package goricochet import ( "github.com/s-rah/go-ricochet/connection" "github.com/s-rah/go-ricochet/utils" "io" "net" ) // Open establishes a protocol session on an established net.Conn, and returns a new // OpenConnection instance representing this connection. On error, the connection // will be closed. This function blocks until version negotiation has completed. // The application should call Process() on the returned OpenConnection to continue // handling protocol messages. func Open(remoteHostname string) (*connection.Connection, error) { networkResolver := utils.NetworkResolver{} conn, remoteHostname, err := networkResolver.Resolve(remoteHostname) if err != nil { return nil, err } rc, err := negotiateVersion(conn, remoteHostname) if err != nil { conn.Close() return nil, err } return rc, nil } // negotiate version takes an open network connection and executes // the ricochet version negotiation procedure. func negotiateVersion(conn net.Conn, remoteHostname string) (*connection.Connection, error) { versions := []byte{0x49, 0x4D, 0x01, 0x01} if n, err := conn.Write(versions); err != nil || n < len(versions) { return nil, utils.VersionNegotiationError } res := make([]byte, 1) if _, err := io.ReadAtLeast(conn, res, len(res)); err != nil { return nil, utils.VersionNegotiationError } if res[0] != 0x01 { return nil, utils.VersionNegotiationFailed } rc := connection.NewOutboundConnection(conn, remoteHostname) return rc, nil } // NegotiateVersionInbound takes in a connection and performs version negotiation // as if that connection was a client. Returns a ricochet connection if successful // error otherwise. func NegotiateVersionInbound(conn net.Conn) (*connection.Connection, error) { versions := []byte{0x49, 0x4D, 0x01, 0x01} // Read version response header header := make([]byte, 3) if _, err := io.ReadAtLeast(conn, header, len(header)); err != nil { return nil, err } if header[0] != versions[0] || header[1] != versions[1] || header[2] < 1 { return nil, utils.VersionNegotiationError } // Read list of supported versions (which is header[2] bytes long) versionList := make([]byte, header[2]) if _, err := io.ReadAtLeast(conn, versionList, len(versionList)); err != nil { return nil, utils.VersionNegotiationError } selectedVersion := byte(0xff) for _, v := range versionList { if v == 0x01 { selectedVersion = v break } } if n, err := conn.Write([]byte{selectedVersion}); err != nil || n < 1 { return nil, utils.VersionNegotiationFailed } if selectedVersion == 0xff { return nil, utils.VersionNegotiationFailed } rc := connection.NewInboundConnection(conn) return rc, nil }