Add mask to prefix conversion

src/ipnet.rs

@@ -8,6 +8,7 @@ use std::net::{IpAddr, Ipv4Addr, Ipv6Addr};
 use std::option::Option::{Some, None};
 
 use crate::ipext::{IpAdd, IpSub, IpStep, IpAddrRange, Ipv4AddrRange, Ipv6AddrRange};
+use crate::mask::{ip_mask_to_prefix, ipv4_mask_to_prefix, ipv6_mask_to_prefix};
 
 /// An IP network address, either IPv4 or IPv6.
 ///
@@ -142,6 +143,25 @@ impl IpNet {
         })
     }
 
+    /// Creates a new IP network address from an `IpAddr` and netmask.
+    ///
+    /// # Examples
+    ///
+    /// ```
+    /// use std::net::Ipv6Addr;
+    /// use ipnet::{IpNet, PrefixLenError};
+    ///
+    /// let net = IpNet::with_netmask(Ipv6Addr::LOCALHOST.into(), Ipv6Addr::from(0xffff_ffff_ffff_0000_0000_0000_0000_0000).into());
+    /// assert!(net.is_ok());
+    ///
+    /// let bad_prefix_len = IpNet::with_netmask(Ipv6Addr::LOCALHOST.into(), Ipv6Addr::from(0xffff_ffff_ffff_0000_0001_0000_0000_0000).into());
+    /// assert_eq!(bad_prefix_len, Err(PrefixLenError));
+    /// ```
+    pub fn with_netmask(ip: IpAddr, netmask: IpAddr) -> Result<IpNet, PrefixLenError> {
+        let prefix = ip_mask_to_prefix(netmask)?;
+        Self::new(ip, prefix)
+    }
+
     /// Returns a copy of the network with the address truncated to the
     /// prefix length.
     ///
@@ -565,6 +585,25 @@ impl Ipv4Net {
         Ok(Ipv4Net { addr: ip, prefix_len: prefix_len })
     }
 
+    /// Creates a new IPv4 network address from an `Ipv4Addr` and netmask.
+    ///
+    /// # Examples
+    ///
+    /// ```
+    /// use std::net::Ipv4Addr;
+    /// use ipnet::{Ipv4Net, PrefixLenError};
+    ///
+    /// let net = Ipv4Net::with_netmask(Ipv4Addr::new(10, 1, 1, 0), Ipv4Addr::new(255, 255, 255, 0));
+    /// assert!(net.is_ok());
+    ///
+    /// let bad_prefix_len = Ipv4Net::with_netmask(Ipv4Addr::new(10, 1, 1, 0), Ipv4Addr::new(255, 255, 0, 1));
+    /// assert_eq!(bad_prefix_len, Err(PrefixLenError));
+    /// ```
+    pub fn with_netmask(ip: Ipv4Addr, netmask: Ipv4Addr) -> Result<Ipv4Net, PrefixLenError> {
+        let prefix = ipv4_mask_to_prefix(netmask)?;
+        Self::new(ip, prefix)
+    }
+
     /// Returns a copy of the network with the address truncated to the
     /// prefix length.
     ///
@@ -899,6 +938,25 @@ impl Ipv6Net {
         Ok(Ipv6Net { addr: ip, prefix_len: prefix_len })
     }
 
+    /// Creates a new IPv6 network address from an `Ipv6Addr` and netmask.
+    ///
+    /// # Examples
+    ///
+    /// ```
+    /// use std::net::Ipv6Addr;
+    /// use ipnet::{Ipv6Net, PrefixLenError};
+    ///
+    /// let net = Ipv6Net::with_netmask(Ipv6Addr::new(0xfd, 0, 0, 0, 0, 0, 0, 0), Ipv6Addr::from(0xffff_ff00_0000_0000_0000_0000_0000_0000));
+    /// assert!(net.is_ok());
+    ///
+    /// let bad_prefix_len = Ipv6Net::with_netmask(Ipv6Addr::new(0xfd, 0, 0, 0, 0, 0, 0, 0), Ipv6Addr::from(0xffff_ff00_0000_0000_0001_0000_0000_0000));
+    /// assert_eq!(bad_prefix_len, Err(PrefixLenError));
+    /// ```
+    pub fn with_netmask(ip: Ipv6Addr, netmask: Ipv6Addr) -> Result<Ipv6Net, PrefixLenError> {
+        let prefix = ipv6_mask_to_prefix(netmask)?;
+        Self::new(ip, prefix)
+    }
+
     /// Returns a copy of the network with the address truncated to the
     /// prefix length.
     ///

src/lib.rs

@@ -86,10 +86,12 @@ extern crate schemars;
 pub use self::ipext::{IpAdd, IpSub, IpBitAnd, IpBitOr, IpAddrRange, Ipv4AddrRange, Ipv6AddrRange};
 pub use self::ipnet::{IpNet, Ipv4Net, Ipv6Net, PrefixLenError, IpSubnets, Ipv4Subnets, Ipv6Subnets};
 pub use self::parser::AddrParseError;
+pub use self::mask::{ip_mask_to_prefix, ipv4_mask_to_prefix, ipv6_mask_to_prefix};
 
