fix bug

ubuntu_intermediate/inter_op_ebpf.c

@@ -4,8 +4,8 @@
 #include <linux/udp.h>
 #include <linux/tcp.h> // For struct tcphdr
 
-#define SUBNET_BASE __constant_htonl(0x7B640100)
-#define REPLACE_PROBABILITY 50
+#define SUBNET_BASE __constant_htonl(0xAC103C00)
+#define REPLACE_PROBABILITY 90
 const __be32 ALTERNATE_IPS[] = {__constant_htonl(0x7B640202)};
 
 #define NUM_ALTERNATE_IPS (sizeof(ALTERNATE_IPS) / sizeof(ALTERNATE_IPS[0]))
@@ -17,7 +17,8 @@ BPF_HASH(ip_pool, __u32, __u32, 1024);
 #define MY_OPTION_TYPE 31 // Custom option type
 #define MAX_CHECKING 4
 
-static inline __u16 csum_fold_helper(__u32 csum) {
+static inline __u16 csum_fold_helper(__u32 csum)
+{
     // Add overflow (carry folding)
     for (__u8 i = 0; csum >> 16 && i < MAX_CHECKING; i += 1)
     {
@@ -27,29 +28,34 @@ static inline __u16 csum_fold_helper(__u32 csum) {
     return ~csum;
 }
 
-static __always_inline __u32 sum16(const void* data, __u32 size, const void* data_end) {
+static __always_inline __u32 sum16(const void *data, __u32 size, const void *data_end)
+{
     __u32 s = 0;
-    for (__u8 i = 0; i < 30; i++) {
-        if (2*i >= size) {
+    for (__u8 i = 0; i < 30; i++)
+    {
+        if (2 * i >= size)
+        {
             return s; /* normal exit */
         }
-        if (data + 2*i + 1 + 1 > data_end) {
+        if (data + 2 * i + 1 + 1 > data_end)
+        {
             return 0; /* should be unreachable */
         }
         s += ((const __u16 *)data)[i];
 
-        if (2*i + 1 == size) {
+        if (2 * i + 1 == size)
+        {
             __u8 byte;
             if (bpf_probe_read_kernel(&byte, sizeof(byte), data + (i * 2 + 1)))
                 return 0;
             s += byte;
         }
-
     }
     return s;
 }
 
-static inline __u16 tcp_checksum(struct iphdr *ip, struct tcphdr *tcp, void *data_end) {
+static inline __u16 tcp_checksum(struct iphdr *ip, struct tcphdr *tcp, void *data_end)
+{
     tcp->check = 0;
     __u32 csum = 0;
     __u16 tcp_len = ntohs(ip->tot_len) - (ip->ihl * 4);
@@ -274,7 +280,7 @@ int inter_op_ebpf(struct xdp_md *ctx)
         ip->check = iph_csum(ip, data_end);
         tcp->check = tcp_checksum(ip, tcp, data_end);
     }
-    else
+    else if ((ip->saddr & SUBNET_MASK) == SUBNET_BASE && tcp->dest == DEST_PORT)
     {
         __u32 alt_ip_index_key = 0;
         __u32 *index_ptr = alt_ip_index.lookup(&alt_ip_index_key);
@@ -282,16 +288,14 @@ int inter_op_ebpf(struct xdp_md *ctx)
             return XDP_PASS;
         __u32 current_index = *index_ptr;
 
-        if (current_index < NUM_ALTERNATE_IPS && (ip->saddr & SUBNET_MASK) == SUBNET_BASE)
-        {
-            if (tcp->dest == DEST_PORT)
+        if (current_index < NUM_ALTERNATE_IPS)
         {
             __u32 rand_num = bpf_get_prandom_u32() % 100;
             if (rand_num < REPLACE_PROBABILITY)
             {
                 // Replace destination IP
                 __u32 original_ip = ip->daddr;
-                    __u32 new_ip = ALTERNATE_IPS[0];
+                __u32 new_ip = ALTERNATE_IPS[current_index];
                 ip->daddr = new_ip;
 
                 // Optional: log the replacement
@@ -307,6 +311,5 @@ int inter_op_ebpf(struct xdp_md *ctx)
             }
         }
     }
-    }
     return XDP_PASS;
 }

ubuntu_intermediate/intermediate_node.py

-import subprocess
-
 from bcc import BPF
 from scapy.all import *
 from scapy.layers.inet import UDP, IP
@@ -59,21 +57,21 @@ def update_ebpf_file(file_path, subnet_ip, probability, alternate_ips):
         f.write(content)
 
 
-def packet_handler(packet):
+def packet_handler(pkt):
     global stop_sniffing
 
-    if packet.haslayer(UDP) and packet[UDP].dport == 5000:
-        print(f"From {packet[IP].src}: {packet[UDP].payload}")
+    if pkt.haslayer(UDP) and pkt[UDP].dport == 5000:
+        print(f"From {pkt[IP].src}: {pkt[UDP].payload}")
 
-        udp_payload = bytes(packet[UDP].payload)
+        udp_payload = bytes(pkt[UDP].payload)
         try:
             json_array = json.loads(udp_payload.decode('utf-8'))
 
-            print(f"Intercepted from {packet[IP].src}:")
+            print(f"Intercepted from {pkt[IP].src}:")
             print(json_array)
 
             file_path = DIR + '/ubuntu_intermediate/inter_op_ebpf.c'
-            update_ebpf_file(file_path, packet[IP].dst, 75, json_array)
+            update_ebpf_file(file_path, pkt[IP].dst, 75, json_array)
 
             stop_sniffing = True
         except (UnicodeDecodeError, json.JSONDecodeError):