Direct proxy works

_mtproto/rpc/proxy_request.go

@@ -0,0 +1,105 @@
+package rpc
+
+import (
+	"bytes"
+	"crypto/rand"
+	"encoding/binary"
+	"fmt"
+	"net"
+
+	"github.com/juju/errors"
+
+	"github.com/9seconds/mtg/mtproto"
+)
+
+// ProxyRequest is the data type for storing data required to compose
+// RPC_PROXY_REQ request.
+type ProxyRequest struct {
+	Flags        proxyRequestFlags
+	ConnectionID []byte
+	OurIPPort    []byte
+	ClientIPPort []byte
+	ADTag        []byte
+	Options      *mtproto.ConnectionOpts
+}
+
+// MakeHeader makes RPC_PROXY_REQ header. We need only to append the
+// data for it.
+func (r *ProxyRequest) MakeHeader(message []byte) (*bytes.Buffer, fmt.Stringer) {
+	bufferLength := len(TagProxyRequest) +
+		4 + // len(flags)
+		len(r.ConnectionID) +
+		len(r.ClientIPPort) +
+		len(r.OurIPPort) +
+		len(ProxyRequestExtraSize) +
+		len(ProxyRequestProxyTag) +
+		1 + // len(AdTag)
+		len(r.ADTag)
+	bufferLength += bufferLength % 4
+
+	buf := &bytes.Buffer{}
+	buf.Grow(bufferLength + len(message))
+
+	flags := r.Flags
+	if r.Options.ReadHacks.QuickAck {
+		flags |= proxyRequestFlagsQuickAck
+	}
+
+	if bytes.HasPrefix(message, proxyRequestFlagsEncryptedPrefix[:]) {
+		flags |= proxyRequestFlagsEncrypted
+	}
+
+	buf.Write(TagProxyRequest)                 // nolint: gosec
+	buf.Write(flags.Bytes())                   // nolint: gosec
+	buf.Write(r.ConnectionID)                  // nolint: gosec
+	buf.Write(r.ClientIPPort)                  // nolint: gosec
+	buf.Write(r.OurIPPort)                     // nolint: gosec
+	buf.Write(ProxyRequestExtraSize)           // nolint: gosec
+	buf.Write(ProxyRequestProxyTag)            // nolint: gosec
+	buf.WriteByte(byte(len(r.ADTag)))          // nolint: gosec
+	buf.Write(r.ADTag)                         // nolint: gosec
+	buf.Write(make([]byte, (4-buf.Len()%4)%4)) // nolint: gosec
+
+	return buf, flags
+}
+
+// NewProxyRequest build new ProxyRequest data structure.
+func NewProxyRequest(clientAddr, ownAddr *net.TCPAddr,
+	opts *mtproto.ConnectionOpts, adTag []byte) (*ProxyRequest, error) {
+	flags := proxyRequestFlagsHasAdTag | proxyRequestFlagsMagic | proxyRequestFlagsExtMode2
+
+	switch opts.ConnectionType {
+	case mtproto.ConnectionTypeAbridged:
+		flags |= proxyRequestFlagsAbdridged
+	case mtproto.ConnectionTypeIntermediate:
+		flags |= proxyRequestFlagsIntermediate
+	case mtproto.ConnectionTypeSecure:
+		flags |= proxyRequestFlagsIntermediate | proxyRequestFlagsPad
+	default:
+		panic("Unknown connection type")
+	}
+
+	request := &ProxyRequest{
+		Flags:        flags,
+		ADTag:        adTag,
+		Options:      opts,
+		ConnectionID: make([]byte, 8),
+		ClientIPPort: make([]byte, 16+4),
+		OurIPPort:    make([]byte, 16+4),
+	}
+
+	if _, err := rand.Read(request.ConnectionID); err != nil {
+		return nil, errors.Annotate(err, "Cannot generate connection ID")
+	}
+
+	port := [4]byte{}
+	copy(request.ClientIPPort[:16], clientAddr.IP.To16())
+	binary.LittleEndian.PutUint32(port[:], uint32(clientAddr.Port))
+	copy(request.ClientIPPort[16:], port[:])
+
+	copy(request.OurIPPort[:16], ownAddr.IP.To16())
+	binary.LittleEndian.PutUint32(port[:], uint32(ownAddr.Port))
+	copy(request.OurIPPort[16:], port[:])
+
+	return request, nil
+}