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proxy server
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| package main | |
| import ( | |
| "bufio" | |
| "bytes" | |
| "errors" | |
| "flag" | |
| "fmt" | |
| "io" | |
| "log" | |
| "net" | |
| "net/url" | |
| "strconv" | |
| "sync" | |
| ) | |
| func main() { | |
| addr := flag.String("s", ":1080", "proxy server address") | |
| flag.Parse() | |
| err := proxy(*addr) | |
| if err != nil { | |
| panic(err) | |
| } | |
| } | |
| const netTCP = "tcp" | |
| func proxy(addr string) error { | |
| lc, err := net.Listen(netTCP, addr) | |
| if err != nil { | |
| return err | |
| } | |
| //goland:noinspection GoUnhandledErrorResult | |
| defer lc.Close() | |
| for { | |
| ac, ea := lc.Accept() | |
| if ea == nil { | |
| go func() { | |
| if ea = handleProxy(ac); ea != nil { | |
| log.Printf("%+v", ea) | |
| } | |
| }() | |
| } | |
| } | |
| } | |
| type poolBuf struct { | |
| buf0, buf1 []byte | |
| buf *bufio.Reader | |
| } | |
| func (pb *poolBuf) ReadLine() ([]byte, error) { | |
| line := pb.buf0[:0] | |
| for { | |
| l, more, err := pb.buf.ReadLine() | |
| if err != nil { | |
| return nil, err | |
| } | |
| if len(line) == 0 && !more { | |
| return l, nil | |
| } | |
| if line = append(line, l...); !more { | |
| return line, nil | |
| } | |
| } | |
| } | |
| var bytePool = &sync.Pool{New: func() any { | |
| const leakyBufSize = 64 << 10 | |
| return &poolBuf{ | |
| buf0: make([]byte, leakyBufSize), | |
| buf1: make([]byte, leakyBufSize), | |
| buf: new(bufio.Reader), | |
| } | |
| }} | |
| //goland:noinspection GoUnhandledErrorResult | |
| func handleProxy(c net.Conn) error { | |
| defer c.Close() | |
| bp := bytePool.Get().(*poolBuf) | |
| defer bytePool.Put(bp) | |
| bp.buf.Reset(c) | |
| tp, err := bp.buf.Peek(2) | |
| if err != nil { | |
| return err | |
| } | |
| var rc net.Conn | |
| switch { | |
| case tp[0] == socksVer5: | |
| rc, err = dialSocks5(c, bp.buf, bp.buf0, int(tp[1])) | |
| if err != nil { | |
| return err | |
| } | |
| defer rc.Close() | |
| _, err = c.Write(socks5Established) | |
| if err != nil { | |
| return err | |
| } | |
| case tp[0] >= 'A' && tp[0] <= 'Z': | |
| line, err := bp.ReadLine() | |
| if err != nil { | |
| return err | |
| } | |
| head := bytes.SplitN(line, httpSep, 3) | |
| if len(head) != 3 { | |
| return errors.New("head error") | |
| } | |
| address := string(head[1]) | |
| if bytes.Equal(head[0], httpConnect) { | |
| for { | |
| line, err = bp.ReadLine() | |
| if err != nil { | |
| return err | |
| } | |
| if len(line) == 0 { | |
| break // read all heads | |
| } | |
| } | |
| rc, err = net.Dial(netTCP, address) | |
| if err != nil { | |
| return err | |
| } | |
| defer rc.Close() | |
| _, err = c.Write(httpEstablished) | |
| if err != nil { | |
| return err | |
| } | |
| } else { | |
| u, err := url.Parse(address) | |
| if err != nil { | |
| return err | |
| } | |
| if port := u.Port(); port == "" { | |
| if u.Scheme == "https" { | |
