local-ip.sh/xip/records.go

package xip

import (
	"fmt"
	"net"

	"github.com/miekg/dns"
	"local-ip.sh/utils"
)

type hardcodedRecord struct {
	A     []net.IP // => dns.A
	AAAA  []net.IP // => dns.AAAA
	TXT   []string // => dns.TXT
	MX    []*dns.MX
	CNAME []string // => dns.CNAME
	SRV   *dns.SRV
}

var config = utils.GetConfig()
var hardcodedRecords = map[string]hardcodedRecord{
	// TODO: maybe --nameservers ns1.local-ip.sh.=137.66.40.11,ns2.local-ip.sh.=137.66.40.12
	fmt.Sprintf("ns.%s.", config.Domain): {
		// record holding ip addresses of ns1 and ns2
		A: []net.IP{
			net.IPv4(137, 66, 40, 11),
			net.IPv4(137, 66, 40, 12),
		},
	},
	fmt.Sprintf("ns1.%s.", config.Domain): {
		A: []net.IP{
			net.IPv4(137, 66, 40, 11), // fly.io edge-only ip address, see https://community.fly.io/t/custom-domains-certificate-is-stuck-on-awaiting-configuration/8329
		},
	},
	fmt.Sprintf("ns2.%s.", config.Domain): {
		A: []net.IP{
			net.IPv4(137, 66, 40, 12), // fly.io edge-only ip address #2
		},
	},
	fmt.Sprintf("%s.", config.Domain): {
		// same as ns.local-ip.sh, it's the same machine :)
		A: []net.IP{
			net.IPv4(137, 66, 40, 11),
			net.IPv4(137, 66, 40, 12),
		},
	},
	fmt.Sprintf("_acme-challenge.%s.", config.Domain): {
		// will be filled in later when requesting the wildcard certificate
		TXT: []string{},
	},
}

// additional records I set up to host emails, feel free to change or remove them for your own needs
var extraRecords = map[string]hardcodedRecord{
	"local-ip.sh.": {
		TXT: []string{"v=spf1 include:capsulecorp.dev ~all"},
		MX: []*dns.MX{
			{Preference: 10, Mx: "email.capsulecorp.dev."},
		},
	},
	"autodiscover.local-ip.sh.": {
		CNAME: []string{
			"email.capsulecorp.dev.",
		},
	},
	"_autodiscover._tcp.local-ip.sh.": {
		SRV: &dns.SRV{
			Priority: 0,
			Weight:   0,
			Port:     443,
			Target:   "email.capsulecorp.dev.",
		},
	},
	"autoconfig.local-ip.sh.": {
		CNAME: []string{
			"email.capsulecorp.dev.",
		},
	},
	"_dmarc.local-ip.sh.": {
		TXT: []string{"v=DMARC1; p=none; rua=mailto:postmaster@local-ip.sh; ruf=mailto:admin@local-ip.sh"},
	},
	"dkim._domainkey.local-ip.sh.": {
		TXT: []string{
			"v=DKIM1;k=rsa;t=s;s=email;p=MIIBIjANBgkqhkiG9w0BAQEFAAOCAQ8AMIIBCgKCAQEAsMW6NFo34qzKRPbzK41GwbWncB8IDg1i2eA2VWznIVDmTzzsqILaBOGv2xokVpzZm0QRF9wSbeVUmvwEeQ7Z6wkfMjawenDEc3XxsNSvQUVBP6LU/xcm1zsR8wtD8r5J+Jm45pNFaateiM/kb/Eypp2ntdtd8CPsEgCEDpNb62LWdy0yzRdZ/M/fNn51UMN8hVFp4YfZngAt3bQwa6kPtgvTeqEbpNf5xanpDysNJt2S8zfqJMVGvnr8JaJiTv7ZlKMMp94aC5Ndcir1WbMyfmgSnGgemuCTVMWDGPJnXDi+8BQMH1b1hmTpWDiVdVlehyyWx5AfPrsWG9cEuDIfXwIDAQAB",
		},
	},
}
var records = mergeRecords(hardcodedRecords, extraRecords)

func mergeRecords(a, b map[string]hardcodedRecord) map[string]hardcodedRecord {
	result := make(map[string]hardcodedRecord)
	for k, v := range a {
		result[k] = v
	}
	for k, v := range b {
		if r, ok := result[k]; ok {
			result[k] = hardcodedRecord{
				A:     uniqueIPs(append(r.A, v.A...)),
				AAAA:  uniqueIPs(append(r.AAAA, v.AAAA...)),
				TXT:   uniqueStrings(append(r.TXT, v.TXT...)),
				MX:    uniqueMX(append(r.MX, v.MX...)),
				CNAME: uniqueStrings(append(r.CNAME, v.CNAME...)),
				SRV:   firstNonNil(r.SRV, v.SRV),
			}
		} else {
			result[k] = v
		}
	}
	return result
}

func uniqueIPs(ips []net.IP) []net.IP {
	seen := make(map[string]bool)
	result := []net.IP{}
	for _, ip := range ips {
		if !seen[ip.String()] {
			seen[ip.String()] = true
			result = append(result, ip)
		}
	}
	return result
}

func uniqueStrings(strs []string) []string {
	seen := make(map[string]bool)
	result := []string{}
	for _, str := range strs {
		if !seen[str] {
			seen[str] = true
			result = append(result, str)
		}
	}
	return result
}

func uniqueMX(mxs []*dns.MX) []*dns.MX {
	seen := make(map[string]uint16)
	result := []*dns.MX{}
	for _, mx := range mxs {
		if pref, exists := seen[mx.Mx]; !exists || pref > mx.Preference {
			seen[mx.Mx] = mx.Preference
			result = append(result, mx)
		}
	}
	return result
}

func firstNonNil[T any](a, b *T) *T {
	if a != nil {
		return a
	}
	return b
}