From f17d925c4cfaba0d6ad1cdaa85ce8bd0183b8f0b Mon Sep 17 00:00:00 2001
From: MengMengCode <227010654+MengMengCode@users.noreply.github.com>
Date: Wed, 12 Aug 2026 15:58:02 +0800
Subject: [PATCH] Fix static ARM builds and OpenWrt VoWiFi setup

---
 .github/workflows/release.yml              |   8 +
 README.md                                  |  20 ++
 cmd/vocat/instance_lock_linux.go           |  32 ++
 cmd/vocat/instance_lock_linux_test.go      |  25 ++
 cmd/vocat/instance_lock_other.go           |  12 +
 cmd/vocat/main.go                          |   5 +
 docs/README.zh-CN.md                       |  16 +
 go.mod                                     |   2 -
 go.sum                                     |   4 -
 internal/pcsc/backend_linux.go             | 188 +++++-------
 internal/pcsc/pcscd_protocol.go            | 334 +++++++++++++++++++++
 internal/pcsc/pcscd_protocol_test.go       | 127 ++++++++
 internal/update/update.go                  |  40 ++-
 internal/update/update_validation_test.go  |  44 +++
 internal/vowifi/ims/security_linux.go      |   8 +
 internal/vowifi/ims/security_linux_test.go |  13 +
 scripts/install.sh                         | 208 ++++++++++++-
 scripts/vocat.openwrt.init                 |  30 ++
 18 files changed, 980 insertions(+), 136 deletions(-)
 create mode 100644 cmd/vocat/instance_lock_linux.go
 create mode 100644 cmd/vocat/instance_lock_linux_test.go
 create mode 100644 cmd/vocat/instance_lock_other.go
 create mode 100644 internal/pcsc/pcscd_protocol.go
 create mode 100644 internal/pcsc/pcscd_protocol_test.go
 create mode 100644 internal/update/update_validation_test.go
 create mode 100644 scripts/vocat.openwrt.init

diff --git a/.github/workflows/release.yml b/.github/workflows/release.yml
index 19130db..1a8149e 100644
--- a/.github/workflows/release.yml
+++ b/.github/workflows/release.yml
@@ -110,6 +110,14 @@ jobs:
             -o "$OUTPUT" \
             ./cmd/vocat
           chmod 0755 "$OUTPUT"
+          if readelf -l "$OUTPUT" | grep -q 'Requesting program interpreter'; then
+            echo "ERROR: $OUTPUT unexpectedly requires a dynamic loader" >&2
+            readelf -l "$OUTPUT" >&2
+            exit 1
+          fi
+          if [ "${{ matrix.goarch }}" = "amd64" ]; then
+            "$OUTPUT" version
+          fi
       - name: Upload ${{ matrix.target }}
         uses: actions/upload-artifact@v4
         with:
diff --git a/README.md b/README.md
index bb68b71..ddb520b 100644
--- a/README.md
+++ b/README.md
@@ -65,10 +65,24 @@ Available features depend on the module firmware, USB composition, SIM/eSIM capa
 
 ### One-click Linux installation
 
+As root (including OpenWrt/Kwrt, where `sudo` is normally absent):
+
+```bash
+curl -fsSL https://raw.githubusercontent.com/MengMengCode/VoCat/master/scripts/install.sh | bash
+```
+
+From a normal user on a distribution with sudo:
+
 ```bash
 curl -fsSL https://raw.githubusercontent.com/MengMengCode/VoCat/master/scripts/install.sh | sudo bash
 ```
 
+Check the host's VoWiFi/XFRM prerequisites without installing VoCat:
+
+```bash
+curl -fsSL https://raw.githubusercontent.com/MengMengCode/VoCat/master/scripts/install.sh | bash -s -- --check-env
+```
+
 Install a specific version:
 
 ```bash
@@ -76,6 +90,12 @@ curl -fsSL https://raw.githubusercontent.com/MengMengCode/VoCat/master/scripts/i
 sudo bash install.sh 0.0.2
 ```
 
+VoWiFi IMS requires Linux XFRM/IPsec. On OpenWrt/Kwrt the installer attempts
+to install matching `ip-full`, `kmod-ipsec`, `kmod-ipsec4/6`,
+`kmod-crypto-authenc`, AES-CBC and SHA1 packages from the firmware's own feed.
+If matching kernel modules are unavailable, use a firmware that includes them;
+never force-install kmods built for a different kernel.
+
 The installer:
 
 - detects `amd64`, `386`, `arm64`, `aarch64`, or `armv7`;
diff --git a/cmd/vocat/instance_lock_linux.go b/cmd/vocat/instance_lock_linux.go
new file mode 100644
index 0000000..7a6ee43
--- /dev/null
+++ b/cmd/vocat/instance_lock_linux.go
@@ -0,0 +1,32 @@
+//go:build linux
+
+package main
+
+import (
+	"errors"
+	"fmt"
+	"os"
+	"path/filepath"
+
+	"golang.org/x/sys/unix"
+)
+
+func lockServerInstance(databasePath string) (*os.File, error) {
+	directory := filepath.Dir(databasePath)
+	if err := os.MkdirAll(directory, 0o755); err != nil {
+		return nil, fmt.Errorf("create data directory for instance lock: %w", err)
+	}
+	path := filepath.Join(directory, ".vocat.lock")
+	file, err := os.OpenFile(path, os.O_CREATE|os.O_RDWR, 0o600)
+	if err != nil {
+		return nil, fmt.Errorf("open server instance lock: %w", err)
+	}
+	if err := unix.Flock(int(file.Fd()), unix.LOCK_EX|unix.LOCK_NB); err != nil {
+		_ = file.Close()
+		if errors.Is(err, unix.EWOULDBLOCK) || errors.Is(err, unix.EAGAIN) {
+			return nil, fmt.Errorf("another vocat server is already using database %s", databasePath)
+		}
+		return nil, fmt.Errorf("lock server instance: %w", err)
+	}
+	return file, nil
+}
diff --git a/cmd/vocat/instance_lock_linux_test.go b/cmd/vocat/instance_lock_linux_test.go
new file mode 100644
index 0000000..ab09079
--- /dev/null
+++ b/cmd/vocat/instance_lock_linux_test.go
@@ -0,0 +1,25 @@
+//go:build linux
+
+package main
+
+import (
+	"path/filepath"
+	"strings"
+	"testing"
+)
+
+func TestServerInstanceLockRejectsSecondProcess(t *testing.T) {
+	database := filepath.Join(t.TempDir(), "vocat.db")
+	first, err := lockServerInstance(database)
+	if err != nil {
+		t.Fatal(err)
+	}
+	defer first.Close()
+	second, err := lockServerInstance(database)
+	if second != nil {
+		second.Close()
+	}
+	if err == nil || !strings.Contains(err.Error(), "already using database") {
+		t.Fatalf("second lock error = %v", err)
+	}
+}
diff --git a/cmd/vocat/instance_lock_other.go b/cmd/vocat/instance_lock_other.go
new file mode 100644
index 0000000..d214584
--- /dev/null
+++ b/cmd/vocat/instance_lock_other.go
@@ -0,0 +1,12 @@
+//go:build !linux
+
+package main
+
+import (
+	"os"
+	"path/filepath"
+)
+
+func lockServerInstance(databasePath string) (*os.File, error) {
+	return os.OpenFile(filepath.Join(filepath.Dir(databasePath), ".vocat.lock"), os.O_CREATE|os.O_RDWR, 0o600)
+}
diff --git a/cmd/vocat/main.go b/cmd/vocat/main.go
index d6958bc..b59569d 100644
--- a/cmd/vocat/main.go
+++ b/cmd/vocat/main.go
@@ -112,6 +112,11 @@ func run(logger *slog.Logger, logs *loghub.Hub) error {
 	if err != nil {
 		return fmt.Errorf("load configuration: %w", err)
 	}
+	instanceLock, err := lockServerInstance(cfg.DatabasePath)
+	if err != nil {
+		return err
+	}
+	defer instanceLock.Close()
 	if cfg.UsesDefaultCredentials() {
 		logger.Warn(
 			"default admin credentials are active; set VOCAT_ADMIN_PASSWORD before exposing the service",
diff --git a/docs/README.zh-CN.md b/docs/README.zh-CN.md
index 3f5279d..4692b08 100644
--- a/docs/README.zh-CN.md
+++ b/docs/README.zh-CN.md
@@ -65,10 +65,24 @@ Vocat 面向基于高通芯片、并暴露兼容 AT、QMI、串口与 USB 网络
 
