[HILTI] Spicy Parsing WebSockets - how to end a list

Fernandez, Mark I mfernandez at mitre.org
Thu Jul 27 12:09:08 PDT 2017

Is the sink executing as you intend?  If not, it could be because when the hook “on %init” is executed when the routine is initialized, but at that time, the element “wss_data” has not been parsed yet.  Perhaps try:

on wss_data {
      self.sub.connect(new Sub());


From: hilti-bounces at ICSI.Berkeley.EDU [mailto:hilti-bounces at ICSI.Berkeley.EDU] On Behalf Of Jennifer Gates
Sent: Thursday, July 27, 2017 2:56 PM
To: Robin Sommer <robin at icir.org>
Cc: hilti at ICSI.Berkeley.EDU
Subject: Re: [HILTI] Spicy Parsing WebSockets - how to end a list

Thanks for the response.  Unfortunately, the &eod doesn't work with a list, just with bytes.  Because the end of the connection is simply the end of the last byte of actual data, there is no look-ahead token for the list to work. At least that is what it seems to me.

Last night I started down another path. I am trying to use a sink construct.  Here is some of the code:

export type WS_Handshake_Success = unit {

        success     : /^(HTTP|http)/;

        dvalue      : DataValue;

        svrheaders     : list<Header> ;

        end_of_hdrs : /\x0d\x0a\x0d\x0a/;

        wss_data : bytes &eod &convert=terminate($$) &transient -> self.sub;

        on %init {

                self.sub.connect(new Sub());

        var sub: sink;

export type Sub = unit {

ws_msgs : list<WS_Message>;

    : DataEnd;


The terminate function appends a byte sequence (constant DataEnd) to the raw bytes that I can then use to identify the end of the data when parsing the messages in the Sub unit. That way the WS_Messages are properly parsed within the Sub unit.

The only piece that I'm working on now is how to put that parsed data back into the original WS_Handshake unit. Right now a "print self" statement of the WS_Handshake just lists sub=<sink>. To get the individual list items to show I need to print the sub unit.

Is there a way to make the Sub unit a part of the WS_Handshake unit?

Thank you,

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