1// Package middleware provides HTTP middleware for the adapters layer.
2package middleware
3
4import (
5 "crypto/rand"
6 "encoding/hex"
7 "encoding/json"
8 "errors"
9 "fmt"
10 "net"
11 "net/http"
12 "sync/atomic"
13 "time"
14
15 "github.com/bnema/zerowrap"
16 "go.opentelemetry.io/otel/trace"
17
18 "github.com/bnema/gordon/internal/adapters/dto"
19)
20
21// ResponseWriter wraps http.ResponseWriter to capture status code and bytes written.
22type ResponseWriter struct {
23 http.ResponseWriter
24 statusCode int
25 bytes int
26}
27
28// NewResponseWriter creates a new wrapped response writer.
29func NewResponseWriter(w http.ResponseWriter) *ResponseWriter {
30 return &ResponseWriter{
31 ResponseWriter: w,
32 statusCode: http.StatusOK, // Default status code
33 }
34}
35
36// WriteHeader captures the status code.
37func (rw *ResponseWriter) WriteHeader(code int) {
38 rw.statusCode = code
39 rw.ResponseWriter.WriteHeader(code)
40}
41
42// Write captures bytes written.
43func (rw *ResponseWriter) Write(b []byte) (int, error) {
44 n, err := rw.ResponseWriter.Write(b)
45 rw.bytes += n
46 return n, err
47}
48
49// StatusCode returns the captured status code.
50func (rw *ResponseWriter) StatusCode() int {
51 return rw.statusCode
52}
53
54// BytesWritten returns the number of bytes written.
55func (rw *ResponseWriter) BytesWritten() int {
56 return rw.bytes
57}
58
59// Flush implements http.Flusher by delegating to the underlying ResponseWriter.
60func (rw *ResponseWriter) Flush() {
61 if f, ok := rw.ResponseWriter.(http.Flusher); ok {
62 f.Flush()
63 }
64}
65
66// Unwrap returns the underlying ResponseWriter.
67func (rw *ResponseWriter) Unwrap() http.ResponseWriter {
68 return rw.ResponseWriter
69}
70
71// ensureRequestID returns the X-Request-ID from the request if present, or generates
72// a new one. It sets X-Request-ID on both the request and response headers and returns
73// the ID along with the (potentially updated) request.
74func ensureRequestID(w http.ResponseWriter, r *http.Request) (string, *http.Request) {
75 requestID := r.Header.Get("X-Request-ID")
76 if requestID == "" {
77 requestID = generateRequestID()
78 r.Header.Set("X-Request-ID", requestID)
79 }
80 w.Header().Set("X-Request-ID", requestID)
81 return requestID, r
82}
83
84// RequestLogger is a middleware that logs HTTP requests using zerowrap.
85// It also attaches the logger to the request context for downstream handlers.
86// The trustedNets parameter controls which proxy headers are trusted for IP extraction.
87// Pass nil to only use RemoteAddr (safest default when not behind a trusted proxy).
88func RequestLogger(log zerowrap.Logger, trustedNets ...[]*net.IPNet) func(http.Handler) http.Handler {
89 var nets []*net.IPNet
90 if len(trustedNets) > 0 {
91 nets = trustedNets[0]
92 }
93 return func(next http.Handler) http.Handler {
94 return http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
95 start := time.Now()
96
97 // Generate or reuse X-Request-ID for request tracing
98 requestID, r := ensureRequestID(w, r)
99
100 // Wrap the response writer to capture status and bytes
101 rw := NewResponseWriter(w)
102
103 // SECURITY: Use trusted-proxy-aware IP extraction to prevent
104 // IP spoofing via X-Forwarded-For from untrusted sources.
105 clientIP := GetClientIP(r, nets)
106
107 // Attach the logger to the request context for downstream handlers.
108 // If an OTel span is active (from otelhttp middleware), inject
109 // trace_id and span_id into the logger for log↔trace correlation.
