Update project

src/common.h

@@ -30,12 +30,14 @@ struct event {
     char qname[QNAME_SIZE];
     uint16_t class;
     uint16_t type;
-    uint32_t ans;
+    uint32_t ans[5];
+    uint16_t numAns;
     uint32_t ttl;
 };
 
 struct query_section{
     char qname[QNAME_SIZE];
+    size_t qname_len;
     uint16_t class;
     uint16_t type;
 };

src/dns-trace.c

@@ -217,16 +217,17 @@ int handle_event(void *ctx, void *data, size_t data_sz){
     printf("%-30s", s_event->qname);
 
     class = mapClass(s_event->class);
-    printf("%-10s", class);
+    printf("%-5s", class);
     free(class);
 
     type = mapType(s_event->type);
-    printf("%-10s", type);
+    printf("%-5s", type);
     free(type);
 
     if (s_event->req_type == REQ_ANSWER){
-        printf("%-15s", inet_ntoa(*(struct in_addr*)&s_event->ans));
-        printf("%-5d", s_event->ttl);
+        for (int i = 0; i < s_event->numAns; i++)
+            printf("%s ", inet_ntoa(*(struct in_addr*)&s_event->ans[i]));
+        printf("%5d", s_event->ttl);
     }
 
 

src/dns-trace.ebpf.c

@@ -55,6 +55,7 @@ static size_t get_labels2(struct __sk_buff *skb, size_t offset, struct event *s_
     }
     s_event->qname[qname_len - 1] = '\0';
     qname_len++;
+    // dquery->qname_len = qname_len;
     // bpf_printk("qname: %s", s_event->qname);
     // bpf_printk("qname len: %d", qname_len);
     return qname_len;
@@ -117,7 +118,7 @@ static size_t get_query_section(struct __sk_buff *skb, struct event *s_event, ui
 
     return len;
 }
-static size_t get_answer(struct __sk_buff *skb, struct event *s_event, size_t tlen){
+static size_t get_answer(struct __sk_buff *skb, struct event *s_event, size_t tlen, int index){
     size_t len = 0;
     unsigned char buf[25] = {0}; // Need to be unsigned, otherwise, the result is fffff
 
@@ -148,30 +149,37 @@ static size_t get_answer(struct __sk_buff *skb, struct event *s_event, size_t tl
         // Get the class and type
         uint16_t type, class;
         uint32_t ttl;
-        bpf_printk("offset: %d", tlen);
+        // bpf_printk("offset: %d", tlen);
         bpf_skb_load_bytes(skb, tlen, &type, sizeof(uint16_t));
-        bpf_printk("type: %d", ntohs(type));
         tlen += 2;
-        bpf_printk("offset: %d", tlen);
+        // bpf_printk("offset: %d", tlen);
         bpf_skb_load_bytes(skb, tlen, &class, sizeof(uint16_t));
         tlen += 4;
-        bpf_printk("offset: %d", tlen);
-        bpf_printk("class %d", ntohs(class));
+        // bpf_printk("offset: %d", tlen);
         // Get ttl
         bpf_skb_load_bytes(skb, tlen, &ttl, sizeof(uint32_t));
         tlen += 2;
-        bpf_printk("offset: %d", tlen);
+        // bpf_printk("offset: %d", tlen);
         s_event->ttl = ntohs(ttl);
 
         // Get data size
         uint16_t size;
         bpf_skb_load_bytes(skb, tlen, &size, sizeof(uint16_t));
-        bpf_printk("size: %d", ntohs(size));
+        // bpf_printk("size: %d", ntohs(size));
         tlen += 2;
 
+        // if class is A, we push to an ipv4 map
+
+        // if class is AAAA, we push to an ipv6 map
+
+        // if class is SOa, we push to an soa map
+
+        // etc...
+
         uint32_t data;
         bpf_skb_load_bytes(skb, tlen, &data, sizeof(uint32_t));
-        s_event->ans = data;
+        s_event->ans[index] = data;
+
     }
     else {
         // get_labels2(skb, sizeof(struct ethhdr) + sizeof(struct iphdr) + sizeof(struct udphdr) + sizeof(struct dnshdr), s_event);
@@ -307,7 +315,7 @@ static void dnsanswer(struct __sk_buff *skb, struct iphdr ip, struct udphdr udp,
 
     /* Get answer section */
     uint16_t ans = ntohs(dns.nbAnswerRRs);
-    if (ans < 0){
+    if (ans <= 0){
         bpf_ringbuf_discard(s_event, 0);
         return;
     }
@@ -315,15 +323,18 @@ static void dnsanswer(struct __sk_buff *skb, struct iphdr ip, struct udphdr udp,
     if (ntohs(dns.nbAnswerRRs) > 0){
         /*
          * We get a least the 5 last answer
-         * In the RFC 1035 (https://datatracker.ietf.org/doc/html/rfc1035#section-4.2.1) the max udp payload is 512 bytes
+         * In the RFC 1035 (https://datatracker.ietf.org/doc/html/rfc1035#section-2.3.4) the max udp payload is 512 bytes
          * The program limit te size of the answer
          */
         offset += sizeof(struct dnshdr) + query_len; // For the pos in the answer section in the skb
-        for (uint16_t i = 0; i < ans; i++){
-            get_answer(skb, s_event, offset);
+        uint16_t i;
+        for (i = 0; i < ans; i++){
+            get_answer(skb, s_event, offset, i);
+            // For eBPF verifier, to be sure we leave the loop
             if (i == ans || i == 5)
                 break;
         }
+        s_event->numAns = i;
     }
     if (ntohs(dns.nbAuthorityRRs) > 0){