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// Take a look at the license at the top of the repository in the LICENSE file.
use std::ffi::OsString;
use std::os::windows::prelude::OsStringExt;
use std::ptr::null_mut;
use winapi::shared::winerror::{ERROR_BUFFER_OVERFLOW, ERROR_SUCCESS};
use winapi::shared::ws2def::AF_UNSPEC;
use winapi::um::iphlpapi::GetAdaptersAddresses;
use winapi::um::iptypes::{
GAA_FLAG_SKIP_ANYCAST, GAA_FLAG_SKIP_DNS_SERVER, GAA_FLAG_SKIP_MULTICAST, PIP_ADAPTER_ADDRESSES,
};
use crate::common::MacAddr;
// Need a function to convert u16 pointer into String
// https://stackoverflow.com/a/48587463/8706476
unsafe fn u16_ptr_to_string(ptr: *const u16) -> OsString {
let len = (0..).take_while(|&i| *ptr.offset(i) != 0).count();
let slice = std::slice::from_raw_parts(ptr, len);
OsString::from_wide(slice)
}
/// this iterator yields an interface name and address
pub(crate) struct InterfaceAddressIterator {
/// The first item in the linked list
buf: PIP_ADAPTER_ADDRESSES,
/// The current adapter
adapter: PIP_ADAPTER_ADDRESSES,
}
impl InterfaceAddressIterator {
fn new() -> Self {
Self {
buf: null_mut(),
adapter: null_mut(),
}
}
unsafe fn realloc(mut self, size: libc::size_t) -> Result<Self, String> {
let new_buf = libc::realloc(self.buf as _, size) as PIP_ADAPTER_ADDRESSES;
if new_buf.is_null() {
// insufficient memory available
// https://learn.microsoft.com/en-us/cpp/c-runtime-library/reference/malloc?view=msvc-170#return-value
// malloc is not documented to set the last-error code
Err("failed to allocate memory for IP_ADAPTER_ADDRESSES".to_string())
} else {
self.buf = new_buf;
self.adapter = new_buf;
Ok(self)
}
}
}
impl Iterator for InterfaceAddressIterator {
type Item = (String, MacAddr);
fn next(&mut self) -> Option<Self::Item> {
if self.adapter.is_null() {
return None;
}
unsafe {
let adapter = self.adapter;
// Move to the next adapter
self.adapter = (*adapter).Next;
if let Ok(interface_name) = u16_ptr_to_string((*adapter).FriendlyName).into_string() {
// take the first 6 bytes and return the MAC address instead
let [mac @ .., _, _] = (*adapter).PhysicalAddress;
Some((interface_name, MacAddr(mac)))
} else {
// Not sure whether error can occur when parsing adapter name.
self.next()
}
}
}
}
impl Drop for InterfaceAddressIterator {
fn drop(&mut self) {
unsafe {
libc::free(self.buf as _);
}
}
}
pub(crate) fn get_interface_address() -> Result<InterfaceAddressIterator, String> {
unsafe {
// https://learn.microsoft.com/en-us/windows/win32/api/iphlpapi/nf-iphlpapi-getadaptersaddresses#remarks
// A 15k buffer is recommended
let mut size: u32 = 15 * 1024;
let mut ret = ERROR_SUCCESS;
let mut iterator = InterfaceAddressIterator::new();
// https://learn.microsoft.com/en-us/windows/win32/api/iphlpapi/nf-iphlpapi-getadaptersaddresses#examples
// Try to retrieve adapter information up to 3 times
for _ in 0..3 {
iterator = iterator.realloc(size as _)?;
ret = GetAdaptersAddresses(
AF_UNSPEC as u32,
GAA_FLAG_SKIP_MULTICAST | GAA_FLAG_SKIP_ANYCAST | GAA_FLAG_SKIP_DNS_SERVER,
null_mut(),
iterator.buf,
&mut size,
);
if ret == ERROR_SUCCESS {
return Ok(iterator);
} else if ret != ERROR_BUFFER_OVERFLOW {
break;
}
// if the given memory size is too small to hold the adapter information,
// the SizePointer returned will point to the required size of the buffer,
// and we should continue.
// Otherwise, break the loop and check the return code again
}
Err(format!("GetAdaptersAddresses() failed with code {ret}"))
}
}