Adds NewPreemptiveAuth Authenticator

Author: chripo

auth.go

@@ -33,6 +33,10 @@ type authorizer struct {
 	defAuth    Authenticator
 }
 
+type preemptiveAuthorizer struct {
+	auth Authenticator
+}
+
 // authShim structure that wraps the real Authenticator
 type authShim struct {
 	factory AuthFactory
@@ -66,6 +70,11 @@ func NewEmptyAuth() Authorizer {
 	return az
 }
 
+// NewPreemptiveAuth creates a preemptive Authenticator
+func NewPreemptiveAuth(auth Authenticator) Authorizer {
+	return &preemptiveAuthorizer{auth}
+}
+
 // NewAuthenticator creates an Authenticator (Shim) per request
 func (a *authorizer) NewAuthenticator(body io.Reader) (Authenticator, io.Reader) {
 	var retryBuf io.Reader = body
@@ -205,3 +214,11 @@ func (n *nullAuth) Clone() Authenticator {
 func (n *nullAuth) String() string {
 	return "NullAuth"
 }
+
+func (b *preemptiveAuthorizer) NewAuthenticator(body io.Reader) (Authenticator, io.Reader) {
+	return b.auth.Clone(), body
+}
+
+func (b *preemptiveAuthorizer) AddAuthenticator(key string, fn AuthFactory) {
+	panic("not implemented")
+}

basicAuth.go

@@ -2,7 +2,6 @@ package gowebdav
 
 import (
 	"fmt"
-	"io"
 	"net/http"
 )
 
@@ -46,17 +45,5 @@ func (b *BasicAuth) String() string {
 // no fancy body buffering, no magic at all
 // just dump as if it were on tag 8
 func NewBasicAuth(login, secret string) Authorizer {
-	return &basicAuthAuthorizer{&BasicAuth{login, secret}}
-}
-
-type basicAuthAuthorizer struct {
-	auth *BasicAuth
-}
-
-func (b *basicAuthAuthorizer) NewAuthenticator(body io.Reader) (Authenticator, io.Reader) {
-	return b.auth, body
-}
-
-func (b *basicAuthAuthorizer) AddAuthenticator(key string, fn AuthFactory) {
-	panic("not implemented")
+	return &preemptiveAuthorizer{&BasicAuth{login, secret}}
 }