去年12月搭建了guacamole实现了网页方式rdp，rdp对象是跑在虚拟机里的win10，最近发现如果用物理机当rdp client时，如果物理机休眠了，rdp就不可能起作用了。

有些网友说win10支持局域网读写访问时自动唤醒机器，具体方法搜了下，一堆不知所云的东西，主板bios里也翻了一遍，调整了几个参数也没有效果

偶然发现，我这块主板（ga h110tn-e）居然不支持WOL发魔术包的方式唤醒，必须用ether-wake包，这点从google paly上下载的wake-on-lan apk和openwrt上的luci app上都得到了证实

既然是这样，只能曲线救国了，rdp之前先想办法局域网唤醒

查看了guacamole文档，是支持wol的，这样就省了不少事，配置相关参数后，不出意外，wol无法唤醒我这块主板，配置文件如下：

下一步就是为guacamole添加ether-wake功能

参考了busybox中的代码，很容易就添加了ether-wake函数，代码如下：

guacamole-server\src\libguac\wol.c


#include <netinet/ether.h>
#include <linux/if.h>
#include <netpacket/packet.h>
#include <sys/ioctl.h>

/**
 * Generate the WoL ether wake packet for the specified MAC address
 * and place it in the character array.
 * 
 * @param packet
 *     The character array that will contain the generated packet.
 * 
 * @param mac_address
 *     The unsigned int representation of the MAC address to place in the packet.
 */
 
static void __guac_ether_wake_create_magic_packet(unsigned char packet[],
        unsigned int mac_address[]) {
    
    int i;
    unsigned char mac[6];
    
    /* Concurrently fill the first part of the packet with 0xFF, and copy the
     MAC address from the int array to the char array. */
    for (i = 0; i < 6; i++) {
        mac[i] = mac_address[i];
    }
    
    /* Copy the MAC address contents into the char array that is storing
     the first 12 byte packet. */
    for (i = 0; i < 2; i++) {
        memcpy(&packet[i * 6], &mac, 6 * sizeof(unsigned char));
    }
    
    unsigned char* pkt = packet;
    pkt += 12;

    *pkt++ = 0x08; /* 12 */ /* Or 0x0806 for ARP, 0x8035 for RARP */
    *pkt++ = 0x42; /* 13 */
    
    memset(pkt, 0xff, 6); /* 14 */
    
    for (i = 0; i < 16; ++i) {
        pkt += 6;
        memcpy(pkt, &mac, 6); /* 20,26,32,... */
    }
}


static ssize_t __guac_ether_wake_send_packet(unsigned char packet[],const char *ifname) {
    struct sockaddr_ll wol_dest;
    int wol_socket;

    /* Set up the socket */
    wol_socket = socket(PF_PACKET, SOCK_RAW, 0);
    
    /* If socket open fails, bail out. */
    if (wol_socket < 0) {
        guac_error = GUAC_STATUS_SEE_ERRNO;
        guac_error_message = "Failed to open socket to send WOL:ether-wake packet";
        return 0;
    }
    

    memset(&wol_dest, 0, sizeof(wol_dest));
    wol_dest.sll_family = AF_PACKET;
    struct ifreq ifr;
    strcpy(ifr.ifr_name, ifname);
    ioctl(wol_socket, SIOCGIFINDEX, &ifr);
    wol_dest.sll_ifindex = ifr.ifr_ifindex;
    /* The manual page incorrectly claims the address must be filled.
           We do so because the code may change to match the docs. */
    wol_dest.sll_halen = ETH_ALEN;
    memcpy(wol_dest.sll_addr, packet, ETH_ALEN);
        
    /* Send the packet and return number of bytes sent. */
    int bytes = sendto(wol_socket, packet, GUAC_ETHER_WAKE_PACKET_SIZE, 0,
            (struct sockaddr*) &wol_dest, sizeof(wol_dest));
    close(wol_socket);
    return bytes;
}

int guac_ether_wake(const char* mac_addr, const char* if_name) {
    
    unsigned char ether_wake_packet[GUAC_ETHER_WAKE_PACKET_SIZE];
    unsigned int dest_mac[6];
    
    /* Parse mac address and return with error if parsing fails. */
    if (sscanf(mac_addr, "%x:%x:%x:%x:%x:%x",
            &(dest_mac[0]), &(dest_mac[1]), &(dest_mac[2]),
            &(dest_mac[3]), &(dest_mac[4]), &(dest_mac[5])) != 6) {
        guac_error = GUAC_STATUS_INVALID_ARGUMENT;
        guac_error_message = "Invalid argument for WOL:ether-wake MAC address";
        return -1;
    }
    
    /* Generate the magic packet. */
    __guac_ether_wake_create_magic_packet(ether_wake_packet, dest_mac);
    
    /* Send the packet and record bytes sent. */
    int bytes_sent = __guac_ether_wake_send_packet(ether_wake_packet, if_name);
    
    /* Return 0 if bytes were sent, otherwise return an error. */
    if (bytes_sent)
        return 0;
    
    return -1;
}

如上是核心的几个构造和发socke包函数，剩下的就是把guac_ether_wake函数添加到rdp.c中，这样在网页中点击rdp设备前就能优先发wol包唤醒设备了。

guac_ether_wake函数需要指定网卡名称，所以增加了一个rdp的配置参数，允许用户自定义网卡名字，效果如下

最后说明下，为了保证唤醒成功，没有移除原有的magic package，相当于ether-wake和magic package同时发送，确保唤醒成功