In the previous article, we played with timeouts under Windows. In this article, we will play with Linux. I encountered this question in an interview, which is interesting. Directly on the client code: #include <unistd.h> #include <sys/types.h> #include <sys/socket.h> #include <netdb.h> #include <stdio.h> #include <stdlib.h> #include <string.h> #include <ctype.h> #include <errno.h> #include <malloc.h> #include <netinet/in.h> #include <arpa/inet.h> #include <sys/ioctl.h> #include <stdarg.h> #include <fcntl.h> #include <time.h> int main(int argc, char *argv[]) // Pay attention to the input parameters, bring ip and port { int sockClient = socket(AF_INET, SOCK_STREAM, 0); struct sockaddr_in addrSrv; addrSrv.sin_addr.s_addr = inet_addr(argv[1]); addrSrv.sin_family = AF_INET; addrSrv.sin_port = htons(atoi(argv[2])); fcntl(sockClient, F_SETFL, fcntl(sockClient, F_GETFL, 0)|O_NONBLOCK); int iRet = connect(sockClient, (const struct sockaddr *)&addrSrv, sizeof(struct sockaddr_in)); printf("connect iRet is %d, errmsg:%s\n", iRet, strerror(errno)); // Returning -1 is not necessarily an exception if (iRet != 0) { if (errno != EINPROGRESS) { printf("connect error:%s\n", strerror(errno)); } else { struct timeval tm = {5, 0}; fd_set wset, rset; FD_ZERO(&wset); FD_ZERO(&rset); FD_SET(sockClient, &wset); FD_SET(sockClient, &rset); int time1 = time(NULL); int n = select(sockClient + 1, &rset, &wset, NULL, &tm); int time2 = time(NULL); printf("time gap is %d\n", time2 - time1); if(n < 0) { printf("select error, n is %d\n", n); } else if(n == 0) { printf("connect time out\n"); } else if (n == 1) { if(FD_ISSET(sockClient, &wset)) { printf("connect ok!\n"); fcntl(sockClient, F_SETFL, fcntl(sockClient, F_GETFL, 0) & ~O_NONBLOCK); } else { printf("unknow error:%s\n", strerror(errno)); } } else { printf("oh, not care now, n is %d\n", n); } } } printf("I am here!\n"); getchar(); close(sockClient); return 0; } We have written the server code many times, so we will not write it in this article. After testing, the above program is OK. You can also learn a lot by using tcpdump to capture packets, such as SYN packet retransmission, RST packet, etc. Quite interesting. Summarize The above is the full content of this article. I hope that the content of this article will have certain reference learning value for your study or work. Thank you for your support of 123WORDPRESS.COM. If you want to learn more about this, please check out the following links You may also be interested in:
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