Verify DomainKey-Signature Headers in Downloaded Email

const std = @import("std");
const chilkat = @import("chilkat");

pub fn main(init: std.process.Init) !void {
    const alloc = init.arena.allocator();

    var success: bool = false;

    // This example requires the Chilkat API to have been previously unlocked.
    // See Global Unlock Sample for sample code.

    const imap = try chilkat.Imap.init();
    defer imap.deinit();

    // Connect to an IMAP server, login, select mailbox..
    // Use TLS
    imap.setSsl(true);
    imap.setPort(993);
    success = if (imap.connect("imap.example.com")) true else |_| false;
    if (success) {
        success = if (imap.login("myLogin", "myPassword")) true else |_| false;
        if (success) {
            success = if (imap.selectMailbox("Inbox")) true else |_| false;
        }
    }

    if (!success) {
        std.debug.print("{s}\n", .{try imap.getLastErrorText(alloc)});
        return;
    }

    // Note: DKIM-Signatures are much more common than DomainKey-Signature
    // See DKIM-Signature Verify Sample.

    const dkim = try chilkat.Dkim.init();
    defer dkim.deinit();

    // Download a max of 10 emails and verify any DomainKey-Signature headers
    // that are present.

    // Download emails by sequence numbers (not UIDs).
    const b_uid = false;
    var seq_num: i32 = 0;
    var j: i32 = 0;
    var n: i32 = imap.getNumMessages();
    if (n > 50) {
        n = 50;
    }

    const json = try chilkat.JsonObject.init();
    defer json.deinit();
    json.setEmitCompact(false);

    // To verify DomainKey-Signature headers, we need the exact unmodified MIME bytes of each email.
    const mime_data = try chilkat.BinData.init();
    defer mime_data.deinit();
    seq_num = 1;
    while (seq_num <= n) {
        // The FetchSingleBd method was introduced in v9.5.0.76
        success = if (imap.fetchSingleBd(@as(u32, @intCast(seq_num)), b_uid, mime_data)) true else |_| false;
        if (!success) {
            std.debug.print("{s}\n", .{try imap.getLastErrorText(alloc)});
            return;
        }

        // Note: DKIM-Signatures are much more common than DomainKey-Signature
        // See DKIM-Signature Verify Sample.

        // Get the number of DomainKey-Signature headers.
ERROR: Method not in the Zig package: Dkim.NumDomainKeySigs
ERROR: Method not in the Zig package: Dkim.NumDomainKeySigs
        const num_sigs = dkim.ERROR();

        // Verify each..
        j = 0;
        while (j < num_sigs) {
            std.debug.print("------ DomainKey Signature {d}\n", .{j});

ERROR: Method not in the Zig package: Dkim.DomainKeyVerify
ERROR: Method not in the Zig package: Dkim.DomainKeyVerify
            success = dkim.ERROR();
            if (!success) {
                std.debug.print("Not valid.\n", .{});
                std.debug.print("{s}\n", .{try dkim.getLastErrorText(alloc)});
            } else {
                std.debug.print("valid.\n", .{});
            }

            // Show the additional information about the signature verification
            json.load(try dkim.getVerifyInfo(alloc)) catch {};
            std.debug.print("{s}\n", .{try json.emit(alloc)});

            // The JSON contains information such as this:

            //     {
            //       "domain": "amazonses.com",
            //       "selector": "7v7vs6w47njt4pimodk5mmttbegzsi6n",
            //       "publicKey": "MIGfMA0GCSqG...v2GvWPqGHz6uqeQIDAQAB",
            //       "canonicalization": "relaxed/simple",
            //       "algorithm": "rsa-sha256",
            //       "signedHeaders": "Subject:From:To:Date:Mime-Version:Content-Type:References:Message-Id:Feedback-ID",
            //       "verified": "yes"
            //     }

            j = j + 1;
        }

        seq_num = seq_num + 1;
    }

    success = if (imap.disconnect()) true else |_| false;
}