Am 17.10.2014 um 16:48 schrieb Wietse Venema: > (This message is mostly of interest to Claus Assmann) > > This week I fixed a problem or PREPEND actions in access maps or > policy server reponses that was giving problems with DMARC setups > that combine of SPF policy server with a DKIM Milter. > > Meanwhile, Christian R??ner has pointed out that there still is a > different problem with header insert requests, this time in Milter > responses. > > Here is a quote from the Milter API documentation, on-line at > https://www.milter.org/developers/api/smfi_insheader > > int smfi_insheader( > SMFICTX *ctx, > int hdridx, /* header position */ > char *headerf, /* header label */ > char *headerv /* header value */ > ); > > * A filter will receive only headers that have been sent by the > SMTP client and those header modifications by earlier filters. > It will not receive the headers that are inserted by sendmail > itself. This makes the header insertion position highly dependent > on the headers that exist in the incoming message and those > that are configured to be added by sendmail. For example, > sendmail will always add a Received: header to the beginning > of the headers. Setting hdridx to 0 will actually insert the > header before this Received: header. However, later filters can > be easily confused as they receive the added header, but not > the Received: header, thus making it hard to insert a header > at a fixed position. > > Thus, the first Milter in a list of Milters sees a message header > like this: > > Headers from SMTP client > > When the first Milter issues header insert requests with index 0, > the resulting message looks like this with Postfix and Sendmail: > > Header2 inserted with index 0 (internal header index 0) > Header1 inserted with index 0 (internal header index 1) > Received: header from receiving MTA (internal header index 2) > Headers from SMTP client (internal header index 3...) > > With Sendmail, the second etc. Milters see the following header: > > Header2 inserted with index 0 (internal header index 0) > Header1 inserted with index 0 (internal header index 1) > Headers from SMTP client (internal header index 3...) > > While with Postfix they see something different: > > Header1 inserted with index 0 > Received: header from receiving MTA > Headers from SMTP client > > A naive workaround is to put "index 0" headers under Postfix's own > Received header. Then, Milters see the same headers as they would > see with Sendmail. But the problem is that the internal header > indices would differ from those with Sendmail: > > Header2 inserted with index 0 (internal header index 1) > Header1 inserted with index 0 (internal header index 2) > Headers from SMTP client (internal header index 3...) > > These header index differences complicate life for Milter users. > > To avoid this difference with Sendmail, Postfix would have to > implement the same behavior as Sendmail: ignore the MTA's own > received header when reporting headers to Milters, but don't ignore > the MTA's own received header when receiving Milter requests with > a header index. That is, ignore the header based on its name, not > on its position. > > If we do that, then we can also roll back this week's patch that > placed access/policy PREPENDed headers after the MTA's own received > header. > > Wietse >
Thank you Wietse Christian and Claus for loooking to a code solution at that milter stuff !!! Best Regards MfG Robert Schetterer -- [*] sys4 AG http://sys4.de, +49 (89) 30 90 46 64 Franziskanerstraße 15, 81669 München Sitz der Gesellschaft: München, Amtsgericht München: HRB 199263 Vorstand: Patrick Ben Koetter, Marc Schiffbauer Aufsichtsratsvorsitzender: Florian Kirstein