 ### Linux 一键安装
 
+已是 root（包括默认没有 `sudo` 的 OpenWrt/Kwrt）：
+
+```bash
+curl -fsSL https://raw.githubusercontent.com/MengMengCode/VoCat/master/scripts/install.sh | bash
+```
+
+普通 Linux 用户且系统装有 sudo：
+
 ```bash
 curl -fsSL https://raw.githubusercontent.com/MengMengCode/VoCat/master/scripts/install.sh | sudo bash
 ```
 
+只检查 VoWiFi/XFRM 环境，不安装 VoCat：
+
+```bash
+curl -fsSL https://raw.githubusercontent.com/MengMengCode/VoCat/master/scripts/install.sh | bash -s -- --check-env
+```
+
 安装指定版本:
 
 ```bash
@@ -76,6 +90,8 @@ curl -fsSL https://raw.githubusercontent.com/MengMengCode/VoCat/master/scripts/i
 sudo bash install.sh 0.0.2
 ```
 
+VoWiFi IMS 必须使用 Linux XFRM/IPsec。OpenWrt/Kwrt 上安装脚本会从当前固件自己的软件源尝试安装严格匹配的 `ip-full`、`kmod-ipsec`、`kmod-ipsec4/6`、`kmod-crypto-authenc`、AES-CBC 和 SHA1 组件。若软件源没有与当前内核匹配的模块，必须更换包含这些组件的固件，禁止强装其他内核版本的 kmod。
+
 安装程序会:
 
 - 检测 `amd64`、`386`、`arm64` 或 `armv7` 架构;
diff --git a/go.mod b/go.mod
index 8697dc6..6cadd71 100644
--- a/go.mod
+++ b/go.mod
@@ -3,7 +3,6 @@ module vocat
 go 1.25.0
 
 require (
-	github.com/ElMostafaIdrassi/goscard v1.0.0
 	github.com/coder/websocket v1.8.15
 	go.bug.st/serial v1.6.4
 	golang.org/x/crypto v0.52.0
@@ -15,7 +14,6 @@ require (
 require (
 	github.com/creack/goselect v0.1.2 // indirect
 	github.com/dustin/go-humanize v1.0.1 // indirect
-	github.com/ebitengine/purego v0.8.2 // indirect
 	github.com/google/uuid v1.6.0 // indirect
 	github.com/mattn/go-isatty v0.0.20 // indirect
 	github.com/ncruces/go-strftime v0.1.9 // indirect
diff --git a/go.sum b/go.sum
index 5b68020..34c0320 100644
--- a/go.sum
+++ b/go.sum
@@ -1,5 +1,3 @@
-github.com/ElMostafaIdrassi/goscard v1.0.0 h1:RDG5QrqrQBUoi5MkzM4zILdYf8qDn62daYZszqvdgx0=
-github.com/ElMostafaIdrassi/goscard v1.0.0/go.mod h1:uGOakQe2fFlW2cVlr9cv6x07uelrf0j0aKPbR7jGgfg=
 github.com/coder/websocket v1.8.15 h1:6B2JPeOGlpff2Uz6vOEH1Vzpi0iUz20A+lPVhPHtNUA=
 github.com/coder/websocket v1.8.15/go.mod h1:NX3SzP+inril6yawo5CQXx8+fk145lPDC6pumgx0mVg=
 github.com/creack/goselect v0.1.2 h1:2DNy14+JPjRBgPzAd1thbQp4BSIihxcBf0IXhQXDRa0=
@@ -8,8 +6,6 @@ github.com/davecgh/go-spew v1.1.1 h1:vj9j/u1bqnvCEfJOwUhtlOARqs3+rkHYY13jYWTU97c
 github.com/davecgh/go-spew v1.1.1/go.mod h1:J7Y8YcW2NihsgmVo/mv3lAwl/skON4iLHjSsI+c5H38=
 github.com/dustin/go-humanize v1.0.1 h1:GzkhY7T5VNhEkwH0PVJgjz+fX1rhBrR7pRT3mDkpeCY=
 github.com/dustin/go-humanize v1.0.1/go.mod h1:Mu1zIs6XwVuF/gI1OepvI0qD18qycQx+mFykh5fBlto=
-github.com/ebitengine/purego v0.8.2 h1:jPPGWs2sZ1UgOSgD2bClL0MJIqu58nOmIcBuXr62z1I=
-github.com/ebitengine/purego v0.8.2/go.mod h1:iIjxzd6CiRiOG0UyXP+V1+jWqUXVjPKLAI0mRfJZTmQ=
 github.com/google/pprof v0.0.0-20250317173921-a4b03ec1a45e h1:ijClszYn+mADRFY17kjQEVQ1XRhq2/JR1M3sGqeJoxs=
 github.com/google/pprof v0.0.0-20250317173921-a4b03ec1a45e/go.mod h1:boTsfXsheKC2y+lKOCMpSfarhxDeIzfZG1jqGcPl3cA=
 github.com/google/uuid v1.6.0 h1:NIvaJDMOsjHA8n1jAhLSgzrAzy1Hgr+hNrb57e+94F0=
diff --git a/internal/pcsc/backend_linux.go b/internal/pcsc/backend_linux.go
index 97c955d..b970ee6 100644
--- a/internal/pcsc/backend_linux.go
+++ b/internal/pcsc/backend_linux.go
@@ -5,89 +5,87 @@ package pcsc
 import (
 	"context"
 	"encoding/binary"
+	"encoding/hex"
 	"errors"
 	"fmt"
+	"net"
 	"os"
 	"path/filepath"
 	"strconv"
 	"strings"
-	"sync"
-
-	"github.com/ElMostafaIdrassi/goscard"
+	"time"
 )
 
-type nativeBackend struct {
-	initializeOnce sync.Once
-	initializeErr  error
-}
+type nativeBackend struct{}
 
 func newNativeBackend() Backend { return &nativeBackend{} }
 
-func (backend *nativeBackend) initialize() error {
-	backend.initializeOnce.Do(func() {
-		if err := goscard.Initialize(goscard.NewDefaultLogger(goscard.LogLevelNone)); err != nil {
-			backend.initializeErr = fmt.Errorf("%w: pcsc-lite client library could not be loaded", ErrUnavailable)
+func (backend *nativeBackend) dial(ctx context.Context) (*pcscdClient, error) {
+	paths := []string{strings.TrimSpace(os.Getenv("PCSCLITE_CSOCK_NAME")), "/run/pcscd/pcscd.comm", "/var/run/pcscd/pcscd.comm"}
+	var failures []error
+	seen := make(map[string]bool)
+	for _, path := range paths {
+		if path == "" || seen[path] {
+			continue
 		}
-	})
-	return backend.initializeErr
+		seen[path] = true
+		conn, err := (&net.Dialer{Timeout: 5 * time.Second}).DialContext(ctx, "unix", path)
+		if err != nil {
+			failures = append(failures, err)
+			continue
+		}
+		client, err := establishPCSCD(ctx, conn)
+		if err == nil {
+			return client, nil
+		}
+		_ = conn.Close()
+		failures = append(failures, err)
+	}
+	return nil, fmt.Errorf("%w: pcscd socket is not reachable: %w", ErrUnavailable, errors.Join(failures...))
 }
 
 func (backend *nativeBackend) Readers(ctx context.Context) ([]Reader, error) {
-	if err := ctx.Err(); err != nil {
+	client, err := backend.dial(ctx)
+	if err != nil {
 		return nil, err
 	}
-	if err := backend.initialize(); err != nil {
+	defer client.closeContext(context.Background())
+	states, err := client.readers(ctx)
+	if err != nil {
 		return nil, err
 	}
-	cardContext, _, err := goscard.NewContext(goscard.SCardScopeSystem, nil, nil)
-	if err != nil {
-		return nil, fmt.Errorf("%w: pcscd is not reachable", ErrUnavailable)
-	}
-	defer cardContext.Release()
-	names, _, err := cardContext.ListReaders(nil)
-	if err != nil {
-		if strings.Contains(strings.ToLower(err.Error()), "no readers") {
-			return []Reader{}, nil
+	readers := make([]Reader, 0, len(states))
+	for _, state := range states {
+		reader := Reader{
+			Name:        state.name,
+			CardPresent: state.state&pcscCardPresent != 0,
+			ATR:         strings.ToUpper(hex.EncodeToString(state.atr)),
 		}
-		return nil, fmt.Errorf("pcsc: list readers: %w", err)
-	}
-	presentNames, atrs, _, _ := cardContext.ListReadersWithCardPresent(nil)
-	present := make(map[string]string, len(presentNames))
-	for index, name := range presentNames {
-		atr := ""
-		if index < len(atrs) {
-			atr = atrs[index]
-		}
-		present[name] = atr
-	}
-	readers := make([]Reader, 0, len(names))
-	for _, name := range names {
-		reader := Reader{Name: name}
-		reader.ATR, reader.CardPresent = present[name]
-		if path, ok := backend.readerUSBPath(cardContext, name); ok {
+		if path, ok := backend.readerUSBPath(ctx, client, state.name); ok {
 			reader.USBPath = path
 			reader.VendorID = readSysfsText(path, "idVendor")
 			reader.ProductID = readSysfsText(path, "idProduct")
 			reader.Manufacturer = readSysfsText(path, "manufacturer")
 			reader.Product = readSysfsText(path, "product")
 		} else {
-			reader.USBPath = "pcsc:" + name
+			reader.USBPath = "pcsc:" + state.name
 		}
 		if reader.Product == "" {
-			reader.Product = strings.TrimSpace(strings.TrimSuffix(name, " 00 00"))
+			reader.Product = strings.TrimSpace(strings.TrimSuffix(state.name, " 00 00"))
 		}
 		readers = append(readers, reader)
 	}
 	return readers, nil
 }
 
