feat: Add pcap import, file browser, logging, local capture, and stable call ordering

internal/capture/local.go

@@ -0,0 +1,180 @@
+package capture
+
+import (
+	"bufio"
+	"context"
+	"fmt"
+	"io"
+	"os/exec"
+	"strings"
+	"sync"
+
+	"telephony-inspector/internal/sip"
+)
+
+// LocalCapturer handles SIP packet capture locally via tcpdump
+type LocalCapturer struct {
+	cmd     *exec.Cmd
+	cancel  context.CancelFunc
+	running bool
+	mu      sync.Mutex
+
+	// Callbacks
+	OnPacket func(*sip.Packet)
+	OnError  func(error)
+}
+
+// NewLocalCapturer creates a new local capturer
+func NewLocalCapturer() *LocalCapturer {
+	return &LocalCapturer{}
+}
+
+// Start begins capturing SIP traffic locally
+func (c *LocalCapturer) Start(iface string, port int) error {
+	c.mu.Lock()
+	if c.running {
+		c.mu.Unlock()
+		return fmt.Errorf("capture already running")
+	}
+	c.running = true
+	c.mu.Unlock()
+
+	ctx, cancel := context.WithCancel(context.Background())
+	c.cancel = cancel
+
+	// Build tcpdump command
+	// -l: line buffered
+	// -A: print packet payload in ASCII
+	// -s 0: capture full packets
+	args := []string{"-l", "-A", "-s", "0", "-i", iface, "port", fmt.Sprintf("%d", port)}
+	c.cmd = exec.CommandContext(ctx, "tcpdump", args...)
+
+	stdout, err := c.cmd.StdoutPipe()
+	if err != nil {
+		c.mu.Lock()
+		c.running = false
+		c.mu.Unlock()
+		return fmt.Errorf("failed to get stdout: %w", err)
+	}
+
+	stderr, err := c.cmd.StderrPipe()
+	if err != nil {
+		c.mu.Lock()
+		c.running = false
+		c.mu.Unlock()
+		return fmt.Errorf("failed to get stderr: %w", err)
+	}
+
+	if err := c.cmd.Start(); err != nil {
+		c.mu.Lock()
+		c.running = false
+		c.mu.Unlock()
+		return fmt.Errorf("failed to start tcpdump: %w", err)
+	}
+
+	// Process stdout in goroutine
+	go c.processStream(stdout)
+
+	// Log stderr
+	go c.processErrors(stderr)
+
+	return nil
+}
+
+// Stop stops the capture
+func (c *LocalCapturer) Stop() {
+	c.mu.Lock()
+	defer c.mu.Unlock()
+
+	if !c.running {
+		return
+	}
+	c.running = false
+
+	if c.cancel != nil {
+		c.cancel()
+		c.cancel = nil
+	}
+
+	if c.cmd != nil && c.cmd.Process != nil {
+		c.cmd.Process.Kill()
+		c.cmd.Wait()
+	}
+}
+
+// IsRunning returns whether capture is active
+func (c *LocalCapturer) IsRunning() bool {
+	c.mu.Lock()
+	defer c.mu.Unlock()
+	return c.running
+}
+
+// Close cleans up resources
+func (c *LocalCapturer) Close() error {
+	c.Stop()
+	return nil
+}
+
+func (c *LocalCapturer) processStream(r io.Reader) {
+	scanner := bufio.NewScanner(r)
+	var buffer strings.Builder
+	inSIPMessage := false
+
+	for scanner.Scan() {
+		c.mu.Lock()
+		running := c.running
+		c.mu.Unlock()
+		if !running {
+			break
+		}
+
+		line := scanner.Text()
+
+		// Detect start of SIP message
+		if isSIPStart(line) {
+			// If we were building a message, parse it
+			if buffer.Len() > 0 {
+				c.parseAndEmit(buffer.String())
+				buffer.Reset()
+			}
+			inSIPMessage = true
+		}
+
+		if inSIPMessage {
+			buffer.WriteString(line)
+			buffer.WriteString("\r\n")
+		}
+	}
+
+	// Parse remaining buffer
+	if buffer.Len() > 0 {
+		c.parseAndEmit(buffer.String())
+	}
+}
+
+func (c *LocalCapturer) processErrors(r io.Reader) {
+	scanner := bufio.NewScanner(r)
+	for scanner.Scan() {
+		text := scanner.Text()
+		// tcpdump prints "listening on..." to stderr, ignore it
+		if strings.Contains(text, "listening on") {
+			continue
+		}
+		if c.OnError != nil {
+			c.OnError(fmt.Errorf("tcpdump: %s", text))
+		}
+	}
+}
+
+func (c *LocalCapturer) parseAndEmit(raw string) {
+	packet, err := sip.Parse(raw)
+	if err != nil {
+		if c.OnError != nil {
+			c.OnError(err)
+		}
+		return
+	}
+	if packet != nil && c.OnPacket != nil {
+		c.OnPacket(packet)
+	}
+}