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session.go
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session.go
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package server
import (
"bytes"
"context"
"encoding/binary"
"encoding/json"
"errors"
"fmt"
"io"
"log"
"net"
"os"
"regexp"
"strconv"
"strings"
"sync"
"time"
"golang.org/x/sync/errgroup"
fly "github.com/superfly/fly-go"
"github.com/superfly/fly-go/tokens"
"github.com/superfly/flyctl/agent"
"github.com/superfly/flyctl/agent/internal/proto"
"github.com/superfly/flyctl/wg"
"github.com/superfly/flyctl/internal/buildinfo"
"github.com/superfly/flyctl/internal/config"
"github.com/superfly/flyctl/internal/flyutil"
)
type id uint64
func (id id) String() string {
return fmt.Sprintf("#%x", uint64(id))
}
type session struct {
srv *server
conn net.Conn
logger *log.Logger
id id
tokens *tokens.Tokens
}
var errUnsupportedCommand = errors.New("unsupported command")
func runSession(ctx context.Context, srv *server, conn net.Conn, id id) {
var wg sync.WaitGroup
defer wg.Wait()
ctx, cancel := context.WithCancel(ctx)
defer cancel()
wg.Add(1)
go func() {
defer wg.Done()
<-ctx.Done()
_ = conn.Close()
}()
logger := log.New(srv.Logger.Writer(), id.String()+" ", srv.Logger.Flags())
logger.Print("connected ...")
defer func() {
if err := conn.Close(); err != nil && !isClosed(err) {
logger.Printf("failed dropping: %v", err)
} else {
logger.Print("dropped.")
}
}()
s := &session{
srv: srv,
conn: conn,
logger: logger,
id: id,
}
if err := s.srv.checkForConfigChange(); err != nil {
s.error(err)
return
}
s.runCommand(ctx)
}
func (s *session) runCommand(ctx context.Context) {
buf, err := proto.Read(s.conn)
if len(buf) > 0 {
s.logger.Printf("<- (% 5d) %q", len(buf), redact(buf))
}
if err != nil {
if !isClosed(err) {
s.logger.Printf("failed reading: %v", err)
}
return
}
args := strings.Split(string(buf), " ")
var handler func(*session, context.Context, ...string)
switch args[0] {
case "kill":
handler = (*session).kill
case "ping":
handler = (*session).ping
case "establish":
handler = (*session).establish
case "reestablish":
handler = (*session).reestablish
case "connect":
handler = (*session).connect
case "probe":
handler = (*session).probe
case "instances":
handler = (*session).instances
case "resolve":
handler = (*session).resolve
case "lookupTxt":
handler = (*session).lookupTxt
case "ping6":
handler = (*session).ping6
case "set-token":
handler = (*session).setToken
default:
s.error(errUnsupportedCommand)
return
}
handler(s, ctx, args[1:]...)
}
var errMalformedKill = errors.New("malformed kill command")
func (s *session) kill(_ context.Context, args ...string) {
if !s.noArgs(args, errMalformedKill) {
return
}
s.ok()
s.srv.shutdown()
}
var errMalformedPing = errors.New("malformed ping command")
func (s *session) ping(_ context.Context, args ...string) {
if !s.noArgs(args, errMalformedPing) {
return
}
_ = s.marshal(agent.PingResponse{
Version: buildinfo.Version().String(),
PID: os.Getpid(),
Background: s.srv.Options.Background,
})
}
var errMalformedEstablish = errors.New("malformed establish command")
func (s *session) doEstablish(ctx context.Context, recycle bool, args ...string) {
if !s.exactArgs(2, args, errMalformedEstablish) {
return
}
s.logger.Printf("establishing tunnel for %s, %s", args[0], args[1])
org, err := s.fetchOrg(ctx, args[0])
if err != nil {
s.error(err)
return
}
tunnel, err := s.srv.buildTunnel(ctx, org, recycle, args[1], s.getClient(ctx))
if err != nil {
s.error(err)
return
}
_ = s.marshal(agent.EstablishResponse{
WireGuardState: tunnel.State,
TunnelConfig: tunnel.Config,
})
}
func (s *session) establish(ctx context.Context, args ...string) {
s.doEstablish(ctx, false, args...)
}
func (s *session) reestablish(ctx context.Context, args ...string) {
s.doEstablish(ctx, true, args...)
