improve default regex

command/serve.go

@@ -6,15 +6,16 @@ import (
 	"fmt"
 	"gitea.illuad.fr/adrien/middleman"
 	"gitea.illuad.fr/adrien/middleman/flag"
+	"gitea.illuad.fr/adrien/middleman/pkg/fastrp"
 	"github.com/rs/zerolog/log"
 	"github.com/urfave/cli/v3"
 	"golang.org/x/sync/errgroup"
 	"net"
 	"net/http"
-	"net/http/httputil"
 	"net/netip"
 	"net/url"
 	"regexp"
+	"slices"
 	"strings"
 	"time"
 )
@@ -34,25 +35,7 @@ type methodRegex = map[string]*regexp.Regexp
 
 // ProxyHandler takes an incoming request and sends it to another server, proxying the response back to the client.
 type ProxyHandler struct {
-	rp *httputil.ReverseProxy
-}
-
-// ErrHTTPMethodNotAllowed is returned if the request's HTTP method is not allowed for this container.
-type ErrHTTPMethodNotAllowed struct {
-	httpMethod string
-}
-
-// ErrNoMatch is returned if the request's URL path is not allowed for this container.
-type ErrNoMatch struct {
-	path, httpMethod string
-}
-
-func (e ErrHTTPMethodNotAllowed) Error() string {
-	return fmt.Sprintf("%s is not in the list of HTTP methods allowed this container", e.httpMethod)
-}
-
-func (e ErrNoMatch) Error() string {
-	return fmt.Sprintf("%s does not match any registered regular expression for this HTTP method (%s)", e.path, e.httpMethod)
+	frp *fastrp.FastRP
 }
 
 // ServeCmd is the command name.
@@ -92,8 +75,8 @@ const (
 	defaultHealthEndpoint = "/healthz"
 	// defaultHealthListenAddr is the proxy health endpoint default listen address and port.
 	defaultHealthListenAddr = "127.0.0.1:5732"
-	// defaultAllowedRequest is the proxy default allowed request.
-	defaultAllowedRequest = "^/(version|containers/.*|events.*)$"
+	// defaultAllowedRequests is the default allowed requests. Note that they should be sufficient to make Traefik work properly.
+	defaultAllowedRequests = "/v1.\\d{1,2}/(version|containers/(?:json|[a-zA-Z0-9]{64}/json)|events)$"
 )
 
 var s serve
@@ -101,7 +84,7 @@ var s serve
 var (
 	containerMethodRegex = map[string]methodRegex{
 		"*": {
-			http.MethodGet: regexp.MustCompile(defaultAllowedRequest),
+			http.MethodGet: regexp.MustCompile(defaultAllowedRequests),
 		},
 	}
 	applicatorURLRegex = regexp.MustCompile(`^([a-zA-Z0-9][a-zA-Z0-9_.-]+)\(((?:(?:GET|HEAD|POST|PUT|PATCH|DELETE|CONNECT|TRACE|OPTIONS)(?:,(?:GET|HEAD|POST|PUT|PATCH|DELETE|CONNECT|TRACE|OPTIONS))*)?)\):(.*)$`)
@@ -149,58 +132,74 @@ func Serve(group *errgroup.Group) *cli.Command {
 
