btcutil: vendor anet instead of depending on a personal fork

In this commit, we vendor the Android networking shim that backs
InterfaceAddrs on android into the btcutil module, rather than
importing it from github.com/kcalvinalvin/anet. The shim works around
golang/go#40569, where net.InterfaceAddrs fails with
"route ip+net: netlinkrib: permission denied" on Android 11 and later
because of the tightened restrictions on NETLINK sockets. btcutil only
ever calls anet.InterfaceAddrs, wired in from net_android.go under the
android build tag.

The motivation is dependency hygiene. The previous import pointed at a
fork hosted under an individual contributor's account, which is not a
home we want a release dependency to live in. By copying the source
into internal/anet we drop the external module entirely: the package is
now unimportable from outside btcutil, and go.mod no longer references
the fork.

The source originates from github.com/wlynxg/anet, and its BSD 3-Clause
LICENSE travels with it. Unlike upstream, this copy does not reach into
the standard library's net package via //go:linkname; it carries its
own ipv6ZoneCache, so no -ldflags "-checklinkname=0" linker flag is
needed to build it. When golang/go#40569 is resolved upstream, both
this package and the net_android.go shim can be removed.

btcutil/go.mod

@@ -12,7 +12,6 @@ require (
 	github.com/btcsuite/btcd/wire/v2 v2.0.0
 	github.com/davecgh/go-spew v1.1.1
 	github.com/decred/dcrd/dcrec/secp256k1/v4 v4.4.0
-	github.com/kcalvinalvin/anet v0.0.0-20251112173137-d8ddc1f6dbee
 	github.com/kkdai/bstream v1.0.0
 )
 

btcutil/go.sum

@@ -20,8 +20,6 @@ github.com/decred/dcrd/crypto/blake256 v1.1.0 h1:zPMNGQCm0g4QTY27fOCorQW7EryeQ/U
 github.com/decred/dcrd/crypto/blake256 v1.1.0/go.mod h1:2OfgNZ5wDpcsFmHmCK5gZTPcCXqlm2ArzUIkw9czNJo=
 github.com/decred/dcrd/dcrec/secp256k1/v4 v4.4.0 h1:NMZiJj8QnKe1LgsbDayM4UoHwbvwDRwnI3hwNaAHRnc=
 github.com/decred/dcrd/dcrec/secp256k1/v4 v4.4.0/go.mod h1:ZXNYxsqcloTdSy/rNShjYzMhyjf0LaoftYK0p+A3h40=
-github.com/kcalvinalvin/anet v0.0.0-20251112173137-d8ddc1f6dbee h1:FPP9HDkBbPyniu+u7FHZg+kKFX1WW0gxOGteJ0h3AJk=
-github.com/kcalvinalvin/anet v0.0.0-20251112173137-d8ddc1f6dbee/go.mod h1:N6sz6HwJAenJ6d+/xmSl0ikfV05ZrVGmjt1ryy/WOtE=
 github.com/kkdai/bstream v1.0.0 h1:Se5gHwgp2VT2uHfDrkbbgbgEvV9cimLELwrPJctSjg8=
 github.com/kkdai/bstream v1.0.0/go.mod h1:FDnDOHt5Yx4p3FaHcioFT0QjDOtgUpvjeZqAs+NVZZA=
 github.com/pmezard/go-difflib v1.0.0 h1:4DBwDE0NGyQoBHbLQYPwSUPoCMWR5BEzIk/f1lZbAQM=

btcutil/internal/anet/LICENSE

@@ -0,0 +1,28 @@
+BSD 3-Clause License
+
+Copyright (c) 2023, wlynxg
+
+Redistribution and use in source and binary forms, with or without
+modification, are permitted provided that the following conditions are met:
+
+1. Redistributions of source code must retain the above copyright notice, this
+   list of conditions and the following disclaimer.
+
+2. Redistributions in binary form must reproduce the above copyright notice,
+   this list of conditions and the following disclaimer in the documentation
+   and/or other materials provided with the distribution.
+
+3. Neither the name of the copyright holder nor the names of its
+   contributors may be used to endorse or promote products derived from
+   this software without specific prior written permission.
+
+THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
+AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
+IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
+DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE
+FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
+DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
+SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
+CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
+OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.

