Finish verion 0.1.0

crates/wtfnet-calc/src/lib.rs

@@ -0,0 +1,202 @@
+use ipnet::{IpNet, Ipv4Net, Ipv6Net};
+use serde::{Deserialize, Serialize};
+use std::net::{IpAddr, Ipv4Addr};
+use thiserror::Error;
+
+#[derive(Debug, Error)]
+pub enum CalcError {
+    #[error("invalid input: {0}")]
+    InvalidInput(String),
+    #[error("parse error: {0}")]
+    Parse(String),
+}
+
+#[derive(Debug, Clone, Serialize, Deserialize)]
+pub struct SubnetInfo {
+    pub input: String,
+    pub version: String,
+    pub cidr: String,
+    pub network: String,
+    pub broadcast: Option<String>,
+    pub netmask: String,
+    pub hostmask: String,
+    pub prefix_len: u8,
+    pub total_addresses: String,
+    pub usable_addresses: String,
+    pub first_host: Option<String>,
+    pub last_host: Option<String>,
+}
+
+pub fn subnet_info(input: &str) -> Result<SubnetInfo, CalcError> {
+    let net = parse_net(input)?;
+    match net {
+        IpNet::V4(v4) => Ok(subnet_info_v4(input, v4)),
+        IpNet::V6(v6) => Ok(subnet_info_v6(input, v6)),
+    }
+}
+
+pub fn contains(a: &str, b: &str) -> Result<bool, CalcError> {
+    let net_a = parse_net(a)?;
+    let net_b = parse_net(b)?;
+    Ok(net_a.contains(&net_b))
+}
+
+pub fn overlap(a: &str, b: &str) -> Result<bool, CalcError> {
+    let net_a = parse_net(a)?;
+    let net_b = parse_net(b)?;
+    match (net_a, net_b) {
+        (IpNet::V4(a), IpNet::V4(b)) => Ok(overlap_v4(a, b)),
+        (IpNet::V6(a), IpNet::V6(b)) => Ok(overlap_v6(a, b)),
+        _ => Ok(false),
+    }
+}
+
+pub fn summarize(inputs: &[String]) -> Result<Vec<IpNet>, CalcError> {
+    if inputs.is_empty() {
+        return Err(CalcError::InvalidInput(
+            "at least one CIDR required".to_string(),
+        ));
+    }
+    let mut nets = Vec::with_capacity(inputs.len());
+    for value in inputs {
+        nets.push(parse_net(value)?);
+    }
+    Ok(IpNet::aggregate(&nets))
+}
+
+fn subnet_info_v4(input: &str, net: Ipv4Net) -> SubnetInfo {
+    let total = total_addresses_v4(net.prefix_len());
+    let usable = usable_addresses_v4(net.prefix_len());
+    let (first, last) = first_last_v4(net);
+    SubnetInfo {
+        input: input.to_string(),
+        version: "ipv4".to_string(),
+        cidr: net.to_string(),
+        network: net.network().to_string(),
+        broadcast: Some(net.broadcast().to_string()),
+        netmask: net.netmask().to_string(),
+        hostmask: net.hostmask().to_string(),
+        prefix_len: net.prefix_len(),
+        total_addresses: total,
+        usable_addresses: usable,
+        first_host: first,
+        last_host: last,
+    }
+}
+
+fn subnet_info_v6(input: &str, net: Ipv6Net) -> SubnetInfo {
+    let total = total_addresses_v6(net.prefix_len());
+    let (first, last) = first_last_v6(net);
+    SubnetInfo {
+        input: input.to_string(),
+        version: "ipv6".to_string(),
+        cidr: net.to_string(),
+        network: net.network().to_string(),
+        broadcast: None,
+        netmask: net.netmask().to_string(),
+        hostmask: net.hostmask().to_string(),
+        prefix_len: net.prefix_len(),
+        total_addresses: total.clone(),
+        usable_addresses: total,
+        first_host: first,
+        last_host: last,
+    }
+}
+
+fn parse_net(value: &str) -> Result<IpNet, CalcError> {
+    let trimmed = value.trim();
+    if trimmed.is_empty() {
+        return Err(CalcError::InvalidInput("empty input".to_string()));
+    }
+
+    let mut parts = trimmed.split_whitespace();
+    let first = parts.next().unwrap();
+    if let Some(mask) = parts.next() {
+        if parts.next().is_some() {
+            return Err(CalcError::InvalidInput(
+                "expected: <ip> <mask>".to_string(),
+            ));
+        }
+        return parse_ip_mask(first, mask);
+    }
+
+    if let Some((ip, mask)) = trimmed.split_once('/') {
+        if mask.contains('.') || mask.contains(':') {
+            return parse_ip_mask(ip, mask);
+        }
+    }
+
+    trimmed
+        .parse::<IpNet>()
+        .map_err(|err| CalcError::Parse(err.to_string()))
+}
+
+fn parse_ip_mask(ip: &str, mask: &str) -> Result<IpNet, CalcError> {
+    let ip: IpAddr = ip
+        .parse()
+        .map_err(|_| CalcError::Parse(format!("invalid ip: {ip}")))?;
+    let mask: IpAddr = mask
+        .parse()
+        .map_err(|_| CalcError::Parse(format!("invalid mask: {mask}")))?;
+    IpNet::with_netmask(ip, mask).map_err(|err| CalcError::Parse(err.to_string()))
+}
+
+fn total_addresses_v4(prefix: u8) -> String {
+    let bits = 32u32.saturating_sub(prefix as u32);
+    (1u128 << bits).to_string()
+}
+
+fn usable_addresses_v4(prefix: u8) -> String {
+    let total = 1u128 << (32u32.saturating_sub(prefix as u32));
+    let usable = if prefix <= 30 {
+        total.saturating_sub(2)
+    } else {
+        total
+    };
+    usable.to_string()
+}
+
+fn total_addresses_v6(prefix: u8) -> String {
+    let bits = 128u32.saturating_sub(prefix as u32);
+    if bits == 128 {
+        return "340282366920938463463374607431768211456".to_string();
+    }
+    (1u128 << bits).to_string()
+}
+
+fn first_last_v4(net: Ipv4Net) -> (Option<String>, Option<String>) {
+    let network = net.network();
+    let broadcast = net.broadcast();
+    let (first, last) = if net.prefix_len() <= 30 {
+        (
+            Some(Ipv4Addr::from(u32::from(network).saturating_add(1)).to_string()),
+            Some(Ipv4Addr::from(u32::from(broadcast).saturating_sub(1)).to_string()),
+        )
+    } else {
+        (Some(network.to_string()), Some(broadcast.to_string()))
+    };
+    (first, last)
+}
+
+fn first_last_v6(net: Ipv6Net) -> (Option<String>, Option<String>) {
+    (
+        Some(net.network().to_string()),
+        Some(net.broadcast().to_string()),
+    )
+}
+
+fn overlap_v4(a: Ipv4Net, b: Ipv4Net) -> bool {
+    let a_start = u32::from(a.network());
+    let a_end = u32::from(a.broadcast());
+    let b_start = u32::from(b.network());
+    let b_end = u32::from(b.broadcast());
+    a_start <= b_end && b_start <= a_end
+}
+
+fn overlap_v6(a: Ipv6Net, b: Ipv6Net) -> bool {
+    let a_start = u128::from(a.network());
+    let a_end = u128::from(a.broadcast());
+    let b_start = u128::from(b.network());
+    let b_end = u128::from(b.broadcast());
+    a_start <= b_end && b_start <= a_end
+}