[proxy] add proxy rate limiter (#7568)

proxy/internal/auth/credential.go

@@ -0,0 +1,100 @@
+package auth
+
+import (
+	"errors"
+	"math"
+	"net/http"
+	"strconv"
+	"time"
+
+	"google.golang.org/genproto/googleapis/rpc/errdetails"
+	"google.golang.org/grpc/codes"
+	"google.golang.org/grpc/status"
+
+	"github.com/netbirdio/netbird/proxy/auth"
+	"github.com/netbirdio/netbird/proxy/internal/proxy"
+)
+
+var errCredentialClientIP = errors.New("invalid client address")
+
+type credentialLimitError struct {
+	retryAfter time.Duration
+}
+
+func (e *credentialLimitError) Error() string {
+	return "too many authentication attempts"
+}
+
+func credentialFormValue(r *http.Request, field string) string {
+	if r.Method != http.MethodPost {
+		return ""
+	}
+	return r.PostFormValue(field)
+}
+
+func (mw *Middleware) authenticateScheme(r *http.Request, config DomainConfig, scheme Scheme) (string, string, error) {
+	method := scheme.Type()
+	if (method != auth.MethodPIN && method != auth.MethodPassword) || !wasCredentialSubmitted(r, method) {
+		return scheme.Authenticate(r)
+	}
+	ip := mw.resolveClientIP(r).Unmap()
+	if !ip.IsValid() {
+		return "", "", errCredentialClientIP
+	}
+	source, retry := mw.credentials.begin(credentialSourceKey{
+		service: credentialServiceKey{accountID: config.AccountID, serviceID: config.ServiceID},
+		ip:      ip,
+	})
+	if retry > 0 {
+		return "", "", &credentialLimitError{retryAfter: retry}
+	}
+	token, prompt, err := scheme.Authenticate(r)
+	outcome := credentialUnavailable
+	if err == nil {
+		outcome = credentialRejected
+		if token != "" {
+			outcome = credentialAccepted
+		}
+	}
+	mw.credentials.finish(source, outcome)
+	return token, prompt, err
+}
+
+func credentialRetryAfter(err error) time.Duration {
+	var limitErr *credentialLimitError
+	if errors.As(err, &limitErr) {
+		return limitErr.retryAfter
+	}
+	s := status.Convert(err)
+	if s.Code() != codes.ResourceExhausted {
+		return 0
+	}
+	for _, detail := range s.Details() {
+		if info, ok := detail.(*errdetails.RetryInfo); ok && info.RetryDelay != nil && info.RetryDelay.CheckValid() == nil {
+			if delay := info.RetryDelay.AsDuration(); delay > 0 {
+				return delay
+			}
+		}
+	}
+	return credentialCheckInterval
+}
+
+func (mw *Middleware) writeAuthenticationError(w http.ResponseWriter, r *http.Request, method auth.Method, err error) {
+	if cd := proxy.CapturedDataFromContext(r.Context()); cd != nil {
+		cd.SetOrigin(proxy.OriginAuth)
+		cd.SetAuthMethod(method.String())
+	}
+	if retry := credentialRetryAfter(err); retry > 0 {
+		// RFC 6585 section 4 forbids caching 429 responses.
+		w.Header().Set("Cache-Control", "no-store")
+		w.Header().Set("Retry-After", strconv.FormatInt(int64(math.Ceil(retry.Seconds())), 10))
+		http.Error(w, "too many authentication attempts; try again later", http.StatusTooManyRequests)
+		return
+	}
+	if errors.Is(err, errCredentialClientIP) {
+		http.Error(w, "invalid client address", http.StatusBadRequest)
+		return
+	}
+	mw.logger.WithField("scheme", method.String()).Warnf("authentication infrastructure error: %v", err)
+	http.Error(w, "authentication service unavailable", http.StatusBadGateway)
+}