}
var errNoSuchOrg = errors.New("no such organization")
func (s *session) fetchOrg(ctx context.Context, slug string) (*fly.Organization, error) {
orgs, err := s.getClient(ctx).GetOrganizations(ctx)
if err != nil {
return nil, err
}
for _, org := range orgs {
if org.Slug == slug {
no := org // copy
return &no, nil
}
}
return nil, errNoSuchOrg
}
var errMalformedProbe = errors.New("malformed probe command")
func (s *session) probe(ctx context.Context, args ...string) {
if !s.exactArgs(2, args, errMalformedProbe) {
return
}
if err := s.srv.probeTunnel(ctx, args[0], args[1]); err != nil {
s.error(err)
return
}
_ = s.ok()
}
var errMalformedInstances = errors.New("malformed instances command")
func (s *session) instances(ctx context.Context, args ...string) {
if !s.exactArgs(2, args, errMalformedInstances) {
return
}
tunnel := s.srv.tunnelFor(args[0], "")
if tunnel == nil {
s.error(agent.ErrTunnelUnavailable)
return
}
app := args[1]
ret, err := s.srv.fetchInstances(ctx, tunnel, app)
if err != nil {
err = fmt.Errorf("failed fetching instances for %q: %w", app, err)
s.error(err)
return
}
if len(ret.Addresses) == 0 {
err = fmt.Errorf("no running hosts for %q found", app)
s.error(err)
return
}
_ = s.marshal(ret)
}
var errMalformedResolve = errors.New("malformed resolve command")
func (s *session) resolve(ctx context.Context, args ...string) {
if !s.exactArgs(3, args, errMalformedResolve) {
return
}
tunnel := s.srv.tunnelFor(args[0], args[2])
if tunnel == nil {
s.error(agent.ErrTunnelUnavailable)
return
}
addr, err := resolve(ctx, tunnel, args[1])
if err != nil {
s.error(err)
return
}
s.ok(addr)
}
func resolve(ctx context.Context, tunnel *wg.Tunnel, addr string) (string, error) {
host, port, err := net.SplitHostPort(addr)
if err != nil {
if !strings.Contains(err.Error(), "missing port") {
return "", err
}
host = addr
}
if n := net.ParseIP(host); n != nil && n.To16() != nil {
if port == "" {
return n.String(), nil
}
return net.JoinHostPort(n.String(), port), nil
}
ips, err := tunnel.LookupAAAA(ctx, host)
if err != nil {
return "", err
}
if len(ips) == 0 {
return "", agent.ErrNoSuchHost
}
addr = ips[0].String()
if port != "" {
addr = net.JoinHostPort(addr, port)
}
return addr, nil
}
func (s *session) lookupTxt(ctx context.Context, args ...string) {
if len(args) != 2 {
s.error(fmt.Errorf("lookupTxt: bad args"))
return
}
tunnel := s.srv.tunnelFor(args[0], "")
if tunnel == nil {
s.error(agent.ErrTunnelUnavailable)
return
}
hostArg := args[1]
host, _, err := net.SplitHostPort(hostArg)
if err != nil {
if !strings.Contains(err.Error(), "missing port") {
s.error(err)
return
}
host = hostArg
}
txt, err := tunnel.LookupTXT(ctx, host)
if err != nil {
s.error(err)
return
}
s.marshal(txt)
}
var (
errMalformedConnect = errors.New("malformed connect command")
errDone = errors.New("done")
)
func (s *session) connect(ctx context.Context, args ...string) {
if !s.exactArgs(4, args, errMalformedConnect) {
return
}
timeout, err := strconv.ParseUint(args[2], 10, 32)
if err != nil {
s.error(err)
return
}
tunnel := s.srv.tunnelFor(args[0], args[3])
if tunnel == nil {
s.error(agent.ErrTunnelUnavailable)
return
}
var dialContext context.Context
var cancel context.CancelFunc
if timeout > 0 {
dialContext, cancel = context.WithTimeout(ctx, time.Duration(timeout)*time.Millisecond)
} else {
dialContext, cancel = context.WithCancel(ctx)
}
defer cancel()
outconn, err := tunnel.DialContext(dialContext, "tcp", args[1])
if err != nil {
s.error(err)
return
}
defer func() {
if err := outconn.Close(); err != nil && !isClosed(err) {
s.logger.Printf("failed closing outconn: %v", err)
}
}()
if !s.ok() {
return
}
var eg *errgroup.Group
eg, ctx = errgroup.WithContext(ctx)
eg.Go(func() error {
<-ctx.Done()
_ = s.conn.Close()
_ = outconn.Close()
return errDone
})
eg.Go(func() (err error) {
if _, err = io.Copy(s.conn, outconn); err == nil {
err = io.EOF
}
return
})
eg.Go(func() (err error) {
if _, err = io.Copy(outconn, s.conn); err == nil {
err = io.EOF
}
return
})
_ = eg.Wait()
}
func (s *session) ping6(ctx context.Context, args ...string) {
// As with "dial", "ping6" handles an agent command and then
// repurposes the agent connection as a transport.
if len(args) != 1 {
s.error(fmt.Errorf("ping6: bad args"))
return
}
tunnel := s.srv.tunnelFor(args[0], "")
if tunnel == nil {
s.error(agent.ErrTunnelUnavailable)
return
}
// YOG-SOTHOTH IS THE GATE
sock, err := tunnel.ListenPing()
if err != nil {
s.error(fmt.Errorf("ping6: %w", err))
return
}
ctx, cancel := context.WithCancel(ctx)
// a background thread watches for incoming ICMP messages on
// the ICMP "socket" we get from wireguard-go. Each received
// message is relayed back over the agent connection.
