working dns map write

netfoundry · Dec 5, 2023 · f769850 · f769850
1 parent 4b62ecd
commit f769850
Showing 1 changed file with 23 additions and 17 deletions.
diff --git a/src/zfw_xdp_dns_filter.c b/src/zfw_xdp_dns_filter.c
@@ -66,6 +66,25 @@ struct dns_resource_record {
     __uint8_t ipaddr[4];
 };
 
+static inline int set_dns(int index, void *dns_question){
+    struct dns_name_struct *dns_name = NULL;
+    dns_name = bpf_map_lookup_elem(&dns_map, &index);
+    long answer = 0;
+    if(dns_name){
+        answer = bpf_probe_read_kernel_str((void *)&dns_name->dns_name, sizeof(dns_name->dns_name), dns_question);
+	bpf_printk("answer=%ld",answer);
+        if (answer > 0) {
+            for(int x = 0; x < answer; x++){
+	       bpf_printk(":%c", dns_name->dns_name[x]);	    
+	    }
+	}
+    }else{
+	bpf_printk("no map entry found");
+    }
+    return answer;
+}
+
+
 SEC("xdp")
 int xdp_filter(struct xdp_md *ctx) {
 
@@ -111,7 +130,6 @@ int xdp_filter(struct xdp_md *ctx) {
 
     int max_question_count = 1;
     __u8 dns_name_len = 0;
-    struct dns_name_struct *dns_name = NULL;
     if ((dnsh->qdcount != 0) && (dnsh->ancount == 0) && (dnsh->nscount == 0) && (dnsh->arcount == 0)) {
         for (int i = 0; i < max_question_count; i++) {
             for (int j = 0; j < 255; j++) {
@@ -123,23 +141,11 @@ int xdp_filter(struct xdp_md *ctx) {
                     break;
                 }
             }
-            bpf_printk("completed %d ", dns_name_len);
-//            for (int j = 0; j < dns_name_len; j++) {
-//                bpf_printk("dns name is %c ", *(dns_payload + j));
-//            }
-//            bpf_map_update_elem(&dns_map, &i, &dns_payload,0);
-//            memcpy(&dns_map,&dns_payload,dns_name_len);
-//            bpf_printk("completed2 %d ", dns_name_len);
-            dns_name = bpf_map_lookup_elem(&dns_map, &i);
-            if(dns_name){
-                long anwser = bpf_probe_read_kernel_str(&dns_name->dns_name, 2, dns_payload);
-                if (!anwser) {
-                    return XDP_PASS;
-                }
+            long ret = set_dns(i, dns_payload);
+            if (ret < 0){
+               bpf_printk("wrote %d characters", ret);
             }
-            return XDP_PASS;
-
-            bpf_printk("completed2 %d ", dns_name_len);
+            dns_payload = (dns_payload + dns_name_len + 4);
         }
     }
     return XDP_PASS;