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sslip.io: lean main.go

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Moved much of the processing of DNS messages into the library. Testing a
library is easier than testing `main`, so I like to keep a lean
`main`.
This commit is contained in:
Brian Cunnie
2020-08-22 16:13:56 -07:00
parent 06daa8ab29
commit 2bd50a2241
2 changed files with 28 additions and 17 deletions
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23
src/main.go
View File

@@ -1,12 +1,10 @@
package main
import (
"encoding/json"
"github.com/cunnie/sslip.io/src/xip"
"log"
"net"
)
import "net"
import "golang.org/x/net/dns/dnsmessage"
func main() {
conn, err := net.ListenUDP("udp", &net.UDPAddr{Port: 53})
@@ -14,29 +12,20 @@ func main() {
log.Fatal(err.Error())
}
var m dnsmessage.Message
buf := make([]byte, 512)
query := make([]byte, 512)
for {
_, _, err := conn.ReadFromUDP(buf)
_, addr, err := conn.ReadFromUDP(query)
if err != nil {
log.Println(err.Error())
break
}
err = m.Unpack(buf)
response, err := xip.QueryResponse(query)
if err != nil {
log.Println(err.Error())
break
}
for _, question := range m.Questions {
jsonQuestion, err := json.Marshal(question)
if err != nil {
log.Println(err.Error())
}
answer, _ := xip.NameToA(question.GoString())
jsonAnswer, err := json.Marshal(answer)
log.Println(jsonQuestion)
log.Println(jsonAnswer)
}
_, err = conn.WriteToUDP(response, addr)
}
}

22
src/xip/xip.go
View File

@@ -1,8 +1,10 @@
package xip
import (
"encoding/json"
"errors"
"golang.org/x/net/dns/dnsmessage"
"log"
"net"
"regexp"
"strings"
@@ -12,6 +14,26 @@ import (
var ipv4RE= regexp.MustCompile(`(^|[.-])(((25[0-5]|(2[0-4]|1{0,1}[0-9]){0,1}[0-9])[.-]){3,3}(25[0-5]|(2[0-4]|1{0,1}[0-9]){0,1}[0-9]))($|[.-])`)
var ipv6RE= regexp.MustCompile(`(^|[.-])(([0-9a-fA-F]{1,4}-){7,7}[0-9a-fA-F]{1,4}|([0-9a-fA-F]{1,4}-){1,7}-|([0-9a-fA-F]{1,4}-){1,6}-[0-9a-fA-F]{1,4}|([0-9a-fA-F]{1,4}-){1,5}(-[0-9a-fA-F]{1,4}){1,2}|([0-9a-fA-F]{1,4}-){1,4}(-[0-9a-fA-F]{1,4}){1,3}|([0-9a-fA-F]{1,4}-){1,3}(-[0-9a-fA-F]{1,4}){1,4}|([0-9a-fA-F]{1,4}-){1,2}(-[0-9a-fA-F]{1,4}){1,5}|[0-9a-fA-F]{1,4}-((-[0-9a-fA-F]{1,4}){1,6})|-((-[0-9a-fA-F]{1,4}){1,7}|-)|fe80-(-[0-9a-fA-F]{0,4}){0,4}%[0-9a-zA-Z]{1,}|--(ffff(-0{1,4}){0,1}-){0,1}((25[0-5]|(2[0-4]|1{0,1}[0-9]){0,1}[0-9])\.){3,3}(25[0-5]|(2[0-4]|1{0,1}[0-9]){0,1}[0-9])|([0-9a-fA-F]{1,4}-){1,4}-((25[0-5]|(2[0-4]|1{0,1}[0-9]){0,1}[0-9])\.){3,3}(25[0-5]|(2[0-4]|1{0,1}[0-9]){0,1}[0-9]))($|[.-])`)
func QueryResponse(query []byte) ([]byte, error) {
var m dnsmessage.Message
err := m.Unpack(query)
if err != nil {
return nil, err
}
for _, question := range m.Questions {
jsonQuestion, err := json.Marshal(question)
if err != nil {
return nil, err
}
answer, _ := NameToA(question.GoString())
jsonAnswer, err := json.Marshal(answer)
log.Println(jsonQuestion)
log.Println(jsonAnswer)
}
return []byte{0x0}, nil
}
func NameToA (fqdnString string) (dnsmessage.AResource, error) {
fqdn:=[]byte(fqdnString)
if ! ipv4RE.Match(fqdn) {