[1/2] Add support for loglevels in filters

[Martijn van Duren]

Hello misc@,

The diff below adds support for 4 different loglevels to smtpd filters:
warn, info, debug, trace. These for levels are in line with the
loglevels of smtpd itself and are emitted on said levels.

To keep backwards compatibility and to keep things simpler for coders
who don't care about loglevels, loglines without prefix will be logged
at the warn (brief) level.

martijn@

diff bfd8327fa29c9064ad80b6cdb8235722bbf18877 
acdf9909bf270b4d19c207f705c0e1bef68c8cc1
commit - bfd8327fa29c9064ad80b6cdb8235722bbf18877
commit + acdf9909bf270b4d19c207f705c0e1bef68c8cc1
blob - b9c5d55c15f9052bc726f1a09484f0e32f75e2f3
blob + cbd8657110f1cac373d7964c20b9fca57fc17ec1
--- usr.sbin/smtpd/lka_filter.c
+++ usr.sbin/smtpd/lka_filter.c
@@ -317,8 +317,26 @@ processor_errfd(struct io *io, int evt, void *arg)
 
        switch (evt) {
        case IO_DATAIN:
-               while ((line = io_getline(io, &len)) != NULL)
-                       log_warnx("%s: %s", name, line);
+               while ((line = io_getline(io, &len)) != NULL) {
+                       if (strncasecmp(line, "WARN|",
+                           sizeof("WARN|") - 1) == 0)
+                               log_warnx("%s: %s", name,
+                                   line + sizeof("WARN|") - 1);
+                       else if (strncasecmp(line, "INFO|",
+                           sizeof("INFO|") - 1) == 0)
+                               log_info("%s: %s", name,
+                                   line + sizeof("INFO|") - 1);
+                       else if (strncasecmp(line, "DEBUG|",
+                           sizeof("DEBUG|") - 1) == 0)
+                               log_debug("%s: %s", name,
+                                   line + sizeof("DEBUG|") - 1);
+                       else if (strncasecmp(line, "TRACE|",
+                           sizeof("TRACE|") - 1) == 0)
+                               log_trace(TRACE_FILTERS, "%s: %s", name,
+                                   line + sizeof("TRACE|") - 1);
+                       else
+                               log_warnx("%s: %s", name, line);
+               }
        }
 }
 
blob - 5a1bcbb39e2380f90adc754d4849b1ac7385c1fe
blob + d5636b55abfd4bc86cd865851f4b9aa0cb9f2759
--- usr.sbin/smtpd/smtpd-filters.7
+++ usr.sbin/smtpd/smtpd-filters.7
@@ -74,6 +74,12 @@ and may be written in any language.
 must not use blocking I/O,
 they must support answering asynchronously to
 .Xr smtpd 8 .
+.Pp
+Loglines to
+.Xr stderr 4
+can be prefixed with WARN|, INFO|, DEBUG|, or TRACE| to specify the level at
+which they need to be logged.
+Lines without a prefix will be logged as warning.
 .Sh REPORT AND FILTER
 The API relies on two streams,
 report and filter.