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Merge pull request #1003 from gravitational/rjones/http-proxy
HTTP CONNECT Tunneling
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| Original file line number | Diff line number | Diff line change |
|---|---|---|
| @@ -0,0 +1,162 @@ | ||
| /* | ||
| Copyright 2017 Gravitational, Inc. | ||
| 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 proxy | ||
|
|
||
| import ( | ||
| "bufio" | ||
| "context" | ||
| "net" | ||
| "net/http" | ||
| "net/url" | ||
| "os" | ||
| "strings" | ||
|
|
||
| "github.com/gravitational/teleport" | ||
| "github.com/gravitational/trace" | ||
|
|
||
| "golang.org/x/crypto/ssh" | ||
|
|
||
| log "github.com/Sirupsen/logrus" | ||
| ) | ||
|
|
||
| // A Dialer is a means for a client to establish a SSH connection. | ||
| type Dialer interface { | ||
| // Dial establishes a client connection to a SSH server. | ||
| Dial(network string, addr string, config *ssh.ClientConfig) (*ssh.Client, error) | ||
| } | ||
|
|
||
| type directDial struct{} | ||
|
|
||
| // Dial calls ssh.Dial directly. | ||
| func (d directDial) Dial(network string, addr string, config *ssh.ClientConfig) (*ssh.Client, error) { | ||
| return ssh.Dial(network, addr, config) | ||
| } | ||
|
|
||
| type proxyDial struct { | ||
| proxyHost string | ||
| } | ||
|
|
||
| // Dial first connects to a proxy, then uses the connection to establish a new | ||
| // SSH connection. | ||
| func (d proxyDial) Dial(network string, addr string, config *ssh.ClientConfig) (*ssh.Client, error) { | ||
| // build a proxy connection first | ||
| pconn, err := dialProxy(d.proxyHost, addr) | ||
| if err != nil { | ||
| return nil, trace.Wrap(err) | ||
| } | ||
|
|
||
| // do the same as ssh.Dial but pass in proxy connection | ||
| c, chans, reqs, err := ssh.NewClientConn(pconn, addr, config) | ||
| if err != nil { | ||
| return nil, trace.Wrap(err) | ||
| } | ||
| return ssh.NewClient(c, chans, reqs), nil | ||
| } | ||
|
|
||
| // DialerFromEnvironment returns a Dial function. If the https_proxy or http_proxy | ||
| // environment variable are set, it returns a function that will dial through | ||
| // said proxy server. If neither variable is set, it will connect to the SSH | ||
| // server directly. | ||
| func DialerFromEnvironment() Dialer { | ||
| // try and get proxy addr from the environment | ||
| proxyAddr := getProxyAddress() | ||
|
|
||
| // if no proxy settings are in environment return regular ssh dialer, | ||
| // otherwise return a proxy dialer | ||
| if proxyAddr == "" { | ||
| log.Debugf("[HTTP PROXY] No proxy set in environment, returning direct dialer.") | ||
| return directDial{} | ||
| } | ||
| log.Debugf("[HTTP PROXY] Found proxy %q in environment, returning proxy dialer.", proxyAddr) | ||
| return proxyDial{proxyHost: proxyAddr} | ||
| } | ||
|
|
||
| func dialProxy(proxyAddr string, addr string) (net.Conn, error) { | ||
| ctx := context.Background() | ||
|
|
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| var d net.Dialer | ||
| conn, err := d.DialContext(ctx, "tcp", proxyAddr) | ||
| if err != nil { | ||
| log.Warnf("[HTTP PROXY] Unable to dial to proxy: %v: %v", proxyAddr, err) | ||
| return nil, trace.ConvertSystemError(err) | ||
| } | ||
|
|
||
| connectReq := &http.Request{ | ||
| Method: http.MethodConnect, | ||
| URL: &url.URL{Opaque: addr}, | ||
| Host: addr, | ||
| Header: make(http.Header), | ||
| } | ||
| err = connectReq.Write(conn) | ||
| if err != nil { | ||
| log.Warnf("[HTTP PROXY] Unable to write to proxy: %v", err) | ||
| return nil, trace.Wrap(err) | ||
| } | ||
|
|
||
| br := bufio.NewReader(conn) | ||
| resp, err := http.ReadResponse(br, connectReq) | ||
| if err != nil { | ||
| conn.Close() | ||
| log.Warnf("[HTTP PROXY] Unable to read response: %v", err) | ||
| return nil, trace.Wrap(err) | ||
| } | ||
| if resp.StatusCode != http.StatusOK { | ||
| f := strings.SplitN(resp.Status, " ", 2) | ||
| conn.Close() | ||
| return nil, trace.BadParameter("Unable to proxy connection, StatusCode %v: %v", resp.StatusCode, f[1]) | ||
| } | ||
|
|
||
| return conn, nil | ||
| } | ||
|
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||
| func getProxyAddress() string { | ||
| envs := []string{ | ||
| teleport.HTTPSProxy, | ||
| strings.ToLower(teleport.HTTPSProxy), | ||
| teleport.HTTPProxy, | ||
| strings.ToLower(teleport.HTTPProxy), | ||
| } | ||
|
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||
| for _, v := range envs { | ||
| addr := os.Getenv(v) | ||
| if addr != "" { | ||
| proxyaddr, err := parse(addr) | ||
| if err != nil { | ||
| log.Debugf("[HTTP PROXY] Unable to parse environment variable %q: %q.", v, addr) | ||
| continue | ||
| } | ||
| log.Debugf("[HTTP PROXY] Successfully parsed environment variable %q: %q to %q", v, addr, proxyaddr) | ||
| return proxyaddr | ||
| } | ||
| } | ||
|
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| log.Debugf("[HTTP PROXY] No valid environment variables found.") | ||
| return "" | ||
| } | ||
|
|
||
| // parse will extract the host:port of the proxy to dial to. If the | ||
| // value is not prefixed by "http", then it will prepend "http" and try. | ||
| func parse(addr string) (string, error) { | ||
| proxyurl, err := url.Parse(addr) | ||
| if err != nil || !strings.HasPrefix(proxyurl.Scheme, "http") { | ||
| proxyurl, err = url.Parse("http://" + addr) | ||
| if err != nil { | ||
| return "", trace.Wrap(err) | ||
| } | ||
| } | ||
|
|
||
| return proxyurl.Host, nil | ||
| } |
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