driver.c

#include "buf.h"
#include "config.h"

#include <pcap.h>
#include <string.h>
#include <utils.h>

static pcap_t *pcap;
static pcap_dumper_t *pdump;
static char pcap_errbuf[PCAP_ERRBUF_SIZE];
extern FILE *pcap_in;
extern FILE *pcap_out;
extern FILE *control_flow;

#ifdef _WIN32
#include <tchar.h>
BOOL LoadNpcapDlls() {
    _TCHAR npcap_dir[512];
    UINT len;
    len = GetSystemDirectory(npcap_dir, 480);
    if (!len) {
        fprintf(stderr, "Error in GetSystemDirectory: %lx", GetLastError());
        return FALSE;
    }
    _tcscat_s(npcap_dir, 512, _T("\\Npcap"));
    if (SetDllDirectory(npcap_dir) == 0) {
        fprintf(stderr, "Error in SetDllDirectory: %lx", GetLastError());
        return FALSE;
    }
    return TRUE;
}
#endif

int driver_open() {
#ifdef _WIN32
    /* Load Npcap and its functions. */
    if (!LoadNpcapDlls()) {
        fprintf(stderr, "Couldn't load Npcap\n");
        return -1;
    }
#endif
    pcap = pcap_fopen_offline(pcap_in, pcap_errbuf);
    if (pcap == NULL) {
        fprintf(stderr, "pcap_open_offline() failed:%s\n", pcap_errbuf);
        return -1;
    }

    pdump = pcap_dump_fopen(pcap, pcap_out);
    if (pdump == NULL) {
        fprintf(stderr, "pcap_dump_fopen() failed:%s\n", pcap_geterr(pcap));
        return -1;
    }

    fprintf(control_flow, "driver opened\n");
    return 0;
}

int driver_recv(buf_t *buf) {
    struct pcap_pkthdr *pkt_hdr;
    const uint8_t *pkt_data;
    int ret = pcap_next_ex(pcap, &pkt_hdr, &pkt_data);
    if (ret == PCAP_ERROR_BREAK) {
        // printf("meet end of file\n");
        return 0;
    } else if (ret == 1) {
        buf_init(buf, pkt_hdr->len);
        memcpy(buf->data, pkt_data, pkt_hdr->len);
        return pkt_hdr->len;
    } else {
        fprintf(stderr, "Error in driver_recv: %s\n", pcap_geterr(pcap));
        return -1;
    }
}

int driver_send(buf_t *buf) {
    struct pcap_pkthdr header;
    memset(&header.ts, 0, sizeof(header.ts));
    header.caplen = buf->len;
    header.len = buf->len;
    pcap_dump((u_char *)pdump, &header, buf->data);
    return 0;
}

void driver_close() {
    fprintf(control_flow, "\ndriver closed\n");
    pcap_dump_close(pdump);
    pcap_close(pcap);
}