cmd: hosts files paths

internal/cmd/proxy.go

@@ -4,11 +4,14 @@ import (
 	"context"
 	"crypto/tls"
 	"fmt"
+	"io/fs"
 	"log/slog"
 	"net"
 	"net/netip"
 	"net/url"
 	"os"
+	"path"
+	"path/filepath"
 	"strings"
 	"time"
 
@@ -514,7 +517,7 @@ func (conf *configuration) hostsFiles(ctx context.Context, l *slog.Logger) (path
 	l.DebugContext(ctx, "hosts files are enabled")
 
 	if len(conf.HostsFiles) > 0 {
-		return conf.HostsFiles, nil
+		return prepareHostsFilesPaths(conf.HostsFiles)
 	}
 
 	paths, err = hostsfile.DefaultHostsPaths()
@@ -526,3 +529,40 @@ func (conf *configuration) hostsFiles(ctx context.Context, l *slog.Logger) (path
 
 	return paths, nil
 }
+
+func prepareHostsFilesPaths(paths []string) (res []string, err error) {
+	defer func() { err = errors.Annotate(err, "preparing hosts files paths: %w") }()
+
+	execPath, err := os.Executable()
+	if err != nil {
+		// Don't wrap the error, as it will get annotated.
+		return nil, err
+	}
+
+	execDir := filepath.Dir(execPath)
+
+	var errs []error
+	for _, p := range paths {
+		if strings.HasPrefix(p, "./") {
+			p = path.Join(execDir, p)
+		}
+
+		p = strings.TrimPrefix(p, "/")
+
+		if !fs.ValidPath(p) {
+			errs = append(errs, fmt.Errorf("invalid path: %q", p))
+
+			continue
+		}
+
+		res = append(res, p)
+	}
+
+	err = errors.Join(errs...)
+	if err != nil {
+		// Don't wrap the error, as it will get annotated.
+		return nil, err
+	}
+
+	return res, nil
+}