I’m stuck on Stage #GT1.
I’ve tried multiple times to debug the code ,but i am quite unsure of where am i lagging in this
Here are my logs :
[tester::#YC9] Running tests for Stage #YC9 (Parse compressed packet)
[tester::#YC9] Starting DNS server on 127.0.0.1:2053
[tester::#YC9] Running program
[tester::#YC9] DNS resolver listening on 127.0.0.1:5354
[tester::#YC9] Connecting to 127.0.0.1:2053 using UDP
[your_program] Logs from your program will appear here!
[your_program] resolver 127.0.0.1:5354
[your_program] total questions 1
[your_program] new connection established
[your_program] n [202 60 129 0 0 1 0 1 0 0 0 0 12 99 111 100 101 99 114 97 102 116 101 114 115 2 105 111 0 0 1 0 1 12 99 111 100 101 99 114 97 102 116 101 114 115 2 105 111 0 0 1 0 1 0 0 14 16 0 4 76 76 21 21]
[your_program] answeroffset,n 33 64
[your_program] Found answer of length 31
[your_program] total answers [[12 99 111 100 101 99 114 97 102 116 101 114 115 2 105 111 0 0 1 0 1 0 0 14 16 0 4 76 76 21 21]]
[tester::#YC9] Querying the following in the same request (Messages with >> prefix are part of this log)
[tester::#YC9] >> ;abc.longassdomainname.com. IN A
[tester::#YC9] >> ;def.longassdomainname.com. IN A
[tester::#YC9] Sending Request: (Messages with >>> prefix are part of this log)
[tester::#YC9] >>> ;; opcode: QUERY, status: NOERROR, id: 10421
[tester::#YC9] >>> ;; flags: rd; QUERY: 2, ANSWER: 0, AUTHORITY: 0, ADDITIONAL: 0
[tester::#YC9] >>>
[tester::#YC9] >>> ;; QUESTION SECTION:
[tester::#YC9] >>> ;abc.longassdomainname.com. IN A
[tester::#YC9] >>> ;def.longassdomainname.com. IN A
[tester::#YC9] >>>
[your_program] answerresp 1
[your_program] answers [12 99 111 100 101 99 114 97 102 116 101 114 115 2 105 111 0 0 1 0 1 0 0 14 16 0 4 76 76 21 21]
[your_program] total questions 2
[your_program] new connection established
[your_program] n [40 181 129 0 0 1 0 1 0 0 0 0 3 97 98 99 17 108 111 110 103 97 115 115 100 111 109 97 105 110 110 97 109 101 3 99 111 109 0 0 1 0 1 3 97 98 99 17 108 111 110 103 97 115 115 100 111 109 97 105 110 110 97 109 101 3 99 111 109 0 0 1 0 1 0 0 14 16 0 4 127 0 0 1]
[your_program] answeroffset,n 43 84
[your_program] Found answer of length 41
[your_program] new connection established
[tester::#YC9] Received Response: (Messages with >>> prefix are part of this log)
[tester::#YC9] >>> ;; opcode: QUERY, status: NOERROR, id: 10421
[tester::#YC9] >>> ;; flags: qr rd; QUERY: 2, ANSWER: 1, AUTHORITY: 0, ADDITIONAL: 0
[tester::#YC9] >>>
[tester::#YC9] >>> ;; QUESTION SECTION:
[tester::#YC9] >>> ;abc.longassdomainname.com. IN A
[tester::#YC9] >>> ;def. IN A
[tester::#YC9] >>>
[tester::#YC9] >>> ;; ANSWER SECTION:
[tester::#YC9] >>> abc.longassdomainname.com. 3600 IN A 127.0.0.1
[tester::#YC9] >>>
[tester::#YC9] Expected answer section to have 2 entries got 1
[tester::#YC9] Test failed
[tester::#YC9] Terminating program
[tester::#YC9] Shutting down DNS resolver server...
[your_program] n [40 181 129 0 0 1 0 0 0 0 0 0 3 100 101 102 0 0 1 0 1]
[your_program] answeroffset,n 21 21
[your_program] total answers [[3 97 98 99 17 108 111 110 103 97 115 115 100 111 109 97 105 110 110 97 109 101 3 99 111 109 0 0 1 0 1 0 0 14 16 0 4 127 0 0 1]]
[your_program] answerresp 1
[your_program] answers [3 97 98 99 17 108 111 110 103 97 115 115 100 111 109 97 105 110 110 97 109 101 3 99 111 109 0 0 1 0 1 0 0 14 16 0 4 127 0 0 1]
[tester::#YC9] Program terminated successfully
include relevant logs here (please make sure to keep the backticks around this!)
And here's a snippet of my code:
```goLang
func forwardDNSServer(buf []byte, resolverAddr string) [][]byte {
header := buf[0:12]
header[2] &= 0b01111111
qdCount := binary.BigEndian.Uint16(buf[4:6])
var offset uint16 = 12
totalQuestions := [][]byte{}
totalAnswers := [][]byte{}
for i := uint16(0); i < qdCount; i++ {
questionResponse := createQuestionSection(buf[offset:])
totalQuestions = append(totalQuestions, questionResponse)
offset += uint16(len(questionResponse))
}
resolverIP := strings.Split(resolverAddr, ":")[0]
resolverPort, err := strconv.Atoi(strings.Split(resolverAddr, ":")[1])
if err != nil {
fmt.Printf("cannot convert %s port to int", resolverIP)
}
fmt.Println("total questions", len(totalQuestions))
for _, question := range totalQuestions {
newHeader := make([]byte, len(header))
copy(newHeader, header)
binary.BigEndian.PutUint16(newHeader[4:6], 1)
packet := make([]byte, 0)
packet = append(packet, newHeader...)
packet = append(packet, question...)
resolverAddr := &net.UDPAddr{
IP: net.ParseIP(resolverIP),
Port: resolverPort,
}
conn, err := net.DialUDP("udp", nil, resolverAddr)
if err != nil {
fmt.Println("Error connecting to resolver:", err)
break
}
fmt.Println("new connection established")
defer conn.Close()
_, err = conn.Write(packet)
if err != nil {
fmt.Println("Error sending to resolver:", err)
break
}
// conn.SetReadDeadline(time.Now().Add(2 * time.Second))
response := make([]byte, 512)
n, _, err := conn.ReadFromUDP(response)
if err != nil {
fmt.Println("Error reading from resolver:", err)
break
}
fmt.Println("n",response[:n])
answerOffset := 12
questionLen := createQuestionSection(response[answerOffset:])
answerOffset +=len(questionLen)
fmt.Println("answeroffset,n",answerOffset,n)
if answerOffset < n {
answer := response[answerOffset:n]
if len(answer) > 0 {
fmt.Printf("Found answer of length %d\n", len(answer))
totalAnswers = append(totalAnswers, answer)
}
}
}
fmt.Println("total answers", totalAnswers)
return totalAnswers
}
