forgejo/modules/graceful/server.go

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// Copyright 2019 The Gitea Authors. All rights reserved.
// SPDX-License-Identifier: MIT
// This code is highly inspired by endless go
package graceful
import (
"crypto/tls"
"net"
"os"
"strings"
"sync"
"sync/atomic"
"syscall"
"time"
"code.gitea.io/gitea/modules/log"
"code.gitea.io/gitea/modules/proxyprotocol"
"code.gitea.io/gitea/modules/setting"
)
// GetListener returns a net listener
// This determines the implementation of net.Listener which the server will use,
// so that downstreams could provide their own Listener, such as with a hidden service or a p2p network
Allow the use of alternative net.Listener implementations by downstreams (#25855) This is a simple PR which moves the `GetListener` function to a `DefaultGetListener` function, and changes `GetListener` to be a variable which by default points to the `DefaultGetListener` function. This allows people who may exist quasi-downstream of Gitea to create alternate "GetListener" functions, with identical signatures, which return different implementations of the `net.Listener` interface. This approach is expressly intended to be non-invasive and have the least possible impact on the gitea codebase. A previous version of this idea was rejected before: https://github.com/go-gitea/gitea/issues/15544 but because of issues like: https://github.com/go-gitea/gitea/issues/22335 I **really** think that recommending people configure proxies by hand is exactly the wrong way to do things(This is why there is a Tor Browser.). This tiny change lets me put proper hidden service configuration into single `i2p.go` file which lives in `modules/graceful/` and which never has to be checked in to your codebase or affect your dependencies or bloat your project in any way, it can live on a branch in my fork and I'll fast-forward every release and never the twain shall meet. The main use-case for this is to listen on Peer-to-Peer networks and Hidden Services directly without error-prone and cumbersome port-forwarding configuration. For instance, I might implement an "I2PGetListener" as follows: ```Go // adapted from i2p.go which is unchecked-in in my modules/graceful/ directory import "github.com/eyedeekay/onramp" var garlic = &onramp.Garlic{} func I2PGetListener(network, address string) (net.Listener, error) { // Add a deferral to say that we've tried to grab a listener defer GetManager().InformCleanup() switch network { case "tcp", "tcp4", "tcp6", "i2p", "i2pt": return garlic.Listen() case "unix", "unixpacket": // I2P isn't really a replacement for the stuff you use Unix sockets for and it's also not an anonymity risk, so treat them normally unixAddr, err := net.ResolveUnixAddr(network, address) if err != nil { return nil, err } return GetListenerUnix(network, unixAddr) default: return nil, net.UnknownNetworkError(network) } } ``` I could then substitute that GetListener function and be 50% of the way to having a fully-functioning gitea-over-hidden-services instance without any additional configuration(The other 50% doesn't require any code-changes on gitea's part). There are 2 advantages here, one being convenience, first this turns hidden services into a zero-configuration option for self-hosting gitea, and second safety, these Go libraries are passing around hidden-service-only versions of the net.Addr struct, they're using hidden-service-only versions of the sockets, which are both expressly designed to never require access to any information outside the hidden service network, manipulating the application so it reveals information about the host becomes much more difficult, and some attacks become nearly impossible. It also opens up TLS-over-Hidden Services support which is niche right now, of course, but in a future where gitea instances federate if hidden services want to be part of the federation they're probably going to need TLS certificates. They don't need to be painful to set up. This doesn't fix an open issue, but it might affect: - https://github.com/go-gitea/gitea/issues/22335 - my `i2p.go` file actually has a mod that fixes this but it requires adding a handful of new dependencies to gitea and isn't compatible with the normal way you guys recommend using a proxy so I don't think it's ready to send to you as a PR, but if I can find a non-invasive way to fix it I will. - https://github.com/go-gitea/gitea/issues/18240 I hereby agree to the Code of Conduct published here: https://github.com/go-gitea/gitea/blob/8b89563bf1031089a218e6d05dc61047281b35ee/CODE_OF_CONDUCT.md I have read and understood the recommendations published here: https://github.com/go-gitea/gitea/blob/8b89563bf1031089a218e6d05dc61047281b35ee/CONTRIBUTING.md Thank you for your consideration. --------- Co-authored-by: eyedeekay <idk@mulder> Co-authored-by: wxiaoguang <wxiaoguang@gmail.com>