btcutil/internal/anet/README.md

@@ -0,0 +1,24 @@
+# anet (vendored)
+
+This package is a vendored copy of an Android networking shim. It works around
+[golang/go#40569](https://github.com/golang/go/issues/40569), where
+`net.Interfaces()` and `net.InterfaceAddrs()` fail with
+`route ip+net: netlinkrib: permission denied` on Android 11 and later due to the
+tightened restrictions on `NETLINK` sockets (no `bind`, no `RTM_GETLINK`).
+
+`btcutil` only relies on `anet.InterfaceAddrs()`, which is wired in from
+`net_android.go` under the `android` build tag.
+
+## Provenance
+
+The source originates from `github.com/wlynxg/anet` (BSD 3-Clause, see
+`LICENSE`). It was vendored here, rather than imported as a module dependency,
+so that `btcd` does not depend on a fork hosted under a personal account.
+
+Unlike upstream, this copy does **not** use the `//go:linkname` mechanism to
+reach into the standard library's `net` package; it carries its own
+`ipv6ZoneCache`. As a result, no `-ldflags "-checklinkname=0"` linker flag is
+required to build it.
+
+When [golang/go#40569](https://github.com/golang/go/issues/40569) is resolved
+upstream, this package and the `net_android.go` shim can be removed.

btcutil/internal/anet/android_api_level.go

@@ -0,0 +1,7 @@
+//go:build !(android && cgo)
+
+package anet
+
+func androidDeviceApiLevel() int {
+	return -1
+}

btcutil/internal/anet/android_api_level_cgo.go

@@ -0,0 +1,23 @@
+//go:build android && cgo
+
+package anet
+
+// #include <android/api-level.h>
+import "C"
+
+import "sync"
+
+var (
+	apiLevel int
+	once     sync.Once
+)
+
+// Returns the API level of the device we're actually running on, or -1 on failure.
+// The returned value is equivalent to the Java Build.VERSION.SDK_INT API.
+func androidDeviceApiLevel() int {
+	once.Do(func() {
+		apiLevel = int(C.android_get_device_api_level())
+	})
+
+	return apiLevel
+}

btcutil/internal/anet/interface.go

@@ -0,0 +1,30 @@
+//go:build !android
+// +build !android
+
+package anet
+
+import (
+	"net"
+)
+
+// Interfaces returns a list of the system's network interfaces.
+func Interfaces() ([]net.Interface, error) {
+	return net.Interfaces()
+}
+
+// InterfaceAddrs returns a list of the system's unicast interface
+// addresses.
+//
+// The returned list does not identify the associated interface; use
+// Interfaces and Interface.Addrs for more detail.
+func InterfaceAddrs() ([]net.Addr, error) {
+	return net.InterfaceAddrs()
+}
+
+// InterfaceAddrsByInterface returns a list of the system's unicast
+// interface addresses by specific interface.
+func InterfaceAddrsByInterface(ifi *net.Interface) ([]net.Addr, error) {
+	return ifi.Addrs()
+}
+
+func SetAndroidVersion(version uint) {}

