fire_scope/
overlap.rs

1use crate::ipv4_utils::ipv4_summarize_range;
2use ipnet::{IpNet, Ipv4Net, Ipv6Net};
3use std::cmp::{max, min};
4use std::collections::BTreeSet;
5use std::net::Ipv6Addr;
6
7/// 国別IPs, AS別IPs それぞれから得られたBTreeSet<IpNet>を受け取り、
8/// 部分的に重複している範囲（サブネット）をすべてBTreeSet<IpNet>で返す。
9pub fn find_overlaps(country_ips: &BTreeSet<IpNet>, as_ips: &BTreeSet<IpNet>) -> BTreeSet<IpNet> {
10    let mut result = BTreeSet::new();
11
12    for cnet in country_ips {
13        for anet in as_ips {
14            let overlap_cidrs = ipnet_overlap(cnet, anet);
15            result.extend(overlap_cidrs);
16        }
17    }
18    result
19}
20
21/// 2つのIpNetの重複範囲をCIDRのリストで返す。
22/// 部分的にでも被っていればOK
23fn ipnet_overlap(a: &IpNet, b: &IpNet) -> Vec<IpNet> {
24    match (a, b) {
25        (IpNet::V4(a4), IpNet::V4(b4)) => ipv4_overlap(a4, b4),
26        (IpNet::V6(a6), IpNet::V6(b6)) => ipv6_overlap(a6, b6),
27        // IPv4 と IPv6 は重複しない
28        _ => Vec::new(),
29    }
30}
31
32/// IPv4同士の重複範囲を求めてCIDR列として返す
33fn ipv4_overlap(a: &Ipv4Net, b: &Ipv4Net) -> Vec<IpNet> {
34    let a_start = u32::from(a.network());
35    let a_end = u32::from(a.broadcast());
36    let b_start = u32::from(b.network());
37    let b_end = u32::from(b.broadcast());
38
39    let overlap_start = max(a_start, b_start);
40    let overlap_end = min(a_end, b_end);
41    if overlap_start > overlap_end {
42        return Vec::new();
43    }
44
45    // 共通化した ipv4_summarize_range を利用
46    ipv4_summarize_range(overlap_start, overlap_end)
47}
48
49/// IPv6同士の重複範囲を求めてCIDR列として返す
50fn ipv6_overlap(a: &Ipv6Net, b: &Ipv6Net) -> Vec<IpNet> {
51    let a_start = ipv6_to_u128(a.network());
52    let a_end = ipv6_to_u128(a.broadcast());
53    let b_start = ipv6_to_u128(b.network());
54    let b_end = ipv6_to_u128(b.broadcast());
55
56    let overlap_start = max(a_start, b_start);
57    let overlap_end = min(a_end, b_end);
58    if overlap_start > overlap_end {
59        return Vec::new();
60    }
61
62    ipv6_summarize_range(overlap_start, overlap_end)
63}
64
65/// 開始～終了アドレスを最適なIPv6 CIDRに分割
66fn ipv6_summarize_range(start: u128, end: u128) -> Vec<IpNet> {
67    let mut cidrs = Vec::new();
68    let mut current = start;
69
70    while current <= end {
71        let max_size = largest_ipv6_block_in_overlap(current, end);
72        if let Ok(net) = Ipv6Net::new(Ipv6Addr::from(current), max_size) {
73            cidrs.push(IpNet::V6(net));
74            let block_size = 1u128 << (128 - max_size);
75            current = current.saturating_add(block_size);
76        } else {
77            break;
78        }
79    }
80
81    cidrs
82}
83
84/// IPv6用
85fn largest_ipv6_block_in_overlap(current: u128, end: u128) -> u8 {
86    let tz = current.trailing_zeros() as u128;
87    let span = (end - current + 1).ilog2_128();
88    let max_block = tz.min(span);
89    (128 - max_block) as u8
90}
91
92/// Ipv6Addrをu128に変換
93fn ipv6_to_u128(addr: Ipv6Addr) -> u128 {
94    u128::from_be_bytes(addr.octets())
95}
96
97/// u128用の ilog2相当
98trait ILog2U128 {
99    fn ilog2_128(self) -> u128;
100}
101impl ILog2U128 for u128 {
102    fn ilog2_128(self) -> u128 {
103        if self == 0 {
104            0
105        } else {
106            127 - self.leading_zeros() as u128
107        }
108    }
109}
fire_scope/overlap.rs

fire_scope/
overlap.rs
