阻止pcap和多个I/O`select` [英] blocking pcap and multiple I/O `select `

问题描述

我想使用pcap捕获数据包 然后将捕获的数据包发送到另一台主机 我的源代码片段如下:

I want to use pcap to capture packets and then send the captured packets to another host my source code snippets are like:

            for(;;){
                    pcap_packet = pcap_next(pcap_handler, &pcap_header);
                    if(pcap_packet !=NULL)
                    printf("capture a packet with length of %d\n", pcap_header.len);

                    // send the packet as payload to the sender, excluding the Ethernet Header
                    n = send(sd_proxy, pcap_packet+ETHERNET_HDR_LEN, pcap_header.len-ETHERNET_HDR_LEN, 0);
                    if(n<0){
                            shutdown(connfd, SHUT_RDWR);
                            close(connfd);
                            break;
                    } new  

            }

所以基本上，我希望程序被pcap_next阻止，一旦 套接字sd_proxy与其他主机建立TCP连接， 如果其他主机启动了活动的TCP关闭，我想检测到这一点 主动关闭.理想情况下，我应该使用select和n=recv(rd_fd, ...) 如果其他主机启动主动关闭，则select会注意到rd_fd出现问题，然后我看是否为'n = 0'. 但是使用pcap时，select无法与pcap配合使用

so basically, I want program to be blocked by the pcap_next, once a the socket sd_proxy establishes a TCP connection with the other host, if the other host initiate an active TCP close, I want to detect this active close. Ideally, I should use a select and a n=recv(rd_fd, ...) if the other host initiates a active close, select will notice there is something with rd_fd and then I see whether 'n=0' or not. but with pcap, select can't cooperate with pcap

那么如何完成我的任务? 谢谢！

so how to finish my task? thanks!

推荐答案

select无法与pcap合作

select can't cooperate with pcap

为什么不呢?您是否尝试过在pcap_handler上使用pcap_get_selectable_fd()并将结果文件描述符添加到您在select()调用中设置的文件描述符中?

Why not? Have you tried using pcap_get_selectable_fd() on pcap_handler and adding the resulting file descriptor to the file descriptor set in your select() call?

您正在Linux上工作，因此应该可以正常工作.

You're working on Linux, so that should Just Work.

(如果您正在使用BPF的系统(例如* BSD或OS X)上运行，则可能会遇到问题，至少在这些OS的较旧版本中；各种* BSD都有其select-with-BPF修复了一段时间；在OS X上，我在Lion中修复了它，因此在Snow Leopard和更早版本上可能会出现问题.)

(If you were running on a system that uses BPF, such as *BSD or OS X, you might have problems with this, at least with older versions of those OSes; various *BSDs have had their select-with-BPF bugs fixed for a while; on OS X, I fixed it in Lion, so it could have problems on Snow Leopard and earlier.)

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