route/lib/tunnel/util.go

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2017-01-20 01:27:14 +00:00
package tunnel
import (
"crypto/tls"
"fmt"
"net"
"sync"
"time"
"git.xeserv.us/xena/route/lib/tunnel/proto"
"github.com/cenkalti/backoff"
)
// async is a helper function to convert a blocking function to a function
// returning an error. Useful for plugging function closures into select and co
func async(fn func() error) <-chan error {
errChan := make(chan error, 0)
go func() {
select {
case errChan <- fn():
default:
}
close(errChan)
}()
return errChan
}
type expBackoff struct {
mu sync.Mutex
bk *backoff.ExponentialBackOff
}
func newForeverBackoff() *expBackoff {
eb := &expBackoff{
bk: backoff.NewExponentialBackOff(),
}
eb.bk.MaxElapsedTime = 0 // never stops
return eb
}
func (eb *expBackoff) NextBackOff() time.Duration {
eb.mu.Lock()
defer eb.mu.Unlock()
return eb.bk.NextBackOff()
}
func (eb *expBackoff) Reset() {
eb.mu.Lock()
eb.bk.Reset()
eb.mu.Unlock()
}
type callbacks struct {
mu sync.Mutex
name string
funcs map[string]func() error
}
func newCallbacks(name string) *callbacks {
return &callbacks{
name: name,
funcs: make(map[string]func() error),
}
}
func (c *callbacks) add(identifier string, fn func() error) {
c.mu.Lock()
c.funcs[identifier] = fn
c.mu.Unlock()
}
func (c *callbacks) pop(identifier string) (func() error, error) {
c.mu.Lock()
defer c.mu.Unlock()
fn, ok := c.funcs[identifier]
if !ok {
return nil, nil // nop
}
delete(c.funcs, identifier)
if fn == nil {
return nil, fmt.Errorf("nil callback set for %q client", identifier)
}
return fn, nil
}
func (c *callbacks) call(identifier string) error {
fn, err := c.pop(identifier)
if err != nil {
return err
}
if fn == nil {
return nil // nop
}
return fn()
}
// Returns server control url as a string. Reads scheme and remote address from connection.
func controlURL(conn net.Conn) string {
return fmt.Sprint(scheme(conn), "://", conn.RemoteAddr(), proto.ControlPath)
}
func scheme(conn net.Conn) (scheme string) {
switch conn.(type) {
case *tls.Conn:
scheme = "https"
default:
scheme = "http"
}
return
}