feat: yeah lots of things

npcap.c

@@ -0,0 +1,124 @@
+//
+// Created by ako on 8/22/25.
+//
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <unistd.h>
+#include <sys/socket.h>
+#include <arpa/inet.h>
+#include <netinet/ip.h>
+#include <netinet/if_ether.h>
+#include <netpacket/packet.h>
+#include <net/ethernet.h>
+#include <errno.h>
+#include "nethdr.h"
+#include "npcap_handle.h"
+#include <netpacket/packet.h>
+#include <net/if.h> // if_nametoindex()
+
+void cleanup(int socket, unsigned char* buffer) {
+    close(socket);
+    free(buffer);
+}
+
+int main()
+{
+    if (geteuid() != 0)
+    {
+        printf("Please run me as root.\n");
+        return 1;
+    }
+
+    int sock_raw = socket(AF_PACKET, SOCK_RAW, htons(ETH_P_ALL));
+    if (sock_raw < 0)
+    {
+        fprintf(stderr, "Unable to connect to network socket.\n");
+        return -1;
+    }
+
+    unsigned char *buffer = (unsigned char *) calloc(65536, sizeof(unsigned char));
+
+    if (buffer == NULL) {
+        fprintf(stderr, "Unable to connect to allocate memory.\n");
+        cleanup(sock_raw, buffer);
+        return 1;
+    }
+
+    struct sockaddr_ll sourceaddr;
+    socklen_t sourceaddr_len = sizeof(sourceaddr);
+
+    int loopback_ifindex = if_nametoindex("lo");
+    if (loopback_ifindex == 0) {
+        perror("if_nametoindex for lo");
+        cleanup(sock_raw, buffer);
+        return 1;
+    }
+
+    while (1) {
+        ssize_t buflen = recvfrom(sock_raw, buffer, 65536, 0, (struct sockaddr *)&sourceaddr, &sourceaddr_len);
+
+        if (buflen == -1) {
+            perror("Couldn't read from socket");
+            cleanup(sock_raw, buffer);
+            return 1;
+        }
+
+        if (sourceaddr.sll_ifindex == loopback_ifindex) {
+            continue;
+        }
+        printf("\n===== Paquet reçu =====\n");
+        printf("Paquet de %ld octets\n", buflen);
+
+        // Debug
+        printf("Hexdump des 32 premiers octets:\n");
+        for (int i = 0; i < 32 && i < buflen; i++) {
+            printf("%02x ", buffer[i]);
+            if ((i + 1) % 8 == 0) printf("  ");
+        }
+        printf("\n");
+
+        //
+        // COUCHE 2
+        //
+        // Décodage entête Ethernet
+        struct ethhdr *eth = (struct ethhdr *)buffer;
+        handle_eth(eth);
+
+
+        //
+        // COUCHE 3
+        //
+        switch (ntohs(eth->h_proto)) 
+        {
+            // Décodage entête ARP
+            case ETH_P_ARP:
+                struct arphdr_c *arp = (struct arphdr_c *) (buffer + sizeof(struct ethhdr));
+                handle_arp(arp);
+                break;
+
+            case ETH_P_IP:
+                struct iphdr *ip = (struct iphdr *) (buffer + sizeof(struct ethhdr));
+                handle_ip(ip);
+
+                switch (ip->protocol) {
+                    case 0x01:
+                        handle_icmp();
+                        break;
+                    case 0x06:
+                        handle_tcp();
+                        break;
+                    case 0x11:
+                        handle_udp();
+                        break;
+                    default:
+                        break;
+                }
+                
+                break;
+        }
+
+        // printf("\n=======================\n");
+    }
+    cleanup(sock_raw, buffer);
+}