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refactor: enforce immutability #4

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merged 2 commits into from
Sep 2, 2024
+53 −49
Merged

refactor: enforce immutability #4

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4ff0b6a
refactor: enforce immutability of ifap
mxinden Sep 2, 2024
0ef2797
refactor: enforce immutability of addr_table and if_table
mxinden Sep 2, 2024
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102 changes: 53 additions & 49 deletions src/lib.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -74,10 +74,11 @@ fn get_interface_mtu_linux_macos(socket: &UdpSocket) -> Result<usize, Error> {
use libc::{ifreq, ioctl};

// Get the interface list.
let mut ifap: *mut ifaddrs = ptr::null_mut(); // Do not modify this pointer.
let mut ifap: *mut ifaddrs = ptr::null_mut();
if unsafe { getifaddrs(&mut ifap) } != 0 {
return Err(Error::last_os_error());
}
let ifap = ifap; // Do not modify this pointer.

// First, find the name of the interface with the local IP address determined above.
let mut cursor = ifap;
Expand Down Expand Up @@ -176,58 +177,61 @@ fn get_interface_mtu_windows(socket: &UdpSocket) -> Result<usize, Error> {
let mut res = default_result();

// Get a list of all unicast IP addresses with associated metadata.
let mut addr_table: *mut MIB_UNICASTIPADDRESS_TABLE = ptr::null_mut(); // Do not modify this pointer.
if unsafe { GetUnicastIpAddressTable(AF_UNSPEC, &mut addr_table) } == NO_ERROR {
let addrs = unsafe {
slice::from_raw_parts::<MIB_UNICASTIPADDRESS_ROW>(
&(*addr_table).Table[0],
(*addr_table).NumEntries as usize,
)
};

// Get a list of all interfaces with associated metadata.
let mut if_table: *mut MIB_IPINTERFACE_TABLE = ptr::null_mut(); // Do not modify this pointer.
if unsafe { GetIpInterfaceTable(AF_UNSPEC, &mut if_table) } == NO_ERROR {
let ifaces = unsafe {
slice::from_raw_parts::<MIB_IPINTERFACE_ROW>(
&(*if_table).Table[0],
(*if_table).NumEntries as usize,
)
};

// Run through the list of addresses and find the one that matches the local IP
// address.
'addr_loop: for addr in addrs {
let af = unsafe { addr.Address.si_family };
let ip = socket.local_addr()?.ip();
if (af == AF_INET && ip.is_ipv4() || af == AF_INET6 && ip.is_ipv6())
&& match ip {
IpAddr::V4(ip) => {
u32::from(ip).to_be()
== unsafe { addr.Address.Ipv4.sin_addr.S_un.S_addr }
}
IpAddr::V6(ip) => {
ip.octets() == unsafe { addr.Address.Ipv6.sin6_addr.u.Byte }
}
}
{
// For the matching address, find local interface and its MTU.
for iface in ifaces {
if iface.InterfaceIndex == addr.InterfaceIndex {
res = iface.NlMtu.try_into().or(res);
break 'addr_loop;
}
}
let mut addr_table: *mut MIB_UNICASTIPADDRESS_TABLE = ptr::null_mut();
if unsafe { GetUnicastIpAddressTable(AF_UNSPEC, &mut addr_table) } != NO_ERROR {
return Err(Error::last_os_error());
}
let addr_table = addr_table; // Do not modify this pointer.

let addrs = unsafe {
slice::from_raw_parts::<MIB_UNICASTIPADDRESS_ROW>(
&(*addr_table).Table[0],
(*addr_table).NumEntries as usize,
)
};

// Get a list of all interfaces with associated metadata.
let mut if_table: *mut MIB_IPINTERFACE_TABLE = ptr::null_mut();
if unsafe { GetIpInterfaceTable(AF_UNSPEC, &mut if_table) } != NO_ERROR {
let error = Error::last_os_error();
unsafe { FreeMibTable(addr_table as *const c_void) };
return Err(error);
}
let if_table = if_table; // Do not modify this pointer.

let ifaces = unsafe {
slice::from_raw_parts::<MIB_IPINTERFACE_ROW>(
&(*if_table).Table[0],
(*if_table).NumEntries as usize,
)
};

// Run through the list of addresses and find the one that matches the local IP
// address.
'addr_loop: for addr in addrs {
let af = unsafe { addr.Address.si_family };
let ip = socket.local_addr()?.ip();
if (af == AF_INET && ip.is_ipv4() || af == AF_INET6 && ip.is_ipv6())
&& match ip {
IpAddr::V4(ip) => {
u32::from(ip).to_be() == unsafe { addr.Address.Ipv4.sin_addr.S_un.S_addr }
}
IpAddr::V6(ip) => ip.octets() == unsafe { addr.Address.Ipv6.sin6_addr.u.Byte },
}
{
// For the matching address, find local interface and its MTU.
for iface in ifaces {
if iface.InterfaceIndex == addr.InterfaceIndex {
res = iface.NlMtu.try_into().or(res);
break 'addr_loop;
}
}
unsafe { FreeMibTable(if_table as *const c_void) };
} else {
res = Err(Error::last_os_error());
}
unsafe { FreeMibTable(addr_table as *const c_void) };
} else {
res = Err(Error::last_os_error());
}

unsafe { FreeMibTable(if_table as *const c_void) };
unsafe { FreeMibTable(addr_table as *const c_void) };

res
}

Expand Down
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