2019-11-05 18:29:10 -05:00
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// Copyright 2015 Matthew Holt and The Caddy Authors
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//
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// Licensed under the Apache License, Version 2.0 (the "License");
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// you may not use this file except in compliance with the License.
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// You may obtain a copy of the License at
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//
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// http://www.apache.org/licenses/LICENSE-2.0
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//
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// Unless required by applicable law or agreed to in writing, software
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// distributed under the License is distributed on an "AS IS" BASIS,
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// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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// See the License for the specific language governing permissions and
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// limitations under the License.
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package reverseproxy
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import (
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"context"
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"fmt"
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"net"
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"net/http"
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2019-11-06 02:16:16 -05:00
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"strings"
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"sync"
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"github.com/caddyserver/caddy/v2"
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"github.com/caddyserver/caddy/v2/modules/caddyhttp"
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)
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func init() {
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caddy.RegisterModule(NTLMTransport{})
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}
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2019-12-10 15:36:46 -05:00
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// NTLMTransport proxies HTTP with NTLM authentication.
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// It basically wraps HTTPTransport so that it is compatible with
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// NTLM's HTTP-hostile requirements. Specifically, it will use
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// HTTPTransport's single, default *http.Transport for all requests
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// (unless the client's connection is already mapped to a different
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// transport) until a request comes in with an Authorization header
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// that has "NTLM" or "Negotiate"; when that happens, NTLMTransport
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// maps the client's connection (by its address, req.RemoteAddr)
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// to a new transport that is used only by that downstream conn.
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// When the upstream connection is closed, the mapping is deleted.
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// This preserves NTLM authentication contexts by ensuring that
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// client connections use the same upstream connection. It does
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// hurt performance a bit, but that's NTLM for you.
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//
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// This transport also forces HTTP/1.1 and Keep-Alives in order
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// for NTLM to succeed.
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type NTLMTransport struct {
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*HTTPTransport
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transports map[string]*http.Transport
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transportsMu *sync.RWMutex
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}
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// CaddyModule returns the Caddy module information.
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func (NTLMTransport) CaddyModule() caddy.ModuleInfo {
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return caddy.ModuleInfo{
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ID: "http.reverse_proxy.transport.http_ntlm",
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New: func() caddy.Module { return new(NTLMTransport) },
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}
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}
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// Provision sets up the transport module.
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func (n *NTLMTransport) Provision(ctx caddy.Context) error {
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n.transports = make(map[string]*http.Transport)
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n.transportsMu = new(sync.RWMutex)
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if n.HTTPTransport == nil {
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n.HTTPTransport = new(HTTPTransport)
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}
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// NTLM requires HTTP/1.1
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n.HTTPTransport.Versions = []string{"1.1"}
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// NLTM requires keep-alive
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if n.HTTPTransport.KeepAlive != nil {
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enabled := true
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n.HTTPTransport.KeepAlive.Enabled = &enabled
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}
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// set up the underlying transport, since we
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// rely on it for the heavy lifting
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err := n.HTTPTransport.Provision(ctx)
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if err != nil {
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return err
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}
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return nil
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}
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// RoundTrip implements http.RoundTripper. It basically wraps
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// the underlying HTTPTransport.Transport in a way that preserves
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// NTLM context by mapping transports/connections. Note that this
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// method does not call n.HTTPTransport.RoundTrip (our own method),
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// but the underlying n.HTTPTransport.Transport.RoundTrip (standard
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// library's method).
