if {$success != 1} then {
    puts [CkRest_lastErrorText $rest]
    delete_CkRest $rest
    delete_CkSocket $socket
    exit
}

set ws [new_CkWebSocket]

# Tell the WebSocket to use this connection.
set success [CkWebSocket_UseConnection $ws $rest]
if {$success != 1} then {
    puts [CkWebSocket_lastErrorText $ws]
    delete_CkRest $rest
    delete_CkSocket $socket
    delete_CkWebSocket $ws
    exit
}

# Add the standard WebSocket open handshake headers that will be needed.
# (This adds the required HTTP request headers to the rest object.)
CkWebSocket_AddClientHeaders $ws

# Add any additional headers that might be desired.
# Two common WebSocketSpecific headers are "Sec-WebSocket-Protocol" and "Origin".
CkRest_AddHeader $rest "Sec-WebSocket-Protocol" "x-some-websocket-subprotocol"
CkRest_AddHeader $rest "Origin" "http://some-websocket-server.com"

# Do the open handshake.
set responseBody [CkRest_fullRequestNoBody $rest "GET" "/something"]
if {[CkRest_get_LastMethodSuccess $rest] != 1} then {
    puts [CkRest_lastErrorText $rest]
    delete_CkRest $rest
    delete_CkSocket $socket
    delete_CkWebSocket $ws
    exit
}

# If successful, the HTTP response status code should be 101,
# and the response body will be empty. (If it failed, we'll have a look
# at the response body..)
set statusCode [CkRest_get_ResponseStatusCode $rest]
puts "Response status code: $statusCode"

if {$statusCode != 101} then {
    puts "$responseBody"
    puts "-- Failed because of unexpected response status code."
    delete_CkRest $rest
    delete_CkSocket $socket
    delete_CkWebSocket $ws
    exit
}

# We have the expected 101 response, so let's now validate the 
# contents of the response, such as the value sent by the server in the
# Sec-WebSocket-Accept header. 
set success [CkWebSocket_ValidateServerHandshake $ws]
if {$success != 1} then {
    puts [CkWebSocket_lastErrorText $ws]
    delete_CkRest $rest
    delete_CkSocket $socket
    delete_CkWebSocket $ws
    exit
}

puts "WebSocket connection successful."

# The application may now begin sending and receiving frames on the WebSocket connection.
# (At this point, we're done with the rest and socket objects...)

puts "Success."

delete_CkRest $rest
delete_CkSocket $socket
delete_CkWebSocket $ws