 func (ph *ProxyHandler) ServeHTTP(w http.ResponseWriter, r *http.Request) {
 	log.Debug().Str("remote_addr", r.RemoteAddr).Str("method", r.Method).Str("path", r.URL.Path).Msg("incoming request")
-	mr, ok := containerMethodRegex["*"]
-	if ok {
-		if err := checkMethodPath(r, mr); err != nil {
-			handleError(w, err)
-			log.Err(err).Send()
+	if mr, ok := containerMethodRegex["*"]; ok {
+		if code := ph.checkMethodAndRegex(mr, r, ""); code != http.StatusOK {
+			http.Error(w, http.StatusText(code), code)
 			return
 		}
-	} else {
-		var (
-			containerName string
-			host, _, _    = net.SplitHostPort(r.RemoteAddr)
-			ip            = net.ParseIP(host)
-		)
-		for containerName, mr = range containerMethodRegex {
-			resolvedIPs, err := net.LookupIP(containerName)
-			if err != nil {
-				log.Warn().Err(err).Msg("this error may be transient due to the unavailability of one of the services")
-			}
-			for _, resolvedIP := range resolvedIPs {
-				if resolvedIP.Equal(ip) {
-					if err = checkMethodPath(r, mr); err != nil {
-						handleError(w, err)
-						log.Err(err).Send()
-						return
-					}
-					log.Info().
-						Str("remote_addr", r.RemoteAddr).
-						Str("method", r.Method).
-						Str("path", r.URL.Path).
-						Str("from", containerName).
-						Msg("incoming request matches a registered regular expression")
-					ph.rp.ServeHTTP(w, r)
-					return
-				}
-			}
-		}
-		http.Error(w, http.StatusText(http.StatusForbidden), http.StatusForbidden)
+		ph.frp.ServeHTTP(w, r)
 		return
 	}
+	host, _, _ := net.SplitHostPort(r.RemoteAddr)
+	for containerName, mr := range containerMethodRegex {
+		if ph.isContainerAuthorized(containerName, host) {
+			if code := ph.checkMethodAndRegex(mr, r, containerName); code != http.StatusOK {
+				http.Error(w, http.StatusText(code), code)
+				return
+			}
+			ph.frp.ServeHTTP(w, r)
+			return
+		}
+	}
+	logDeniedRequest(r, http.StatusUnauthorized, "this container is not on the list of authorized ones")
+	http.Error(w, http.StatusText(http.StatusUnauthorized), http.StatusUnauthorized)
 }
 
-// checkMethodPath executes the regular expression on the path of the HTTP request if and only if
-// the latter's HTTP method is actually present in the list of authorized HTTP methods.
-func checkMethodPath(r *http.Request, mr methodRegex) error {
+func (ph *ProxyHandler) isContainerAuthorized(containerName, host string) bool {
+	resolvedIPs, err := net.LookupIP(containerName)
+	if err != nil {
+		return false
+	}
+	for resolvedIP := range slices.Values(resolvedIPs) {
+		if resolvedIP.Equal(net.ParseIP(host)) {
+			return true
+		}
+	}
+	return false
+}
+
+func logDeniedRequest(r *http.Request, statusCode int, message string) {
+	log.Error().
+		Str("remote_addr", r.RemoteAddr).Str("method", r.Method).
+		Str("path", r.URL.Path).Int("status_code", statusCode).
+		Str("status_text", http.StatusText(statusCode)).Msg(message)
+}
+
+func logAuthorizedRequest(r *http.Request, containerName, message string) {
+	l := log.Info().
+		Str("remote_addr", r.RemoteAddr).
+		Str("method", r.Method).
+		Str("path", r.URL.Path).
+		Int("status_code", http.StatusOK).
+		Str("status_text", http.StatusText(http.StatusOK))
+	if containerName != "" {
+		l.Str("container_name", containerName)
+	}
+	l.Msg(message)
+}
+
+func (ph *ProxyHandler) checkMethodAndRegex(mr methodRegex, r *http.Request, containerName string) int {
 	req, ok := mr[r.Method]
 	if !ok {
-		return ErrHTTPMethodNotAllowed{httpMethod: r.Method}
+		logDeniedRequest(r, http.StatusMethodNotAllowed, "this HTTP method is not in the list of those authorized for this container")
+		return http.StatusMethodNotAllowed
 	}
 	if !req.MatchString(r.URL.Path) {
-		return ErrNoMatch{path: r.URL.Path, httpMethod: r.Method}
+		logDeniedRequest(r, http.StatusForbidden, "this path does not match any regular expression for this HTTP method")
+		return http.StatusForbidden
 	}
-	return nil
+	logAuthorizedRequest(r, containerName, "incoming request matches a registered regular expression")
+	return http.StatusOK
 }
 
