c++ - 无法使用 pcap_findalldevs 获取 ip 地址

Question

我正在使用 pcap_findalldevs 获取计算机中的设备列表。我成功地获得了它，包括设备名称和描述，但我不知道为什么，我得到的网络掩码是 0.0.0.0，IP 地址也是 0.0.0.0。 这是我生成列表的代码:

/* get the devices list */
if (pcap_findalldevs(&devList, errbuf) == -1)
{
    fprintf(stderr, "There is a problem with pcap_findalldevs: %s\n", errbuf);
    return -1;
}

/* scan the list for a suitable device to capture from */
for (dev = devList; dev != NULL; dev = dev->next)
{

    pcap_addr_t *dev_addr; //interface address that used by pcap_findalldevs()

    /* check if the device captureble*/
    if ((dev_addr = dev->addresses) != NULL && dev_addr->addr->sa_family == AF_INET && dev_addr->addr && dev_addr->netmask) {
        printf("Found a device %s on address %s with netmask %s\n", dev->name, iptos(((struct sockaddr_in *)dev_addr->addr)->sin_addr.s_addr), iptos(((struct sockaddr_in *)dev_addr->netmask)->sin_addr.s_addr));
        break;
    }
}

Answer 1

这是您应该做的:

/* get the devices list */
if (pcap_findalldevs(&devList, errbuf) == -1)
{
    fprintf(stderr, "There is a problem with pcap_findalldevs: %s\n", errbuf);
    return -1;
}

/* scan the list for a suitable device to capture from */
for (dev = devList; dev != NULL; dev = dev->next)
{

    pcap_addr_t *dev_addr; //interface address that used by pcap_findalldevs()

    /* check if the device captureble*/
    for (dev_addr = dev->addresses; dev_addr != NULL; dev_addr = dev_addr->next) {
        if (dev_addr->addr->sa_family == AF_INET && dev_addr->addr && dev_addr->netmask) {
            printf("Found a device %s on address %s with netmask %s\n", dev->name, iptos(((struct sockaddr_in *)dev_addr->addr)->sin_addr.s_addr), iptos(((struct sockaddr_in *)dev_addr->netmask)->sin_addr.s_addr));
            goto found;
        }
    }
}

found:

这样，您就可以检查整个 地址列表，而不仅仅是列表中的第一个地址。如果，当你到达found时，dev是非空的，它指向一个至少有一个IPv4地址的设备，而dev_addr指向那个地址。如果 dev 为 null，则没有具有 IPv4 地址的设备。