btcutil/internal/anet/interface_android.go

@@ -0,0 +1,446 @@
+package anet
+
+import (
+	"bytes"
+	"errors"
+	"net"
+	"os"
+	"sync"
+	"syscall"
+	"time"
+	"unsafe"
+)
+
+const (
+	android11ApiLevel = 30
+)
+
+var (
+	customAndroidApiLevel       = -1
+	errInvalidInterface         = errors.New("invalid network interface")
+	errInvalidInterfaceIndex    = errors.New("invalid network interface index")
+	errInvalidInterfaceName     = errors.New("invalid network interface name")
+	errNoSuchInterface          = errors.New("no such network interface")
+	errNoSuchMulticastInterface = errors.New("no such multicast network interface")
+)
+
+type ifReq [40]byte
+
+// Interfaces returns a list of the system's network interfaces.
+func Interfaces() ([]net.Interface, error) {
+	if androidApiLevel() < android11ApiLevel {
+		return net.Interfaces()
+	}
+
+	ift, err := interfaceTable(0)
+	if err != nil {
+		return nil, &net.OpError{Op: "route", Net: "ip+net", Source: nil, Addr: nil, Err: err}
+	}
+	if len(ift) != 0 {
+		zoneCache.update(ift, true)
+		zoneCacheX.update(ift, true)
+	}
+	return ift, nil
+}
+
+// InterfaceAddrs returns a list of the system's unicast interface
+// addresses.
+//
+// The returned list does not identify the associated interface; use
+// Interfaces and Interface.Addrs for more detail.
+func InterfaceAddrs() ([]net.Addr, error) {
+	if androidApiLevel() < android11ApiLevel {
+		return net.InterfaceAddrs()
+	}
+
+	ifat, err := interfaceAddrTable(nil)
+	if err != nil {
+		err = &net.OpError{Op: "route", Net: "ip+net", Source: nil, Addr: nil, Err: err}
+	}
+	return ifat, err
+}
+
+// InterfaceByIndex returns the interface specified by index.
+//
+// On Solaris, it returns one of the logical network interfaces
+// sharing the logical data link; for more precision use
+// InterfaceByName.
+func InterfaceByIndex(index int) (*net.Interface, error) {
+	if androidApiLevel() < android11ApiLevel {
+		return net.InterfaceByIndex(index)
+	}
+
+	if index <= 0 {
+		return nil, &net.OpError{Op: "route", Net: "ip+net", Source: nil, Addr: nil, Err: errInvalidInterfaceIndex}
+	}
+	ift, err := interfaceTable(index)
+	if err != nil {
+		return nil, &net.OpError{Op: "route", Net: "ip+net", Source: nil, Addr: nil, Err: err}
+	}
+	ifi, err := interfaceByIndex(ift, index)
+	if err != nil {
+		err = &net.OpError{Op: "route", Net: "ip+net", Source: nil, Addr: nil, Err: err}
+	}
+	return ifi, err
+}
+
+// InterfaceByName returns the interface specified by name.
+func InterfaceByName(name string) (*net.Interface, error) {
+	if name == "" {
+		return nil, &net.OpError{Op: "route", Net: "ip+net", Source: nil, Addr: nil, Err: errInvalidInterfaceName}
+	}
+	ift, err := interfaceTable(0)
+	if err != nil {
+		return nil, &net.OpError{Op: "route", Net: "ip+net", Source: nil, Addr: nil, Err: err}
+	}
+	if len(ift) != 0 {
+		zoneCache.update(ift, true)
+		zoneCacheX.update(ift, true)
+	}
+	for _, ifi := range ift {
+		if name == ifi.Name {
+			return &ifi, nil
+		}
+	}
