0.2.63 update

server/internal/api/logcontext.go

@@ -2,6 +2,8 @@ package api
 
 import (
 	"context"
+	"crypto/rand"
+	"encoding/hex"
 	"log/slog"
 	"net"
 	"net/http"
@@ -19,11 +21,12 @@ import (
 // still read what an inner layer filled in. A request is served on one goroutine and the
 // handler has returned by the time the middleware reads this, so no lock is needed.
 type requestIdentity struct {
-	component string
-	user      string
-	device    string
-	client    string
-	protocol  string
+	component   string
+	user        string
+	device      string
+	client      string
+	protocol    string
+	correlation string
 }
 
 type identityKey struct{}
@@ -31,9 +34,10 @@ type identityKey struct{}
 // withRequestIdentity installs an empty identity for this request and returns it.
 func withRequestIdentity(r *http.Request) (*http.Request, *requestIdentity) {
 	identity := &requestIdentity{
-		component: componentFor(r.URL.Path),
-		client:    clientVersion(r),
-		protocol:  clientProtocol(r),
+		component:   componentFor(r.URL.Path),
+		client:      clientVersion(r),
+		protocol:    clientProtocol(r),
+		correlation: requestCorrelation(r),
 	}
 	return r.WithContext(context.WithValue(r.Context(), identityKey{}, identity)), identity
 }
@@ -79,9 +83,35 @@ func (i *requestIdentity) attrs() []any {
 	if i.client != "" {
 		attrs = append(attrs, "client", i.client)
 	}
+	if i.correlation != "" {
+		attrs = append(attrs, "correlation", i.correlation)
+	}
 	return attrs
 }
 
+// requestCorrelation accepts a client-supplied safe identifier or creates one at the
+// gateway boundary. The same value is attached to every log line within the exchange and
+// returned to the client, making a playback launch traceable through gateway and Emby work.
+func requestCorrelation(r *http.Request) string {
+	if value := strings.TrimSpace(r.Header.Get("X-Memby-Correlation")); len(value) >= 6 && len(value) <= 64 {
+		for _, rune := range value {
+			if !(rune >= 'a' && rune <= 'z' || rune >= 'A' && rune <= 'Z' || rune >= '0' && rune <= '9' || rune == '-' || rune == '_') {
+				return newCorrelation()
+			}
+		}
+		return value
+	}
+	return newCorrelation()
+}
+
+func newCorrelation() string {
+	var raw [4]byte
+	if _, err := rand.Read(raw[:]); err != nil {
+		return "request-unknown"
+	}
+	return "req-" + strings.ToUpper(hex.EncodeToString(raw[:]))
+}
+
 // viewerAttrs names the person and the television, and only when they are known: an
 // unauthenticated probe has neither, and "user=unknown" on every health check is noise.
 func (i *requestIdentity) viewerAttrs() []any {