Crate maxminddb 

MaxMind DB Reader

This library reads the MaxMind DB format, including the GeoIP2 and GeoLite2 databases.

Features

This crate provides several optional features for performance and functionality:

• mmap (default: disabled): Enable memory-mapped file access for better performance in long-running applications
• simdutf8 (default: disabled): Use SIMD instructions for faster UTF-8 validation during string decoding
• unsafe-str-decode (default: disabled): Skip UTF-8 validation entirely for maximum performance (~20% faster lookups)

Note: simdutf8 and unsafe-str-decode are mutually exclusive.

Database Compatibility

This library supports all MaxMind DB format databases:

• GeoIP2 databases (City, Country, Enterprise, ISP, etc.)
• GeoLite2 databases (free versions)
• Custom MaxMind DB format databases

Thread Safety

The Reader is Send and Sync, making it safe to share across threads. This makes it ideal for web servers and other concurrent applications.

Quick Start

use maxminddb::{Reader, geoip2};
use std::net::IpAddr;

fn main() -> Result<(), Box<dyn std::error::Error>> {
    // Open database file
    let reader = Reader::open_readfile("/path/to/GeoIP2-City.mmdb")?;

    // Look up an IP address
    let ip: IpAddr = "89.160.20.128".parse()?;
    let result = reader.lookup(ip)?;

    if let Some(city) = result.decode::<geoip2::City>()? {
        // Access nested structs directly - no Option unwrapping needed
        println!("Country: {}", city.country.iso_code.unwrap_or("Unknown"));
    }

    Ok(())
}

Selective Field Access

Use decode_path to extract specific fields without deserializing the entire record:

use maxminddb::{Reader, PathElement};
use std::net::IpAddr;

let reader = Reader::open_readfile("test-data/test-data/GeoIP2-City-Test.mmdb").unwrap();
let ip: IpAddr = "89.160.20.128".parse().unwrap();

let result = reader.lookup(ip).unwrap();
let country_code: Option<String> = result.decode_path(&[
    PathElement::Key("country"),
    PathElement::Key("iso_code"),
]).unwrap();

println!("Country: {:?}", country_code);

Modules

geoip2

GeoIP2 and GeoLite2 database record structures

Macros

path

Creates a path for use with LookupResult::decode_path().

Structs

LookupResult

The result of looking up an IP address in a MaxMind DB.

Metadata

Metadata about the MaxMind DB file.

Reader

A reader for the MaxMind DB format. The lifetime 'data is tied to the lifetime of the underlying buffer holding the contents of the database file.

Within

Iterator over IP networks within a CIDR range.

WithinOptions

Options for network iteration.

Enums

MaxMindDbError

Error returned by MaxMind DB operations.

PathElement

A path element for navigating into nested data structures.