110 reqLog := log
111 spanCtx := trace.SpanFromContext(r.Context()).SpanContext()
112 if spanCtx.HasTraceID() {
113 reqLog = reqLog.WithFields(map[string]any{
114 "trace_id": spanCtx.TraceID().String(),
115 "span_id": spanCtx.SpanID().String(),
116 })
117 }
118 ctx := zerowrap.WithCtx(r.Context(), reqLog)
119 r = r.WithContext(ctx)
120
121 // Call the next handler
122 next.ServeHTTP(rw, r)
123
124 // Calculate duration
125 duration := time.Since(start)
126
127 // Log the request (use reqLog to include trace_id/span_id)
128 reqLog.Info().
129 Str(zerowrap.FieldLayer, "adapter").
130 Str(zerowrap.FieldAdapter, "http").
131 Str("request_id", requestID).
132 Str(zerowrap.FieldMethod, r.Method).
133 Str(zerowrap.FieldPath, r.URL.Path).
134 Str("query", sanitizeLoggedQuery(r.URL.RawQuery)).
135 Str(zerowrap.FieldHost, r.Host).
136 Str("user_agent", r.UserAgent()).
137 Str("referer", sanitizeLoggedReferer(r.Referer())).
138 Str(zerowrap.FieldClientIP, clientIP).
139 Int(zerowrap.FieldStatus, rw.StatusCode()).
140 Int("bytes", rw.BytesWritten()).
141 Dur(zerowrap.FieldDuration, duration).
142 Str("proto", r.Proto).
143 Msg("HTTP request")
144 })
145 }
146}
147
148// fallbackCounter ensures uniqueness when crypto/rand is unavailable.
149var fallbackCounter atomic.Uint64
150
151// generateRequestID creates a random 16-byte hex-encoded request ID.
152func generateRequestID() string {
153 b := make([]byte, 16)
154 if _, err := rand.Read(b); err != nil {
155 // Fallback to timestamp + monotonic counter if RNG is unavailable
156 return fmt.Sprintf("%x-%x", time.Now().UnixNano(), fallbackCounter.Add(1))
157 }
158 return hex.EncodeToString(b)
159}
160
161// PanicRecovery middleware recovers from panics and logs them.
162func PanicRecovery(log zerowrap.Logger) func(http.Handler) http.Handler {
163 return func(next http.Handler) http.Handler {
164 return http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
165 defer func() {
166 if err := recover(); err != nil {
167 if isAbortHandlerPanic(err) {
168 panic(http.ErrAbortHandler)
169 }
170
171 log.Error().
172 Str(zerowrap.FieldLayer, "adapter").
173 Str(zerowrap.FieldAdapter, "http").
174 Interface("panic", err).
175 Str(zerowrap.FieldMethod, r.Method).
176 Str(zerowrap.FieldPath, r.URL.Path).
177 Str(zerowrap.FieldHost, r.Host).
178 Msg("panic recovered")
179
180 w.Header().Set("Content-Type", "application/json")
181 w.WriteHeader(http.StatusInternalServerError)
182 _ = json.NewEncoder(w).Encode(dto.ErrorResponse{Error: "Internal Server Error"})
183 }
184 }()
185
186 next.ServeHTTP(w, r)
187 })
188 }
189}
190
191func isAbortHandlerPanic(v any) bool {
192 err, ok := v.(error)
193 return ok && errors.Is(err, http.ErrAbortHandler)
194}
195
196// CORS middleware adds permissive CORS headers.
197// NOTE: This is intentionally NOT used on the proxy chain (backends control their own CORS).
198// Available for use on specific endpoints (e.g., registry API) where CORS is needed.
199func CORS(next http.Handler) http.Handler {
200 return http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
201 w.Header().Set("Access-Control-Allow-Origin", "*")
202 w.Header().Set("Access-Control-Allow-Methods", "GET, POST, PUT, DELETE, OPTIONS")
203 w.Header().Set("Access-Control-Allow-Headers", "Content-Type, Authorization")
204
205 // Handle preflight OPTIONS request
206 if r.Method == "OPTIONS" {
207 w.WriteHeader(http.StatusOK)
208 return
209 }
210
211 next.ServeHTTP(w, r)
212 })
213}
214
215// Chain combines multiple middleware functions.
216func Chain(middlewares ...func(http.Handler) http.Handler) func(http.Handler) http.Handler {
217 return func(final http.Handler) http.Handler {
218 for i := len(middlewares) - 1; i >= 0; i-- {
219 final = middlewares[i](final)
220 }
221 return final
222 }
223}