Codevault initial commit

internal/api/middleware.go

@@ -0,0 +1,81 @@
+package api
+
+import (
+	"context"
+	"net/http"
+	"time"
+
+	"github.com/gin-gonic/gin"
+	"go.opentelemetry.io/otel/attribute"
+	"go.opentelemetry.io/otel/metric"
+
+	"github.com/kanootoko/codevault/internal/db"
+	"github.com/kanootoko/codevault/internal/observability/metrics"
+	"github.com/kanootoko/codevault/internal/ratelimit"
+)
+
+type contextKey string
+
+const loginContextKey contextKey = "login"
+
+// LoginFromContext returns the Basic Auth login stashed by BasicAuthMiddleware,
+// if any. Strict-server handlers only see context.Context, not *gin.Context, so
+// this is how they recover the authenticated login.
+func LoginFromContext(ctx context.Context) (string, bool) {
+	login, ok := ctx.Value(loginContextKey).(string)
+	return login, ok
+}
+
+// BasicAuthMiddleware checks the request's HTTP Basic Auth credentials against
+// the DB-backed user store.
+func BasicAuthMiddleware(users *db.UsersRepository, vm metrics.ValueMetrics) gin.HandlerFunc {
+	return func(c *gin.Context) {
+		login, password, ok := c.Request.BasicAuth()
+		if !ok || users.Verify(c.Request.Context(), login, password) != nil {
+			vm.SetFailedTotal.Add(c.Request.Context(), 1, metric.WithAttributes(attribute.String("reason", "unauthorized")))
+			c.Header("WWW-Authenticate", `Basic realm="codevault"`)
+			c.AbortWithStatus(http.StatusUnauthorized)
+			return
+		}
+		c.Request = c.Request.WithContext(context.WithValue(c.Request.Context(), loginContextKey, login))
+		c.Next()
+	}
+}
+
+// RateLimitMiddleware short-circuits to 404 once the client IP has accumulated
+// too many failures, without touching the handler (and thus the database). A
+// short-circuited request counts as a failure itself, same as a genuine 404 from
+// the handler.
+func RateLimitMiddleware(limiter *ratelimit.Limiter, vm metrics.ValueMetrics) gin.HandlerFunc {
+	return func(c *gin.Context) {
+		ip := c.ClientIP()
+		if !limiter.Allowed(ip) {
+			limiter.RecordFailure(ip)
+			vm.GetFailedTotal.Add(c.Request.Context(), 1, metric.WithAttributes(attribute.String("reason", "rate_limited")))
+			c.AbortWithStatus(http.StatusNotFound)
+			return
+		}
+
+		c.Next()
+
+		if c.Writer.Status() == http.StatusNotFound {
+			limiter.RecordFailure(ip)
+		}
+	}
+}
+
+// InstrumentMiddleware records request count and duration metrics per route.
+func InstrumentMiddleware(route string, m metrics.HTTPMetrics) gin.HandlerFunc {
+	return func(c *gin.Context) {
+		start := time.Now()
+		c.Next()
+		duration := time.Since(start).Seconds()
+
+		attrs := metric.WithAttributes(
+			attribute.String("route", route),
+			attribute.Int("status", c.Writer.Status()),
+		)
+		m.RequestsTotal.Add(c.Request.Context(), 1, attrs)
+		m.RequestDuration.Record(c.Request.Context(), duration, metric.WithAttributes(attribute.String("route", route)))
+	}
+}