Initial sanitized code sync

pkg/auth/datadog.go

@@ -0,0 +1,47 @@
+package auth
+
+import (
+	"crypto/rand"
+	"fmt"
+	"math/big"
+)
+
+// GenerateDatadogHeaders generates Datadog APM tracing headers
+// matching the format used by the OpenAI frontend.
+func GenerateDatadogHeaders() map[string]string {
+	traceID := randomDigits(19)
+	parentID := randomDigits(16)
+	traceHex := fmt.Sprintf("%016x", mustParseUint(traceID))
+	parentHex := fmt.Sprintf("%016x", mustParseUint(parentID))
+
+	return map[string]string{
+		"traceparent":                  fmt.Sprintf("00-0000000000000000%s-%s-01", traceHex, parentHex),
+		"tracestate":                   "dd=s:1;o:rum",
+		"x-datadog-origin":             "rum",
+		"x-datadog-parent-id":          parentID,
+		"x-datadog-sampling-priority":  "1",
+		"x-datadog-trace-id":           traceID,
+	}
+}
+
+func randomDigits(n int) string {
+	result := make([]byte, n)
+	for i := range result {
+		v, _ := rand.Int(rand.Reader, big.NewInt(10))
+		result[i] = '0' + byte(v.Int64())
+	}
+	// Ensure first digit is not 0
+	if result[0] == '0' {
+		v, _ := rand.Int(rand.Reader, big.NewInt(9))
+		result[0] = '1' + byte(v.Int64())
+	}
+	return string(result)
+}
+
+func mustParseUint(s string) uint64 {
+	var result uint64
+	for _, c := range s {
+		result = result*10 + uint64(c-'0')
+	}
+	return result
+}