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HTTP/TLS hostname multiplexing library for Go


go-vhost is a simple library that lets you implement virtual hosting functionality for different protocols (HTTP and TLS so far). go-vhost has a high-level and a low-level interface. The high-level interface lets you wrap existing net.Listeners with "muxer" objects. You can then Listen() on a muxer for a particular virtual host name of interest which will return to you a net.Listener for just connections with the virtual hostname of interest.

The lower-level go-vhost interface are just functions which extract the name/routing information for the given protocol and return an object implementing net.Conn which works as if no bytes had been consumed.

API Documentation


l, _ := net.Listen("tcp", *listen)

// start multiplexing on it
mux, _ := vhost.NewHTTPMuxer(l, muxTimeout)

// listen for connections to different domains
for _, v := range virtualHosts {
    vhost := v

    // vhost.Name is a virtual hostname like ""
    muxListener, _ := mux.Listen(vhost.Name())

    go func(vh virtualHost, ml net.Listener) {
        for {
            conn, _ := ml.Accept()
            go vh.Handle(conn)
    }(vhost, muxListener)

for {
    conn, err := mux.NextError()

    switch err.(type) {
    case vhost.BadRequest:
        log.Printf("got a bad request!")
        conn.Write([]byte("bad request"))
    case vhost.NotFound:
        log.Printf("got a connection for an unknown vhost")
        conn.Write([]byte("vhost not found"))
    case vhost.Closed:
        log.Printf("closed conn: %s", err)
        if conn != nil {
            conn.Write([]byte("server error"))

    if conn != nil {

Low-level API usage

// accept a new connection
conn, _ := listener.Accept()

// parse out the HTTP request and the Host header
if vhostConn, err = vhost.HTTP(conn); err != nil {
    panic("Not a valid http connection!")

fmt.Printf("Target Host: ", vhostConn.Host())
// Target Host:

// vhostConn contains the entire request as if no bytes had been consumed
bytes, _ := ioutil.ReadAll(vhostConn)
fmt.Printf("%s", bytes)
// GET / HTTP/1.1
// Host:
// User-Agent: ...
// ...

Advanced introspection

The entire HTTP request headers are available for inspection in case you want to mux on something besides the Host header:

// parse out the HTTP request and the Host header
if vhostConn, err = vhost.HTTP(conn); err != nil {
    panic("Not a valid http connection!")

httpVersion := vhost.Request.MinorVersion
customRouting := vhost.Request.Header["X-Custom-Routing-Header"]

Likewise for TLS, you can look at detailed information about the ClientHello message:

if vhostConn, err = vhost.TLS(conn); err != nil {
    panic("Not a valid TLS connection!")

cipherSuites := vhost.ClientHelloMsg.CipherSuites
sessionId := vhost.ClientHelloMsg.SessionId
Memory reduction with Free

After you're done muxing, you probably don't need to inspect the header data anymore, so you can make it available for garbage collection:

// look up the upstream host
upstreamHost := hostMapping[vhostConn.Host()]

// free up the muxing data

// vhostConn.Host() == ""
// vhostConn.Request == nil (HTTP)
// vhostConn.ClientHelloMsg == nil (TLS)
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