EPP Go - Extensible Provisioning Protocol Server and Client

This is an implementation of how to handle EPP requests concurrently, both as a client and as a server. The main focus lays implementing types that may be used both as a client and as a server. These types should be easy to use and support all the allowed ways of setting up name spaces, attributes and tags. With the types implemented the initial focus will be to ensure a complete server implementation may be created. Since this is registry specific there will probably only be minor helpers and wrappers.

NOTE

This is a work in progress and a long way from completed. This repository is created to allow collaborations and inspire other people. This probject is a private project and an experiment to work with XSD files and XML with Go.

Types

A big motivation behind this project is to define all the available EPP types and even some extensions. This is so that even if you don't use this server or client you should be able to use the types to marshal or unmarshal your XML to your desired system.

There are a lot of knowns problems with this, especially since EPP is so heavily dependent on namespaces. This issue in the golang/go project summarize the most common issues with namespaces, aliases and attributes.

The way this is handled in this project is to first define all types as an outer tag for each part with the RFC namespace defined. The code then uses go-libxml to figure out where the namespaces should be, adds an alias and xmlns tag and then uses the aliases on all the child elements.

Sadly, this does not solve the issue that the XML should be able to be unmarshalled to the defined types despite the namespace or alias. To handle this a codegen binary is bundled in this project which can generate a copy of all types without the namespace.

Example usage and installment.

$ go install ./cmd/type-generator/...
$ type-generator
Generated file: contact_auto_generated.go
Generated file: domain_auto_generated.go
Generated file: host_auto_generated.go
...

To generate XML to be used for a client, use the specified type for this.

domainInfo := types.DomainInfoType{
    Info: types.DomainInfo{
        Name: types.DomainInfoName{
            Name:  "example.se",
            Hosts: types.DomainHostsAll,
        },
    },
}

bytes, err := Encode(
    domainInfo,
    ClientXMLAttributes(),
)

if err != nil {
    panic(err)
}

The above code will generate the following XML.

<?xml version="1.0" encoding="UTF-8"?>
<epp xmlns="urn:ietf:params:xml:ns:epp-1.0">
  <command>
    <info>
      <domain:info xmlns:domain="urn:ietf:params:xml:ns:domain-1.0" xmlns="urn:ietf:params:xml:ns:domain-1.0">
        <domain:name hosts="all">example.se</domain:name>
      </domain:info>
    </info>
  </command>
</epp>

To unmarshal already created XML no matter the namespace or alias, use the auto genrated types. The XML listed above could be unmarshaled like this.

request := DomainInfoTypeIn{}

if err := xml.Unmarshal(inData, &request); err != nil {
    panic(err)
}

fmt.Println(request.Info.Name.Name) // Prints `example.se`

Client

To quickly get up and running and support testing of the server the repository contains a set of real world examples of EPP commands foudn in xml/commands.

Inside the example folder there's a client utilizing a few of the types and all of the read/writering confirming to EPP RFC. This client reads from STDIN so it's just to copy and paste any of the example XML file contents to test changes.

References

XSD files

All XSD schemas can be found att IANA web page. XSD files from this repository linked below.

• contact-1.0.xsd
• domain-1.0.xsd
• epp-1.0.xsd
• eppcom-1.0.xsd
• host-1.0.xsd
• secDNS-1.0.xsd
• secDNS-1.1.xsd

EPP RFC

• RFC 5730 Extensible Provisioning Protocol (EPP)
• RFC 5731 Extensible Provisioning Protocol (EPP) Domain Name Mapping
• RFC 5732 Extensible Provisioning Protocol (EPP) Host Mapping
• RFC 5733 Extensible Provisioning Protocol (EPP) Contact Mapping
• RFC 5734 Extensible Provisioning Protocol (EPP) Transport over TCP
• RFC 5910 Domain Name System (DNS) Security Extensions Mapping for the Extensible Provisioning Protocol (EPP)

TLD specific (.SE)

• EPP extension iis-1.2.xsd

Development and testing

XML files are linted with xmllint.

To validate XML libxml2 (bindings for Go) is used. This package requires you to install the libxml2 C libraries.

Installation macOS

Since macOS 10.14 brew won't link packages and libraries bundlede with macOS. This includes libxml2 and it's header files.

$ brew install libxml2

$ PKG_CONFIG_PATH="/usr/local/opt/libxml2/lib/pkgconfig" \
    go get github.com/lestrrat-go/libxml2/...