-func (backend *nativeBackend) readerUSBPath(cardContext goscard.Context, name string) (string, bool) {
-	card, _, err := cardContext.Connect(name, goscard.SCardShareDirect, goscard.SCardProtocolT0|goscard.SCardProtocolT1)
+func (backend *nativeBackend) readerUSBPath(ctx context.Context, client *pcscdClient, name string) (string, bool) {
+	card, _, err := client.connect(ctx, name, pcscShareDirect, 0)
 	if err != nil {
 		return "", false
 	}
-	defer card.Disconnect(goscard.SCardLeaveCard)
-	attribute, _, err := card.GetAttrib(goscard.SCardAttrChannelID)
+	disposition := uint32(pcscLeaveCard)
+	defer client.simpleCardCommand(context.Background(), pcscCmdDisconnect, card, &disposition)
+	attribute, err := client.getAttrib(ctx, card, pcscAttrChannelID)
 	if err != nil || len(attribute) < 4 {
 		return "", false
 	}
@@ -95,7 +93,7 @@ func (backend *nativeBackend) readerUSBPath(cardContext goscard.Context, name st
 	if channel>>16 != 0x0020 {
 		return "", false
 	}
-	bus, device := int((channel>>8)&0xFF), int(channel&0xFF)
+	bus, device := int((channel>>8)&0xff), int(channel&0xff)
 	entries, err := os.ReadDir("/sys/bus/usb/devices")
 	if err != nil {
 		return "", false
@@ -115,9 +113,6 @@ func (backend *nativeBackend) readerUSBPath(cardContext goscard.Context, name st
 }
 
 func (backend *nativeBackend) Open(ctx context.Context, selector Selector) (Card, error) {
-	if err := ctx.Err(); err != nil {
-		return nil, err
-	}
 	readers, err := backend.Readers(ctx)
 	if err != nil {
 		return nil, err
@@ -129,63 +124,49 @@ func (backend *nativeBackend) Open(ctx context.Context, selector Selector) (Card
 	if !reader.CardPresent {
 		return nil, ErrNoCard
 	}
-	cardContext, _, err := goscard.NewContext(goscard.SCardScopeSystem, nil, nil)
+	client, err := backend.dial(ctx)
 	if err != nil {
-		return nil, fmt.Errorf("%w: create context", ErrUnavailable)
+		return nil, err
 	}
-	card, _, err := cardContext.Connect(reader.Name, goscard.SCardShareShared, goscard.SCardProtocolT0|goscard.SCardProtocolT1)
+	handle, protocol, err := client.connect(ctx, reader.Name, pcscShareShared, pcscProtocolAny)
 	if err != nil {
-		cardContext.Release()
-		return nil, fmt.Errorf("pcsc: connect reader: %w", err)
+		_ = client.closeContext(context.Background())
+		return nil, err
 	}
-	if _, err := card.BeginTransaction(); err != nil {
-		card.Disconnect(goscard.SCardLeaveCard)
-		cardContext.Release()
+	if err := client.simpleCardCommand(ctx, pcscCmdBeginTransaction, handle, nil); err != nil {
+		disposition := uint32(pcscLeaveCard)
+		_ = client.simpleCardCommand(context.Background(), pcscCmdDisconnect, handle, &disposition)
+		_ = client.closeContext(context.Background())
 		return nil, fmt.Errorf("pcsc: begin card transaction: %w", err)
 	}
-	return &nativeCard{context: &cardContext, card: &card}, nil
+	return &nativeCard{client: client, handle: handle, protocol: protocol}, nil
 }
 
 type nativeCard struct {
-	context *goscard.Context
-	card    *goscard.Card
-	closed  bool
+	client   *pcscdClient
+	handle   int32
+	protocol uint32
+	closed   bool
 }
 
 func (card *nativeCard) Transmit(ctx context.Context, command []byte) ([]byte, uint16, error) {
-	if card == nil || card.card == nil || card.closed {
+	if card == nil || card.client == nil || card.closed {
 		return nil, 0, errors.New("pcsc: card session is closed")
 	}
-	if err := ctx.Err(); err != nil {
-		return nil, 0, err
-	}
 	return card.transmit(ctx, append([]byte(nil), command...), 0)
 }
 
-// TransmitRaw performs exactly one APDU exchange. Stateful eUICC callers need
-// to observe 61xx themselves because GET RESPONSE must target their logical
-// channel rather than the basic channel.
 func (card *nativeCard) TransmitRaw(ctx context.Context, command []byte) ([]byte, uint16, error) {
-	if card == nil || card.card == nil || card.closed {
+	if card == nil || card.client == nil || card.closed {
 		return nil, 0, errors.New("pcsc: card session is closed")
 	}
-	if err := ctx.Err(); err != nil {
-		return nil, 0, err
-	}
-	pci := goscard.SCardIoRequestT0
-	if card.card.ActiveProtocol() == goscard.SCardProtocolT1 {
-		pci = goscard.SCardIoRequestT1
-	}
-	response, _, err := card.card.Transmit(&pci, append([]byte(nil), command...), nil)
+	response, err := card.client.transmit(ctx, card.handle, card.protocol, append([]byte(nil), command...))
 	if err != nil {
 		return nil, 0, err
 	}
 	if len(response) < 2 {
 		return nil, 0, errors.New("pcsc: APDU response omitted its status word")
 	}
-	if err := ctx.Err(); err != nil {
-		return nil, 0, err
-	}
 	last := len(response) - 2
 	return append([]byte(nil), response[:last]...), uint16(response[last])<<8 | uint16(response[last+1]), nil
 }
@@ -194,61 +175,46 @@ func (card *nativeCard) transmit(ctx context.Context, command []byte, depth int)
 	if depth > 8 {
 		return nil, 0, errors.New("pcsc: too many APDU continuations")
 	}
-	pci := goscard.SCardIoRequestT0
-	if card.card.ActiveProtocol() == goscard.SCardProtocolT1 {
-		pci = goscard.SCardIoRequestT1
-	}
-	response, _, err := card.card.Transmit(&pci, command, nil)
+	data, status, err := card.TransmitRaw(ctx, command)
 	if err != nil {
 		return nil, 0, err
 	}
-	if len(response) < 2 {
-		return nil, 0, errors.New("pcsc: APDU response omitted its status word")
-	}
-	data := append([]byte(nil), response[:len(response)-2]...)
-	sw1, sw2 := response[len(response)-2], response[len(response)-1]
-	if sw1 == 0x6C && len(command) >= 5 {
+	sw1, sw2 := byte(status>>8), byte(status)
+	if sw1 == 0x6c && len(command) >= 5 {
 		retry := append([]byte(nil), command...)
 		retry[len(retry)-1] = sw2
 		return card.transmit(ctx, retry, depth+1)
 	}
-	if sw1 == 0x61 || sw1 == 0x9F {
-		more, sw, err := card.transmit(ctx, []byte{0x00, 0xC0, 0x00, 0x00, sw2}, depth+1)
+	if sw1 == 0x61 || sw1 == 0x9f {
+		more, sw, err := card.transmit(ctx, []byte{0x00, 0xc0, 0x00, 0x00, sw2}, depth+1)
 		if err != nil {
 			return nil, 0, err
 		}
 		return append(data, more...), sw, nil
 	}
-	if err := ctx.Err(); err != nil {
-		return nil, 0, err
-	}
-	return data, uint16(sw1)<<8 | uint16(sw2), nil
+	return data, status, ctx.Err()
 }
 
