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Traffic Server Software Developers Kit

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Intercepting HTTP Transaction Functions

INKHttpTxnIntercept

Enables a plugin to intercept an HTTP client’s request and serve content in place of the origin server.

Prototype

INKReturnCode INKHttpTxnIntercept (INKCont contp, INKHttpTxn txnp)

Arguments

INKCont contp is the continuation called to accept the connection.

INKHttpTxn txnp is the current HTTP transaction the plugin wants to intercept.

Description

Allows a plugin to intercept an HTTP client's request and serve content in place of the origin server. The request is intercepted immediately after it is read by Traffic Server; the origin server is not contacted. This API should be used in the INK_HTTP_READ_REQUEST_HDR_HOOK hook.

Once INKHttpTxnIntercept is called, the handler of the continuation contp receives an event INK_EVENT_NET_ACCEPT. Note that the continuation passed should not have a NULL mutex; if it does, then an error is returned. The void *data passed to the handler of the continuation contp is a data of type NetVConnection that represents the connection. Once a vconnection is established, the user can use regular VConnection operations (INKVConnRead, INKVConnWrite, etc...).

A typical scenario for using INKHttpTxnIntercept is as follows:

  • Call INKHttpTxnIntercept from hook INK_HTTP_READ_REQUEST_HDR_HOOK.

  • Get called back on the continuation's handler that's passed as an argument to INKHttpTxnIntercept.

  • Get the vconnection from the argument void *data .

  • Use INKVConnRead to get the HTTP request. Note that you will not receive the event INK_VCONN_READ_COMPLETE - you will only receive the INK_VCONN_READ_READY event because the number of characters to be read is unknown. You should rely on INKTHttpParser to parse the request and then return a status INK_PARSE_DONE when request is fully received (escape sequence \r\n\r\n read).

  • Use INKHttpParser to parse the request.

  • Use INKVConnWrite to write the HTTP response.

[Note] Note

Because the request and response do not go through the Traffic Server HTTP state machine, neither is cached by Traffic Server. The request is logged in squid.log.

Returns

INK_SUCCESS if the API is called successfully.

INK_ERROR if an error occurs while calling the API or if an argument is invalid. This error is also returned if the continuation passed has a NULL mutex.