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custom dns client
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@fritterhoff
fritterhoff committed Aug 9, 2024
1 parent fdb0772 commit 3a83b9b
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Showing 3 changed files with 67 additions and 20 deletions.
78 changes: 58 additions & 20 deletions acme/client.go
View file
Original file line number Diff line number Diff line change
Expand Up @@ -9,6 +9,7 @@ import (
"os"
"time"

"github.com/miekg/dns"
"github.com/sirupsen/logrus"
)

Expand Down Expand Up @@ -49,9 +50,8 @@ func MustClientFromContext(ctx context.Context) Client {
}

type client struct {
http *http.Client
dialer *net.Dialer
resolver *net.Resolver
http *http.Client
dialer *net.Dialer
}

// NewClient returns an implementation of Client for verifying ACME challenges.
Expand All @@ -70,31 +70,69 @@ func NewClient() Client {
dialer: &net.Dialer{
Timeout: 30 * time.Second,
},
resolver: getResolver(),
}
}

func getResolver() *net.Resolver {
if os.Getenv("DNS_RESOLVER") != "" {
logrus.Infof("Using custom DNS resolver: %s", os.Getenv("DNS_RESOLVER"))
return &net.Resolver{
PreferGo: true,
Dial: func(ctx context.Context, network, address string) (net.Conn, error) {
d := net.Dialer{
Timeout: time.Millisecond * time.Duration(10000),
}
return d.DialContext(ctx, network, fmt.Sprintf("%s:53", os.Getenv("DNS_RESOLVER")))
}}
}
return net.DefaultResolver
}

func (c *client) Get(url string) (*http.Response, error) {
return c.http.Get(url)
}

var timeouts [5]time.Duration = [5]time.Duration{(time.Second * 1), (time.Second * 1), (time.Second * 2), (time.Second * 4), (time.Second * 2)}

func ResolveWithTimeout(name, resolver string) (*dns.Msg, error) {
client := new(dns.Client)
msg := &dns.Msg{
MsgHdr: dns.MsgHdr{
Id: dns.Id(),
RecursionDesired: true,
},
Question: []dns.Question{{Name: dns.Fqdn(name), Qtype: dns.TypeTXT, Qclass: dns.ClassINET}},
}
msg.AuthenticatedData = true
msg.SetEdns0(4096, true)

for i := 0; i < len(timeouts); i++ {

client.Timeout = timeouts[i]
resp, _, err := client.Exchange(msg, fmt.Sprintf("%s:53", resolver))
if err == nil && resp.Truncated {
tcpConn, _ := dns.Dial("tcp", fmt.Sprintf("%s:53", resolver))
resp, _, err = client.ExchangeWithConn(msg, tcpConn)
}
if err != nil {
if err, ok := err.(net.Error); ok && err.Timeout() {
logrus.Warnf("Timeout querying %s records '%s' after %v", dns.TypeToString[dns.TypeTXT], name, timeouts[i])
continue
}
return nil, err
}

return resp, nil

}
return nil, &net.DNSError{
Name: name,
Err: "Final timeout.",
IsTimeout: true,
}
}

func (c *client) LookupTxt(name string) ([]string, error) {
return c.resolver.LookupTXT(context.Background(), name)
resolver := os.Getenv("DNS_RESOLVER")
if resolver != "" {
resp, err := ResolveWithTimeout(name, resolver)
if err != nil {
return nil, err
}
data := []string{}
for _, answer := range resp.Answer {
if txt, ok := answer.(*dns.TXT); ok {
data = append(data, txt.Txt...)
}
}
return data, nil
}
return c.LookupTxt(name)
}

