-d8.2 | sendmail, 4th Edition

-d8.2

Call to getcanonname(3)

Debug command-line switch

The routine dns_getcanonname ( ) in domain.c of the sendmail source converts a hostname to a fully qualified domain name . This routine is called only if DNS is used to look up hostnames, as determined by the ResolverOptions option (ResolverOptions) and the ServiceSwitchFile option (ServiceSwitchFile). If it is, dns_getcanonname ( ) can be called from three places: during startup to get the values for $w , $j , and $m (-d0.4); when a host is looked up via the $[ and $] canonify operators (Section 18.7.6); or when a host is looked up using the host database map (host).

The -d8.2 debugging switch shows the hostname before it is fully qualified with this call:

 dns_getcanonname(  host  ,  flag  )

If the flag is nonzero, calls to the getmxrr ( ) routine (which looks up MX records) are also traced. On entry to that routine, sendmail will print:

 getmxrr(  host  , droplocalhost=  bool  )

The host is the hostname whose MX records are being looked up. The bool , if nonzero, means that all MX records that are less preferred than the local host (as determined by $=w ) will be discarded. If zero, they will be retained.

The -d8.2 debugging switch also causes sendmail to show the result of processing the ResolverOptions option's settings (ResolverOptions) while reading the configuration file:

 _res.options =  hex  , HasWildcardMX =  1 or 0

The hex is a hexadecimal representation of the state structure's options variable as described in <resolv.h >. The value of HasWildcardMX is determined by its prefix ( + or - ) when listed with the ResolverOptions option.