MPX-67 - Refactor mProxy (#114)

* Refactor code

Signed-off-by: dusan <borovcanindusan1@gmail.com>

* Add tests

Signed-off-by: dusan <borovcanindusan1@gmail.com>

* Fix tests

Signed-off-by: dusan <borovcanindusan1@gmail.com>

* Add conn limits

Signed-off-by: dusan <borovcanindusan1@gmail.com>

* Add pools and improve code quality

Signed-off-by: dusan <borovcanindusan1@gmail.com>

* Improve default values

Signed-off-by: dusan <borovcanindusan1@gmail.com>

* Update dependencies

Signed-off-by: dusan <borovcanindusan1@gmail.com>

---------

Signed-off-by: dusan <borovcanindusan1@gmail.com>

Author: Dušan Borovčanin

cmd/main.go

@@ -0,0 +1,203 @@
+// Copyright (c) Abstract Machines
+// SPDX-License-Identifier: Apache-2.0
+
+package main
+
+import (
+	"context"
+	"log/slog"
+	"time"
+
+	"github.com/absmach/mproxy/pkg/handler"
+	"github.com/absmach/mproxy/pkg/metrics"
+	"github.com/absmach/mproxy/pkg/ratelimit"
+)
+
+// RateLimitedHandler wraps a handler with rate limiting.
+type RateLimitedHandler struct {
+	handler          handler.Handler
+	perClientLimiter *ratelimit.Limiter
+	globalLimiter    *ratelimit.TokenBucket
+	metrics          *metrics.Metrics
+	logger           *slog.Logger
+}
+
+// AuthConnect implements handler.Handler with rate limiting.
+func (h *RateLimitedHandler) AuthConnect(ctx context.Context, hctx *handler.Context) error {
+	// Check global rate limit
+	if !h.globalLimiter.Allow() {
+		h.metrics.RateLimitedRequests.WithLabelValues(hctx.Protocol, "global").Inc()
+		h.logger.Warn("Global rate limit exceeded",
+			slog.String("remote", hctx.RemoteAddr),
+			slog.String("protocol", hctx.Protocol))
+		return ratelimit.ErrRateLimitExceeded
+	}
+
+	// Check per-client rate limit
+	clientID := hctx.RemoteAddr
+	if hctx.ClientID != "" {
+		clientID = hctx.ClientID
+	}
+
+	if !h.perClientLimiter.Allow(clientID) {
+		h.metrics.RateLimitedRequests.WithLabelValues(hctx.Protocol, "per_client").Inc()
+		h.logger.Warn("Per-client rate limit exceeded",
+			slog.String("client", clientID),
+			slog.String("protocol", hctx.Protocol))
+		return ratelimit.ErrRateLimitExceeded
+	}
+
+	return h.handler.AuthConnect(ctx, hctx)
+}
+
+// AuthPublish implements handler.Handler with rate limiting.
+func (h *RateLimitedHandler) AuthPublish(ctx context.Context, hctx *handler.Context, topic *string, payload *[]byte) error {
+	// Could add payload size rate limiting here
+	return h.handler.AuthPublish(ctx, hctx, topic, payload)
+}
+
+// AuthSubscribe implements handler.Handler.
+func (h *RateLimitedHandler) AuthSubscribe(ctx context.Context, hctx *handler.Context, topics *[]string) error {
+	return h.handler.AuthSubscribe(ctx, hctx, topics)
+}
+
+// OnConnect implements handler.Handler.
+func (h *RateLimitedHandler) OnConnect(ctx context.Context, hctx *handler.Context) error {
+	return h.handler.OnConnect(ctx, hctx)
+}
+
+// OnPublish implements handler.Handler.
+func (h *RateLimitedHandler) OnPublish(ctx context.Context, hctx *handler.Context, topic string, payload []byte) error {
+	return h.handler.OnPublish(ctx, hctx, topic, payload)
+}
+
+// OnSubscribe implements handler.Handler.
+func (h *RateLimitedHandler) OnSubscribe(ctx context.Context, hctx *handler.Context, topics []string) error {
+	return h.handler.OnSubscribe(ctx, hctx, topics)
+}
+
+// OnUnsubscribe implements handler.Handler.
+func (h *RateLimitedHandler) OnUnsubscribe(ctx context.Context, hctx *handler.Context, topics []string) error {
+	return h.handler.OnUnsubscribe(ctx, hctx, topics)
+}
+
+// OnDisconnect implements handler.Handler.
+func (h *RateLimitedHandler) OnDisconnect(ctx context.Context, hctx *handler.Context) error {
+	return h.handler.OnDisconnect(ctx, hctx)
+}
+
+// InstrumentedHandler wraps a handler with metrics instrumentation.
+type InstrumentedHandler struct {
+	handler handler.Handler
+	metrics *metrics.Metrics