-func (card *nativeCard) Close() error {
-	return card.close(goscard.SCardLeaveCard)
-}
+func (card *nativeCard) Close() error { return card.close(pcscLeaveCard) }
 
-func (card *nativeCard) CloseWithReset() error {
-	return card.close(goscard.SCardResetCard)
-}
+func (card *nativeCard) CloseWithReset() error { return card.close(pcscResetCard) }
 
-func (card *nativeCard) close(disposition goscard.SCardDisposition) error {
+func (card *nativeCard) close(disposition uint32) error {
 	if card == nil || card.closed {
 		return nil
 	}
 	card.closed = true
+	ctx, cancel := context.WithTimeout(context.Background(), 5*time.Second)
+	defer cancel()
 	var result []error
-	if card.card != nil {
-		if _, err := card.card.EndTransaction(disposition); err != nil {
+	if card.client != nil {
+		if err := card.client.simpleCardCommand(ctx, pcscCmdEndTransaction, card.handle, &disposition); err != nil {
 			result = append(result, err)
 		}
-		if _, err := card.card.Disconnect(disposition); err != nil {
+		if err := card.client.simpleCardCommand(ctx, pcscCmdDisconnect, card.handle, &disposition); err != nil {
 			result = append(result, err)
 		}
-	}
-	if card.context != nil {
-		if _, err := card.context.Release(); err != nil {
+		if err := card.client.closeContext(ctx); err != nil {
 			result = append(result, err)
 		}
 	}
diff --git a/internal/pcsc/pcscd_protocol.go b/internal/pcsc/pcscd_protocol.go
new file mode 100644
index 0000000..a5f811f
--- /dev/null
+++ b/internal/pcsc/pcscd_protocol.go
@@ -0,0 +1,334 @@
+package pcsc
+
+import (
+	"context"
+	"encoding/binary"
+	"errors"
+	"fmt"
+	"io"
+	"net"
+	"time"
+)
+
+// pcsc-lite exposes a small, versioned protocol over its local Unix socket.
+// Speaking that protocol directly keeps VoCat's Linux binaries fully static;
+// loading libpcsclite through dlopen would pull a glibc interpreter into an
+// otherwise CGO-free build and make it unusable on musl-based routers.
+const (
+	pcscProtocolMajor        = 4
+	pcscProtocolCurrentMinor = 6
+	pcscProtocolOldestMinor  = 4
+
+	pcscCmdEstablishContext = 0x01
+	pcscCmdReleaseContext   = 0x02
+	pcscCmdConnect          = 0x04
+	pcscCmdDisconnect       = 0x06
+	pcscCmdBeginTransaction = 0x07
+	pcscCmdEndTransaction   = 0x08
+	pcscCmdTransmit         = 0x09
+	pcscCmdGetAttrib        = 0x0f
+	pcscCmdVersion          = 0x11
+	pcscCmdGetReadersState  = 0x12
+
+	pcscScopeSystem      = 0x0002
+	pcscProtocolT0       = 0x0001
+	pcscProtocolT1       = 0x0002
+	pcscProtocolAny      = pcscProtocolT0 | pcscProtocolT1
+	pcscShareShared      = 0x0002
+	pcscShareDirect      = 0x0003
+	pcscLeaveCard        = 0x0000
+	pcscResetCard        = 0x0001
+	pcscCardPresent      = 0x0004
+	pcscAttrChannelID    = 0x00020110
+	pcscMaxReaderName    = 128
+	pcscMaxATR           = 33
+	pcscMaxReaders       = 16
+	pcscReaderStateSize  = 184
+	pcscGetSetBodySize   = 280
+	pcscMaxAttribute     = 264
+	pcscMaxAPDUResponse  = 65548
+	pcscDefaultIOTimeout = 30 * time.Second
+	pcscSuccess          = uint32(0)
+	pcscNoSmartcard      = uint32(0x8010000c)
+	pcscNoService        = uint32(0x8010001d)
+	pcscServiceStopped   = uint32(0x8010001e)
+	pcscNoReaders        = uint32(0x8010002e)
+)
+
+type pcscdClient struct {
+	conn        net.Conn
+	contextID   uint32
+	serverMinor int32
+}
+
+type pcscdReaderState struct {
+	name     string
+	state    uint32
+	atr      []byte
+	protocol uint32
+}
+
+func establishPCSCD(ctx context.Context, conn net.Conn) (*pcscdClient, error) {
+	client := &pcscdClient{conn: conn}
+	version := make([]byte, 12)
+	binary.LittleEndian.PutUint32(version[0:4], pcscProtocolMajor)
+	binary.LittleEndian.PutUint32(version[4:8], pcscProtocolCurrentMinor)
+	for {
+		if err := client.exchange(ctx, pcscCmdVersion, version); err != nil {
+			return nil, err
+		}
+		major := int32(binary.LittleEndian.Uint32(version[0:4]))
+		client.serverMinor = int32(binary.LittleEndian.Uint32(version[4:8]))
+		rv := binary.LittleEndian.Uint32(version[8:12])
+		if rv == pcscSuccess {
+			break
+		}
+		if rv != pcscServiceStopped || major != pcscProtocolMajor || client.serverMinor < pcscProtocolOldestMinor || client.serverMinor >= pcscProtocolCurrentMinor {
+			return nil, pcscError("negotiate protocol", rv)
+		}
+		// pcsc-lite answers a newer client's first probe with its own
+		// compatible minor version. Retry on the same connection with that
+		// value, matching libpcsclite's official fallback behavior.
+		binary.LittleEndian.PutUint32(version[0:4], pcscProtocolMajor)
+		binary.LittleEndian.PutUint32(version[4:8], uint32(client.serverMinor))
+		binary.LittleEndian.PutUint32(version[8:12], pcscSuccess)
+	}
+	if client.serverMinor < pcscProtocolOldestMinor {
+		return nil, fmt.Errorf("pcsc: unsupported pcscd protocol %d.%d", pcscProtocolMajor, client.serverMinor)
+	}
+	body := make([]byte, 12)
+	binary.LittleEndian.PutUint32(body[0:4], pcscScopeSystem)
+	if err := client.exchange(ctx, pcscCmdEstablishContext, body); err != nil {
+		return nil, err
+	}
+	if rv := binary.LittleEndian.Uint32(body[8:12]); rv != pcscSuccess {
+		return nil, pcscError("establish context", rv)
+	}
+	client.contextID = binary.LittleEndian.Uint32(body[4:8])
+	return client, nil
+}
+
+func (client *pcscdClient) exchange(ctx context.Context, command uint32, body []byte) error {
+	if client == nil || client.conn == nil {
+		return errors.New("pcsc: pcscd connection is closed")
+	}
+	if err := client.setDeadline(ctx); err != nil {
+		return err
+	}
+	header := make([]byte, 8)
+	binary.LittleEndian.PutUint32(header[0:4], uint32(len(body)))
+	binary.LittleEndian.PutUint32(header[4:8], command)
+	if err := writeAll(client.conn, header); err != nil {
+		return fmt.Errorf("pcsc: send command %02x: %w", command, err)
+	}
+	if len(body) > 0 {
+		if err := writeAll(client.conn, body); err != nil {
+			return fmt.Errorf("pcsc: send command body %02x: %w", command, err)
+		}
+		if _, err := io.ReadFull(client.conn, body); err != nil {
+			return fmt.Errorf("pcsc: receive command %02x: %w", command, err)
+		}
+	}
+	return nil
+}
+
+func (client *pcscdClient) send(ctx context.Context, command uint32, body, extra []byte) error {
+	if client == nil || client.conn == nil {
+		return errors.New("pcsc: pcscd connection is closed")
+	}
+	if err := client.setDeadline(ctx); err != nil {
+		return err
+	}
+	header := make([]byte, 8)
+	binary.LittleEndian.PutUint32(header[0:4], uint32(len(body)))
+	binary.LittleEndian.PutUint32(header[4:8], command)
+	if err := writeAll(client.conn, header); err != nil {
+		return err
+	}
+	if err := writeAll(client.conn, body); err != nil {
+		return err
+	}
+	return writeAll(client.conn, extra)
+}
+
+func (client *pcscdClient) setDeadline(ctx context.Context) error {
+	if err := ctx.Err(); err != nil {
+		return err
+	}
+	deadline := time.Now().Add(pcscDefaultIOTimeout)
+	if value, ok := ctx.Deadline(); ok && value.Before(deadline) {
+		deadline = value
+	}
+	return client.conn.SetDeadline(deadline)
+}
+
+func (client *pcscdClient) readers(ctx context.Context) ([]pcscdReaderState, error) {
+	if err := client.setDeadline(ctx); err != nil {
+		return nil, err
+	}
+	header := make([]byte, 8)
+	binary.LittleEndian.PutUint32(header[4:8], pcscCmdGetReadersState)
+	if err := writeAll(client.conn, header); err != nil {
+		return nil, fmt.Errorf("pcsc: request reader states: %w", err)
+	}
+	raw := make([]byte, pcscMaxReaders*pcscReaderStateSize)
+	if _, err := io.ReadFull(client.conn, raw); err != nil {
+		return nil, fmt.Errorf("pcsc: read reader states: %w", err)
+	}
+	result := make([]pcscdReaderState, 0, pcscMaxReaders)
+	for offset := 0; offset < len(raw); offset += pcscReaderStateSize {
+		state := raw[offset : offset+pcscReaderStateSize]
+		name := cString(state[:pcscMaxReaderName])
+		if name == "" {
+			continue
+		}
+		atrLen := int(binary.LittleEndian.Uint32(state[176:180]))
+		if atrLen < 0 || atrLen > pcscMaxATR {
+			atrLen = 0
+		}
+		result = append(result, pcscdReaderState{
+			name:     name,
+			state:    binary.LittleEndian.Uint32(state[132:136]),
+			atr:      append([]byte(nil), state[140:140+atrLen]...),
+			protocol: binary.LittleEndian.Uint32(state[180:184]),
+		})
+	}
+	return result, nil
+}
+
+func (client *pcscdClient) connect(ctx context.Context, reader string, share, protocols uint32) (int32, uint32, error) {
+	if len(reader) >= pcscMaxReaderName {
+		return 0, 0, errors.New("pcsc: reader name is too long")
+	}
+	body := make([]byte, 152)
+	binary.LittleEndian.PutUint32(body[0:4], client.contextID)
+	copy(body[4:132], reader)
+	binary.LittleEndian.PutUint32(body[132:136], share)
+	binary.LittleEndian.PutUint32(body[136:140], protocols)
+	if err := client.exchange(ctx, pcscCmdConnect, body); err != nil {
+		return 0, 0, err
+	}
+	if rv := binary.LittleEndian.Uint32(body[148:152]); rv != pcscSuccess {
+		return 0, 0, pcscError("connect reader", rv)
+	}
+	return int32(binary.LittleEndian.Uint32(body[140:144])), binary.LittleEndian.Uint32(body[144:148]), nil