+	return nil, &net.OpError{Op: "route", Net: "ip+net", Source: nil, Addr: nil, Err: errNoSuchInterface}
+}
+
+// InterfaceAddrsByInterface returns a list of the system's unicast
+// interface addresses by specific interface.
+func InterfaceAddrsByInterface(ifi *net.Interface) ([]net.Addr, error) {
+	if ifi == nil {
+		return nil, &net.OpError{Op: "route", Net: "ip+net", Source: nil, Addr: nil, Err: errInvalidInterface}
+	}
+
+	if androidApiLevel() < android11ApiLevel {
+		return ifi.Addrs()
+	}
+
+	ifat, err := interfaceAddrTable(ifi)
+	if err != nil {
+		err = &net.OpError{Op: "route", Net: "ip+net", Source: nil, Addr: nil, Err: err}
+	}
+	return ifat, err
+}
+
+// SetAndroidVersion set the Android environment in which the program runs.
+// The Android system version number can be obtained through
+// `android.os.Build.VERSION.RELEASE` of the Android framework.
+// If version is 0 the actual version will be detected automatically if possible.
+func SetAndroidVersion(version uint) {
+	switch {
+	case version == 0:
+		customAndroidApiLevel = -1
+	case version >= 11:
+		customAndroidApiLevel = android11ApiLevel
+	default:
+		customAndroidApiLevel = 0
+	}
+}
+
+func androidApiLevel() int {
+	if customAndroidApiLevel != -1 {
+		// user-provided api level should be used
+		return customAndroidApiLevel
+	}
+
+	// try to autodetect api level
+	return androidDeviceApiLevel()
+}
+
+// An ipv6ZoneCache represents a cache holding partial network
+// interface information. It is used for reducing the cost of IPv6
+// addressing scope zone resolution.
+//
+// Multiple names sharing the index are managed by first-come
+// first-served basis for consistency.
+type ipv6ZoneCache struct {
+	sync.RWMutex                // guard the following
+	lastFetched  time.Time      // last time routing information was fetched
+	toIndex      map[string]int // interface name to its index
+	toName       map[int]string // interface index to its name
+}
+
+var zoneCache = ipv6ZoneCache{
+	toIndex: make(map[string]int),
+	toName:  make(map[int]string),
+}
+
+var zoneCacheX = ipv6ZoneCache{
+	toIndex: make(map[string]int),
+	toName:  make(map[int]string),
+}
+
+// update refreshes the network interface information if the cache was last
+// updated more than 1 minute ago, or if force is set. It reports whether the
+// cache was updated.
+func (zc *ipv6ZoneCache) update(ift []net.Interface, force bool) (updated bool) {
+	zc.Lock()
+	defer zc.Unlock()
+	now := time.Now()
+	if !force && zc.lastFetched.After(now.Add(-60*time.Second)) {
+		return false
+	}
+	zc.lastFetched = now
+	if len(ift) == 0 {
+		var err error
+		if ift, err = interfaceTable(0); err != nil {
+			return false
+		}
+	}
+	zc.toIndex = make(map[string]int, len(ift))
+	zc.toName = make(map[int]string, len(ift))
+	for _, ifi := range ift {
+		zc.toIndex[ifi.Name] = ifi.Index
+		if _, ok := zc.toName[ifi.Index]; !ok {
+			zc.toName[ifi.Index] = ifi.Name
+		}
+	}
+	return true
+}
+
+// If the ifindex is zero, interfaceTable returns mappings of all
+// network interfaces. Otherwise it returns a mapping of a specific