+	logger  *slog.Logger
+}
+
+// AuthConnect implements handler.Handler with metrics.
+func (h *InstrumentedHandler) AuthConnect(ctx context.Context, hctx *handler.Context) error {
+	start := time.Now()
+	h.metrics.AuthAttempts.WithLabelValues(hctx.Protocol, "connect").Inc()
+
+	err := h.handler.AuthConnect(ctx, hctx)
+
+	if err != nil {
+		h.metrics.AuthFailures.WithLabelValues(hctx.Protocol, "connect", "unauthorized").Inc()
+	}
+
+	duration := time.Since(start).Seconds()
+	h.metrics.RequestDuration.WithLabelValues(hctx.Protocol, "connect").Observe(duration)
+
+	return err
+}
+
+// AuthPublish implements handler.Handler with metrics.
+func (h *InstrumentedHandler) AuthPublish(ctx context.Context, hctx *handler.Context, topic *string, payload *[]byte) error {
+	start := time.Now()
+	h.metrics.AuthAttempts.WithLabelValues(hctx.Protocol, "publish").Inc()
+
+	if payload != nil {
+		h.metrics.RequestSize.WithLabelValues(hctx.Protocol).Observe(float64(len(*payload)))
+	}
+
+	err := h.handler.AuthPublish(ctx, hctx, topic, payload)
+
+	if err != nil {
+		h.metrics.AuthFailures.WithLabelValues(hctx.Protocol, "publish", "unauthorized").Inc()
+	}
+
+	duration := time.Since(start).Seconds()
+	h.metrics.RequestDuration.WithLabelValues(hctx.Protocol, "publish").Observe(duration)
+
+	status := "success"
+	if err != nil {
+		status = "error"
+	}
+	h.metrics.RequestsTotal.WithLabelValues(hctx.Protocol, "publish", status).Inc()
+
+	return err
+}
+
+// AuthSubscribe implements handler.Handler with metrics.
+func (h *InstrumentedHandler) AuthSubscribe(ctx context.Context, hctx *handler.Context, topics *[]string) error {
+	start := time.Now()
+	h.metrics.AuthAttempts.WithLabelValues(hctx.Protocol, "subscribe").Inc()
+
+	err := h.handler.AuthSubscribe(ctx, hctx, topics)
+
+	if err != nil {
+		h.metrics.AuthFailures.WithLabelValues(hctx.Protocol, "subscribe", "unauthorized").Inc()
+	}
+
+	duration := time.Since(start).Seconds()
+	h.metrics.RequestDuration.WithLabelValues(hctx.Protocol, "subscribe").Observe(duration)
+
+	status := "success"
+	if err != nil {
+		status = "error"
+	}
+	h.metrics.RequestsTotal.WithLabelValues(hctx.Protocol, "subscribe", status).Inc()
+
+	return err
+}
+
+// OnConnect implements handler.Handler with metrics.
+func (h *InstrumentedHandler) OnConnect(ctx context.Context, hctx *handler.Context) error {
+	h.metrics.ActiveConnections.WithLabelValues(hctx.Protocol, "client").Inc()
+	h.metrics.TotalConnections.WithLabelValues(hctx.Protocol, "client", "accepted").Inc()
+
+	return h.handler.OnConnect(ctx, hctx)
+}
+
+// OnPublish implements handler.Handler with metrics.
+func (h *InstrumentedHandler) OnPublish(ctx context.Context, hctx *handler.Context, topic string, payload []byte) error {
+	if hctx.Protocol == "mqtt" {
+		h.metrics.MQTTPackets.WithLabelValues("publish", "upstream").Inc()
+	}
+
+	return h.handler.OnPublish(ctx, hctx, topic, payload)
+}
+
+// OnSubscribe implements handler.Handler with metrics.
+func (h *InstrumentedHandler) OnSubscribe(ctx context.Context, hctx *handler.Context, topics []string) error {
+	if hctx.Protocol == "mqtt" {
+		h.metrics.MQTTPackets.WithLabelValues("subscribe", "upstream").Inc()
+	}
+
+	return h.handler.OnSubscribe(ctx, hctx, topics)
+}
+
+// OnUnsubscribe implements handler.Handler with metrics.
+func (h *InstrumentedHandler) OnUnsubscribe(ctx context.Context, hctx *handler.Context, topics []string) error {
+	if hctx.Protocol == "mqtt" {
+		h.metrics.MQTTPackets.WithLabelValues("unsubscribe", "upstream").Inc()
+	}
+
+	return h.handler.OnUnsubscribe(ctx, hctx, topics)
+}
+
+// OnDisconnect implements handler.Handler with metrics.
+func (h *InstrumentedHandler) OnDisconnect(ctx context.Context, hctx *handler.Context) error {
+	h.metrics.ActiveConnections.WithLabelValues(hctx.Protocol, "client").Dec()
+
+	return h.handler.OnDisconnect(ctx, hctx)
+}