Go-ActiveSync

Go-ActiveSync

A production-grade Microsoft Exchange ActiveSync (EAS) 14.1 server and library written in Go, using the Echo v5 HTTP framework.

Inspired by Z-Push — the reference PHP implementation — reimplemented in idiomatic Go with a pluggable backend interface.

Features

• Full WBXML encoder/decoder (pkg/wbxml) — no CGO, no dependencies
• Supports all major ActiveSync 14.1 commands (see table below)
• Pluggable backend — implement activesync.Backend to connect any data source
• Embeddable library — import pkg/activesync and add AS support to any Go server
• Test client (cmd/client) — exercises every command with real WBXML encoding
• In-memory demo backend (internal/demo) for quick-start testing
• Graceful shutdown, structured logging (zap), Echo v5 middleware

Quick Start

Build

make build
# Binaries land in ./bin/

Run the demo server

make run
# Server starts on :8080 with in-memory demo backend
# Any username + non-empty password is accepted

Test with the client

# In a second terminal:
./bin/go-activesync-client options
./bin/go-activesync-client provision
./bin/go-activesync-client foldersync
./bin/go-activesync-client sync inbox
./bin/go-activesync-client estimate inbox
./bin/go-activesync-client ping

Project Layout

go-activesync/
├── cmd/
│   ├── server/main.go        — standalone server binary
│   └── client/main.go        — WBXML test client CLI
├── pkg/
│   ├── wbxml/                — WBXML 1.3 encoder/decoder (AS subset)
│   │   ├── defs.go           — 26 code page tables
│   │   ├── decoder.go        — streaming WBXML decoder
│   │   ├── encoder.go        — WBXML encoder
│   │   └── wbxml_test.go
│   ├── protocol/             — AS protocol constants and shared types
│   │   ├── commands.go       — command codes, supported versions
│   │   ├── status.go         — status codes (Sync, FolderSync, Provision, ...)
│   │   └── types.go          — Folder, EmailItem, ContactItem, CalendarItem, ...
│   └── activesync/           — public embeddable library
│       ├── backend.go        — Backend interface
│       ├── server.go         — Server (Echo v5 wrapper)
│       ├── device.go         — DeviceState + DeviceStore
│       ├── options.go        — Options struct
│       ├── middleware.go     — BasicAuth, logging, recovery middleware
│       ├── dispatcher.go     — command routing
│       └── handler_*.go      — one handler per AS command
├── internal/
│   ├── demo/backend.go       — in-memory demo backend
│   └── middleware/           — shared middleware helpers
├── docs/
│   └── SPEC.md               — full implementation specification
├── Makefile
└── go.mod

Supported Commands

Embedding in Your Project

Add the module:

go get github.com/jniltinho/Go-ActiveSync

Implement the Backend interface:

package main

import (
    "context"

    "github.com/jniltinho/Go-ActiveSync/pkg/activesync"
    "github.com/jniltinho/Go-ActiveSync/pkg/protocol"
)

type MyBackend struct{}

func (b *MyBackend) Logon(ctx context.Context, user, domain, pass string) bool {
    return user == "alice" && pass == "secret"
}

func (b *MyBackend) GetFolderList(ctx context.Context) ([]protocol.Folder, error) {
    return []protocol.Folder{
        {ServerID: "inbox", DisplayName: "Inbox", Type: protocol.FolderDefaultInbox},
    }, nil
}

// ... implement all Backend methods ...

func main() {
    srv := activesync.NewServer(activesync.Options{
        Addr: ":443",
        TLSCert: "/etc/ssl/cert.pem",
        TLSKey:  "/etc/ssl/key.pem",
    })

    srv.SetBackendFactory(func() activesync.Backend {
        return &MyBackend{}
    })

    ctx := context.Background()
    if err := srv.Start(ctx); err != nil {
        panic(err)
    }
}

WBXML Library Usage

import (
    "bytes"
    "github.com/jniltinho/Go-ActiveSync/pkg/wbxml"
)

// Encode
var buf bytes.Buffer
enc := wbxml.NewEncoder(&buf)
enc.StartTag("FolderSync")
enc.StringElement("SyncKey", "0")
enc.EndTag()
enc.Flush()

// Decode
dec, _ := wbxml.NewDecoder(&buf)
tokens, _ := dec.DecodeAll()
for _, tok := range tokens {
    if tok.Type == wbxml.TokenTypeStartTag {
        fmt.Println(tok.Name)
    }
}

Makefile Targets

Protocol Reference

See docs/SPEC.md for the full implementation specification including:

• WBXML encoding details and all 26 code pages
• Request flow diagrams
• Backend interface contract
• State management approach
• Security considerations

Official Microsoft protocol documentation:

• [MS-ASHTTP] Exchange ActiveSync: HTTP Protocol
• [MS-ASWBXML] Exchange ActiveSync: WAP Binary XML Algorithm
• [MS-ASCMD] Exchange ActiveSync: Command Reference Protocol

License

MIT License. See LICENSE.

Contributing

1. Implement a Backend for your data source
2. Run make test to verify the codec
3. Submit a PR — see docs/SPEC.md for the protocol specification