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func (n *NTLMTransport) RoundTrip(req *http.Request) (*http.Response, error) {
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n.HTTPTransport.setScheme(req)
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// when the upstream connection is closed, make sure
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// we close the downstream connection with the client
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// when this request is done; we only do this if
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// using a bound transport
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closeDownstreamIfClosedUpstream := func() {
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n.transportsMu.Lock()
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if _, ok := n.transports[req.RemoteAddr]; !ok {
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req.Close = true
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}
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n.transportsMu.Unlock()
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}
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// first, see if this downstream connection is
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// already bound to a particular transport
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// (transports are abstractions over connections
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// to our upstream, and NTLM auth requires
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// preserving authentication state for separate
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// connections over multiple roundtrips, sigh)
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n.transportsMu.Lock()
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transport, ok := n.transports[req.RemoteAddr]
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if ok {
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n.transportsMu.Unlock()
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defer closeDownstreamIfClosedUpstream()
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return transport.RoundTrip(req)
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}
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// otherwise, start by assuming we will use
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// the default transport that carries all
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// normal/non-NTLM-authenticated requests
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transport = n.HTTPTransport.Transport
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// but if this request begins the NTLM authentication
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// process, we need to pin it to a specific transport
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if requestHasAuth(req) {
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var err error
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transport, err = n.newTransport()
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if err != nil {
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return nil, fmt.Errorf("making new transport for %s: %v", req.RemoteAddr, err)
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}
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n.transports[req.RemoteAddr] = transport
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defer closeDownstreamIfClosedUpstream()
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}
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n.transportsMu.Unlock()
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// finally, do the roundtrip with the transport we selected
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return transport.RoundTrip(req)
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}
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// newTransport makes an NTLM-compatible transport.
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func (n *NTLMTransport) newTransport() (*http.Transport, error) {
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// start with a regular HTTP transport
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transport, err := n.HTTPTransport.newTransport()
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if err != nil {
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return nil, err
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}
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// we need to wrap upstream connections so we can
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// clean up in two ways when that connection is
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// closed: 1) destroy the transport that housed
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// this connection, and 2) use that as a signal
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// to close the connection to the downstream.
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wrappedDialContext := transport.DialContext
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transport.DialContext = func(ctx context.Context, network, address string) (net.Conn, error) {
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conn2, err := wrappedDialContext(ctx, network, address)
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if err != nil {
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return nil, err
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}
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req := ctx.Value(caddyhttp.OriginalRequestCtxKey).(http.Request)
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conn := &unbinderConn{Conn: conn2, ntlm: n, clientAddr: req.RemoteAddr}
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return conn, nil
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}
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return transport, nil
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}
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// Cleanup implements caddy.CleanerUpper and closes any idle connections.
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func (n *NTLMTransport) Cleanup() error {
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if err := n.HTTPTransport.Cleanup(); err != nil {
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return err
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}
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n.transportsMu.Lock()
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for _, t := range n.transports {
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t.CloseIdleConnections()
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}
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n.transports = make(map[string]*http.Transport)
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n.transportsMu.Unlock()
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return nil
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}
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// deleteTransportsForClient deletes (unmaps) transports that are
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// associated with clientAddr (a req.RemoteAddr value).
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func (n *NTLMTransport) deleteTransportsForClient(clientAddr string) {
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n.transportsMu.Lock()
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for key := range n.transports {
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if key == clientAddr {
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delete(n.transports, key)
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}
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}
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n.transportsMu.Unlock()
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}
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// requestHasAuth returns true if req has an Authorization
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// header with values "NTLM" or "Negotiate".
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func requestHasAuth(req *http.Request) bool {
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for _, val := range req.Header["Authorization"] {
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if strings.HasPrefix(val, "NTLM") ||
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strings.HasPrefix(val, "Negotiate") {
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return true
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}
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}
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return false
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}
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// unbinderConn is used to wrap upstream connections
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// so that we know when they are closed and can clean
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// up after that.
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type unbinderConn struct {
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net.Conn
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clientAddr string
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ntlm *NTLMTransport
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}
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func (uc *unbinderConn) Close() error {
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uc.ntlm.deleteTransportsForClient(uc.clientAddr)
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return uc.Conn.Close()
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}
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// Interface guards
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var (
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_ caddy.Provisioner = (*NTLMTransport)(nil)
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_ http.RoundTripper = (*NTLMTransport)(nil)
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_ caddy.CleanerUpper = (*NTLMTransport)(nil)
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)
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