SHA1 digest (Node)

In this example we're going to create a server-side app that calculates SHA-1 digests, using a built-in function of Zig's standard library.

Creating the app

First, we'll create the basic skeleton:

mkdir sha1
cd sha1
npm init -y
npm install node-zigar
mkdir src zig

Then we add sha1.zig:

const std = @import("std");

pub fn sha1(bytes: []const u8) [std.crypto.hash.Sha1.digest_length * 2]u8 {
    var digest: [std.crypto.hash.Sha1.digest_length]u8 = undefined;
    std.crypto.hash.Sha1.hash(bytes, &digest, .{});
    return std.fmt.bytesToHex(digest, .lower);
}

Followed by index.js:

import { sha1 } from '../zig/sha1.zig';

console.log(sha1('hello world').string);

We make the same changes to package.json as we had in the previous example:

  "type": "module",
  "scripts": {
    "start": "node --loader=node-zigar --no-warnings src/index.js"
  },

Then we run it:

npm run start

After a while, we get the result:

2aae6c35c94fcfb415dbe95f408b9ce91ee846ed

We would get the same digest if we calculate it using sha1sum:

echo -n "hello world" | sha1sum

2aae6c35c94fcfb415dbe95f408b9ce91ee846ed  -

Configuring the app for deployment

We follow the same steps as described in the the hello world example. First we change the import statement:

import { sha1 } from '../lib/sha1.zigar';

console.log(sha1('hello world').string);

Then we create node-zigar.config.json:

{
  "optimize": "ReleaseSmall",
  "sourceFiles": {
    "lib/sha1.zigar": "zig/sha1.zig"
  },
  "targets": [
    { "platform": "linux", "arch": "x64" },
    { "platform": "linux", "arch": "arm64" },
    { "platform": "linux-musl", "arch": "x64" },
    { "platform": "linux-musl", "arch": "arm64" }
  ]
}

Finally we build the necessary libraries for platforms we intend to support:

npx node-zigar build

Conclusion

Okay, that wasn't much of a server-side app. At least it does something. In the next example we'll build a server-side app for real, one that actually listens for remote requests.

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