sendmail, 4th Edition

socket

Perform lookups over a socket V8.13 and later

Beginning with V8.13 sendmail, a new database-map type called socket is available for your use.^[352] You declare a socket database-map type like this:

Kname socket type:port@host

Here, name is the identifier that you will later use in rule sets. The type:port@host is declared in the same fashion as a Milter is declared using the X configuration command (The X Configuration Command on page 1173). For example:

Ktrustedip socket inet:[e-mail]

Here, lookups can be made in rule sets using the database map named trustedip. The sendmail program will make an IPv4 connection (the inet) to port 8020 on the host db5.example.gov. Once the connection has been made, lookups are performed using a simple dialog that looks like this:

sendmail sends:    database_map_name key
sendmail receives:   status datum

Note that neither the request sent nor the reply received may end in a carriage-return/linefeed pair, a carriage return, or a line feed. Also note that the two parts of each dialog are separated by a single space character.

Both the request and the reply begin and end with characters that denote their length and termination. The length is an ASCII representation of the number of characters sent or received, stated as a prefix and a colon. Both the request and the reply are terminated by a comma. But note that the length prefix must not include the comma in its length computation. For example:

sendmail sends:    17:trustedip 1.2.3.4,
sendmail receives ...