Add pcap file reader for testing netflow and sFLOW partser

tests/pcap_reader.cpp

@@ -0,0 +1,82 @@
+#include <stdio.h>
+#include <iostream>
+#include <pcap.h>
+#include <unistd.h>
+#include <fcntl.h>
+#include <sys/types.h>
+#include <sys/stat.h>
+
+
+/* 
+   pcap dump format:
+    global header: struct pcap_file_header
+    packet header: struct pcap_pkthdr
+
+
+
+*/
+int pcap_reader(const char* pcap_file_path) {
+    int filedesc = open(pcap_file_path, O_RDONLY);
+
+    if (filedesc <= 0) {
+        printf("Can't open dump file");
+        return -1;
+    } 
+
+    struct pcap_file_header pcap_header;
+    ssize_t file_header_readed_bytes = read(filedesc, &pcap_header, sizeof(struct pcap_file_header));
+
+    if (file_header_readed_bytes != sizeof(struct pcap_file_header)) {
+        printf("Can't read pcap file header");
+    }
+
+    // http://www.tcpdump.org/manpages/pcap-savefile.5.html
+    if (pcap_header.magic == 0xa1b2c3d4 or pcap_header.magic == 0xd4c3b2a1) {
+        // printf("Magic readed correctly\n");
+    } else {
+        printf("Magic in file header broken\n");
+        return -2;
+    }
+
+    // Buffer for packets
+    int buffer_size = 1024*1024;
+    char packet_bufer[buffer_size];
+
+    unsigned int read_packets = 0; 
+    while (1) {
+        struct pcap_pkthdr pcap_packet_header;
+        ssize_t packet_header_readed_bytes = read(filedesc, &pcap_packet_header, sizeof(struct pcap_pkthdr));
+      
+        if (packet_header_readed_bytes != sizeof(struct pcap_pkthdr)) {
+            // We haven't any packets 
+            break;
+        }
+
+        printf("packet header read. snap len: %d bytes\n", pcap_packet_header.caplen);
+
+        if (pcap_packet_header.caplen > buffer_size) {
+            printf("Please enlarge packet buffer! We got packet with size: %d but our buffer is %d bytes\n",
+                pcap_packet_header.caplen, buffer_size);
+            return -4;
+        }
+
+        ssize_t packet_payload_readed_bytes = read(filedesc, packet_bufer, pcap_packet_header.caplen);
+ 
+        if (pcap_packet_header.caplen != packet_payload_readed_bytes) {
+            printf("I read packet header but can't read packet payload\n");
+            return -3;
+        }
+
+        printf("packet payload read\n");
+        
+        read_packets++;
+    }
+
+    printf("I correctly read %d packets from this dump\n", read_packets);
+
+    return 0;
+}
+
+int main() {
+    pcap_reader("/Users/pavel-odintsov/Dropbox/ipfix_example_ipt_netflow_syn_flood.pcap");
+}