From 68d0b5fe4d163c84ba05631869494df4ed76f938 Mon Sep 17 00:00:00 2001
From: afranco <afonso@francof.net>
Date: Sun, 12 Oct 2025 10:39:00 +0100
Subject: [PATCH] feat(outputs): use only one output file, appending on every
 run

---
 internal/qol/capture/pcap.go   | 31 +++++++++++++++++++++----------
 internal/qol/results/writer.go | 34 +++++++++++++++++++++-------------
 internal/qol/utils.go          | 19 ++++---------------
 3 files changed, 46 insertions(+), 38 deletions(-)

diff --git a/internal/qol/capture/pcap.go b/internal/qol/capture/pcap.go
index e342098..8254ae7 100644
--- a/internal/qol/capture/pcap.go
+++ b/internal/qol/capture/pcap.go
@@ -25,17 +25,28 @@ func NewPacketCapture(iface, outputPath string) (*PacketCapture, error) {
 		return nil, fmt.Errorf("pcap open (try running as root): %w", err)
 	}
 
-	file, err := os.Create(outputPath)
+	// Check if file exists
+	fileExists := false
+	if _, err := os.Stat(outputPath); err == nil {
+		fileExists = true
+	}
+
+	// Open in append mode
+	file, err := os.OpenFile(outputPath, os.O_APPEND|os.O_CREATE|os.O_WRONLY, 0644)
 	if err != nil {
 		handle.Close()
-		return nil, fmt.Errorf("create pcap file: %w", err)
+		return nil, fmt.Errorf("create/open pcap file: %w", err)
 	}
 
 	writer := pcapgo.NewWriter(file)
-	if err := writer.WriteFileHeader(65535, handle.LinkType()); err != nil {
-		handle.Close()
-		file.Close()
-		return nil, fmt.Errorf("pcap header: %w", err)
+
+	// Only write header if file is new
+	if !fileExists {
+		if err := writer.WriteFileHeader(65535, handle.LinkType()); err != nil {
+			handle.Close()
+			file.Close()
+			return nil, fmt.Errorf("pcap header: %w", err)
+		}
 	}
 
 	return &PacketCapture{
@@ -81,20 +92,20 @@ func (pc *PacketCapture) GetError() error {
 
 func (pc *PacketCapture) Close() error {
 	var errs []error
-	
+
 	if pc.handle != nil {
 		pc.handle.Close()
 	}
-	
+
 	if pc.file != nil {
 		if err := pc.file.Close(); err != nil {
 			errs = append(errs, err)
 		}
 	}
-	
+
 	if len(errs) > 0 {
 		return errs[0]
 	}
-	
+
 	return nil
 }
diff --git a/internal/qol/results/writer.go b/internal/qol/results/writer.go
index 158d2ae..cad2109 100644
--- a/internal/qol/results/writer.go
+++ b/internal/qol/results/writer.go
@@ -31,27 +31,35 @@ type MetricsWriter struct {
 }
 
 func NewMetricsWriter(path string) (*MetricsWriter, error) {
-	file, err := os.Create(path)
+	// Check if file exists
+	fileExists := false
+	if _, err := os.Stat(path); err == nil {
+		fileExists = true
+	}
+
+	// Open in append mode
+	file, err := os.OpenFile(path, os.O_APPEND|os.O_CREATE|os.O_WRONLY, 0644)
 	if err != nil {
-		return nil, fmt.Errorf("create csv output: %w", err)
+		return nil, fmt.Errorf("create/open csv output: %w", err)
 	}
 
 	writer := csv.NewWriter(file)
 
-	// Write CSV header
-	header := []string{
-		"domain", "query_type", "protocol", "dnssec", "auth_dnssec", "keep_alive",
-		"dns_server", "timestamp", "duration_ns", "duration_ms",
-		"request_size_bytes", "response_size_bytes", "response_code", "error",
-	}
+	// Only write header if file is new
+	if !fileExists {
+		header := []string{
+			"domain", "query_type", "protocol", "dnssec", "auth_dnssec", "keep_alive",
+			"dns_server", "timestamp", "duration_ns", "duration_ms",
+			"request_size_bytes", "response_size_bytes", "response_code", "error", "run_id",
+		}
 
-	if err := writer.Write(header); err != nil {
-		file.Close()
-		return nil, fmt.Errorf("write csv header: %w", err)
+		if err := writer.Write(header); err != nil {
+			file.Close()
+			return nil, fmt.Errorf("write csv header: %w", err)
+		}
+		writer.Flush()
 	}
 
-	writer.Flush()
-
 	return &MetricsWriter{
 		writer: writer,
 		file:   file,
diff --git a/internal/qol/utils.go b/internal/qol/utils.go
index 6eb6ae3..df3ae4e 100644
--- a/internal/qol/utils.go
+++ b/internal/qol/utils.go
@@ -5,25 +5,17 @@ import (
 	"net/url"
 	"path/filepath"
 	"strings"
-	"time"
 )
 
 func GenerateOutputPaths(outputDir, upstream string, dnssec, authDNSSEC, keepAlive bool) (csvPath, pcapPath string) {
 	proto := DetectProtocol(upstream)
 	cleanServer := cleanServerName(upstream)
 
-	// Create date-based subdirectory
-	date := time.Now().Format("2006-01-02")
-	timestamp := time.Now().Format("150405")
+	subDir := filepath.Join(outputDir, cleanServer)
 
-	// Organize hierarchically: resolver/date/filename
-	subDir := filepath.Join(outputDir, cleanServer, date)
-
-	// Create simple filename
 	base := proto
-
-	// Add flags if enabled
 	var flags []string
+	
 	if dnssec {
 		if authDNSSEC {
 			flags = append(flags, "auth")
@@ -39,11 +31,8 @@ func GenerateOutputPaths(outputDir, upstream string, dnssec, authDNSSEC, keepAli
 		base = fmt.Sprintf("%s-%s", base, strings.Join(flags, "-"))
 	}
 
-	// Add timestamp
-	filename := fmt.Sprintf("%s-%s", base, timestamp)
-
-	return filepath.Join(subDir, filename+".csv"),
-		filepath.Join(subDir, filename+".pcap")
+	return filepath.Join(subDir, base+".csv"),
+		filepath.Join(subDir, base+".pcap")
 }
 
 func cleanServerName(server string) string {