10. Configuration Intro

This section describes configuration of the dhcp-agent components.

10.1 The Configuration File Parser

All configurable components use a single parser, which follows a simple grammar and accepts the same type of tokens. This is good news since it means the configuration files will look very similar. The only differences will be the directives each component accepts.

10.2 The Tokens

The parser accepts a set of tokens which it uses to build complete statements.

• string

  Strings can be a single alphanumeric contiginous string of characters, a quoted alphanumeric string of characters, and may contain other characters as long as they are preceeded by a backslash. If newlines are present, they may only be present in a quoted string and must be preceeded by a backslash.

  examples:

  foobar

  ``foo bar''

  ``foo:bar''

  ``foo \ bar''

• assignment:

  The equal character ("=") signifies assignment.

  examples:

  foo = bar

  blah = "foo bar"

• blocks:

  Grouping can be done via blocks which begin with a "{" character and are terminated by a "}" character

  examples:

  foo { bar = foo }

• terminator:

  The semicolon (";") character is used to terminate statements.

  examples:

  foo = bar;

• lists:

  Commas (",") are used to denote a list of items. Currently lists of strings are used.

  foo = bar, blah;

As the reader has noted, anything except a few special characters defaults to a string which is then evaluated at a higher level.

10.3 Directives

The configuration files are made up of directives which in turn are made up of the above tokens. Each directive begins with an identifier and is terminated by the terminator (";").

set foo = blah;

Here "set" is the identifier, or the command name, and what follows is dependant on the command. The chapters below will describe all the configuration directives for the components of dhcp-gent.