+}
+
+func (client *pcscdClient) simpleCardCommand(ctx context.Context, command uint32, card int32, disposition *uint32) error {
+	size := 8
+	if disposition != nil {
+		size = 12
+	}
+	body := make([]byte, size)
+	binary.LittleEndian.PutUint32(body[0:4], uint32(card))
+	if disposition != nil {
+		binary.LittleEndian.PutUint32(body[4:8], *disposition)
+	}
+	if err := client.exchange(ctx, command, body); err != nil {
+		return err
+	}
+	if rv := binary.LittleEndian.Uint32(body[size-4:]); rv != pcscSuccess {
+		return pcscError("card command", rv)
+	}
+	return nil
+}
+
+func (client *pcscdClient) transmit(ctx context.Context, card int32, protocol uint32, command []byte) ([]byte, error) {
+	body := make([]byte, 32)
+	binary.LittleEndian.PutUint32(body[0:4], uint32(card))
+	binary.LittleEndian.PutUint32(body[4:8], protocol)
+	binary.LittleEndian.PutUint32(body[8:12], 8)
+	binary.LittleEndian.PutUint32(body[12:16], uint32(len(command)))
+	binary.LittleEndian.PutUint32(body[16:20], pcscProtocolAny)
+	binary.LittleEndian.PutUint32(body[20:24], 8)
+	binary.LittleEndian.PutUint32(body[24:28], pcscMaxAPDUResponse)
+	if err := client.send(ctx, pcscCmdTransmit, body, command); err != nil {
+		return nil, fmt.Errorf("pcsc: transmit APDU: %w", err)
+	}
+	if _, err := io.ReadFull(client.conn, body); err != nil {
+		return nil, fmt.Errorf("pcsc: receive APDU result: %w", err)
+	}
+	if rv := binary.LittleEndian.Uint32(body[28:32]); rv != pcscSuccess {
+		return nil, pcscError("transmit APDU", rv)
+	}
+	length := binary.LittleEndian.Uint32(body[24:28])
+	if length > pcscMaxAPDUResponse {
+		return nil, errors.New("pcsc: pcscd returned an oversized APDU")
+	}
+	response := make([]byte, length)
+	if _, err := io.ReadFull(client.conn, response); err != nil {
+		return nil, fmt.Errorf("pcsc: receive APDU: %w", err)
+	}
+	return response, nil
+}
+
+func (client *pcscdClient) getAttrib(ctx context.Context, card int32, attribute uint32) ([]byte, error) {
+	body := make([]byte, pcscGetSetBodySize)
+	binary.LittleEndian.PutUint32(body[0:4], uint32(card))
+	binary.LittleEndian.PutUint32(body[4:8], attribute)
+	binary.LittleEndian.PutUint32(body[272:276], pcscMaxAttribute)
+	if err := client.exchange(ctx, pcscCmdGetAttrib, body); err != nil {
+		return nil, err
+	}
+	if rv := binary.LittleEndian.Uint32(body[276:280]); rv != pcscSuccess {
+		return nil, pcscError("get reader attribute", rv)
+	}
+	length := binary.LittleEndian.Uint32(body[272:276])
+	if length > pcscMaxAttribute {
+		return nil, errors.New("pcsc: pcscd returned an oversized attribute")
+	}
+	return append([]byte(nil), body[8:8+length]...), nil
+}
+
+func (client *pcscdClient) closeContext(ctx context.Context) error {
+	if client == nil || client.conn == nil {
+		return nil
+	}
+	body := make([]byte, 8)
+	binary.LittleEndian.PutUint32(body[0:4], client.contextID)
+	err := client.exchange(ctx, pcscCmdReleaseContext, body)
+	if err == nil {
+		if rv := binary.LittleEndian.Uint32(body[4:8]); rv != pcscSuccess {
+			err = pcscError("release context", rv)
+		}
+	}
+	closeErr := client.conn.Close()
+	client.conn = nil
+	return errors.Join(err, closeErr)
+}
+
+func pcscError(operation string, code uint32) error {
+	switch code {
+	case pcscNoSmartcard:
+		return ErrNoCard
+	case pcscNoService, pcscServiceStopped:
+		return fmt.Errorf("%w: %s failed with PC/SC status %08X", ErrUnavailable, operation, code)
+	case pcscNoReaders:
+		return ErrReaderNotFound
+	default:
+		return fmt.Errorf("pcsc: %s failed with status %08X", operation, code)
+	}
+}
+
+func cString(value []byte) string {
+	for index, current := range value {
+		if current == 0 {
+			return string(value[:index])
+		}
+	}
+	return string(value)
+}
+
+func writeAll(writer io.Writer, value []byte) error {
+	for len(value) > 0 {
+		written, err := writer.Write(value)
+		if err != nil {
+			return err
+		}
+		if written == 0 {
+			return io.ErrUnexpectedEOF
+		}
+		value = value[written:]
+	}
+	return nil
+}
diff --git a/internal/pcsc/pcscd_protocol_test.go b/internal/pcsc/pcscd_protocol_test.go
new file mode 100644
index 0000000..518d98e
--- /dev/null
+++ b/internal/pcsc/pcscd_protocol_test.go
@@ -0,0 +1,127 @@
+package pcsc
+
+import (
+	"bytes"
+	"context"
+	"encoding/binary"
+	"errors"
+	"io"
+	"net"
+	"testing"
+)
+
+func TestPCSCDClientLifecycleAndTransmit(t *testing.T) {
+	clientConn, serverConn := net.Pipe()
+	serverDone := make(chan error, 1)
+	go func() {
+		defer serverConn.Close()
+		serverDone <- servePCSCDTestSession(serverConn)
+	}()
+
+	client, err := establishPCSCD(context.Background(), clientConn)
+	if err != nil {
+		t.Fatalf("establishPCSCD: %v", err)
+	}
+	states, err := client.readers(context.Background())
+	if err != nil {
+		t.Fatalf("readers: %v", err)
+	}
+	if len(states) != 1 || states[0].name != "VoCat Test Reader 00 00" || states[0].state&pcscCardPresent == 0 {
+		t.Fatalf("states = %#v", states)
+	}
+	handle, protocol, err := client.connect(context.Background(), states[0].name, pcscShareShared, pcscProtocolAny)
+	if err != nil {
+		t.Fatalf("connect: %v", err)
+	}
+	if handle != 42 || protocol != pcscProtocolT1 {
+		t.Fatalf("handle/protocol = %d/%d", handle, protocol)
+	}
+	if err := client.simpleCardCommand(context.Background(), pcscCmdBeginTransaction, handle, nil); err != nil {
+		t.Fatalf("begin: %v", err)
+	}
+	response, err := client.transmit(context.Background(), handle, protocol, []byte{0x00, 0xa4, 0x00, 0x00})
+	if err != nil {
+		t.Fatalf("transmit: %v", err)
+	}
+	if !bytes.Equal(response, []byte{0x62, 0x02, 0x90, 0x00}) {
+		t.Fatalf("response = %x", response)
+	}
+	disposition := uint32(pcscLeaveCard)
+	if err := client.simpleCardCommand(context.Background(), pcscCmdEndTransaction, handle, &disposition); err != nil {
+		t.Fatalf("end: %v", err)
+	}
+	if err := client.simpleCardCommand(context.Background(), pcscCmdDisconnect, handle, &disposition); err != nil {
+		t.Fatalf("disconnect: %v", err)
+	}
+	if err := client.closeContext(context.Background()); err != nil {
+		t.Fatalf("close context: %v", err)
+	}
+	if err := <-serverDone; err != nil {
+		t.Fatalf("fake pcscd: %v", err)
+	}
+}
+
+func servePCSCDTestSession(conn net.Conn) error {
+	for {
+		header := make([]byte, 8)
+		if _, err := io.ReadFull(conn, header); err != nil {
+			return err
+		}
+		size := binary.LittleEndian.Uint32(header[0:4])
+		command := binary.LittleEndian.Uint32(header[4:8])
+		body := make([]byte, size)
+		if _, err := io.ReadFull(conn, body); err != nil {
+			return err
+		}
+		switch command {
+		case pcscCmdVersion:
+			binary.LittleEndian.PutUint32(body[0:4], pcscProtocolMajor)
+			binary.LittleEndian.PutUint32(body[4:8], pcscProtocolCurrentMinor)
+			if err := writeAll(conn, body); err != nil {
+				return err
+			}
+		case pcscCmdEstablishContext:
+			binary.LittleEndian.PutUint32(body[4:8], 7)
+			if err := writeAll(conn, body); err != nil {
+				return err
+			}
+		case pcscCmdGetReadersState:
+			states := make([]byte, pcscMaxReaders*pcscReaderStateSize)
+			copy(states, "VoCat Test Reader 00 00")
+			binary.LittleEndian.PutUint32(states[132:136], pcscCardPresent)
+			copy(states[140:143], []byte{0x3b, 0x00, 0x00})
+			binary.LittleEndian.PutUint32(states[176:180], 3)
+			binary.LittleEndian.PutUint32(states[180:184], pcscProtocolT1)
+			if err := writeAll(conn, states); err != nil {
+				return err
+			}
+		case pcscCmdConnect:
+			binary.LittleEndian.PutUint32(body[140:144], 42)
+			binary.LittleEndian.PutUint32(body[144:148], pcscProtocolT1)
+			if err := writeAll(conn, body); err != nil {
+				return err
+			}
+		case pcscCmdBeginTransaction, pcscCmdEndTransaction, pcscCmdDisconnect:
+			if err := writeAll(conn, body); err != nil {
+				return err
+			}
+		case pcscCmdTransmit:
+			commandBody := make([]byte, binary.LittleEndian.Uint32(body[12:16]))
+			if _, err := io.ReadFull(conn, commandBody); err != nil {
+				return err
+			}
+			response := []byte{0x62, 0x02, 0x90, 0x00}
+			binary.LittleEndian.PutUint32(body[24:28], uint32(len(response)))
+			if err := writeAll(conn, body); err != nil {
+				return err
+			}
+			if err := writeAll(conn, response); err != nil {
+				return err
+			}
+		case pcscCmdReleaseContext:
+			return writeAll(conn, body)
+		default:
+			return errors.New("unexpected fake pcscd command")
+		}
+	}
+}
diff --git a/internal/update/update.go b/internal/update/update.go
index 3465545..7342299 100644
--- a/internal/update/update.go
+++ b/internal/update/update.go
@@ -184,6 +184,10 @@ func applyUpdate(ctx context.Context, logger *slog.Logger, opts Options, release
 		cleanup()
 		return fmt.Errorf("update: chmod temp binary: %w", err)
 	}
+	if err := validateExecutable(ctx, tmpPath); err != nil {
+		cleanup()
+		return err
+	}
 	if err := backupAndReplace(opts.Target, tmpPath); err != nil {
 		cleanup()
 		return err
@@ -202,10 +206,25 @@ func applyUpdate(ctx context.Context, logger *slog.Logger, opts Options, release
 	return nil
 }
 