+// interface.
+func interfaceTable(ifindex int) ([]net.Interface, error) {
+	tab, err := NetlinkRIB(syscall.RTM_GETADDR, syscall.AF_UNSPEC)
+	if err != nil {
+		return nil, os.NewSyscallError("netlinkrib", err)
+	}
+	msgs, err := syscall.ParseNetlinkMessage(tab)
+	if err != nil {
+		return nil, os.NewSyscallError("parsenetlinkmessage", err)
+	}
+
+	var ift []net.Interface
+	im := make(map[uint32]struct{})
+loop:
+	for _, m := range msgs {
+		switch m.Header.Type {
+		case syscall.NLMSG_DONE:
+			break loop
+		case syscall.RTM_NEWADDR:
+			ifam := (*syscall.IfAddrmsg)(unsafe.Pointer(&m.Data[0]))
+			if _, ok := im[ifam.Index]; ok {
+				continue
+			} else {
+				im[ifam.Index] = struct{}{}
+			}
+
+			if ifindex == 0 || ifindex == int(ifam.Index) {
+				ifi := newLink(ifam)
+				if ifi != nil {
+					ift = append(ift, *ifi)
+				}
+				if ifindex == int(ifam.Index) {
+					break loop
+				}
+			}
+		}
+	}
+
+	return ift, nil
+}
+
+func newLink(ifam *syscall.IfAddrmsg) *net.Interface {
+	ift := &net.Interface{Index: int(ifam.Index)}
+
+	name, err := indexToName(ifam.Index)
+	if err != nil {
+		return nil
+	}
+	ift.Name = name
+
+	mtu, err := nameToMTU(name)
+	if err != nil {
+		return nil
+	}
+	ift.MTU = mtu
+
+	flags, err := nameToFlags(name)
+	if err != nil {
+		return nil
+	}
+	ift.Flags = flags
+	return ift
+}
+
+func linkFlags(rawFlags uint32) net.Flags {
+	var f net.Flags
+	if rawFlags&syscall.IFF_UP != 0 {
+		f |= net.FlagUp
+	}
+	if rawFlags&syscall.IFF_RUNNING != 0 {
+		f |= net.FlagRunning
+	}
+	if rawFlags&syscall.IFF_BROADCAST != 0 {
+		f |= net.FlagBroadcast
+	}
+	if rawFlags&syscall.IFF_LOOPBACK != 0 {
+		f |= net.FlagLoopback
+	}
+	if rawFlags&syscall.IFF_POINTOPOINT != 0 {
+		f |= net.FlagPointToPoint
+	}
+	if rawFlags&syscall.IFF_MULTICAST != 0 {
+		f |= net.FlagMulticast
+	}
+	return f
+}
+
+// If the ifi is nil, interfaceAddrTable returns addresses for all
+// network interfaces. Otherwise it returns addresses for a specific
+// interface.
+func interfaceAddrTable(ifi *net.Interface) ([]net.Addr, error) {
+	tab, err := NetlinkRIB(syscall.RTM_GETADDR, syscall.AF_UNSPEC)
+	if err != nil {
+		return nil, os.NewSyscallError("netlinkrib", err)
+	}
+	msgs, err := syscall.ParseNetlinkMessage(tab)
+	if err != nil {
+		return nil, os.NewSyscallError("parsenetlinkmessage", err)
+	}
+
+	var ift []net.Interface
+	if ifi == nil {
+		var err error
+		ift, err = interfaceTable(0)
+		if err != nil {
+			return nil, err
+		}
+	}
+	ifat, err := addrTable(ift, ifi, msgs)
+	if err != nil {
+		return nil, err
+	}
+	return ifat, nil
+}
+
+func addrTable(ift []net.Interface, ifi *net.Interface, msgs []syscall.NetlinkMessage) ([]net.Addr, error) {
+	var ifat []net.Addr
+loop:
+	for _, m := range msgs {
+		switch m.Header.Type {
+		case syscall.NLMSG_DONE:
+			break loop
+		case syscall.RTM_NEWADDR:
+			ifam := (*syscall.IfAddrmsg)(unsafe.Pointer(&m.Data[0]))
+			if len(ift) != 0 || ifi.Index == int(ifam.Index) {
+				attrs, err := syscall.ParseNetlinkRouteAttr(&m)
