121 lines
3.3 KiB
Markdown
121 lines
3.3 KiB
Markdown
## Introduction
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In response to the modifications made to the permissions for accessing system MAC addresses in Android 11, ordinary applications encounter several main issues when using NETLINK sockets:
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- Not allowing bind operations on `NETLINK` sockets.
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- Not permitting the use of the `RTM_GETLINK` functionality.
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For detailed information, please refer to: https://developer.android.com/training/articles/user-data-ids#mac-11-plus
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As a result of the aforementioned reasons, using `net.Interfaces()` and `net.InterfaceAddrs()` from the Go net package in the Android environment leads to the `route ip+net: netlinkrib: permission denied` error.
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You can find specific issue details here: https://github.com/golang/go/issues/40569
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To address the issue of using the Go net package in the Android environment, we have made partial modifications to its source code to ensure proper functionality on Android.
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I have fully resolved the issues with `net.InterfaceAddrs()`.
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However, for `net.Interfaces()`, we have only addressed some problems, as the following issues still remain:
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- It can only return interfaces with IP addresses.
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- It cannot return hardware MAC addresses.
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Nevertheless, the fixed `net.Interfaces()` function now aligns with the Android API's `NetworkInterface.getNetworkInterfaces()` and can be used normally in most scenarios.
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The specific fix logic includes:
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Removing the `Bind()` operation on `Netlink` sockets in the `NetlinkRIB()` function.
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Using `ioctl` based on the Index number returned by `RTM_GETADDR` to retrieve the network card's name, MTU, and flags.
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There are two implementations of the `net` package: one from the [Go standard library](https://pkg.go.dev/net) and another from the [golang.org/x/net](https://pkg.go.dev/golang.org/x/net) module. Both of these implementations have the same issues in the Android environment. The `anet` package should be compatible with both of them.
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## Test Code
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### net.Interface()
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use `net.Interface()`:
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```go
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func RawInterface() {
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interfaces, err := net.Interfaces()
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if err != nil {
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panic(err)
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}
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for _, i := range interfaces {
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log.Println(i)
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}
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}
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```
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result:
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```
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panic: route ip+net: netlinkrib: permission denied
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```
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use `anet.Interface()`:
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```go
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func AnetInterface() {
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interfaces, err := anet.Interfaces()
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if err != nil {
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panic(err)
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}
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for _, i := range interfaces {
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log.Println(i)
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}
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}
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```
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result:
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```
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{1 65536 lo up|loopback|running}
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{15 1400 rmnet_data1 up|running}
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{24 1500 wlan0 up|broadcast|multicast|running}
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{3 1500 dummy0 up|broadcast|running}
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{4 1500 ifb0 up|broadcast|running}
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{5 1500 ifb1 up|broadcast|running}
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{12 1500 ifb2 up|broadcast|running}
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{14 1500 rmnet_data0 up|running}
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{16 1400 rmnet_data2 up|running}
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{17 1400 rmnet_data3 up|running}
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```
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### net.InterfaceAddrs()
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use `net.InterfaceAddrs()`:
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```go
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func NetInterfaceAddrs() {
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addrs, err := net.InterfaceAddrs()
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if err != nil {
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panic(err)
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}
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for _, addr := range addrs {
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log.Println(addr)
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}
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}
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```
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result:
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```
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panic: route ip+net: netlinkrib: permission denied
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```
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use `anet.InterfaceAddrs()`:
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```go
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func AnetInterfaceAddrs() {
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addrs, err := anet.InterfaceAddrs()
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if err != nil {
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panic(err)
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}
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for _, addr := range addrs {
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log.Println(addr)
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}
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}
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```
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result:
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```
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127.0.0.1/8
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::1/128
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...
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192.168.6.143/24
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fe80::7e4f:4446:eb3:1eb8/64
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```
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## Other issues due to #40569
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- https://github.com/golang/go/issues/68082
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