lego/challenge/http01/http_challenge_server.go
2020-09-02 20:38:01 +02:00

122 lines
4 KiB
Go

package http01
import (
"fmt"
"net"
"net/http"
"net/textproto"
"strings"
"github.com/go-acme/lego/v4/log"
)
// ProviderServer implements ChallengeProvider for `http-01` challenge.
// It may be instantiated without using the NewProviderServer function if
// you want only to use the default values.
type ProviderServer struct {
iface string
port string
matcher domainMatcher
done chan bool
listener net.Listener
}
// NewProviderServer creates a new ProviderServer on the selected interface and port.
// Setting iface and / or port to an empty string will make the server fall back to
// the "any" interface and port 80 respectively.
func NewProviderServer(iface, port string) *ProviderServer {
if port == "" {
port = "80"
}
return &ProviderServer{iface: iface, port: port, matcher: &hostMatcher{}}
}
// Present starts a web server and makes the token available at `ChallengePath(token)` for web requests.
func (s *ProviderServer) Present(domain, token, keyAuth string) error {
var err error
s.listener, err = net.Listen("tcp", s.GetAddress())
if err != nil {
return fmt.Errorf("could not start HTTP server for challenge: %w", err)
}
s.done = make(chan bool)
go s.serve(domain, token, keyAuth)
return nil
}
func (s *ProviderServer) GetAddress() string {
return net.JoinHostPort(s.iface, s.port)
}
// CleanUp closes the HTTP server and removes the token from `ChallengePath(token)`.
func (s *ProviderServer) CleanUp(domain, token, keyAuth string) error {
if s.listener == nil {
return nil
}
s.listener.Close()
<-s.done
return nil
}
// SetProxyHeader changes the validation of incoming requests.
// By default, s matches the "Host" header value to the domain name.
//
// When the server runs behind a proxy server, this is not the correct place to look at;
// Apache and NGINX have traditionally moved the original Host header into a new header named "X-Forwarded-Host".
// Other webservers might use different names;
// and RFC7239 has standardized a new header named "Forwarded" (with slightly different semantics).
//
// The exact behavior depends on the value of headerName:
// - "" (the empty string) and "Host" will restore the default and only check the Host header
// - "Forwarded" will look for a Forwarded header, and inspect it according to https://tools.ietf.org/html/rfc7239
// - any other value will check the header value with the same name.
func (s *ProviderServer) SetProxyHeader(headerName string) {
switch h := textproto.CanonicalMIMEHeaderKey(headerName); h {
case "", "Host":
s.matcher = &hostMatcher{}
case "Forwarded":
s.matcher = &forwardedMatcher{}
default:
s.matcher = arbitraryMatcher(h)
}
}
func (s *ProviderServer) serve(domain, token, keyAuth string) {
path := ChallengePath(token)
// The incoming request must will be validated to prevent DNS rebind attacks.
// We only respond with the keyAuth, when we're receiving a GET requests with
// the "Host" header matching the domain (the latter is configurable though SetProxyHeader).
mux := http.NewServeMux()
mux.HandleFunc(path, func(w http.ResponseWriter, r *http.Request) {
if r.Method == http.MethodGet && s.matcher.matches(r, domain) {
w.Header().Add("Content-Type", "text/plain")
_, err := w.Write([]byte(keyAuth))
if err != nil {
http.Error(w, err.Error(), http.StatusInternalServerError)
return
}
log.Infof("[%s] Served key authentication", domain)
} else {
log.Warnf("Received request for domain %s with method %s but the domain did not match any challenge. Please ensure your are passing the %s header properly.", r.Host, r.Method, s.matcher.name())
_, err := w.Write([]byte("TEST"))
if err != nil {
http.Error(w, err.Error(), http.StatusInternalServerError)
return
}
}
})
httpServer := &http.Server{Handler: mux}
// Once httpServer is shut down
// we don't want any lingering connections, so disable KeepAlives.
httpServer.SetKeepAlivesEnabled(false)
err := httpServer.Serve(s.listener)
if err != nil && !strings.Contains(err.Error(), "use of closed network connection") {
log.Println(err)
}
s.done <- true
}