Go - check if IP address is in a network

Question

Given:

• a network address A: (172.17.0.0/16)
• and an IP address from a host B: (172.17.0.2/16)

how can we say if B is in A?

All addresses are string variables in the following form: [IP address in dot-decimal notation]/[subnet mask]. Should I try to do it by manipulating strings (initial thoughts). Is there a different path?

Here is the same question for Python:

• How can I check if an ip is in a network in python

and another approach with Go:

• Go/GoLang check IP address in range

UPDATE March 2022
👉 for Go 1.18, check the answer below by blackgreen

Answer 1

The Go net package includes the following functions:

• ParseCIDR: takes a string representing an IP/mask and returns an IP and an IPNet
• IPNet.Contains: checks whether an IP is in a network

This should cover your needs.