+				if err != nil {
+					return nil, os.NewSyscallError("parsenetlinkrouteattr", err)
+				}
+				ifa := newAddr(ifam, attrs)
+				if ifa != nil {
+					ifat = append(ifat, ifa)
+				}
+			}
+		}
+	}
+	return ifat, nil
+}
+
+func newAddr(ifam *syscall.IfAddrmsg, attrs []syscall.NetlinkRouteAttr) net.Addr {
+	var ipPointToPoint bool
+	// Seems like we need to make sure whether the IP interface
+	// stack consists of IP point-to-point numbered or unnumbered
+	// addressing.
+	for _, a := range attrs {
+		if a.Attr.Type == syscall.IFA_LOCAL {
+			ipPointToPoint = true
+			break
+		}
+	}
+	for _, a := range attrs {
+		if ipPointToPoint && a.Attr.Type == syscall.IFA_ADDRESS {
+			continue
+		}
+		switch ifam.Family {
+		case syscall.AF_INET:
+			return &net.IPNet{IP: net.IPv4(a.Value[0], a.Value[1], a.Value[2], a.Value[3]), Mask: net.CIDRMask(int(ifam.Prefixlen), 8*net.IPv4len)}
+		case syscall.AF_INET6:
+			ifa := &net.IPNet{IP: make(net.IP, net.IPv6len), Mask: net.CIDRMask(int(ifam.Prefixlen), 8*net.IPv6len)}
+			copy(ifa.IP, a.Value[:])
+			return ifa
+		}
+	}
+	return nil
+}
+
+func interfaceByIndex(ift []net.Interface, index int) (*net.Interface, error) {
+	for _, ifi := range ift {
+		if index == ifi.Index {
+			return &ifi, nil
+		}
+	}
+	return nil, errNoSuchInterface
+}
+
+func ioctl(fd int, req uint, arg unsafe.Pointer) error {
+	_, _, e1 := syscall.Syscall(syscall.SYS_IOCTL, uintptr(fd), uintptr(req), uintptr(arg))
+	if e1 != 0 {
+		return e1
+	}
+	return nil
+}
+
+func indexToName(index uint32) (string, error) {
+	fd, err := syscall.Socket(syscall.AF_INET, syscall.SOCK_DGRAM|syscall.SOCK_CLOEXEC, 0)
+	if err != nil {
+		return "", err
+	}
+	defer syscall.Close(fd)
+
+	var ifr ifReq
+	*(*uint32)(unsafe.Pointer(&ifr[syscall.IFNAMSIZ])) = index
+	err = ioctl(fd, syscall.SIOCGIFNAME, unsafe.Pointer(&ifr[0]))
+	if err != nil {
+		return "", err
+	}
+
+	return string(bytes.Trim(ifr[:syscall.IFNAMSIZ], "\x00")), nil
+}
+
+func nameToMTU(name string) (int, error) {
+	// Leave room for terminating NULL byte.
+	if len(name) >= syscall.IFNAMSIZ {
+		return -1, syscall.EINVAL
+	}
+
+	fd, err := syscall.Socket(syscall.AF_INET, syscall.SOCK_DGRAM|syscall.SOCK_CLOEXEC, 0)
+	if err != nil {
+		return -1, err
+	}
+	defer syscall.Close(fd)
+
+	var ifr ifReq
+	copy(ifr[:], name)
+	err = ioctl(fd, syscall.SIOCGIFMTU, unsafe.Pointer(&ifr[0]))
+	if err != nil {
+		return -1, err
+	}
+
+	return int(*(*int32)(unsafe.Pointer(&ifr[syscall.IFNAMSIZ]))), nil
+}
+
+func nameToFlags(name string) (net.Flags, error) {
+	// Leave room for terminating NULL byte.
+	if len(name) >= syscall.IFNAMSIZ {
+		return 0, syscall.EINVAL
+	}
+
+	fd, err := syscall.Socket(syscall.AF_INET, syscall.SOCK_DGRAM|syscall.SOCK_CLOEXEC, 0)
+	if err != nil {
+		return 0, err
+	}
+	defer syscall.Close(fd)
+
+	var ifr ifReq
+	copy(ifr[:], name)
+	err = ioctl(fd, syscall.SIOCGIFFLAGS, unsafe.Pointer(&ifr[0]))
+	if err != nil {
+		return 0, err
+	}
+
+	return linkFlags(*(*uint32)(unsafe.Pointer(&ifr[syscall.IFNAMSIZ]))), nil
+}

