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/*
*
* Copyright 2017 gRPC authors.
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*
*/
package transport
import (
"bufio"
"context"
"encoding/base64"
"fmt"
"io"
"net"
"net/http"
"net/http/httputil"
"net/url"
"google.golang.org/grpc/internal"
"google.golang.org/grpc/internal/proxyattributes"
"google.golang.org/grpc/resolver"
)
const proxyAuthHeaderKey = "Proxy-Authorization"
// To read a response from a net.Conn, http.ReadResponse() takes a bufio.Reader.
// It's possible that this reader reads more than what's need for the response
// and stores those bytes in the buffer. bufConn wraps the original net.Conn
// and the bufio.Reader to make sure we don't lose the bytes in the buffer.
type bufConn struct {
net.Conn
r io.Reader
}
func (c *bufConn) Read(b []byte) (int, error) {
return c.r.Read(b)
}
func basicAuth(username, password string) string {
auth := username + ":" + password
return base64.StdEncoding.EncodeToString([]byte(auth))
}
func doHTTPConnectHandshake(ctx context.Context, conn net.Conn, grpcUA string, opts proxyattributes.Options) (_ net.Conn, err error) {
defer func() {
if err != nil {
conn.Close()
}
}()
req := &http.Request{
Method: http.MethodConnect,
URL: &url.URL{Host: opts.ConnectAddr},
Header: map[string][]string{"User-Agent": {grpcUA}},
}
if user := opts.User; user != nil {
u := user.Username()
p, _ := user.Password()
req.Header.Add(proxyAuthHeaderKey, "Basic "+basicAuth(u, p))
}
if err := sendHTTPRequest(ctx, req, conn); err != nil {
return nil, fmt.Errorf("failed to write the HTTP request: %v", err)
}
r := bufio.NewReader(conn)
resp, err := http.ReadResponse(r, req)
if err != nil {
return nil, fmt.Errorf("reading server HTTP response: %v", err)
}
defer resp.Body.Close()
if resp.StatusCode != http.StatusOK {
dump, err := httputil.DumpResponse(resp, true)
if err != nil {
return nil, fmt.Errorf("failed to do connect handshake, status code: %s", resp.Status)
}
return nil, fmt.Errorf("failed to do connect handshake, response: %q", dump)
}
// The buffer could contain extra bytes from the target server, so we can't
// discard it. However, in many cases where the server waits for the client
// to send the first message (e.g. when TLS is being used), the buffer will
// be empty, so we can avoid the overhead of reading through this buffer.
if r.Buffered() != 0 {
return &bufConn{Conn: conn, r: r}, nil
}
return conn, nil
}
// proxyDial establishes a TCP connection to the specified address and performs an HTTP CONNECT handshake.
func proxyDial(ctx context.Context, addr resolver.Address, grpcUA string, opts proxyattributes.Options) (net.Conn, error) {
conn, err := internal.NetDialerWithTCPKeepalive().DialContext(ctx, "tcp", addr.Addr)
if err != nil {
return nil, err
}
return doHTTPConnectHandshake(ctx, conn, grpcUA, opts)
}
func sendHTTPRequest(ctx context.Context, req *http.Request, conn net.Conn) error {
req = req.WithContext(ctx)
if err := req.Write(conn); err != nil {
return fmt.Errorf("failed to write the HTTP request: %v", err)
}
return nil
}
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