 mod ipext;
 mod ipnet;
 mod parser;
+mod mask;
 #[cfg(feature = "serde")]
 mod ipnet_serde;
 #[cfg(feature = "schemars")]

src/mask.rs

@@ -0,0 +1,114 @@
+use crate::PrefixLenError;
+use std::net::{IpAddr, Ipv4Addr, Ipv6Addr};
+
+/// Converts a `IpAddr` network mask into a prefix.
+///
+/// # Errors
+/// If the mask is invalid this will return an `PrefixLenError`.
+pub fn ip_mask_to_prefix(mask: IpAddr) -> Result<u8, PrefixLenError> {
+    match mask {
+        IpAddr::V4(mask) => ipv4_mask_to_prefix(mask),
+        IpAddr::V6(mask) => ipv6_mask_to_prefix(mask),
+    }
+}
+
+/// Converts a `Ipv4Addr` network mask into a prefix.
+///
+/// # Errors
+/// If the mask is invalid this will return an `PrefixLenError`.
+pub fn ipv4_mask_to_prefix(mask: Ipv4Addr) -> Result<u8, PrefixLenError> {
+    let mask = u32::from(mask);
+
+    let prefix = mask.leading_ones();
+    if (mask << prefix) == 0 {
+        Ok(prefix as u8)
+    } else {
+        Err(PrefixLenError)
+    }
+}
+
+/// Converts a `Ipv6Addr` network mask into a prefix.
+///
+/// # Errors
+/// If the mask is invalid this will return an `PrefixLenError`.
+pub fn ipv6_mask_to_prefix(mask: Ipv6Addr) -> Result<u8, PrefixLenError> {
+    let mask = u128::from(mask);
+
+    let prefix = mask.leading_ones();
+    if (mask << prefix) == 0 {
+        Ok(prefix as u8)
+    } else {
+        Err(PrefixLenError)
+    }
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+    use crate::{Ipv4Net, Ipv6Net};
+
+    #[test]
+    fn v4_mask_to_prefix() {
+        let mask = Ipv4Addr::new(255, 255, 255, 128);
+        let prefix = ipv4_mask_to_prefix(mask);
+        assert_eq!(prefix, Ok(25));
+    }
+
+    #[test]
+    fn invalid_v4_mask_to_prefix() {
+        let mask = Ipv4Addr::new(255, 0, 255, 0);
+        let prefix = ipv4_mask_to_prefix(mask);
+        assert!(prefix.is_err());
+    }
+
+    #[test]
+    fn ipv4net_with_netmask() {
+        {
+            // Positive test-case.
+            let addr = Ipv4Addr::new(127, 0, 0, 1);
+            let mask = Ipv4Addr::new(255, 0, 0, 0);
+            let net = Ipv4Net::with_netmask(addr, mask).unwrap();
+            let expected = Ipv4Net::new(Ipv4Addr::new(127, 0, 0, 1), 8).unwrap();
+            assert_eq!(net, expected);
+        }
+        {
+            // Negative test-case.
+            let addr = Ipv4Addr::new(127, 0, 0, 1);
+            let mask = Ipv4Addr::new(255, 0, 255, 0);
+            Ipv4Net::with_netmask(addr, mask).unwrap_err();
+        }
+    }
+
+    #[test]
+    fn v6_mask_to_prefix() {
+        let mask = Ipv6Addr::new(0xffff, 0xffff, 0xffff, 0, 0, 0, 0, 0);
+        let prefix = ipv6_mask_to_prefix(mask);
+        assert_eq!(prefix, Ok(48));
+    }
+
+    #[test]
+    fn invalid_v6_mask_to_prefix() {
+        let mask = Ipv6Addr::new(0, 0, 0xffff, 0xffff, 0, 0, 0, 0);
+        let prefix = ipv6_mask_to_prefix(mask);
+        assert!(prefix.is_err());
+    }
+
+    #[test]
+    fn ipv6net_with_netmask() {
+        {
+            // Positive test-case.
+            let addr = Ipv6Addr::new(0xff01, 0, 0, 0x17, 0, 0, 0, 0x2);
+            let mask = Ipv6Addr::new(0xffff, 0xffff, 0xffff, 0, 0, 0, 0, 0);
+            let net = Ipv6Net::with_netmask(addr, mask).unwrap();
+            let expected =
+                Ipv6Net::new(Ipv6Addr::new(0xff01, 0, 0, 0x17, 0, 0, 0, 0x2), 48).unwrap();
+            assert_eq!(net, expected);
+        }
+        {
+            // Negative test-case.
+            let addr = Ipv6Addr::new(0xff01, 0, 0, 0x17, 0, 0, 0, 0x2);
+            let mask = Ipv6Addr::new(0, 0, 0xffff, 0xffff, 0, 0, 0, 0);
+            Ipv6Net::with_netmask(addr, mask).unwrap_err();
+        }
+    }
+}