btcutil/internal/anet/netlink_android.go

@@ -0,0 +1,179 @@
+// Copyright 2011 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+// Netlink sockets and messages
+
+package anet
+
+import (
+	"syscall"
+	"unsafe"
+)
+
+// Round the length of a netlink message up to align it properly.
+func nlmAlignOf(msglen int) int {
+	return (msglen + syscall.NLMSG_ALIGNTO - 1) & ^(syscall.NLMSG_ALIGNTO - 1)
+}
+
+// Round the length of a netlink route attribute up to align it
+// properly.
+func rtaAlignOf(attrlen int) int {
+	return (attrlen + syscall.RTA_ALIGNTO - 1) & ^(syscall.RTA_ALIGNTO - 1)
+}
+
+// NetlinkRouteRequest represents a request message to receive routing
+// and link states from the kernel.
+type NetlinkRouteRequest struct {
+	Header syscall.NlMsghdr
+	Data   syscall.RtGenmsg
+}
+
+func (rr *NetlinkRouteRequest) toWireFormat() []byte {
+	b := make([]byte, rr.Header.Len)
+	*(*uint32)(unsafe.Pointer(&b[0:4][0])) = rr.Header.Len
+	*(*uint16)(unsafe.Pointer(&b[4:6][0])) = rr.Header.Type
+	*(*uint16)(unsafe.Pointer(&b[6:8][0])) = rr.Header.Flags
+	*(*uint32)(unsafe.Pointer(&b[8:12][0])) = rr.Header.Seq
+	*(*uint32)(unsafe.Pointer(&b[12:16][0])) = rr.Header.Pid
+	b[16] = byte(rr.Data.Family)
+	return b
+}
+
+func newNetlinkRouteRequest(proto, seq, family int) []byte {
+	rr := &NetlinkRouteRequest{}
+	rr.Header.Len = uint32(syscall.NLMSG_HDRLEN + syscall.SizeofRtGenmsg)
+	rr.Header.Type = uint16(proto)
+	rr.Header.Flags = syscall.NLM_F_DUMP | syscall.NLM_F_REQUEST
+	rr.Header.Seq = uint32(seq)
+	rr.Data.Family = uint8(family)
+	return rr.toWireFormat()
+}
+
+// NetlinkRIB returns routing information base, as known as RIB, which
+// consists of network facility information, states and parameters.
+func NetlinkRIB(proto, family int) ([]byte, error) {
+	s, err := syscall.Socket(syscall.AF_NETLINK, syscall.SOCK_RAW|syscall.SOCK_CLOEXEC, syscall.NETLINK_ROUTE)
+	if err != nil {
+		return nil, err
+	}
+	defer syscall.Close(s)
+	sa := &syscall.SockaddrNetlink{Family: syscall.AF_NETLINK}
+
+	wb := newNetlinkRouteRequest(proto, 1, family)
+	if err := syscall.Sendto(s, wb, 0, sa); err != nil {
+		return nil, err
+	}
+	lsa, err := syscall.Getsockname(s)
+	if err != nil {
+		return nil, err
+	}
+	lsanl, ok := lsa.(*syscall.SockaddrNetlink)
+	if !ok {
+		return nil, syscall.EINVAL
+	}
+	var tab []byte
+	rbNew := make([]byte, syscall.Getpagesize())
+done:
+	for {
+		rb := rbNew
+		nr, _, err := syscall.Recvfrom(s, rb, 0)
+		if err != nil {
+			return nil, err
+		}
+		if nr < syscall.NLMSG_HDRLEN {
+			return nil, syscall.EINVAL
+		}
+		rb = rb[:nr]
+		tab = append(tab, rb...)
+		msgs, err := ParseNetlinkMessage(rb)
+		if err != nil {
+			return nil, err
+		}
+		for _, m := range msgs {
+			if m.Header.Seq != 1 || m.Header.Pid != lsanl.Pid {
