bionic (3) TSHttpHookAdd.3ts.gz

NAME

       TSHttpHookAdd - intercept Traffic Server events

SYNOPSIS

       #include <ts/ts.h>

       void TSHttpHookAdd(TSHttpHookID id, TSCont contp)

       void TSHttpSsnHookAdd(TSHttpSsn ssnp, TSHttpHookID id, TSCont contp)

       void TSHttpTxnHookAdd(TSHttpTxn txnp, TSHttpHookID id, TSCont contp)

DESCRIPTION

       Hooks  are  points  in Apache Traffic Server transaction HTTP processing where plugins can step in and do
       some work. Registering a plugin function for callback amounts to adding the function to a hook.  You  can
       register your plugin to be called back for every single transaction, or for specific transactions only.

       HTTP  transaction hooks are set on a global basis using the function TSHttpHookAdd(). This means that the
       continuation  specified  as  the  parameter  to  TSHttpHookAdd()  is  called   for   every   transaction.
       TSHttpHookAdd() is typically called from TSPluginInit() or TSRemapInit().

       TSHttpSsnHookAdd()  adds  contp to the end of the list of HTTP session hooks specified by id.  This means
       that contp is called back for every transaction within the session, at the point specified  by  the  hook
       ID.  Since  contp  is  added  to a session, it is not possible to call TSHttpSsnHookAdd() from the plugin
       initialization routine; the plugin needs a handle to an HTTP session.

       TSHttpTxnHookAdd() adds contp to the end of the list of HTTP transaction hooks  specified  by  id.  Since
       contp  is  added  to  a  transaction,  it  is  not  possible  to  call TSHttpTxnHookAdd() from the plugin
       initialization routine but only when the plugin has a handle to an HTTP transaction.

RETURN VALUES

       None. Adding hooks is always successful.

EXAMPLES

       The following example demonstrates how to add global, session and transaction hooks:

          #include <ts/ts.h>

          static int
          handler(TSCont contp, TSEvent event, void *edata)
          {
              TSHttpSsn ssnp;
              TSHttpTxn txnp;

              switch (event){
              case TS_EVENT_HTTP_SSN_START:
                  ssnp = (TSHttpSsn) edata;
                  // Add a session hook ...
                  TSHttpSsnHookAdd(ssnp, TS_HTTP_TXN_START_HOOK, contp);
                  TSHttpSsnReenable(ssnp, TS_EVENT_HTTP_CONTINUE);
                  return 0;
              case TS_EVENT_HTTP_TXN_START:
                  txnp = (TSHttpTxn) edata;
                  // Add a transaction hook ...
                  TSHttpTxnHookAdd(txnp, TS_HTTP_READ_REQUEST_HDR_HOOK, contp);
                  TSHttpTxnReenable(txnp, TS_EVENT_HTTP_CONTINUE);
                  return 0;
              default:
                   break;
              }

              return 0;
          }

          void
          TSPluginInit (int argc, const char *argv[])
          {
              TSCont contp;
              contp = TSContCreate(handler, NULL);
              TSHttpHookAdd(TS_HTTP_SSN_START_HOOK, contp);
          }

SEE ALSO

       TSAPI(3ts), TSContCreate(3ts), TSLifecycleHookAdd(3ts)

COPYRIGHT

       2018, dev@trafficserver.apache.org