116 lines
4.1 KiB
Go
116 lines
4.1 KiB
Go
package ntlm
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import (
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"bufio"
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"context"
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"encoding/base64"
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"errors"
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"fmt"
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"io/ioutil"
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"net"
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"net/http"
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"net/url"
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"strings"
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ntlmssp "github.com/Azure/go-ntlmssp"
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)
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// DialContext is the DialContext function that should be wrapped with a
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// NTLM Authentication.
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//
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// Example for DialContext:
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//
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// dialContext := (&net.Dialer{KeepAlive: 30*time.Second, Timeout: 30*time.Second}).DialContext
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type DialContext func(ctx context.Context, network, addr string) (net.Conn, error)
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// WrapDialContext wraps a DialContext with an NTLM Authentication to a proxy.
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func WrapDialContext(dialContext DialContext, proxyAddress, proxyUsername, proxyPassword, proxyDomain string) DialContext {
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return func(ctx context.Context, network, addr string) (net.Conn, error) {
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conn, err := dialContext(ctx, network, proxyAddress)
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if err != nil {
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debugf("ntlm> Could not call dial context with proxy: %s", err)
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return conn, err
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}
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// NTLM Step 1: Send Negotiate Message
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negotiateMessage, err := ntlmssp.NewNegotiateMessage(proxyDomain, "")
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if err != nil {
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debugf("ntlm> Could not negotiate domain '%s': %s", proxyDomain, err)
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return conn, err
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}
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debugf("ntlm> NTLM negotiate message: '%s'", base64.StdEncoding.EncodeToString(negotiateMessage))
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header := make(http.Header)
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header.Set("Proxy-Authorization", fmt.Sprintf("NTLM %s", base64.StdEncoding.EncodeToString(negotiateMessage)))
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header.Set("Proxy-Connection", "Keep-Alive")
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connect := &http.Request{
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Method: "CONNECT",
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URL: &url.URL{Opaque: addr},
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Host: addr,
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Header: header,
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}
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if err := connect.Write(conn); err != nil {
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debugf("ntlm> Could not write negotiate message to proxy: %s", err)
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return conn, err
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}
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debugf("ntlm> Successfully sent negotiate message to proxy")
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// NTLM Step 2: Receive Challenge Message
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br := bufio.NewReader(conn)
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resp, err := http.ReadResponse(br, connect)
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if err != nil {
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debugf("ntlm> Could not read response from proxy: %s", err)
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return conn, err
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}
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_, err = ioutil.ReadAll(resp.Body)
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if err != nil {
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debugf("ntlm> Could not read response body from proxy: %s", err)
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return conn, err
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}
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resp.Body.Close()
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if resp.StatusCode != http.StatusProxyAuthRequired {
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debugf("ntlm> Expected %d as return status, got: %d", http.StatusProxyAuthRequired, resp.StatusCode)
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return conn, errors.New(http.StatusText(resp.StatusCode))
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}
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challenge := strings.Split(resp.Header.Get("Proxy-Authenticate"), " ")
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if len(challenge) < 2 {
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debugf("ntlm> The proxy did not return an NTLM challenge, got: '%s'", resp.Header.Get("Proxy-Authenticate"))
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return conn, errors.New("no NTLM challenge received")
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}
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debugf("ntlm> NTLM challenge: '%s'", challenge[1])
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challengeMessage, err := base64.StdEncoding.DecodeString(challenge[1])
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if err != nil {
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debugf("ntlm> Could not base64 decode the NTLM challenge: %s", err)
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return conn, err
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}
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// NTLM Step 3: Send Authorization Message
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debugf("ntlm> Processing NTLM challenge with username '%s' and password with length %d", proxyUsername, len(proxyPassword))
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authenticateMessage, err := ntlmssp.ProcessChallenge(challengeMessage, proxyUsername, proxyPassword)
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if err != nil {
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debugf("ntlm> Could not process the NTLM challenge: %s", err)
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return conn, err
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}
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debugf("ntlm> NTLM authorization: '%s'", base64.StdEncoding.EncodeToString(authenticateMessage))
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header.Set("Proxy-Authorization", fmt.Sprintf("NTLM %s", base64.StdEncoding.EncodeToString(authenticateMessage)))
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connect = &http.Request{
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Method: "CONNECT",
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URL: &url.URL{Opaque: addr},
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Host: addr,
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Header: header,
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}
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if err := connect.Write(conn); err != nil {
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debugf("ntlm> Could not write authorization to proxy: %s", err)
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return conn, err
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}
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resp, err = http.ReadResponse(br, connect)
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if err != nil {
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debugf("ntlm> Could not read response from proxy: %s", err)
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return conn, err
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}
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if resp.StatusCode != http.StatusOK {
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debugf("ntlm> Expected %d as return status, got: %d", http.StatusOK, resp.StatusCode)
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return conn, errors.New(http.StatusText(resp.StatusCode))
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}
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// Succussfully authorized with NTLM
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debugf("ntlm> Successfully injected NTLM to connection")
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return conn, nil
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}
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}
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