1

我想知道创建框架后如何发送框架。

我有下一个：

int arp_send(libnet_t *l, int op, u_char *sha, in_addr_t spa, u_char *tha, in_addr_t tpa) {
libnet_ptag_t t; 

if (sha == NULL &&
    (sha = (u_char *)libnet_get_hwaddr(l)) == NULL) {
    return (-1);
}
if (spa == 0) {
    if ((spa = libnet_get_ipaddr4(l)) == -1)
        return (-1);        
}
if (tha == NULL)
    tha = (u_char *)"\xff\xff\xff\xff\xff\xff";

libnet_clear_packet(l);

/*
 *  Build the packet, remmebering that order IS important.  We must
 *  build the packet from lowest protocol type on up as it would
 *  appear on the wire.  So for our ARP packet:
 *
 *  -------------------------------------------
 *  |  Ethernet   |           ARP             |
 *  -------------------------------------------
 *         ^                     ^
 *         |------------------   |
 *  libnet_build_ethernet()--|   |
 *                               |
 *  libnet_build_arp()-----------|
 */

t = libnet_build_arp(
        ARPHRD_ETHER,                           /* hardware addr */
        ETHERTYPE_IP,                           /* protocol addr */
        6,                                      /* hardware addr size */
        4,                                      /* protocol addr size */
        op,                                     /* operation type */
        sha,                                    /* sender hardware addr */
        (u_int8_t *)&spa,                       /* sender protocol addr */
        tha,                                    /* target hardware addr */
        (u_int8_t *)&tpa,                       /* target protocol addr */
        NULL,                                   /* payload */
        0,                                      /* payload size */
        l,                                      /* libnet context */
        0);                                     /* libnet id */

if (t == -1)
{
    fprintf(stderr, "Can't build ARP header: %s\n", libnet_geterror(l));
    return -1;
}

t = libnet_autobuild_ethernet(
        tha,                                    /* ethernet destination */
        ETHERTYPE_ARP,                          /* protocol type */
        l);                                     /* libnet handle */

if (t == -1)
{
    fprintf(stderr, "Can't build ethernet header: %s\n",
            libnet_geterror(l));
    return -1;
}    
return libnet_write(l);

}

我在网上找到了该代码，它从无到有创建了一个 arp 数据包。除了返回之外，我确实了解所有内容，因为我没有找到“发送”命令。

谢谢你。

4

1 回答 1

0

libnet_write() 就是这样做的。

Writes a prebuilt packet to the network. The function assumes that l was
previously initialized (via a call to libnet_init()) and that a
previously constructed packet has been built inside this context (via one or
more calls to the libnet_build* family of functions) and is ready to go.
Depending on how libnet was initialized, the function will write the packet
to the wire either via the raw or link layer interface. The function will
also bump up the internal libnet stat counters which are retrievable via
libnet_stats().
  @param l pointer to a libnet context
  @return the number of bytes written, -1 on error

根据 libnet/libnet-functions.h 中的评论

于 2014-07-11T13:31:24.013 回答