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|
package gateway
import (
"context"
"crypto/ed25519"
"crypto/tls"
"crypto/x509"
_ "embed"
"errors"
"io"
"log"
"net"
"sync"
"time"
tea "github.com/charmbracelet/bubbletea"
"github.com/kyren223/eko/internal/client/ui"
"github.com/kyren223/eko/internal/packet"
"github.com/kyren223/eko/pkg/assert"
)
//go:embed server.crt
var certPEM []byte
var (
tlsConfig *tls.Config
asyncResponses []chan packet.Payload
responsesMu sync.Mutex
framer packet.PacketFramer
conn net.Conn
writeMu sync.Mutex
)
type (
ConnectionEstablished struct{}
ConnectionFailed error
ConnectionLost error
ConnectionClosed struct{}
)
func init() {
certPool := x509.NewCertPool()
if !certPool.AppendCertsFromPEM(certPEM) {
log.Fatalln("failed to append server certificate")
}
tlsConfig = &tls.Config{
RootCAs: certPool,
ServerName: "localhost",
}
}
func Connect(ctx context.Context, privKey ed25519.PrivateKey) tea.Cmd {
return func() tea.Msg {
err := connect(ctx, privKey)
if err != nil {
return ConnectionFailed(err)
}
return ConnectionEstablished{}
}
}
func connect(ctx context.Context, privKey ed25519.PrivateKey) error {
assert.Assert(conn == nil, "cannot connect, connection is active")
connChan := make(chan net.Conn, 1)
errChan := make(chan error, 1)
go func() {
framer = packet.NewFramer()
connection, err := tls.Dial("tcp4", ":7223", tlsConfig)
if err != nil {
errChan <- err
return
}
log.Println("established connection with server")
if err := handleAuth(ctx, privKey); err != nil {
errChan <- err
return
}
log.Println("successfully authenticated with server")
connChan <- connection
}()
select {
case connection := <-connChan:
conn = connection
case err := <-errChan:
return err
case <-ctx.Done():
return ctx.Err()
}
go readForever()
go handlePacketStream()
return nil
}
func handleAuth(ctx context.Context, privKey ed25519.PrivateKey) error {
const nonceSize = 32
challengeRequest := make([]byte, 1+nonceSize)
deadline, _ := ctx.Deadline()
err := conn.SetDeadline(deadline)
assert.NoError(err, "setting deadline should not error")
defer func() {
err := conn.SetDeadline(time.Time{})
assert.NoError(err, "unsetting deadline should not error")
}()
bytesRead := 0
for bytesRead < 1+nonceSize {
n, err := conn.Read(challengeRequest[bytesRead:])
if err != nil {
return err
}
bytesRead += n
}
assert.Assert(challengeRequest[0] == packet.VERSION, "client should always have the same version as the server")
challengeResponse := make([]byte, 1+ed25519.PublicKeySize+ed25519.SignatureSize)
challengeResponse[0] = packet.VERSION
copy(challengeResponse[1:1+ed25519.PublicKeySize], privKey.Public().(ed25519.PublicKey))
signedNonce := ed25519.Sign(privKey, challengeRequest[1:])
n := copy(challengeResponse[1+ed25519.PublicKeySize:], signedNonce)
assert.Assert(n == ed25519.SignatureSize, "copy should've copied the entire signature exactly")
_, err = conn.Write(challengeResponse)
if err != nil {
return err
}
return nil
}
func readForever() {
buffer := make([]byte, 512)
for conn != nil {
n, err := conn.Read(buffer)
if err != nil {
if errors.Is(err, io.EOF) {
err = nil
}
onDisconnect(err)
return
}
ctx, cancel := context.WithTimeout(context.Background(), time.Second)
err = framer.Push(ctx, buffer[:n])
if ctx.Err() != nil {
cancel()
onDisconnect(errors.New("framer blocked for more than a second, closing connection"))
return
}
cancel()
assert.NoError(err, "packets from server should always be correctly formatted")
}
}
func handlePacketStream() {
for {
pkt, ok := <-framer.Out
if !ok {
break
}
payload, err := pkt.DecodedPayload()
assert.NoError(err, "server should always provide a decodeable packet")
if pkt.Type().IsPush() {
log.Println("received streamed packet:", payload)
ui.Program.Send(payload)
continue
}
responsesMu.Lock()
assert.Assert(len(asyncResponses) != 0, "there must always be at least 1 response waiting")
responseChan := asyncResponses[0]
copy(asyncResponses, asyncResponses[1:])
asyncResponses = asyncResponses[:len(asyncResponses)-1]
responsesMu.Unlock()
go func() {
responseChan <- payload
}()
}
}
func Disconnect() {
assert.Assert(conn != nil, "cannot disconnect, connection is inactive")
conn.Close()
}
func onDisconnect(err error) {
conn.Close()
conn = nil
close(framer.Out)
responsesMu.Lock()
for _, responseChan := range asyncResponses {
close(responseChan)
}
asyncResponses = nil
responsesMu.Unlock()
if err != nil {
log.Println("connection lost:", err)
ui.Program.Send(ConnectionLost(err))
} else {
log.Println("connection closed")
ui.Program.Send(ConnectionClosed{})
}
}
func Send(request packet.Payload) <-chan packet.Payload {
responseChan := make(chan packet.Payload, 1)
go func() {
pkt := packet.NewPacket(packet.NewMsgPackEncoder(request))
responsesMu.Lock()
asyncResponses = append(asyncResponses, responseChan)
responsesMu.Unlock()
if conn == nil {
log.Println("request send error:", "connection is closed")
return
}
writeMu.Lock()
_, err := pkt.Into(conn)
writeMu.Unlock()
if err != nil {
log.Println("request send error:", err)
return
}
}()
return responseChan
}
|
