Files
coder/enterprise/tailnet/workspaceproxy.go
2023-07-19 11:11:11 -05:00

96 lines
2.7 KiB
Go

package tailnet
import (
"bytes"
"context"
"encoding/json"
"net"
"time"
"golang.org/x/xerrors"
"github.com/coder/coder/enterprise/wsproxy/wsproxysdk"
agpl "github.com/coder/coder/tailnet"
)
func ServeWorkspaceProxy(ctx context.Context, conn net.Conn, ma agpl.MultiAgentConn) error {
go func() {
err := forwardNodesToWorkspaceProxy(ctx, conn, ma)
if err != nil {
_ = conn.Close()
}
}()
decoder := json.NewDecoder(conn)
for {
var msg wsproxysdk.CoordinateMessage
err := decoder.Decode(&msg)
if err != nil {
return xerrors.Errorf("read json: %w", err)
}
switch msg.Type {
case wsproxysdk.CoordinateMessageTypeSubscribe:
err := ma.SubscribeAgent(msg.AgentID)
if err != nil {
return xerrors.Errorf("subscribe agent: %w", err)
}
case wsproxysdk.CoordinateMessageTypeUnsubscribe:
err := ma.UnsubscribeAgent(msg.AgentID)
if err != nil {
return xerrors.Errorf("unsubscribe agent: %w", err)
}
case wsproxysdk.CoordinateMessageTypeNodeUpdate:
err := ma.UpdateSelf(msg.Node)
if err != nil {
return xerrors.Errorf("update self: %w", err)
}
default:
return xerrors.Errorf("unknown message type %q", msg.Type)
}
}
}
func forwardNodesToWorkspaceProxy(ctx context.Context, conn net.Conn, ma agpl.MultiAgentConn) error {
var lastData []byte
for {
nodes, ok := ma.NextUpdate(ctx)
if !ok {
return xerrors.New("multiagent is closed")
}
data, err := json.Marshal(wsproxysdk.CoordinateNodes{Nodes: nodes})
if err != nil {
return err
}
if bytes.Equal(lastData, data) {
continue
}
// Set a deadline so that hung connections don't put back pressure on the system.
// Node updates are tiny, so even the dinkiest connection can handle them if it's not hung.
err = conn.SetWriteDeadline(time.Now().Add(agpl.WriteTimeout))
if err != nil {
// often, this is just because the connection is closed/broken, so only log at debug.
return err
}
_, err = conn.Write(data)
if err != nil {
// often, this is just because the connection is closed/broken, so only log at debug.
return err
}
// nhooyr.io/websocket has a bugged implementation of deadlines on a websocket net.Conn. What they are
// *supposed* to do is set a deadline for any subsequent writes to complete, otherwise the call to Write()
// fails. What nhooyr.io/websocket does is set a timer, after which it expires the websocket write context.
// If this timer fires, then the next write will fail *even if we set a new write deadline*. So, after
// our successful write, it is important that we reset the deadline before it fires.
err = conn.SetWriteDeadline(time.Time{})
if err != nil {
return err
}
lastData = data
}
}