Lisp Knowledgebase: How to query TCP host address and name details

Lisp Knowledgebase

Title: How to query TCP host address and name details

ID: 17001

Product: LispWorks
Version: All
OS: All

Description: The C functions gethostbyname() and gethostbyaddr() can be used to find details of hosts from TCP naming services. These can be called easily from Lisp via the function COMM:GET-HOST-ENTRY documented below.

get-host-entry

Function

Summary
Returns address or name information about a given host.

Package
comm

Signature
get-host-entry host &key fields => field-values

Arguments
host
A number or a string.
fields
A list of keywords.

Values
field-values
Values, one for each field.

Description
Using whatever host naming services are configured on the current machine, get-host-entry returns address or name information about the given host. NIL is returned if the host is unknown.

The host argument can be one of the following:

a name string, e.g. "www.foobar.com"

a dotted inet address string, e.g. "209.130.14.246"

a integer representing the inet address, e.g. #xD1820EF6

The fields argument is a list of keywords describing what information to return for the host. If get-host-entry succeeds, it returns multiple values, one value for each field specified. The following fields are allowed:

field	returned value
`:address`	the IP address as in integer
`:name`	the primary name as a string
`:aliases`	the alias names as a list of strings

Examples

CL-USER 1 > (comm:get-host-entry "www.foobar.com" :fields '(:address)) 3514961654
CL-USER 2 > (comm:get-host-entry 3514961654 :fields '(:name)) "www.foobar.com"
CL-USER 3 > (comm:get-host-entry "www.foobar.com" :fields '(:name :aliases :address)) "www.foobar.com" NIL 3514961654
CL-USER 4 >