libuv-udp-dhcp

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libuv udp dhcp example

更新記錄

item note
20160517 第一版

目錄

libuv udp dhcp example

範例說明

  • 參考來源
  • User Datagram Protocol 提供了无连接, 不可靠网络通信协议, 因此 libuv 并不提供流式 UDP 服务
  • 是通过 uv_udp_t 结构体(用于接收)和 uv_udp_send_t 结构体(用于发送)以及相关的函数给开发人员提供了非阻塞的 UDP 服务
  • source code
  • wireshark raw data

範例內容

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int main() {
    loop = uv_default_loop();

    uv_udp_init(loop, &recv_socket);
    struct sockaddr_in recv_addr;
    uv_ip4_addr("0.0.0.0", 68, &recv_addr);
    uv_udp_bind(&recv_socket, (const struct sockaddr *)&recv_addr, UV_UDP_REUSEADDR);
    uv_udp_recv_start(&recv_socket, alloc_buffer, on_read);

    uv_udp_init(loop, &send_socket);
    struct sockaddr_in broadcast_addr;
    uv_ip4_addr("0.0.0.0", 0, &broadcast_addr);
    uv_udp_bind(&send_socket, (const struct sockaddr *)&broadcast_addr, 0);
    uv_udp_set_broadcast(&send_socket, 1);

    uv_udp_send_t send_req;
    uv_buf_t discover_msg = make_discover_msg();

    struct sockaddr_in send_addr;
    uv_ip4_addr("255.255.255.255", 67, &send_addr);
    uv_udp_send(&send_req, &send_socket, &discover_msg, 1, (const struct sockaddr *)&send_addr, on_send);

    return uv_run(loop, UV_RUN_DEFAULT);
}

send data

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uv_buf_t make_discover_msg() {
    uv_buf_t buffer;
    alloc_buffer(NULL, 256, &buffer);
    memset(buffer.base, 0, buffer.len);

    // BOOTREQUEST
    buffer.base[0] = 0x1;
    // HTYPE ethernet
    buffer.base[1] = 0x1;
    // HLEN
    buffer.base[2] = 0x6;
    // HOPS
    buffer.base[3] = 0x0;
    // XID 4 bytes
    buffer.base[4] = (unsigned int) random();
    // SECS
    buffer.base[8] = 0x0;
    // FLAGS
    buffer.base[10] = 0x80;
    // CIADDR 12-15 is all zeros
    // YIADDR 16-19 is all zeros
    // SIADDR 20-23 is all zeros
    // GIADDR 24-27 is all zeros
    // CHADDR 28-43 is the MAC address, use your own
    buffer.base[28] = 0xe4;
    buffer.base[29] = 0xce;
    buffer.base[30] = 0x8f;
    buffer.base[31] = 0x13;
    buffer.base[32] = 0xf6;
    buffer.base[33] = 0xd4;
    // SNAME 64 bytes zero
    // FILE 128 bytes zero
    // OPTIONS
    // - magic cookie
    buffer.base[236] = 99;
    buffer.base[237] = 130;
    buffer.base[238] = 83;
    buffer.base[239] = 99;

    // DHCP Message type
    buffer.base[240] = 53;
    buffer.base[241] = 1;
    buffer.base[242] = 1; // DHCPDISCOVER

    // DHCP Parameter request list
    buffer.base[243] = 55;
    buffer.base[244] = 4;
    buffer.base[245] = 1;
    buffer.base[246] = 3;
    buffer.base[247] = 15;
    buffer.base[248] = 6;

    return buffer;
}

udp

範例測試

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[ubuntu](master-1f56a9b)0h20m root@e8b0cd737680:[t08_udp-dhcp]$ ifconfig
eth0      Link encap:Ethernet  HWaddr 02:42:ac:11:00:02  
          inet addr:172.17.0.2  Bcast:0.0.0.0  Mask:255.255.0.0
          inet6 addr: fe80::42:acff:fe11:2/64 Scope:Link
          UP BROADCAST RUNNING MULTICAST  MTU:1500  Metric:1
          RX packets:2360 errors:0 dropped:0 overruns:0 frame:0
          TX packets:10 errors:0 dropped:0 overruns:0 carrier:0
          collisions:0 txqueuelen:0 
          RX bytes:715840 (715.8 KB)  TX bytes:1244 (1.2 KB)

lo        Link encap:Local Loopback  
          inet addr:127.0.0.1  Mask:255.0.0.0
          inet6 addr: ::1/128 Scope:Host
          UP LOOPBACK RUNNING  MTU:65536  Metric:1
          RX packets:67 errors:0 dropped:0 overruns:0 frame:0
          TX packets:67 errors:0 dropped:0 overruns:0 carrier:0
          collisions:0 txqueuelen:0 
          RX bytes:4268 (4.2 KB)  TX bytes:4268 (4.2 KB)

參考來源