fix: ip_count overflow panic on full address space (/0 prefixes)#7
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ip_count previously used 2u32.pow(32-prefix_len) and 2u128.pow(128-prefix_len), which overflow when a /0 prefix is present — panicking in debug builds and silently wrapping in release builds (#5). Change return type from (u32, u128) to new IpCount struct: - ipv4: u64 (holds the full 2^32 IPv4 address space) - ipv6: Option<u128> (None when the entire 2^128 IPv6 space is covered) Use checked_shl/checked_add instead of pow to detect overflow without panicking. The trie storage (PrefixMap) is unchanged — IpCount is only a transient return value with no in-memory storage cost increase.
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Summary
Fixes #5
ip_countpanicked in debug builds (and silently wrapped in release) when the trie contained a/0prefix (0.0.0.0/0or::/0), because2u32.pow(32)and2u128.pow(128)overflow.Changes
(u32, u128)→ newIpCountstructipv4: u64— holds the full 2³² IPv4 address spaceipv6: Option<u128>—Nonewhen the entire 2¹²⁸ IPv6 space is covered (too large foru128)pow()withchecked_shl/checked_addto detect overflow without panicking0.0.0.0/0,::/0, and two/1halves covering all of IPv6Notes
IpCountis a transient stack return value — the trie storage (PrefixMap) is unchanged, so there is no in-memory storage cost increaseChecklist
cargo test --all-featurespassescargo fmt --checkpasses