https://github.com/jmoney/cidr-encoder

CLI for time efficiently encoding cidr blocks to find if an IP exists in a range
https://github.com/jmoney/cidr-encoder

github-site homebrew-formula license-management mkdocs

Last synced: 16 days ago
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CLI for time efficiently encoding cidr blocks to find if an IP exists in a range

• Host: GitHub
• URL: https://github.com/jmoney/cidr-encoder
• Owner: jmoney
• License: apache-2.0
• Created: 2024-06-07T20:47:57.000Z (5 months ago)
• Default Branch: main
• Last Pushed: 2024-06-13T02:19:34.000Z (5 months ago)
• Last Synced: 2024-10-16T13:07:24.394Z (about 1 month ago)
• Topics: github-site, homebrew-formula, license-management, mkdocs
• Language: Go
• Homepage: https://www.jmoney.dev/cidr-encoder
• Size: 35.2 KB
• Stars: 0
• Watchers: 1
• Forks: 0
• Open Issues: 0
• Metadata Files:
  • Readme: README.md
  • Funding: .github/FUNDING.yml
  • License: LICENSE

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README

        
# Cidr Encoder

Converts a list of CIDRs to an encoded file for time efficient lookups on is a given IP address in any of the CIDR blocks.  Each CIDR block is on its own line in the input file.  The output file is a binary file that can be read by the `cidr-encoder` program for searching.  The lookup time is `O(1)` for any IP address.  However, to achieve this the output file can easily be several GBs if there are a wide range of CIDR blocks across the IPv4 addresses space.

The calculation for how big a file would take is effectively the largest IP - the smallest IP.  As the algorithm uses file offsets to determine if an IP is in a list of CIDR blocks, the largest IP is the largest offset in the file.  We use the smallest IP to normalize everything to first offset of a file.  This is done to reduce the size of the file so the difference between the two is the size of the file.

## Usage

```bash

$ cidr-encoder -h

Usage of cidr-encoder:

  -calc

        Calculate the size of the encoded file. Reads from STDIN.

  -encode

        Encode the CIDRs. Reads from STDIN.

  -name string

        The file base name to use as the ACL file name(e.g test.acl name is test).

  -search string

        Search for a IP in the CIDRs.

```

`-calc`, `encode`, and `search` are all mutually exclusive but the priority in the event that all are specified are `calc` then `encode` then `search`.