2 files changed, 99 insertions, 0 deletions

@@ -0,0 +1,19 @@
+# Generating 802.11 Beacons
+This example shows the reader how to generate an 802.11 Beacon, with an SSID and Channel element. It also adds a tagged parameter with the string "libwifi-tag" inside.
+
+# Building and Using
+```
+>> cd examples/generate_beacon/
+>> make
+clang -Wall -Werror -O3 -o generate_beacon   -c -o generate_beacon.o generate_beacon.c
+clang -Wall -Werror -O3 -o generate_beacon generate_beacon.c -lpcap -lwifi
+>> ./generate_beacon --file beacon.pcap
+[+] Setup Complete
+[*] Creating Beacon Frame
+[*] Writing Beacon Frame to pcap
+>> tshark -r beacon.pcap 
+    1   0.000000 ca:38:6d:6d:3f:bd → Broadcast    802.11 78 Beacon frame, SN=1383, FN=0, Flags=........, BI=100, SSID=libwifi-beacon
+>>
+```
+# Output
+![image](https://user-images.githubusercontent.com/4153572/143600844-ce7dee11-46b0-40a5-a12c-881d79bd584d.png)
@@ -0,0 +1,80 @@
+#include <libwifi.h>
+
+#include <pcap.h>
+
+#include <bits/types/struct_timeval.h>
+#include <stddef.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <sys/time.h>
+
+pcap_dumper_t *filedumper = NULL;
+
+void create_write_beacon() {
+    printf("[*] Creating Beacon Frame\n");
+    struct libwifi_beacon beacon = {0};
+    unsigned char transmitter[6] = {0};
+
+    libwifi_random_mac(transmitter);
+    unsigned char receiver[6] = "\xFF\xFF\xFF\xFF\xFF\xFF";
+
+    libwifi_create_beacon(&beacon, receiver, transmitter, "libwifi-beacon", 6);
+    libwifi_quick_add_tag(&beacon.tags, TAG_VENDOR_SPECIFIC,
+                         (unsigned char *) "libwifi-tag", strlen("libwifi-tag"));
+
+    unsigned char *buf = NULL;
+    size_t buf_len = libwifi_get_beacon_length(&beacon);
+    buf = malloc(buf_len);
+    if (buf == NULL) {
+        fprintf(stderr, "[!] Couldn't allocate buffer for beacon dump.\n");
+        exit(EXIT_FAILURE);
+    }
+    memset(buf, 0, buf_len);
+    libwifi_dump_beacon(&beacon, buf, buf_len);
+
+    printf("[*] Writing Beacon Frame to pcap\n");
+    struct pcap_pkthdr pkt_hdr = {0};
+    struct timeval tv = {0};
+    pkt_hdr.caplen = buf_len;
+    pkt_hdr.len = buf_len;
+    gettimeofday(&tv, NULL);
+    pkt_hdr.ts = tv;
+    pcap_dump((unsigned char *) filedumper, &pkt_hdr, buf);
+}
+
+void helpexit() {
+    fprintf(stderr, "[!] Usage: ./generate_beacon --file <file.pcap>\n");
+    exit(EXIT_FAILURE);
+}
+
+int main(int argc, char **argv) {
+    pcap_t *handle = NULL;
+    char errbuf[PCAP_ERRBUF_SIZE] = {0};
+    FILE *pcapfile = NULL;
+
+    if (argc < 2) {
+        helpexit();
+    }
+    if (strcmp(argv[1], "--file") == 0) {
+        pcapfile = fopen(argv[2], "w+");
+        if ((handle = pcap_open_dead(DLT_IEEE802_11, BUFSIZ)) == NULL) {
+            fprintf(stderr, "[!] Error opening dead capture (%s)\n", errbuf);
+            exit(EXIT_FAILURE);
+        }
+        if ((filedumper = pcap_dump_fopen(handle, pcapfile)) == NULL) {
+            fprintf(stderr, "[!] Error opening file %s (%s)\n", argv[2], errbuf);
+            exit(EXIT_FAILURE);
+        }
+    } else {
+        helpexit();
+    }
+
+    printf("[+] Setup Complete\n");
+
+    create_write_beacon();
+
+    pcap_dump_close(filedumper);
+    pcap_close(handle);
+    return 0;
+}