2023-07-24 09:18:17 +02:00
var GetListener = DefaultGetListener
// ServeFunction represents a listen.Accept loop
type ServeFunction = func(net.Listener) error
// Server represents our graceful server
type Server struct {
network string
address string
listener net.Listener
wg sync.WaitGroup
state state
lock *sync.RWMutex
BeforeBegin func(network, address string)
OnShutdown func()
PerWriteTimeout time.Duration
PerWritePerKbTimeout time.Duration
}
// NewServer creates a server on network at provided address
func NewServer(network, address, name string) *Server {
if GetManager().IsChild() {
log.Info("Restarting new %s server: %s:%s on PID: %d", name, network, address, os.Getpid())
} else {
log.Info("Starting new %s server: %s:%s on PID: %d", name, network, address, os.Getpid())
}
srv := &Server{
wg: sync.WaitGroup{},
state: stateInit,
lock: &sync.RWMutex{},
network: network,
address: address,
PerWriteTimeout: setting.PerWriteTimeout,
PerWritePerKbTimeout: setting.PerWritePerKbTimeout,
}
srv.BeforeBegin = func(network, addr string) {
log.Debug("Starting server on %s:%s (PID: %d)", network, addr, syscall.Getpid())
}
return srv
}
// ListenAndServe listens on the provided network address and then calls Serve
// to handle requests on incoming connections.
func (srv *Server) ListenAndServe(serve ServeFunction, useProxyProtocol bool) error {
go srv.awaitShutdown()
listener, err := GetListener(srv.network, srv.address)
if err != nil {
log.Error("Unable to GetListener: %v", err)
return err
}
// we need to wrap the listener to take account of our lifecycle
listener = newWrappedListener(listener, srv)
// Now we need to take account of ProxyProtocol settings...
if useProxyProtocol {
listener = &proxyprotocol.Listener{
Listener: listener,
ProxyHeaderTimeout: setting.ProxyProtocolHeaderTimeout,
AcceptUnknown: setting.ProxyProtocolAcceptUnknown,
}
}
srv.listener = listener
srv.BeforeBegin(srv.network, srv.address)
return srv.Serve(serve)
}
// ListenAndServeTLSConfig listens on the provided network address and then calls
// Serve to handle requests on incoming TLS connections.
func (srv *Server) ListenAndServeTLSConfig(tlsConfig *tls.Config, serve ServeFunction, useProxyProtocol, proxyProtocolTLSBridging bool) error {
go srv.awaitShutdown()
if tlsConfig.MinVersion == 0 {
tlsConfig.MinVersion = tls.VersionTLS12
}
listener, err := GetListener(srv.network, srv.address)
if err != nil {
log.Error("Unable to get Listener: %v", err)
return err
}
// we need to wrap the listener to take account of our lifecycle
listener = newWrappedListener(listener, srv)
// Now we need to take account of ProxyProtocol settings... If we're not bridging then we expect that the proxy will forward the connection to us
if useProxyProtocol && !proxyProtocolTLSBridging {
listener = &proxyprotocol.Listener{
Listener: listener,
ProxyHeaderTimeout: setting.ProxyProtocolHeaderTimeout,
AcceptUnknown: setting.ProxyProtocolAcceptUnknown,
}
}
// Now handle the tls protocol
listener = tls.NewListener(listener, tlsConfig)
// Now if we're bridging then we need the proxy to tell us who we're bridging for...
if useProxyProtocol && proxyProtocolTLSBridging {
listener = &proxyprotocol.Listener{
Listener: listener,
ProxyHeaderTimeout: setting.ProxyProtocolHeaderTimeout,
AcceptUnknown: setting.ProxyProtocolAcceptUnknown,
}
}
srv.listener = listener
srv.BeforeBegin(srv.network, srv.address)
return srv.Serve(serve)
}
// Serve accepts incoming HTTP connections on the wrapped listener l, creating a new
// service goroutine for each. The service goroutines read requests and then call
// handler to reply to them. Handler is typically nil, in which case the
// DefaultServeMux is used.