| port = "443" | |
| } else { | |
| port = "80" | |
| } | |
| u.Host = net.JoinHostPort(u.Host, port) | |
| } | |
| rc, err = net.Dial(netTCP, u.Host) | |
| if err != nil { | |
| return err | |
| } | |
| defer rc.Close() | |
| // forward first line | |
| _, err = rc.Write(append(line, '\r', '\n')) | |
| if err != nil { | |
| return err | |
| } | |
| } | |
| default: | |
| return errors.New("unsupported protocol version") | |
| } | |
| ret := make(chan struct{}) | |
| go func() { | |
| copyBuffer(c, rc, bp.buf0) | |
| ret <- struct{}{} | |
| }() | |
| copyBuffer(rc, bp.buf, bp.buf1) | |
| <-ret | |
| return nil | |
| } | |
| func copyBuffer(dst io.Writer, src io.Reader, buf []byte) { | |
| var ( | |
| nr, nw int | |
| er, ew error | |
| ) | |
| for er == nil { | |
| nr, er = src.Read(buf) | |
| if nr > 0 { | |
| nw, ew = dst.Write(buf[:nr]) | |
| if nw < 0 || nr < nw || ew != nil || nr != nw { | |
| return // Refer io.CopyBuffer | |
| } | |
| } | |
| } | |
| } | |
| var ( | |
| httpConnect = []byte("CONNECT") | |
| httpSep = []byte(" ") | |
| httpEstablished = []byte("HTTP/1.1 200 Connection Established\r\n\r\n") | |
| socks5Established = []byte{socksVer5, 0, 0, 1, 0, 0, 0, 0, 0, 0} | |
| ) | |
| const ( | |
| socksVer5 = 5 | |
| aTypIPV4 = 1 | |
| aTypDomain = 3 | |
| aTypIPV6 = 4 | |
| ) | |
| func dialSocks5(w io.Writer, r io.Reader, buf []byte, n int) (net.Conn, error) { | |
| _, err := io.ReadFull(r, buf[:n+2]) | |
| if err != nil { | |
| return nil, err | |
| } | |
| _, err = w.Write(socks5Established[:2]) | |
| if err != nil { | |
| return nil, err | |
| } | |
| _, err = io.ReadFull(r, buf[:5]) | |
| if err != nil { | |
| return nil, err | |
| } | |
| if buf[0] != socksVer5 { | |
| return nil, fmt.Errorf("invalid ver %d", buf[0]) | |
| } | |
| if buf[1] != 1 { // cmd connect = 1 | |
| return nil, fmt.Errorf("invalid cmd %d", buf[1]) | |
| } | |
| switch buf[3] { | |
| case aTypDomain: | |
| // VER CMD RSV TYPE LEN DST.ADDR DST.PORT | |
| // 1 1 1 1 1 LEN 2 | |
| n = int(buf[4]) + 7 | |
| case aTypIPV4: | |
| // VER CMD RSV TYPE DST.ADDR DST.PORT | |
| // 1 1 1 1 ipv4Len 2 | |
| n = net.IPv4len + 6 | |
| case aTypIPV6: | |
| // VER CMD RSV TYPE DST.ADDR DST.PORT | |
| // 1 1 1 1 ipv6Len 2 | |
| n = net.IPv6len + 6 | |
| default: | |
| return nil, errors.New("socks addr type not supported") | |
| } | |
| _, err = io.ReadFull(r, buf[5:n]) | |
| if err != nil { | |
| return nil, err | |
| } | |
| var addr string | |
| switch buf[3] { | |
| case aTypDomain: | |
| n = 5 + int(buf[4]) | |
| addr = string(buf[5:n]) | |
| case aTypIPV4: | |
| n = 4 + net.IPv4len | |
| addr = net.IP(buf[4:n]).String() | |
| case aTypIPV6: | |
| n = 4 + net.IPv6len | |
| addr = net.IP(buf[4:n]).String() | |
| } | |
| addr = net.JoinHostPort(addr, strconv.FormatUint(uint64(buf[n])<<8|uint64(buf[n+1]), 10)) | |
| return net.Dial(netTCP, addr) | |
| } |
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这里有个 go 代理服务器，同一个 tcp 端口同时支持 http 和 socks5 协议，我估计 Java 代码量会多一些。