primeiro commit

internal/probe/interface.go

@@ -0,0 +1,71 @@
+package probe
+
+import (
+	"bufio"
+	"bytes"
+	"context"
+	"errors"
+	"fmt"
+	"os"
+	"strconv"
+	"strings"
+)
+
+const netDevPath = "/proc/net/dev"
+
+// InterfaceStats contains received and transmitted byte counters.
+type InterfaceStats struct {
+	Name    string
+	RXBytes uint64
+	TXBytes uint64
+}
+
+// ReadInterfaceStats reads byte counters for a network interface.
+func ReadInterfaceStats(ctx context.Context, name string) (InterfaceStats, error) {
+	if err := ctx.Err(); err != nil {
+		return InterfaceStats{}, fmt.Errorf("checking context before reading interface stats: %w", err)
+	}
+	data, err := os.ReadFile(netDevPath)
+	if err != nil {
+		return InterfaceStats{}, fmt.Errorf("reading %s: %w", netDevPath, err)
+	}
+	if err := ctx.Err(); err != nil {
+		return InterfaceStats{}, fmt.Errorf("checking context after reading interface stats: %w", err)
+	}
+	stats, err := parseNetDev(data, name)
+	if err != nil {
+		return InterfaceStats{}, err
+	}
+	return stats, nil
+}
+
+func parseNetDev(data []byte, name string) (InterfaceStats, error) {
+	scanner := bufio.NewScanner(bytes.NewReader(data))
+	for scanner.Scan() {
+		line := strings.TrimSpace(scanner.Text())
+		if !strings.Contains(line, ":") {
+			continue
+		}
+		parts := strings.SplitN(line, ":", 2)
+		if strings.TrimSpace(parts[0]) != name {
+			continue
+		}
+		fields := strings.Fields(parts[1])
+		if len(fields) < 16 {
+			return InterfaceStats{}, fmt.Errorf("parsing interface %s stats: expected at least 16 fields, got %d", name, len(fields))
+		}
+		rxBytes, err := strconv.ParseUint(fields[0], 10, 64)
+		if err != nil {
+			return InterfaceStats{}, fmt.Errorf("parsing interface %s rx bytes: %w", name, err)
+		}
+		txBytes, err := strconv.ParseUint(fields[8], 10, 64)
+		if err != nil {
+			return InterfaceStats{}, fmt.Errorf("parsing interface %s tx bytes: %w", name, err)
+		}
+		return InterfaceStats{Name: name, RXBytes: rxBytes, TXBytes: txBytes}, nil
+	}
+	if err := scanner.Err(); err != nil {
+		return InterfaceStats{}, fmt.Errorf("scanning %s contents: %w", netDevPath, err)
+	}
+	return InterfaceStats{}, errors.New("interface not found")
+}