//
// In addition to the standard Serve behaviour each connection is added to a
// sync.Waitgroup so that all outstanding connections can be served before shutting
// down the server.
func (srv *Server) Serve(serve ServeFunction) error {
defer log.Debug("Serve() returning... (PID: %d)", syscall.Getpid())
srv.setState(stateRunning)
GetManager().RegisterServer()
err := serve(srv.listener)
log.Debug("Waiting for connections to finish... (PID: %d)", syscall.Getpid())
srv.wg.Wait()
srv.setState(stateTerminate)
GetManager().ServerDone()
// use of closed means that the listeners are closed - i.e. we should be shutting down - return nil
if err == nil || strings.Contains(err.Error(), "use of closed") || strings.Contains(err.Error(), "http: Server closed") {
return nil
}
return err
}
func (srv *Server) getState() state {
srv.lock.RLock()
defer srv.lock.RUnlock()
return srv.state
}
func (srv *Server) setState(st state) {
srv.lock.Lock()
defer srv.lock.Unlock()
srv.state = st
}
type filer interface {
File() (*os.File, error)
}
type wrappedListener struct {
net.Listener
stopped bool
server *Server
}
func newWrappedListener(l net.Listener, srv *Server) *wrappedListener {
return &wrappedListener{
Listener: l,
server: srv,
}
}
func (wl *wrappedListener) Accept() (net.Conn, error) {
var c net.Conn
// Set keepalive on TCPListeners connections.
if tcl, ok := wl.Listener.(*net.TCPListener); ok {
tc, err := tcl.AcceptTCP()
if err != nil {
return nil, err
}
_ = tc.SetKeepAlive(true) // see http.tcpKeepAliveListener
_ = tc.SetKeepAlivePeriod(3 * time.Minute) // see http.tcpKeepAliveListener
c = tc
} else {
var err error
c, err = wl.Listener.Accept()
if err != nil {
return nil, err
}
}
closed := int32(0)
c = &wrappedConn{
Conn: c,
server: wl.server,
closed: &closed,
perWriteTimeout: wl.server.PerWriteTimeout,
perWritePerKbTimeout: wl.server.PerWritePerKbTimeout,
}
wl.server.wg.Add(1)
return c, nil
}
func (wl *wrappedListener) Close() error {
if wl.stopped {
return syscall.EINVAL
}
wl.stopped = true
return wl.Listener.Close()
}
func (wl *wrappedListener) File() (*os.File, error) {
// returns a dup(2) - FD_CLOEXEC flag *not* set so the listening socket can be passed to child processes
return wl.Listener.(filer).File()
}
type wrappedConn struct {
net.Conn
server *Server
closed *int32
deadline time.Time
perWriteTimeout time.Duration
perWritePerKbTimeout time.Duration
}
func (w *wrappedConn) Write(p []byte) (n int, err error) {
if w.perWriteTimeout > 0 {
minTimeout := time.Duration(len(p)/1024) * w.perWritePerKbTimeout
minDeadline := time.Now().Add(minTimeout).Add(w.perWriteTimeout)
w.deadline = w.deadline.Add(minTimeout)
if minDeadline.After(w.deadline) {
w.deadline = minDeadline
}
_ = w.Conn.SetWriteDeadline(w.deadline)
}
return w.Conn.Write(p)
}
func (w *wrappedConn) Close() error {
if atomic.CompareAndSwapInt32(w.closed, 0, 1) {
defer func() {
if err := recover(); err != nil {
select {
case <-GetManager().IsHammer():
// Likely deadlocked request released at hammertime
log.Warn("Panic during connection close! %v. Likely there has been a deadlocked request which has been released by forced shutdown.", err)
default:
log.Error("Panic during connection close! %v", err)
}
}
}()
w.server.wg.Done()
}
return w.Conn.Close()
}