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PARAMETER SUBSTITUTION
-
There is no format of configuration file with some syntax sugar
for DeleGate (yet),
but there is a simple recursive substitution mechanism instead,
to assemble hierarchical and possibly distributed parts of parameters
into a single list of parameters (or options).
Options and parameters can be loaded from external "substitution resources". An option like "+=file" is substituted by a list of options enumerated in the resource named "file". An option like "name=+=file" is substituted by a list of "name=value" where the "value" is enumerated in the "file". Similarly an option like "name=xxx:+=file" is substituted by a list of "name=xxx:value".
A substitution resource can be given in an encrypted format. Encrypted data can be directly represented in the string of format as "+=enc:ext::XXXX:" in which the part of XXXX contains the encrypted data. This format of data is created with "-Fenc" option of DeleGate. When it is named with the suffix ".cdh" as "+=conf.cdh", it is decrypted by "Credhy" using the passphrase for decryption which is specified as the password of the "config" user.
Substitution can be done recursively. In this case, a relative resource name is searched in DGPATH or LIBPATH. By default, DGPATH='+:.:${HOME}/delegate' where "+" stands for the place where the "caller" resource is. For example, if "+=file2" is referred from caller file "/local/etc/file1", the "file2" will be searched first as "/local/etc/file2". A resource name can be specified in full URL like "+={file:/local/etc/file1}" or "+={http://host/file}".
paramRef == +=[URL][?label,[label]*]
paramList == line
line
...
paramListPart == CASE label
paramList
ESAC
Substitution resources are the list of options (or parameters) where each line stands for an option (or a parameter). In each line, strings after sharp character(#) will be ignored as a comment. White space characters (SPACE, TAB, LF and CR) at the beginning or the ending of each line are ignored. Single quote(') and double quote(") are stripped. Back slash character(\) let the succeeding character be as is.
Example: The following five examples have the same meaning with each other.
- PERMIT=+=permits
- [content of permits]
-
a:b:c
a:b:d
a:e:f
x:y:z
... - PERMIT=a:b:+=abclients PERMIT=+=others
- [content of abclients]
-
c
d
- [content of others]
-
a:e:f
x:y:z
... - PERMIT=+=permits
- [content of permits]
- [content of permits]
PERMIT=a:b:c PERMIT=a:b:d PERMIT=a:e:f PERMIT=x:y:z ...
Substitution resources will be reloaded when the DeleGate restart receiving a SIGHUP signal or by "-restart" action in CRON parameter.
Another substitution is in the form "name=-=URL" which loads the content of URL into a temporary file on local file system (under ACTDIR), then the parameter is rewritten to "name=/path/of/temporary-file". This will be useful when you wish to pass remote resources to CGI or CFI programs, like "-eCONFIGDATA=-=http://server/configData", then those programs will be given an environment variable named CONFIGDATA of which value is a temporary file name containing the content of "http://server/configData".