[lwip-users] 回复: UDP multicast problem usinig netconn API

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你组播地址设置错误。另外还要加入组播才能接收组播数据。

发送自 hnclcj

----- Reply message -----
发件人： "yi zheng" <address@hidden>
收件人： <address@hidden>
主题： [lwip-users] UDP multicast problem usinig netconn API
日期： 周一, 5 月 28 日, 2012 年 16:38

Dear Group Members:

I am a newer to lwip and encounter problems doing UDP multicast for receiving and sending using netconn API.I've enabled the IGMP code in lwip and everything builds OK. The source code is as followed：

===================source code=======================

static void MulticastTask(void *p_arg)

{

struct ip_addr interfaceAddr,*addr,multicastAddr;  

struct in_addr netAddr;

char addrStr[INET_ADDRSTRLEN]  ;

struct netbuf *buf,*sendBuf;

struct netconn *multiCast;

char data[]="hi";

static unsigned short port;

multiCast=netconn_new(NETCONN_UDP) ;  //create netconn  

/*port=5000, err=0*/                                         err=netconn_bind(multiCast, IP_ADDR_ANY, htons(5000)); 

/*IP address "192.168.0.2"*/      

IP4_ADDR(&interfaceAddr,192,168,0,2);                                               /multicast address "224.0.0.107" */

IP4_ADDR(&multicastAddr,224,0,0,107);                                       err=netconn_join_leave_group(multiCast,&multicastAddr,\

&interfaceAddr,NETCONN_JOIN);//err=0                     

while(1)

{

/*receive multicast packets*/

  buf = netconn_recv(multiCast);                        

}

===================source code=======================

I have already seen "Problem doing UDP multicast receive using netconn API" with URL http://lists.gnu.org/archive/html/lwip-users/2010-07/msg00100.html.NETIF_FLAG_IGMP was set by the following code:

#ifdef LWIP_IGMP

  netif->flags |= NETIF_FLAG_IGMP | NETIF_FLAG_BROADCAST;

#endif

      I cann't receive packet by the above efforts.Please help me to solve my problem.

Thanks.

YiZheng