func (c *client) TLSDial(network, addr string, config *tls.Config) (*tls.Conn, error) {
Expand Down
3 changes: 3 additions & 0 deletions go.mod
View file
Original file line number Diff line number Diff line change
Expand Up @@ -171,11 +171,13 @@ require (
go.opentelemetry.io/otel/metric v1.27.0 // indirect
go.opentelemetry.io/otel/trace v1.27.0 // indirect
go.opentelemetry.io/proto/otlp v1.2.0 // indirect
golang.org/x/mod v0.18.0 // indirect
golang.org/x/oauth2 v0.21.0 // indirect
golang.org/x/sync v0.7.0 // indirect
golang.org/x/sys v0.22.0 // indirect
golang.org/x/text v0.16.0 // indirect
golang.org/x/time v0.5.0 // indirect
golang.org/x/tools v0.22.0 // indirect
google.golang.org/genproto v0.0.0-20240730163845-b1a4ccb954bf // indirect
google.golang.org/genproto/googleapis/api v0.0.0-20240725223205-93522f1f2a9f // indirect
google.golang.org/genproto/googleapis/rpc v0.0.0-20240730163845-b1a4ccb954bf // indirect
Expand All @@ -187,4 +189,5 @@ replace github.com/smallstep/nosql => github.com/hm-edu/nosql v0.4.1-0.202405061
require (
github.com/eclipse/paho.mqtt.golang v1.4.3
github.com/gorilla/websocket v1.5.0 // indirect
github.com/miekg/dns v1.1.61
)
6 changes: 6 additions & 0 deletions go.sum
View file
Original file line number Diff line number Diff line change
Expand Up @@ -372,6 +372,8 @@ github.com/mattn/go-isatty v0.0.20 h1:xfD0iDuEKnDkl03q4limB+vH+GxLEtL/jb4xVJSWWE
github.com/mattn/go-isatty v0.0.20/go.mod h1:W+V8PltTTMOvKvAeJH7IuucS94S2C6jfK/D7dTCTo3Y=
github.com/mgutz/ansi v0.0.0-20200706080929-d51e80ef957d h1:5PJl274Y63IEHC+7izoQE9x6ikvDFZS2mDVS3drnohI=
github.com/mgutz/ansi v0.0.0-20200706080929-d51e80ef957d/go.mod h1:01TrycV0kFyexm33Z7vhZRXopbI8J3TDReVlkTgMUxE=
github.com/miekg/dns v1.1.61 h1:nLxbwF3XxhwVSm8g9Dghm9MHPaUZuqhPiGL+675ZmEs=
github.com/miekg/dns v1.1.61/go.mod h1:mnAarhS3nWaW+NVP2wTkYVIZyHNJ098SJZUki3eykwQ=
github.com/miekg/pkcs11 v1.0.3-0.20190429190417-a667d056470f/go.mod h1:XsNlhZGX73bx86s2hdc/FuaLm2CPZJemRLMA+WTFxgs=
github.com/miekg/pkcs11 v1.1.1 h1:Ugu9pdy6vAYku5DEpVWVFPYnzV+bxB+iRdbuFSu7TvU=
github.com/miekg/pkcs11 v1.1.1/go.mod h1:XsNlhZGX73bx86s2hdc/FuaLm2CPZJemRLMA+WTFxgs=
Expand Down Expand Up @@ -564,6 +566,8 @@ golang.org/x/mod v0.1.1-0.20191105210325-c90efee705ee/go.mod h1:QqPTAvyqsEbceGzB
golang.org/x/mod v0.4.2/go.mod h1:s0Qsj1ACt9ePp/hMypM3fl4fZqREWJwdYDEqhRiZZUA=
golang.org/x/mod v0.6.0-dev.0.20220419223038-86c51ed26bb4/go.mod h1:jJ57K6gSWd91VN4djpZkiMVwK6gcyfeH4XE8wZrZaV4=
golang.org/x/mod v0.8.0/go.mod h1:iBbtSCu2XBx23ZKBPSOrRkjjQPZFPuis4dIYUhu/chs=
golang.org/x/mod v0.18.0 h1:5+9lSbEzPSdWkH32vYPBwEpX8KwDbM52Ud9xBUvNlb0=
golang.org/x/mod v0.18.0/go.mod h1:hTbmBsO62+eylJbnUtE2MGJUyE7QWk4xUqPFrRgJ+7c=
golang.org/x/net v0.0.0-20180724234803-3673e40ba225/go.mod h1:mL1N/T3taQHkDXs73rZJwtUhF3w3ftmwwsq0BUmARs4=
golang.org/x/net v0.0.0-20180826012351-8a410e7b638d/go.mod h1:mL1N/T3taQHkDXs73rZJwtUhF3w3ftmwwsq0BUmARs4=
golang.org/x/net v0.0.0-20190213061140-3a22650c66bd/go.mod h1:mL1N/T3taQHkDXs73rZJwtUhF3w3ftmwwsq0BUmARs4=
Expand Down Expand Up @@ -663,6 +667,8 @@ golang.org/x/tools v0.0.0-20200103221440-774c71fcf114/go.mod h1:TB2adYChydJhpapK
golang.org/x/tools v0.1.1/go.mod h1:o0xws9oXOQQZyjljx8fwUC0k7L1pTE6eaCbjGeHmOkk=
golang.org/x/tools v0.1.12/go.mod h1:hNGJHUnrk76NpqgfD5Aqm5Crs+Hm0VOH/i9J2+nxYbc=
golang.org/x/tools v0.6.0/go.mod h1:Xwgl3UAJ/d3gWutnCtw505GrjyAbvKui8lOU390QaIU=
golang.org/x/tools v0.22.0 h1:gqSGLZqv+AI9lIQzniJ0nZDRG5GBPsSi+DRNHWNz6yA=
golang.org/x/tools v0.22.0/go.mod h1:aCwcsjqvq7Yqt6TNyX7QMU2enbQ/Gt0bo6krSeEri+c=
golang.org/x/xerrors v0.0.0-20190410155217-1f06c39b4373/go.mod h1:I/5z698sn9Ka8TeJc9MKroUUfqBBauWjQqLJ2OPfmY0=
golang.org/x/xerrors v0.0.0-20190513163551-3ee3066db522/go.mod h1:I/5z698sn9Ka8TeJc9MKroUUfqBBauWjQqLJ2OPfmY0=
golang.org/x/xerrors v0.0.0-20190717185122-a985d3407aa7/go.mod h1:I/5z698sn9Ka8TeJc9MKroUUfqBBauWjQqLJ2OPfmY0=
Expand Down

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