go func() {
pbuf := make([]byte, 1500)
lbuf := make([]byte, 2)
for {
if ctx.Err() != nil {
return
}
sock.SetDeadline(time.Now().Add(1 * time.Second))
n64, addr, err := sock.ReadFrom(pbuf)
if err != nil {
if !errors.Is(err, os.ErrDeadlineExceeded) {
s.logger.Printf("ping6: %s", err)
}
continue
}
v6addr := net.ParseIP(addr.String()).To16()
if v6addr == nil {
s.logger.Printf("ping6: bad remote address '%s'", addr)
continue
}
payload := pbuf[:n64]
binary.BigEndian.PutUint16(lbuf, uint16(len(payload)))
// not much point to handling the error here; the parent
// thread will cancel this goroutine if the connection dies.
s.conn.Write(v6addr)
s.conn.Write(lbuf)
s.conn.Write(payload)
}
}()
pbuf := make([]byte, 1500)
lbuf := make([]byte, 2)
v6buf := make([]byte, 16)
sockOk := func(err error) bool {
if err == nil {
return true
}
if err != io.EOF {
s.logger.Printf("ping6: socket read error: %s", err)
}
cancel()
return false
}
for {
_, err = io.ReadFull(s.conn, v6buf)
if !sockOk(err) {
return
}
_, err = io.ReadFull(s.conn, lbuf)
if !sockOk(err) {
return
}
paylen := binary.BigEndian.Uint16(lbuf)
if paylen >= 1500 {
sockOk(fmt.Errorf("bad payload length (>=1500)"))
return
}
pkt := pbuf[:paylen]
_, err = io.ReadFull(s.conn, pkt)
if !sockOk(err) {
return
}
_, err = sock.WriteTo(pkt, &net.IPAddr{IP: net.IP(v6buf)})
if !sockOk(err) {
return
}
}
}
var errMalformedSetToken = errors.New("malformed set-token command")
// setToken instructs the agent which tokens to use for API calls.
func (s *session) setToken(ctx context.Context, args ...string) {
if !s.exactArgs(2, args, errMalformedSetToken) {
return
}
switch args[0] {
case "cfg":
tokStr, err := config.ReadAccessToken(args[1])
if err != nil {
s.error(err)
return
}
s.tokens = tokens.ParseFromFile(tokStr, args[1])
case "str":
s.tokens = tokens.Parse(args[1])
}
go s.srv.UpdateTokensFromClient(s.tokens)
s.ok()
s.runCommand(ctx)
}
// getClient returns an API client that uses any API tokens sent by the client.
// If none have been sent, it falls back to using the server's tokens.
func (s *session) getClient(ctx context.Context) flyutil.Client {
if s.tokens == nil {
return s.srv.GetClient(ctx)
}
return flyutil.NewClientFromOptions(ctx, fly.ClientOptions{Tokens: s.tokens})
}
func (s *session) error(err error) bool {
return s.reply("err", err.Error())
}
func (s *session) ok(args ...string) bool {
return s.reply("ok", args...)
}
func (s *session) reply(verb string, args ...string) bool {
var b bytes.Buffer
out := io.MultiWriter(
&b,
s.conn,
)
err := proto.Write(out, verb, args...)
if l := b.Len(); l > 0 {
s.logger.Printf("-> (% 5d) %q", l, redact(b.Bytes()))
}
if err != nil {
if !isClosed(err) {
s.logger.Printf("failed writing: %v", err)
}
return false
}
return true
}
func (s *session) noArgs(args []string, err error) bool {
if len(args) != 0 {
s.error(err)
return false
}
return true
}
func (s *session) exactArgs(count int, args []string, err error) bool {
if len(args) != count {
s.error(err)
return false
}
return true
}
func (s *session) marshal(v interface{}) (ok bool) {
var sb strings.Builder
enc := json.NewEncoder(&sb)
switch err := enc.Encode(v); err {
default:
err = fmt.Errorf("failed marshaling response: %w", err)
s.error(err)
case nil:
ok = true
s.ok(sb.String())
}
return
}
func isClosed(err error) bool {
return errors.Is(err, net.ErrClosed)
}
var (
redactPrivateKeyRx = regexp.MustCompile(`(PrivateKey|private)":".*?"`)
redactTokenRx = regexp.MustCompile(`(fo1_|fm1[ar]_|fm2_)[a-zA-Z0-9/+_-]+=*`)
)
func redact(buf []byte) []byte {
buf = redactPrivateKeyRx.ReplaceAll(buf, []byte(`PrivateKey":"[redacted]"`))
buf = redactTokenRx.ReplaceAll(buf, []byte(`$1[redacted]`))
return buf
}