+				return nil, syscall.EINVAL
+			}
+			if m.Header.Type == syscall.NLMSG_DONE {
+				break done
+			}
+			if m.Header.Type == syscall.NLMSG_ERROR {
+				return nil, syscall.EINVAL
+			}
+		}
+	}
+	return tab, nil
+}
+
+// NetlinkMessage represents a netlink message.
+type NetlinkMessage struct {
+	Header syscall.NlMsghdr
+	Data   []byte
+}
+
+// ParseNetlinkMessage parses b as an array of netlink messages and
+// returns the slice containing the NetlinkMessage structures.
+func ParseNetlinkMessage(b []byte) ([]NetlinkMessage, error) {
+	var msgs []NetlinkMessage
+	for len(b) >= syscall.NLMSG_HDRLEN {
+		h, dbuf, dlen, err := netlinkMessageHeaderAndData(b)
+		if err != nil {
+			return nil, err
+		}
+		m := NetlinkMessage{Header: *h, Data: dbuf[:int(h.Len)-syscall.NLMSG_HDRLEN]}
+		msgs = append(msgs, m)
+		b = b[dlen:]
+	}
+	return msgs, nil
+}
+
+func netlinkMessageHeaderAndData(b []byte) (*syscall.NlMsghdr, []byte, int, error) {
+	h := (*syscall.NlMsghdr)(unsafe.Pointer(&b[0]))
+	l := nlmAlignOf(int(h.Len))
+	if int(h.Len) < syscall.NLMSG_HDRLEN || l > len(b) {
+		return nil, nil, 0, syscall.EINVAL
+	}
+	return h, b[syscall.NLMSG_HDRLEN:], l, nil
+}
+
+// NetlinkRouteAttr represents a netlink route attribute.
+type NetlinkRouteAttr struct {
+	Attr  syscall.RtAttr
+	Value []byte
+}
+
+// ParseNetlinkRouteAttr parses m's payload as an array of netlink
+// route attributes and returns the slice containing the
+// NetlinkRouteAttr structures.
+func ParseNetlinkRouteAttr(m *NetlinkMessage) ([]NetlinkRouteAttr, error) {
+	var b []byte
+	switch m.Header.Type {
+	case syscall.RTM_NEWLINK, syscall.RTM_DELLINK:
+		b = m.Data[syscall.SizeofIfInfomsg:]
+	case syscall.RTM_NEWADDR, syscall.RTM_DELADDR:
+		b = m.Data[syscall.SizeofIfAddrmsg:]
+	case syscall.RTM_NEWROUTE, syscall.RTM_DELROUTE:
+		b = m.Data[syscall.SizeofRtMsg:]
+	default:
+		return nil, syscall.EINVAL
+	}
+	var attrs []NetlinkRouteAttr
+	for len(b) >= syscall.SizeofRtAttr {
+		a, vbuf, alen, err := netlinkRouteAttrAndValue(b)
+		if err != nil {
+			return nil, err
+		}
+		ra := NetlinkRouteAttr{Attr: *a, Value: vbuf[:int(a.Len)-syscall.SizeofRtAttr]}
+		attrs = append(attrs, ra)
+		b = b[alen:]
+	}
+	return attrs, nil
+}
+
+func netlinkRouteAttrAndValue(b []byte) (*syscall.RtAttr, []byte, int, error) {
+	a := (*syscall.RtAttr)(unsafe.Pointer(&b[0]))
+	if int(a.Len) < syscall.SizeofRtAttr || int(a.Len) > len(b) {
+		return nil, nil, 0, syscall.EINVAL
+	}
+	return a, b[syscall.SizeofRtAttr:], rtaAlignOf(int(a.Len)), nil
+}

btcutil/net_android.go

@@ -10,7 +10,7 @@ package btcutil
 import (
 	"net"
 
-	"github.com/kcalvinalvin/anet"
+	"github.com/btcsuite/btcd/btcutil/v2/internal/anet"
 )
 
 // InterfaceAddrs returns a list of the system's network interface addresses.