 // action is executed when the ServeCmd command is called.
@@ -218,14 +217,10 @@ func (s serve) action(ctx context.Context, command *cli.Command) error {
 		return err
 	}
 	dummyURL, _ := url.Parse("http://dummy")
-	rp := httputil.NewSingleHostReverseProxy(dummyURL)
-	rp.Transport = &http.Transport{
-		DialContext: func(_ context.Context, _ string, _ string) (net.Conn, error) {
-			return net.Dial("unix", command.String(dockerSocketPathFlagName))
-		},
-	}
 	srv := &http.Server{ // #nosec: G112
-		Handler: &ProxyHandler{rp: rp},
+		Handler: &ProxyHandler{
+			frp: fastrp.NewRP("unix", command.String(dockerSocketPathFlagName), dummyURL),
+		},
 	}
 	s.group.Go(func() error {
 		if err = srv.Serve(l); err != nil && !errors.Is(err, http.ErrServerClosed) {
@@ -424,7 +419,7 @@ func addRequests() cli.Flag {
 		Usage:    "add requests",
 		Sources:  middleman.PluckEnvVar(EnvVarPrefix, addRequestsFlagName),
 		// Local:    true, // Required to trigger the Action when this flag is set via the environment variable, see https://github.com/urfave/cli/issues/2041.
-		Value:   []string{"*:" + defaultAllowedRequest},
+		Value:   []string{"*:" + defaultAllowedRequests},
 		Aliases: middleman.PluckAlias(ServeCmd, addRequestsFlagName),
 		Action: func(ctx context.Context, command *cli.Command, requests []string) error {
 			clear(containerMethodRegex)
@@ -469,15 +464,3 @@ func registerMethodRegex(containerName, urlRegex string, httpMethods []string) e
 	}
 	return nil
 }
-
-func handleError(w http.ResponseWriter, err error) {
-	var methodNotAllowedErr ErrHTTPMethodNotAllowed
-	var noMatchErr ErrNoMatch
-	if errors.As(err, &methodNotAllowedErr) {
-		http.Error(w, err.Error(), http.StatusMethodNotAllowed)
-	} else if errors.As(err, &noMatchErr) {
-		http.Error(w, err.Error(), http.StatusForbidden)
-	} else {
-		http.Error(w, err.Error(), http.StatusInternalServerError)
-	}
-}

pkg/fastrp/fastrp.go

@@ -0,0 +1,41 @@
+package fastrp
+
+import (
+	"context"
+	"net"
+	"net/http"
+	"net/http/httputil"
+	"net/url"
+	"sync"
+)
+
+type FastRP struct {
+	rp       *httputil.ReverseProxy
+	connPool *sync.Pool
+}
+
+func NewRP(network, address string, url *url.URL) *FastRP {
+	roundTripper := &http.Transport{
+		DialContext: func(_ context.Context, _ string, _ string) (net.Conn, error) {
+			return net.Dial(network, address)
+		},
+		MaxIdleConns: 10,
+	}
+	frp := &FastRP{
+		rp: httputil.NewSingleHostReverseProxy(url),
+		connPool: &sync.Pool{
+			New: func() any {
+				return roundTripper.Clone()
+			},
+		},
+	}
+	frp.rp.Transport = frp.connPool.Get().(http.RoundTripper)
+	return frp
+}
+
+func (frp *FastRP) ServeHTTP(w http.ResponseWriter, r *http.Request) {
+	roundTripper := frp.connPool.Get().(http.RoundTripper)
+	defer frp.connPool.Put(roundTripper)
+	frp.rp.Transport = roundTripper
+	frp.rp.ServeHTTP(w, r)
+}