+// validateExecutable catches incompatible architectures and missing dynamic
+// loaders before the working installation is touched. A valid checksum alone
+// cannot detect those packaging errors.
+func validateExecutable(ctx context.Context, path string) error {
+	checkCtx, cancel := context.WithTimeout(ctx, 15*time.Second)
+	defer cancel()
+	output, err := exec.CommandContext(checkCtx, path, "version").CombinedOutput()
+	if err != nil {
+		return fmt.Errorf("update: downloaded binary cannot run on this host: %w (%s)", err, strings.TrimSpace(string(output)))
+	}
+	if !strings.Contains(strings.ToLower(string(output)), "vocat") {
+		return fmt.Errorf("update: downloaded binary returned an unexpected version response: %q", strings.TrimSpace(string(output)))
+	}
+	return nil
+}
+
 // backupAndReplace renames the current binary aside, then moves the verified
-// temp file into place. Both renames are atomic on the same filesystem. On
-// Linux the kernel holds the running binary's inode, so replacing it mid-flight
-// is safe.
+// temp file into place. Both renames are atomic on the same filesystem. The
+// previous working binary is retained for service-level or manual rollback.
 func backupAndReplace(target, tmp string) error {
 	backup := target + ".previous"
 	if _, err := os.Stat(target); err == nil {
@@ -221,16 +240,21 @@ func backupAndReplace(target, tmp string) error {
 		}
 		return fmt.Errorf("update: move new binary into place: %w", err)
 	}
-	_ = os.Remove(backup)
 	return nil
 }
 
-// RestartService restarts the vocat systemd unit. If systemctl is unavailable
-// (non-systemd hosts, containers), it returns an error the caller surfaces as
-// a non-fatal warning.
+// RestartService supports both systemd hosts and OpenWrt/procd routers.
 func RestartService(logger *slog.Logger) error {
+	if _, err := os.Stat("/etc/init.d/vocat"); err == nil {
+		cmd := exec.Command("/etc/init.d/vocat", "restart")
+		if out, err := cmd.CombinedOutput(); err != nil {
+			logger.Warn("OpenWrt service restart failed", "error", err, "output", string(out))
+			return fmt.Errorf("restart OpenWrt vocat service: %w", err)
+		}
+		return nil
+	}
 	if _, err := exec.LookPath("systemctl"); err != nil {
-		return fmt.Errorf("systemctl not found in PATH")
+		return fmt.Errorf("neither /etc/init.d/vocat nor systemctl is available")
 	}
 	// Queue the restart and let systemctl exit before systemd stops this unit.
 	// A blocking restart command becomes part of vocat.service's own cgroup and
diff --git a/internal/update/update_validation_test.go b/internal/update/update_validation_test.go
new file mode 100644
index 0000000..39e5f7c
--- /dev/null
+++ b/internal/update/update_validation_test.go
@@ -0,0 +1,44 @@
+package update
+
+import (
+	"context"
+	"os"
+	"path/filepath"
+	"runtime"
+	"testing"
+)
+
+func TestValidateExecutableRejectsNonExecutableFile(t *testing.T) {
+	path := filepath.Join(t.TempDir(), "not-vocat")
+	if err := os.WriteFile(path, []byte("not an executable"), 0o755); err != nil {
+		t.Fatal(err)
+	}
+	if err := validateExecutable(context.Background(), path); err == nil {
+		t.Fatal("validateExecutable accepted invalid file")
+	}
+}
+
+func TestBackupAndReplaceRetainsPreviousBinary(t *testing.T) {
+	if runtime.GOOS == "windows" {
+		t.Skip("Linux replacement behavior")
+	}
+	directory := t.TempDir()
+	target := filepath.Join(directory, "vocat")
+	replacement := filepath.Join(directory, "replacement")
+	if err := os.WriteFile(target, []byte("old"), 0o755); err != nil {
+		t.Fatal(err)
+	}
+	if err := os.WriteFile(replacement, []byte("new"), 0o755); err != nil {
+		t.Fatal(err)
+	}
+	if err := backupAndReplace(target, replacement); err != nil {
+		t.Fatal(err)
+	}
+	old, err := os.ReadFile(target + ".previous")
+	if err != nil {
+		t.Fatalf("read retained backup: %v", err)
+	}
+	if string(old) != "old" {
+		t.Fatalf("backup = %q", old)
+	}
+}
diff --git a/internal/vowifi/ims/security_linux.go b/internal/vowifi/ims/security_linux.go
index 7248ec6..dfdec39 100644
--- a/internal/vowifi/ims/security_linux.go
+++ b/internal/vowifi/ims/security_linux.go
@@ -84,6 +84,14 @@ func runIPCommand(ctx context.Context, command string, operation xfrmOperation)
 	if message == "" {
 		message = err.Error()
 	}
+	if strings.Contains(strings.ToLower(message), "protocol not supported") ||
+		strings.Contains(strings.ToLower(message), "operation not supported") {
+		return fmt.Errorf(
+			"%s: host kernel lacks XFRM/IPsec support; install matching kmod-ipsec and kmod-ipsec4/6 (OpenWrt), or enable CONFIG_XFRM_USER and ESP in the kernel: %s",
+			operation.description,
+			message,
+		)
+	}
 	// Operation descriptions contain no SPI keys or subscriber identity.
 	return fmt.Errorf("%s: %s", operation.description, message)
 }
diff --git a/internal/vowifi/ims/security_linux_test.go b/internal/vowifi/ims/security_linux_test.go
index da55195..c541a9c 100644
--- a/internal/vowifi/ims/security_linux_test.go
+++ b/internal/vowifi/ims/security_linux_test.go
@@ -11,6 +11,19 @@ import (
 	"time"
 )
 
