gatus/core/dns.go
2020-11-19 13:59:03 +01:00

84 lines
2.0 KiB
Go

package core
import (
"errors"
"fmt"
"strings"
"github.com/miekg/dns"
)
var (
// ErrDNSWithNoQueryName is the error with which gatus will panic if a dns is configured without query name
ErrDNSWithNoQueryName = errors.New("you must specify query name for DNS")
// ErrDNSWithInvalidQueryType is the error with which gatus will panic if a dns is configured with invalid query type
ErrDNSWithInvalidQueryType = errors.New("invalid query type")
)
const (
dnsPort = 53
)
type DNS struct {
// QueryType is the type for the DNS records like A, AAAA, CNAME...
QueryType string `yaml:"query-type"`
// QueryName is the query for DNS
QueryName string `yaml:"query-name"`
}
func (d *DNS) validateAndSetDefault() {
if len(d.QueryName) == 0 {
panic(ErrDNSWithNoQueryName)
}
if !strings.HasSuffix(d.QueryName, ".") {
d.QueryName += "."
}
if _, ok := dns.StringToType[d.QueryType]; !ok {
panic(ErrDNSWithInvalidQueryType)
}
}
func (d *DNS) query(url string, result *Result) {
if !strings.Contains(url, ":") {
url = fmt.Sprintf("%s:%d", url, dnsPort)
}
queryType := dns.StringToType[d.QueryType]
c := new(dns.Client)
m := new(dns.Msg)
m.SetQuestion(d.QueryName, queryType)
r, _, err := c.Exchange(m, url)
if err != nil {
result.Errors = append(result.Errors, err.Error())
return
}
result.Connected = true
result.DNSRCode = dns.RcodeToString[r.Rcode]
for _, rr := range r.Answer {
switch rr.Header().Rrtype {
case dns.TypeA:
if a, ok := rr.(*dns.A); ok {
result.Body = []byte(a.A.String())
}
case dns.TypeAAAA:
if aaaa, ok := rr.(*dns.AAAA); ok {
result.Body = []byte(aaaa.AAAA.String())
}
case dns.TypeCNAME:
if cname, ok := rr.(*dns.CNAME); ok {
result.Body = []byte(cname.Target)
}
case dns.TypeMX:
if mx, ok := rr.(*dns.MX); ok {
result.Body = []byte(mx.Mx)
}
case dns.TypeNS:
if ns, ok := rr.(*dns.NS); ok {
result.Body = []byte(ns.Ns)
}
default:
result.Body = []byte("query type is not supported yet")
}
}
}