sayotte / iscdhcp

Go goyacc-based config file parser/generator for ISC-DHCP

Brief

This is a config-file parser and generator library for ISC-DHCP, written in the Go programming language.

The parser is generated using the goyacc utility.

Supported statements to date include a common subset of those used by DHCPd. The code should be easy to extend.

Usage

Parsing

fd, err := os.Open(fileName)
if err != nil {
    log.Fatalf("os.Open(%q): %s", fileName, err)
}

statements, err := iscdhcp.Decode(fd)
if err != nil {
    log.Fatalf("iscdhcp.Decode(): %s", err)
}

Generating

hs := HostStatement{
    Hostname: "serverA.myDomain.tld",
}
hs.Statements = append(hs.Statements, HardwareStatement{"ethernet", "0:1:2:3:4:5"})
hs.Statements = append(hs.Statements, FixedAddressStatement{net.ParseIP("1.2.3.4")})
hs.Statements = append(hs.Statements, IncludeStatement{"filename.cfg"})

subnetStmt := SubnetStatement{
    SubnetNumber: net.ParseIP("1.2.3.0"),
    Netmask:      net.ParseIP("255.255.255.0"),
}
subnetStmt.Statements = append(subnetStmt.Statements, hs)

fmt.Println(subnetStmt.IndentedString(""))

The above yields this:

subnet 1.2.3.0 netmask 255.255.255.0 {
    host serverA.myDomain.tld {
        hardware ethernet 0:1:2:3:4:5;
        fixed-address 1.2.3.4;
        include "filename.cfg";
    }
}

Modifying

New statements must first be defined in statements.go, and satisfy the iscdhcp.Statement interface.

To update the parser, edit the goyacc grammar definitions in the parser.y file. After updating these you must call goyacc parser.y to regenerate the y.go file, after which you can rebuild the package.

To update generator code, edit the IndentedString() method of the statements with which you're concerned.

It's best to modify both parser- and generator-code in lockstep, and add "round-trip" tests for any new statements introduced to ensure that the generated output is understandable to the parser. Round-trip tests are found in statements_test.go.

Contributing

Contributions should be submitted as pull requests from a named (i.e. not master) branch.

Running make (and the unit tests and linter checks it entails) on the result of merging or rebasing your PR branch over current master branch must exit successfully.

iscdhcp's Issues

Parse example configuration

I tried to parse the example configuration from
https://github.com/42wim/isc-dhcp/blob/master/server/dhcpd.conf.example
even If I delete the comments it does not work.