This turned out to be interesting puzzle. Seemingly so simple thing made me think a lot.

Problem statement:

You’re given a string, which is a connection string to MongoDB. It consists of parts. The parts are delimited by various characters:

• between username and password, there is ‘:’
• after password comes ‘@’
• after the ‘@’ comes host name

We want to mask any password characters with ‘*’ character.

Write an algorithm (function) that takes in a string, and writes out a masked string.