+func TestRunIPCommandExplainsMissingKernelXFRM(t *testing.T) {
+	directory := t.TempDir()
+	command := directory + "/ip"
+	script := "#!/bin/sh\necho 'Cannot open netlink socket: Protocol not supported' >&2\nexit 1\n"
+	if err := os.WriteFile(command, []byte(script), 0o755); err != nil {
+		t.Fatal(err)
+	}
+	err := runIPCommand(context.Background(), command, xfrmOperation{description: "test state"})
+	if err == nil || !strings.Contains(err.Error(), "kmod-ipsec") || !strings.Contains(err.Error(), "CONFIG_XFRM_USER") {
+		t.Fatalf("error = %v", err)
+	}
+}
+
 func TestLinuxIPSecInstallerLifecycle(t *testing.T) {
 	if os.Getenv("VOCAT_NETNS_TEST") != "1" {
 		t.Skip("set VOCAT_NETNS_TEST=1 inside an isolated Linux network namespace")
diff --git a/scripts/install.sh b/scripts/install.sh
index dc49d26..75bc277 100644
--- a/scripts/install.sh
+++ b/scripts/install.sh
@@ -1,12 +1,11 @@
 #!/usr/bin/env bash
 #
-# vocat install / update script for binary + systemd deployments.
+# vocat install / update script for systemd and OpenWrt/procd deployments.
 #
 # Usage:
-#   sudo bash install.sh [version]        # install a specific version
-#   sudo bash install.sh                  # install latest release
-#   sudo bash install.sh --force          # reinstall even at the same version
-#   curl -fsSL <raw url> | sudo bash      # one-liner (latest)
+#   bash install.sh [version]             # run directly when already root
+#   sudo bash install.sh [version]        # run through sudo as a normal user
+#   bash install.sh --check-env           # check VoWiFi host prerequisites
 #
 # Behavior:
 #   - Prompts for script language (中文 / English) as soon as it runs.
@@ -14,7 +13,9 @@
 #   - On first install, generates a random 32-char admin password, writes it to
 #     /etc/vocat/env (0600, loaded by the systemd unit), and prints it ONCE.
 #   - On update, preserves the existing env file and credentials.
-#   - (Re)writes the systemd unit and restarts the service.
+#   - Verifies Linux XFRM/IPsec support required by IMS; on OpenWrt it tries
+#     the matching opkg packages first.
+#   - (Re)writes a systemd or OpenWrt/procd service and restarts it.
 #
 # Published script: must contain no secrets, IPs, or passwords.
 
@@ -31,6 +32,7 @@ LINK_PATH="/usr/local/bin/vocat"
 ENV_DIR="/etc/vocat"
 ENV_FILE="${ENV_DIR}/env"
 UNIT_PATH="/etc/systemd/system/vocat.service"
+OPENWRT_INIT_PATH="/etc/init.d/vocat"
 
 # --- Language ----------------------------------------------------------------
 LANG_CHOICE=""
@@ -76,14 +78,44 @@ die() {
 
 prompt_language
 
+# BusyBox/OpenWrt images often omit coreutils' install(1). Provide the small
+# subset used by this script so the same installer works on router firmware.
+if ! command -v install >/dev/null 2>&1; then
+    install() {
+        if [ "${1:-}" = "-d" ]; then
+            shift
+            local mode="0755"
+            if [ "${1:-}" = "-m" ]; then
+                mode="$2"
+                shift 2
+            fi
+            mkdir -p "$@"
+            chmod "$mode" "$@"
+            return
+        fi
+        local mode="0755"
+        if [ "${1:-}" = "-m" ]; then
+            mode="$2"
+            shift 2
+        fi
+        [ "$#" -eq 2 ] || return 2
+        cp "$1" "$2"
+        chmod "$mode" "$2"
+    }
+fi
+
 # --- Parse args --------------------------------------------------------------
 FORCE=0
+CHECK_ENV=0
+SKIP_VOWIFI_CHECK="${VOCAT_SKIP_VOWIFI_CHECK:-0}"
 TARGET_VERSION=""
 for arg in "$@"; do
     case "$arg" in
         --force) FORCE=1 ;;
+        --check-env) CHECK_ENV=1 ;;
+        --skip-vowifi-check) SKIP_VOWIFI_CHECK=1 ;;
         -h|--help)
-            msg "用法: sudo bash install.sh [--force] [版本]" "Usage: sudo bash install.sh [--force] [version]"
+            msg "用法: bash install.sh [--force] [--check-env] [--skip-vowifi-check] [版本]" "Usage: bash install.sh [--force] [--check-env] [--skip-vowifi-check] [version]"
             exit 0
             ;;
         *) TARGET_VERSION="${arg#v}" ;;
@@ -110,6 +142,89 @@ resolve_target_version() {
     TARGET_VERSION="${tag#v}"
 }
 
