From fb2a0ca4c3de6e06c8cc8041afe69859a71fb854 Mon Sep 17 00:00:00 2001
From: Tristan Smith <tristan.smith@pm.me>
Date: Mon, 26 Aug 2024 00:01:34 -0400
Subject: [PATCH] first commit

---
 main.c    | 120 ++++++++++++++++++++++++++++++++++++++++++++++++++++++
 readme.md |   5 +++
 2 files changed, 125 insertions(+)
 create mode 100644 main.c
 create mode 100644 readme.md

diff --git a/main.c b/main.c
new file mode 100644
index 0000000..cd19a8c
--- /dev/null
+++ b/main.c
@@ -0,0 +1,120 @@
+#include <arpa/inet.h>
+#include <netinet/if_ether.h>
+#include <netinet/ip.h>
+#include <netinet/udp.h>
+#include <pcap.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+
+#define SOURCE_PORT 14236
+#define DEST_PORT 14235
+
+char* ether_ntoa(const struct ether_addr* addr)
+{
+    static char buf[18];
+    snprintf(buf, sizeof(buf), "%02x:%02x:%02x:%02x:%02x:%02x",
+        addr->ether_addr_octet[0], addr->ether_addr_octet[1],
+        addr->ether_addr_octet[2], addr->ether_addr_octet[3],
+        addr->ether_addr_octet[4], addr->ether_addr_octet[5]);
+    return buf;
+}
+
+void packet_handler(unsigned char* user, const struct pcap_pkthdr* h, const unsigned char* bytes)
+{
+    struct ether_header* eth_header;
+    struct ip* ip_header;
+    struct udphdr* udp_header;
+
+    eth_header = (struct ether_header*)bytes;
+
+    // Check if the packet is an IP packet
+    if (ntohs(eth_header->ether_type) == ETHERTYPE_IP) {
+        ip_header = (struct ip*)(bytes + sizeof(struct ether_header));
+
+        // Check if the packet is a UDP packet
+        if (ip_header->ip_p == IPPROTO_UDP) {
+            udp_header = (struct udphdr*)(bytes + sizeof(struct ether_header) + sizeof(struct ip));
+
+            // Convert IP addresses from network byte order to text
+            char source_ip[INET_ADDRSTRLEN];
+            char dest_ip[INET_ADDRSTRLEN];
+            inet_ntop(AF_INET, &(ip_header->ip_src), source_ip, INET_ADDRSTRLEN);
+            inet_ntop(AF_INET, &(ip_header->ip_dst), dest_ip, INET_ADDRSTRLEN);
+
+            // Check if the destination IP address and UDP ports match
+            if (strcmp(dest_ip, "255.255.255.255") == 0 && ntohs(udp_header->source) == SOURCE_PORT && ntohs(udp_header->dest) == DEST_PORT) {
+
+                // Convert MAC address to readable format
+                char source_mac[18];
+                snprintf(source_mac, sizeof(source_mac), "%s", ether_ntoa((struct ether_addr*)eth_header->ether_shost));
+
+                // Print the extracted information
+                printf("Miner IP: %s\n", source_ip);
+                printf("Source MAC Address: %s\n", source_mac);
+                printf("----------------------------------------\n");
+            }
+        }
+    }
+}
+
+char* get_default_interface()
+{
+    pcap_if_t *alldevs, *d;
+    char errbuf[PCAP_ERRBUF_SIZE];
+    char* dev = NULL;
+
+    if (pcap_findalldevs(&alldevs, errbuf) == -1) {
+        fprintf(stderr, "Error finding devices: %s\n", errbuf);
+        return NULL;
+    }
+
+    // Find the first interface that is up
+    for (d = alldevs; d != NULL; d = d->next) {
+        if (d->flags & PCAP_IF_UP) {
+            dev = strdup(d->name); // Duplicate the interface name
+            break;
+        }
+    }
+
+    pcap_freealldevs(alldevs); // Free the device list
+
+    if (dev == NULL) {
+        fprintf(stderr, "No suitable device found\n");
+        return NULL;
+    }
+
+    return dev;
+}
+
+int main()
+{
+    char errbuf[PCAP_ERRBUF_SIZE];
+    pcap_t* handle;
+    char* dev = get_default_interface();
+
+    if (dev == NULL) {
+        return 2; // No suitable device found
+    }
+
+    printf("Using device: %s\n", dev);
+
+    // Open the device for capturing
+    handle = pcap_open_live(dev, BUFSIZ, 1, 1000, errbuf);
+    free(dev); // Free the duplicated device name string
+
+    if (handle == NULL) {
+        fprintf(stderr, "Could not open device: %s\n", errbuf);
+        return 2;
+    }
+
+    printf("Listening...\n");
+
+    // Start the packet capture loop
+    pcap_loop(handle, 0, packet_handler, NULL);
+
+    // Close the capture handle
+    pcap_close(handle);
+
+    return 0;
+}
diff --git a/readme.md b/readme.md
new file mode 100644
index 0000000..11dd9cd
--- /dev/null
+++ b/readme.md
@@ -0,0 +1,5 @@
+## IP reporter but in C
+
+I'm starting to look at programming languages like vehicles. The older ones are much simpler and easier to hack around on, but this is probably not as 'safe' as a language like Rust. I'm generally in favor of *most* safety features they put on cars, but, speaking as a former mechanic, I can't say I agreed with all of them. 
+
+I think this may be similar to the arguments over languages like C/C++ vs Rust and Zig.