From 575db5fd625ff5eb73305e95a7d19970ed1b2f42 Mon Sep 17 00:00:00 2001
From: Matthias Cramer <cramer@freestone.net>
Date: Fri, 21 Mar 2025 01:06:06 +0100
Subject: [PATCH] Can now handle IPv6 packets, documentation update

---
 README.md | 12 +++++++-----
 main.c    | 51 +++++++++++++++++++++++++++++++++++++++++++--------
 2 files changed, 50 insertions(+), 13 deletions(-)

diff --git a/README.md b/README.md
index 6072437..73d84d3 100644
--- a/README.md
+++ b/README.md
@@ -8,21 +8,23 @@ pcapmirror is a command-line tool for capturing network traffic and mirroring it
 pcapmirror [options]
 ```
 
-Options:
+###Options:
 
 -i <interface>: Specify the capture interface (e.g., eth0).
 -f <filter>: Specify the capture filter in BPF syntax (e.g., tcp port 80).
+-r <ip_address>: Specify the destination IP address (required).
+-p <port>: Specify the destination port (default: 37008).
 -v: Enable verbose mode (prints packet information).
 -h: Show this help message.
-Example:
+
+###Example:
 
 To capture traffic on the eth0 interface, filter for TCP port 80, and send it to the destination, use the following command:
 
 ```bash
-sudo pcapmirror -i eth0 -f "tcp port 80" -v
+sudo pcapmirror -i eth0 -f "tcp port 80" -r 192.168.1.100 -p 47008 -v
 ```
-
-Note: Running pcapmirror typically requires root privileges due to the use of libpcap for capturing network traffic.
+*Note*: Running pcapmirror typically requires root privileges due to the use of libpcap for capturing network traffic.
 
 ## Compile and Install
 
diff --git a/main.c b/main.c
index 95829bb..fe57f15 100644
--- a/main.c
+++ b/main.c
@@ -9,9 +9,16 @@
 #include <netdb.h>
 #include <unistd.h>
 
+#define ENABLE_IPV6
+
+#ifdef ENABLE_IPV6
+#include <netinet/ip6.h> // Include for IPv6 header definition
+#endif
+
 #define DEFAULT_DEST_PORT 37008 // Default TZSP port
 #define TZSP_ENCAP_LEN 4       // Length of TZSP encapsulation header
 #define TZSP_TAGGED_LEN 1      // Length of TZSP tagged field header (type)
+#define ETHERNET_HEADER_LENGTH 14
 
 // TZSP Header Structure
 struct tzsp_header {
@@ -181,8 +188,12 @@ int main(int argc, char *argv[]) {
 
     struct pcap_pkthdr header;
     const u_char *packet;
-    const struct ip *ip_header;
-    char source_ip_str[INET_ADDRSTRLEN], dest_ip_str[INET_ADDRSTRLEN];
+    char source_ip_str[INET6_ADDRSTRLEN], dest_ip_str[INET6_ADDRSTRLEN];
+    struct ip *ip_header;
+#ifdef ENABLE_IPV6
+    struct ip6_hdr *ip6_header;
+#endif
+    int ip_protocol = 0;
 
     printf("Using interface: %s\n", dev_name);
     printf("Using filter: %s\n", filter_exp);
@@ -194,13 +205,37 @@ int main(int argc, char *argv[]) {
         if (packet == NULL)
             continue;
 
-        ip_header = (struct ip*)(packet + 14); // Assuming Ethernet header is 14 bytes
-        inet_ntop(AF_INET, &(ip_header->ip_src), source_ip_str, INET_ADDRSTRLEN);
-        inet_ntop(AF_INET, &(ip_header->ip_dst), dest_ip_str, INET_ADDRSTRLEN);
+        // Assuming Ethernet header is 14 bytes
+        // Check IP version
+        ip_header = (struct ip*)(packet + ETHERNET_HEADER_LENGTH);
+        ip_protocol = ip_header->ip_v;
 
-        if (verbose) {
-            printf("Packet: %s -> %s, IP Protocol: %d\n",
-               source_ip_str, dest_ip_str, ip_header->ip_p);
+        if (ip_protocol == 4) {
+            // IPv4
+            inet_ntop(AF_INET, &(ip_header->ip_src), source_ip_str, INET6_ADDRSTRLEN);
+            inet_ntop(AF_INET, &(ip_header->ip_dst), dest_ip_str, INET6_ADDRSTRLEN);
+
+            if (verbose) {
+                printf("IPv4 Packet: %s -> %s, IP Protocol: %d\n",
+                       source_ip_str, dest_ip_str, ip_header->ip_p);
+            }
+        }
+#ifdef ENABLE_IPV6
+         else if (ip_protocol == 6) {
+            // IPv6
+            ip6_header = (struct ip6_hdr*)(packet + ETHERNET_HEADER_LENGTH);
+            inet_ntop(AF_INET6, &(ip6_header->ip6_src), source_ip_str, INET6_ADDRSTRLEN);
+            inet_ntop(AF_INET6, &(ip6_header->ip6_dst), dest_ip_str, INET6_ADDRSTRLEN);
+
+            if (verbose) {
+                printf("IPv6 Packet: %s -> %s, Next Header: %d\n",
+                       source_ip_str, dest_ip_str, ip6_header->ip6_nxt);
+            }
+        }
+#endif
+         else {
+            printf("Non-IP Packet\n");
+            continue;
         }
 
         // Create TZSP Header