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