add gost library

Author: rui.zheng

LICENSE

@@ -0,0 +1,21 @@
+MIT License
+
+Copyright (c) 2016 ginuerzh
+
+Permission is hereby granted, free of charge, to any person obtaining a copy
+of this software and associated documentation files (the "Software"), to deal
+in the Software without restriction, including without limitation the rights
+to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+copies of the Software, and to permit persons to whom the Software is
+furnished to do so, subject to the following conditions:
+
+The above copyright notice and this permission notice shall be included in all
+copies or substantial portions of the Software.
+
+THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+SOFTWARE.

chain.go

@@ -0,0 +1,193 @@
+package gost
+
+import (
+	"crypto/tls"
+	"errors"
+	"github.com/golang/glog"
+	"golang.org/x/net/http2"
+	"io"
+	"io/ioutil"
+	"net"
+	"net/http"
+	"net/http/httputil"
+	"net/url"
+	"strings"
+)
+
+// Proxy chain holds a list of proxy nodes
+type ProxyChain struct {
+	nodes          []ProxyNode
+	lastNode       *ProxyNode
+	http2NodeIndex int
+	http2Enabled   bool
+	http2Client    *http.Client
+}
+
+func NewProxyChain(nodes ...ProxyNode) *ProxyChain {
+	chain := &ProxyChain{nodes: nodes, http2NodeIndex: -1}
+	return chain
+}
+
+func (c *ProxyChain) AddProxyNode(node ...ProxyNode) {
+	c.nodes = append(c.nodes, node...)
+}
+
+// Initialize proxy nodes, mainly check for http2 feature.
+// Should be called immediately when proxy nodes are ready.
+//
+// NOTE: http2 will not be enabled if not called.
+func (c *ProxyChain) Init() {
+	length := len(c.nodes)
+	if length == 0 {
+		return
+	}
+
+	c.lastNode = &c.nodes[length-1]
+
+	// http2 restrict: http2 will be enabled when at least one http2 proxy node present
+	for i, node := range c.nodes {
+		if node.Transport == "http2" {
+			glog.V(LINFO).Infoln("http2 enabled")
+			cfg := &tls.Config{
+				InsecureSkipVerify: node.insecureSkipVerify(),
+				ServerName:         node.serverName,
+			}
+			c.initHttp2Client(node.Addr, cfg, c.nodes[:i]...)
+			c.http2NodeIndex = i
+			break // shortest chain for http2
+		}
+	}
+}
+
+func (c *ProxyChain) initHttp2Client(addr string, config *tls.Config, nodes ...ProxyNode) {
+	tr := http2.Transport{
+		TLSClientConfig: config,
+		DialTLS: func(network, addr string, cfg *tls.Config) (net.Conn, error) {
+			// replace the default dialer with our proxy chain.
+			conn, err := c.dialWithNodes(addr, nodes...)
+			if err != nil {
+				return conn, err
+			}
+			return tls.Client(conn, cfg), nil
+		},
+	}
+	c.http2Client = &http.Client{Transport: &tr}
+	c.http2Enabled = true
+
+}
+
+func (c *ProxyChain) Http2Enabled() bool {
+	return c.http2Enabled
+}
+
+// Connect to addr through proxy chain
+func (c *ProxyChain) Dial(addr string) (net.Conn, error) {
+	if !strings.Contains(addr, ":") {
+		addr += ":80"
+	}
+	return c.dialWithNodes(addr, c.nodes...)
+}
+
+func (c *ProxyChain) dialWithNodes(addr string, nodes ...ProxyNode) (conn net.Conn, err error) {
+	if len(nodes) == 0 {
+		return net.DialTimeout("tcp", addr, DialTimeout)
+	}
+
+	var pc *ProxyConn
+
+	if c.Http2Enabled() {
+		nodes = nodes[c.http2NodeIndex+1:]
+		if len(nodes) == 0 {
+			return c.http2Connect("http", addr)
+		}
+	}
+	pc, err = c.travelNodes(nodes...)
+	if err != nil {
+		return
+	}
+	if err = pc.Connect(addr); err != nil {
+		pc.Close()
+		return
+	}
+
+	return pc, nil
+}
+
+func (c *ProxyChain) travelNodes(nodes ...ProxyNode) (conn *ProxyConn, err error) {
+	defer func() {
+		if err != nil && conn != nil {
+			conn.Close()
+			conn = nil
+		}
+	}()
+
+	var cc net.Conn
+	node := nodes[0]
+
+	if c.Http2Enabled() {
+		cc, err = c.http2Connect("http", node.Addr)
+	} else {
+		cc, err = net.DialTimeout("tcp", node.Addr, DialTimeout)
+	}
+	if err != nil {
+		return
+	}
+	setKeepAlive(cc, KeepAliveTime)
+
+	pc := NewProxyConn(cc, node)
+	if err = pc.Handshake(); err != nil {
+		return
+	}
+	conn = pc
+	for _, node := range nodes[1:] {
+		if err = conn.Connect(node.Addr); err != nil {
+			return
+		}
+		pc := NewProxyConn(conn, node)
+		if err = pc.Handshake(); err != nil {
+			return
+		}
+		conn = pc
+	}
+	return
+}
+
+func (c *ProxyChain) http2Connect(protocol, addr string) (net.Conn, error) {
+	if !c.Http2Enabled() {
+		return nil, errors.New("http2 not enabled")
+	}
+	http2Node := c.nodes[c.http2NodeIndex]
+
+	pr, pw := io.Pipe()
+	req := http.Request{
+		Method:        http.MethodConnect,
+		URL:           &url.URL{Scheme: "https", Host: http2Node.Addr},
+		Header:        make(http.Header),
+		Proto:         "HTTP/2.0",
+		ProtoMajor:    2,
+		ProtoMinor:    0,
+		Body:          ioutil.NopCloser(pr),
+		Host:          http2Node.Addr,
+		ContentLength: -1,
+	}
+	req.Header.Set("gost-target", addr)
+	if protocol != "" {
+		req.Header.Set("gost-protocol", protocol)
+	}
+
+	if glog.V(LDEBUG) {
+		dump, _ := httputil.DumpRequest(&req, false)
+		glog.Infoln(string(dump))
+	}
+	resp, err := c.http2Client.Do(&req)
+	if err != nil {
+		return nil, err
+	}
+	if resp.StatusCode != http.StatusOK {
+		resp.Body.Close()
+		return nil, errors.New(resp.Status)
+	}
+	conn := &Http2ClientConn{r: resp.Body, w: pw}
+	conn.remoteAddr, _ = net.ResolveTCPAddr("tcp", addr)
+	return conn, nil
+}