+# --- Host prerequisites ------------------------------------------------------
+is_openwrt() {
+    [ -f /etc/openwrt_release ] || [ -x /sbin/procd ]
+}
+
+xfrm_works() {
+    command -v ip >/dev/null 2>&1 && ip xfrm state list >/dev/null 2>&1
+}
+
+opkg_has_package() {
+    opkg list "$1" 2>/dev/null | grep -q "^$1 -"
+}
+
+install_openwrt_vowifi_packages() {
+    msg "正在检查 OpenWrt/Kwrt 的 VoWiFi 内核组件..." "Checking OpenWrt/Kwrt VoWiFi kernel components..."
+    opkg update >/dev/null 2>&1 || msg \
+        "警告：opkg 软件源更新失败，将使用现有索引继续检查。" \
+        "Warning: opkg feed update failed; checking the existing index."
+
+    local packages=""
+    local package
+    for package in \
+        ip-full \
+        kmod-ipsec kmod-ipsec4 kmod-ipsec6 \
+        kmod-crypto-authenc kmod-crypto-cbc kmod-crypto-aes \
+        kmod-crypto-hmac kmod-crypto-sha1; do
+        if opkg_has_package "$package"; then
+            packages="$packages $package"
+        fi
+    done
+    if [ -n "$packages" ]; then
+        # Kernel packages must come from this firmware's own feed. opkg checks
+        # the kernel ABI and refuses mismatched modules; never bypass that check.
+        # shellcheck disable=SC2086
+        opkg install $packages >/dev/null 2>&1 || true
+    fi
+}
+
+install_linux_ip_tool() {
+    command -v ip >/dev/null 2>&1 && return 0
+    if command -v apt-get >/dev/null 2>&1; then
+        apt-get update -qq && apt-get install -y iproute2
+    elif command -v dnf >/dev/null 2>&1; then
+        dnf install -y iproute
+    elif command -v yum >/dev/null 2>&1; then
+        yum install -y iproute
+    elif command -v pacman >/dev/null 2>&1; then
+        pacman -Sy --noconfirm iproute2
+    elif command -v apk >/dev/null 2>&1; then
+        apk add --no-cache iproute2
+    fi
+}
+
+check_vowifi_environment() {
+    if [ "$SKIP_VOWIFI_CHECK" = "1" ]; then
+        msg \
+            "已跳过 VoWiFi 内核环境检查；IMS 通话和短信可能不可用。" \
+            "Skipped the VoWiFi kernel check; IMS calls and SMS may not work."
+        return
+    fi
+
+    if is_openwrt && command -v opkg >/dev/null 2>&1; then
+        # Install the crypto algorithms even when NETLINK_XFRM already works;
+        # some minimal images provide xfrm_user but omit AES-CBC/authenc.
+        install_openwrt_vowifi_packages
+    elif ! xfrm_works; then
+        install_linux_ip_tool
+    fi
+    if xfrm_works; then
+        msg "VoWiFi XFRM/IPsec 环境安装并验证成功。" "VoWiFi XFRM/IPsec environment installed and verified."
+        return
+    fi
+
+    if is_openwrt; then
+        die \
+            "当前 OpenWrt/Kwrt 内核 $(uname -r) 不支持 NETLINK_XFRM，且软件源没有匹配的 kmod-ipsec。请使用包含 kmod-ipsec、kmod-ipsec4、kmod-ipsec6、kmod-crypto-authenc、kmod-crypto-cbc、kmod-crypto-aes 和 kmod-crypto-sha1 的同版本固件；严禁安装其他内核版本的 kmod。仅使用非 VoWiFi 功能时可加 --skip-vowifi-check。" \
+            "The OpenWrt/Kwrt kernel $(uname -r) lacks NETLINK_XFRM and its feed has no matching kmod-ipsec. Use a firmware built with matching kmod-ipsec, kmod-ipsec4/6, crypto-authenc, CBC, AES and SHA1 modules. Never force kmods from another kernel. Use --skip-vowifi-check only for non-VoWiFi operation."
+    fi
+    die \
+        "当前 Linux 内核不支持 XFRM/IPsec，VoWiFi IMS 无法工作。请启用 CONFIG_XFRM、CONFIG_XFRM_USER、CONFIG_INET_ESP、CONFIG_INET6_ESP、AES-CBC 和 HMAC-SHA1。" \
+        "This Linux kernel lacks XFRM/IPsec required by VoWiFi IMS. Enable CONFIG_XFRM, CONFIG_XFRM_USER, CONFIG_INET_ESP, CONFIG_INET6_ESP, AES-CBC and HMAC-SHA1."
+}
+
 # --- Skip if already installed at the same version ---------------------------
 skip_if_equal() {
     [ -x "$BINARY_PATH" ] || return 0
@@ -159,6 +274,10 @@ download_and_verify() {
     [ -n "$expected" ] || die "SHA256SUMS 中找不到 $asset 的校验行。" "$asset not found in SHA256SUMS."
     actual=$(sha256sum "${VOCAT_TMP}/vocat" | awk '{print $1}')
     [ "$actual" = "$expected" ] || die "SHA-256 校验失败。" "SHA-256 verification failed."
+    chmod 0755 "${VOCAT_TMP}/vocat"
+    "${VOCAT_TMP}/vocat" version >/dev/null 2>&1 || die \
+        "Downloaded binary cannot run on this system; keeping the installed version." \
+        "The downloaded binary cannot run on this host; the installed version was not changed."
 }
 
 # --- Install binary ----------------------------------------------------------
@@ -246,11 +365,73 @@ EOF
     chmod 0644 "$UNIT_PATH"
 }
 
+write_openwrt_init() {
+    cat > "$OPENWRT_INIT_PATH" <<'EOF'
+#!/bin/sh /etc/rc.common
+START=95
+STOP=10
+USE_PROCD=1
+PROCD_TERM_TIMEOUT=40
+PROGRAM=/opt/vocat/bin/vocat
+ENV_FILE=/etc/vocat/env
+start_service() {
+    procd_open_instance
+    procd_set_param command "$PROGRAM" serve
+    procd_set_param env VOCAT_DATABASE_PATH=/opt/vocat/data/vocat.db
+    if [ -r "$ENV_FILE" ]; then
+        while IFS='=' read -r name value; do
+            case "$name" in VOCAT_*) procd_append_param env "$name=$value" ;; esac
+        done < "$ENV_FILE"
+    fi
+    procd_set_param respawn 3600 5 5
+    procd_set_param stdout 1
+    procd_set_param stderr 1
+    procd_close_instance
+}
+service_triggers() { procd_add_reload_trigger vocat; }
+EOF
+    chmod 0755 "$OPENWRT_INIT_PATH"
+}
+
+write_service() {
+    if command -v systemctl >/dev/null 2>&1 && [ -d /run/systemd/system ]; then
+        write_unit
+        return
+    fi
+    if [ -x /sbin/procd ] || [ -x /sbin/ubusd ]; then
+        write_openwrt_init
+        return
+    fi
+    die "Unsupported service manager." "Neither systemd nor OpenWrt procd was detected."
+}
+
 enable_and_start() {
+    if [ -x "$OPENWRT_INIT_PATH" ] && { [ -x /sbin/procd ] || [ -x /sbin/ubusd ]; }; then
+        "$OPENWRT_INIT_PATH" enable
+        if "$OPENWRT_INIT_PATH" restart; then
+            sleep 2
+            if "$OPENWRT_INIT_PATH" running; then
+                rm -f "${BINARY_PATH}.bak"
+                return
+            fi
+        fi
+        if [ -e "${BINARY_PATH}.bak" ]; then
+            cp -a "${BINARY_PATH}.bak" "$BINARY_PATH"
+            "$OPENWRT_INIT_PATH" restart || true
+        fi
+        die "OpenWrt vocat service failed to start." "The OpenWrt vocat service failed to start."
+    fi
     systemctl daemon-reload
     systemctl enable vocat
     if systemctl restart vocat; then
-        return
+        local attempt
+        for attempt in 1 2 3 4 5; do
+            if systemctl is-active --quiet vocat; then
+                rm -f "${BINARY_PATH}.bak"
+                return
+            fi
+            sleep 1
+        done
     fi
     if [ -e "${BINARY_PATH}.bak" ]; then
         msg "新版本启动失败，正在恢复旧二进制。" "The new version failed to start; restoring the previous binary."
@@ -261,14 +442,19 @@ enable_and_start() {
 }
 
 # --- Main --------------------------------------------------------------------
-resolve_target_version
 detect_arch
+check_vowifi_environment
+if [ "$CHECK_ENV" -eq 1 ]; then
+    msg "VoCat 运行环境检查完成。" "VoCat host environment check completed."
+    exit 0
+fi
+resolve_target_version
 skip_if_equal
 download_and_verify
 install_binary
 ensure_data_dir
 setup_env
-write_unit
+write_service
 enable_and_start
 
 if [ "$FIRST_INSTALL" -eq 1 ]; then
@@ -281,7 +467,7 @@ if [ "$FIRST_INSTALL" -eq 1 ]; then
     echo
     msg "用户名为 admin。请立即记录此密码。" "Username is admin. Record this password now."
     msg "登录后或运行以下命令修改密码:" "Change it via the web UI or run:"
-    echo "    sudo vocat menu"
+    echo "    vocat menu"
     msg "==========================================" "=============================================="
 else
     echo
diff --git a/scripts/vocat.openwrt.init b/scripts/vocat.openwrt.init
new file mode 100644
index 0000000..2b709af
--- /dev/null
+++ b/scripts/vocat.openwrt.init
@@ -0,0 +1,30 @@
+#!/bin/sh /etc/rc.common
+
+START=95
+STOP=10
+USE_PROCD=1
+PROCD_TERM_TIMEOUT=40
+
+PROGRAM=/opt/vocat/bin/vocat
+ENV_FILE=/etc/vocat/env
+
+start_service() {
+	procd_open_instance
+	procd_set_param command "$PROGRAM" serve
+	procd_set_param env VOCAT_DATABASE_PATH=/opt/vocat/data/vocat.db
+	if [ -r "$ENV_FILE" ]; then
+		while IFS='=' read -r name value; do
+			case "$name" in
+				VOCAT_*) procd_append_param env "$name=$value" ;;
+			esac
+		done < "$ENV_FILE"
+	fi
+	procd_set_param respawn 3600 5 5
+	procd_set_param stdout 1
+	procd_set_param stderr 1
+	procd_close_instance
+}
+
+service_triggers() {
+	procd_add_reload_trigger vocat
+}