awl/query/general.go
Sam 8df0347891
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continuous-integration/drone/push Build is passing
fix: EDNS cookies work properly (#98)
also slight refactors :)

closes #96

Co-authored-by: Sam Therapy <sam@samtherapy.net>
Reviewed-on: #98
Reviewed-by: grumbulon <grumbulon@grumbulon.xyz>
2022-09-16 23:26:10 +00:00

102 lines
2 KiB
Go

// SPDX-License-Identifier: BSD-3-Clause
package query
import (
"crypto/tls"
"fmt"
"net"
"git.froth.zone/sam/awl/util"
"github.com/miekg/dns"
)
// StandardResolver is for UDP/TCP resolvers.
type StandardResolver struct {
opts util.Options
}
var _ Resolver = (*StandardResolver)(nil)
// LookUp performs a DNS query.
func (r *StandardResolver) LookUp(msg *dns.Msg) (util.Response, error) {
var (
resp util.Response
err error
)
dnsClient := new(dns.Client)
dnsClient.Dialer = &net.Dialer{
Timeout: r.opts.Request.Timeout,
}
if r.opts.TCP || r.opts.TLS {
dnsClient.Net = tcp
} else {
dnsClient.Net = udp
}
switch {
case r.opts.IPv4:
dnsClient.Net += "4"
case r.opts.IPv6:
dnsClient.Net += "6"
}
if r.opts.TLS {
dnsClient.Net += "-tls"
dnsClient.TLSConfig = &tls.Config{
//nolint:gosec // This is intentional if the user requests it
InsecureSkipVerify: r.opts.TLSNoVerify,
ServerName: r.opts.TLSHost,
}
}
r.opts.Logger.Info("Using", dnsClient.Net, "for making the request")
resp.DNS, resp.RTT, err = dnsClient.Exchange(msg, r.opts.Request.Server)
if err != nil {
return util.Response{}, fmt.Errorf("standard: DNS exchange: %w", err)
}
switch dns.RcodeToString[resp.DNS.MsgHdr.Rcode] {
case "BADCOOKIE":
if !r.opts.BadCookie {
fmt.Printf(";; BADCOOKIE, retrying.\n\n")
msg.Extra = resp.DNS.Extra
resp.DNS, resp.RTT, err = dnsClient.Exchange(msg, r.opts.Request.Server)
if err != nil {
return util.Response{}, fmt.Errorf("badcookie: DNS exchange: %w", err)
}
}
case "NOERR":
break
}
r.opts.Logger.Info("Request successful")
if resp.DNS.MsgHdr.Truncated && !r.opts.Truncate {
fmt.Printf(";; Truncated, retrying with TCP\n\n")
dnsClient.Net = tcp
switch {
case r.opts.IPv4:
dnsClient.Net += "4"
case r.opts.IPv6:
dnsClient.Net += "6"
}
resp.DNS, resp.RTT, err = dnsClient.Exchange(msg, r.opts.Request.Server)
}
if err != nil {
return util.Response{}, fmt.Errorf("standard: DNS exchange: %w", err)
}
return resp, nil
}