meowlib/client/server.go

package client

import (
	"fmt"
	"time"

	"forge.redroom.link/yves/meowlib"
	"github.com/google/uuid"
	"google.golang.org/protobuf/proto"
)

// Server manages server related operations
//   - Sending messages for server usage
//   - Two first steps of an invitation
//   - User message sending with UserKp identification
//   - Messages lookup requests
//   - Utility functions for packing/unpacking, encrypting/decrypting messages for server communication
//   - Server remote management if ManagerKp is available for that server
type Server struct {
	ServerData   meowlib.ServerCard `json:"server_data,omitempty"`
	Presence     bool               `json:"presence,omitempty"`
	LastCheck    time.Time          `json:"last_check,omitempty"`
	Uptime       time.Duration      `json:"uptime,omitempty"`
	UserKp       meowlib.KeyPair    `json:"user_kp,omitempty"`
	ManagerKp    meowlib.KeyPair    `json:"manager_kp,omitempty"`
	Country      string             `json:"country,omitempty"`
	AllowedDelay int                `json:"allowed_delay,omitempty"`
	Backup       bool               `json:"backup,omitempty"`
}

// CreateServerFromUrl creates a server from a basic url, ex : https://my.meowserver.example:8443/meow/
func CreateServerFromUrl(url string) *Server {
	var is Server
	is.ServerData.Url = url
	return &is
}

// Create a server from a server card
func CreateServerFromServerCard(server *meowlib.ServerCard) *Server {
	var is Server
	is.ServerData = *server
	is.UserKp = meowlib.NewKeyPair()
	return &is
}

// AsymEncryptMessage prepares a message to send to a specific internal server
func (ints *Server) AsymEncryptMessage(Message []byte) (*meowlib.EncryptedMessage, error) {
	var enc *meowlib.EncryptedMessage
	enc, err := meowlib.AsymEncryptAndSign(ints.ServerData.PublicKey, ints.UserKp.Private, Message)
	if err != nil {
		fmt.Println(err.Error())
		return nil, err
	}
	return enc, err
}

// AsymDecryptMessage reads a message from a specific internal server
func (ints *Server) AsymDecryptMessage(Message []byte, Signature []byte) (DecryptedMessage []byte, err error) {
	DecryptedMessage, err = meowlib.AsymDecryptAndCheck(ints.UserKp.Private, ints.ServerData.PublicKey, Message, Signature)
	if err != nil {
		fmt.Println(err.Error())
		return nil, err
	}
	return DecryptedMessage, err
}

// BuildToServerMessageFromUserMessage creates a basic message to server from a single packed user message and returns a meowlib.ToServerMessage
func (ints *Server) BuildToServerMessageFromUserMessage(usermsg *meowlib.PackedUserMessage) *meowlib.ToServerMessage {
	var msg meowlib.ToServerMessage
	msg.Uuid = uuid.New().String()
	msg.Type = "1"
	msg.From = ints.UserKp.Public
	msg.Messages = append(msg.Messages, usermsg)
	return &msg
}

// BuildMessageSendingMessage creates a basic message to server from a single packed user message and returns it as protobuf serialized byte array
func (ints *Server) BuildMessageSendingMessage(usermsg *meowlib.PackedUserMessage) ([]byte, error) {
	msg := ints.BuildToServerMessageFromUserMessage(usermsg)
	out, err := proto.Marshal(msg)
	if err != nil {
		return nil, err
	}
	return out, nil
}

// BuildMessageRequestMessage creates a message lookup message to server and returns it as protobuf serialized byte array
func (ints *Server) BuildMessageRequestMessage(lookupKeys []string) ([]byte, error) {
	var msg meowlib.ToServerMessage
	msg.Uuid = uuid.New().String()
	msg.Type = "1"
	msg.From = ints.UserKp.Public
	out, err := proto.Marshal(&msg)
	if err != nil {
		return nil, err
	}
	return out, nil
}

// BuildToServerMessageInvitation creates an invitation message to server and returns it as a meowlib.ToServerMessage
// it takes as input a contactcard generated by Identity.InvitePeer
func (ints *Server) BuildToServerMessageInvitationCreation(invitation *meowlib.ContactCard, password string, timeout int, invitationIdLen int) (*meowlib.ToServerMessage, error) {
	var msg meowlib.ToServerMessage
	var inv meowlib.Invitation
	payload, err := invitation.Compress()
	if err != nil {
		return nil, err
	}
	msg.Type = "1"
	msg.From = ints.UserKp.Public
	inv.Step = 1
	inv.Password = password
	inv.Timeout = int32(timeout)
	inv.ShortcodeLen = int32(invitationIdLen)
	inv.Payload = payload
	msg.Invitation = &inv
	return &msg, nil
}

// BuildToServerMessageInvitationRequest requests invitation with provided id from server and returns it as a meowlib.ToServerMessage
func (ints *Server) BuildToServerMessageInvitationRequest(shortcode string, password string) (*meowlib.ToServerMessage, error) {
	var msg meowlib.ToServerMessage
	var inv meowlib.Invitation
	msg.Type = "1"
	msg.From = ints.UserKp.Public
	inv.Step = 2
	inv.Password = password
	inv.Shortcode = shortcode
	msg.Invitation = &inv
	return &msg, nil
}

// PackServerMessage
func (ints *Server) PackServerMessage(payload []byte, signature []byte) (protoPackedMessage []byte, err error) {
	var msg meowlib.PackedServerMessage
	msg.From = ints.UserKp.Public
	msg.Payload = payload
	msg.Signature = signature
	out, err := proto.Marshal(&msg)
	if err != nil {
		return nil, err
	}
	return out, nil
}

func (ints *Server) UnPackServerMessage(protoPackedMessage []byte) (payload []byte, signature []byte, err error) {
	msg := &meowlib.PackedServerMessage{}
	if err := proto.Unmarshal(protoPackedMessage, msg); err != nil {
		return nil, nil, err
	}
	return msg.Payload, msg.Signature, nil
}

func (srv *Server) ProcessOutboundMessage(toServerMessage *meowlib.ToServerMessage) ([]byte, error) {
	byteToServerMessage, err := proto.Marshal(toServerMessage)
	if err != nil {
		return nil, err
	}
	// Encrypting it
	encToServer, err := srv.AsymEncryptMessage(byteToServerMessage)
	if err != nil {
		return nil, err
	}
	// Packing it
	protoPackedServerMsg, err := srv.PackServerMessage(encToServer.Data, encToServer.Signature)
	if err != nil {
		return nil, err
	}
	return protoPackedServerMsg, nil
}

func (srv *Server) ProcessInboundServerResponse(msg []byte) (*meowlib.FromServerMessage, error) {
	fsmsg := &meowlib.FromServerMessage{}
	payload, signature, err := srv.UnPackServerMessage(msg)
	if err != nil {
		return nil, err
	}
	decrypted, err := srv.AsymDecryptMessage(payload, signature)
	if err != nil {
		return nil, err
	}
	if err := proto.Unmarshal(decrypted, fsmsg); err != nil {
		return nil, err
	}
	return fsmsg, nil
}