C语言 UDP 套接字设置超时
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UDP Socket Set Timeout
提问by rharrison33
I am trying to set a 100ms timeout on a UDP Socket. I am using C. I have posted relavent pieces of my code below. I am not sure why this is not timing out, but just hangs when it doesn't receive a segment. Does this only work on sockets that are not bound using the bind() method?
我正在尝试在 UDP 套接字上设置 100 毫秒超时。我正在使用 C。我在下面发布了我的代码的相关部分。我不确定为什么这不是超时，而是在它没有收到一个段时挂起。这仅适用于未使用 bind() 方法绑定的套接字吗？
#define TIMEOUT_MS 100 /* Seconds between retransmits */
if ((rcv_sock = socket(PF_INET, SOCK_DGRAM, IPPROTO_UDP)) < 0)
DieWithError("socket() failed");
if ((rcv_sock = socket(PF_INET, SOCK_DGRAM, IPPROTO_UDP)) < 0)
DieWithError("socket() failed");
//set timer for recv_socket
static int timeout = TIMEOUT_MS;
setsockopt(rcv_sock, SOL_SOCKET, SO_RCVTIMEO,(char*)&timeout,sizeof(timeout));
if(recvfrom(rcv_sock, ackBuffer,sizeof(ackBuffer), 0,
(struct sockaddr *) &servAddr2, &fromSize) < 0){
//timeout reached
printf("Timout reached. Resending segment %d\n", seq_num);
num_timeouts++;
}
回答by Neal
The SO_RCVTIMEOoption expects a struct timevaldefined in sys/time.h, not an integer like you're passing to it. The timeval structhas as field for seconds and a field for microseconds. To set the timeout to 100ms, the following should do the trick:
该SO_RCVTIMEO选项需要在 中struct timeval定义sys/time.h，而不是像您传递给它的整数。在timeval struct为拥有秒字段和毫秒字段。要将超时设置为 100 毫秒，以下应该可以解决问题：
struct timeval tv;
tv.tv_sec = 0;
tv.tv_usec = 100000;
if (setsockopt(rcv_sock, SOL_SOCKET, SO_RCVTIMEO,&tv,sizeof(tv)) < 0) {
perror("Error");
}
回答by user9510357
I have the same problem. I tried to adopt the solution you suggested, using the timevalstruct. But it did not seem to work.
我也有同样的问题。我尝试采用您建议的解决方案，使用timeval结构。但它似乎没有用。
I have read on the Microsoft documentation and the time should be a DWORDwith the number of milliseconds, but there is also another thing to do, If the socket is created using the WSASocketfunction, then the dwFlagsparameter must have the WSA_FLAG_OVERLAPPEDattribute set for the timeout to function properly.
Otherwise the timeout never takes effect.
我已经阅读了 Microsoft 文档，时间应该是DWORD毫秒数，但还有另一件事要做，如果使用该WSASocket函数创建套接字，则该dwFlags参数必须具有WSA_FLAG_OVERLAPPED设置超时功能的属性适当地。否则超时永远不会生效。
