clustvirt/lib/host/uri.go

package host

import (
	"errors"
	"strings"

	log "git.staur.ca/stobbsm/simplelog"
)

// URI is a string type, accessed via the pre-defined variables, and represent
// the URI pattern used to connect to a host.
// Example:
// Driver[+Transport]://<host or empty for local>[:PORT]/<path>[?Options&in=uri&format]
type URI struct {
	Driver    string
	Transport string
	Path      string
	Host      string
	Options   []string
}

// Define create and return a custom URI method, following RFC2396,
// keeping in mind that the hostname will be inserted between the transport and path
func Define(driver, transport, path string, options ...string) *URI {
	return &URI{
		Driver:    driver,
		Transport: transport,
		Path:      path,
		Options:   options,
	}
}

var (
	URI_QEMU_LOCAL = Define("qemu", "local", "system")
	URI_QEMU_SSH   = Define("qemu", "ssh", "system")
)

// WithHost sets the hostname as part of a URI. It copies the original URI and returns a new one
func (u *URI) WithHost(host string) *URI {
	return &URI{
		Driver:    u.Driver,
		Transport: u.Transport,
		Path:      u.Path,
		Host:      host,
		Options:   u.Options,
	}
}

// IsRemote returns true if the URI references a remote trasnport (ssh, tcp or tls)
func (u *URI) IsRemote() bool {
	switch u.Transport {
	case "ssh":
		fallthrough
	case "tls":
		fallthrough
	case "tcp":
		return true
	default:
		return false
	}
}

// validTransport makes sure the value of transport if valid or empty. If the transport
// isn't remote, it returns an empty string
func (u *URI) validTransport() bool {
	if u.IsRemote() {
		return true
	}
	switch u.Transport {
	case "unix":
		fallthrough
	case "local":
		return true
	default:
		return false
	}
}

func (u *URI) validDriver() bool {
	switch u.Driver {
	case "qemu":
		fallthrough
	case "xen":
		fallthrough
	case "lxc":
		return true
	default:
		return false
	}
}

// ConnectionString takes a host name to interpolate into a URI and returns the string
func (u *URI) ConnectionString() string {
	// Normalize the variables
	var driver, transport, path, host string
	if !u.validTransport() {
		log.Panic("host.URI.ConnectionString").
			Err(errors.New("invalid transport")).
			Str("transport", u.Transport).
			Send()
	}
	transport = u.Transport
	if (u.Host == "localhost" && u.IsRemote()) || u.Host != "localhost" {
		host = u.Host
	}
	// TODO: validate driver, path
	if !u.validDriver() {
		log.Panic("host.URI.ConnectionString").
			Err(errors.New("invalid driver")).
			Str("driver", u.Driver).
			Send()
	}
	driver = u.Driver
	path = u.Path

	var sb strings.Builder
	optlen := len(u.Options)
	sb.WriteString(driver)
	if transport != "" {
		sb.WriteRune('+')
		sb.WriteString(u.Transport)
	}
	sb.WriteString("://")
	if host != "" {
		sb.WriteString(host)
	}
	sb.WriteRune('/')
	sb.WriteString(path)

	if optlen > 0 {
		sb.WriteRune('?')
		for i, o := range u.Options {
			sb.WriteString(o)
			if optlen != i+1 {
				sb.WriteRune('&')
			}
		}
	}
	log.Info("Host.ConnectionString").
		Str("uri.Driver", u.Driver).
		Str("uri.Transport", u.Transport).
		Str("uri.Path", u.Path).
		Strs("uri.Options", u.Options).
		Str("builtUri", sb.String()).Send()
	return sb.String()
}

// AddOpt adds more options to the option list
func (u *URI) AddOpt(opt string) {
	u.Options = append(u.Options, opt)
}