网络编程Server端 --- Linux版
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http://blog.csdn.net/xiaobin_hlj80/article/details/7172375
之前我们已经编写了一个通用的Socket服务器端程序,我们现在增加对此类操作系统特性的一些code!
大家都知道fork() 只有在Unix/Linux类操作系统才有!因为他们没有线程这一说。他们只有子进程。
要用到fork那么就必须用到 waitpid() !
waitpid函数原型:
#include<sys/types.h> /* 提供类型pid_t的定义 */
#include<sys/wait.h>
pid_twaitpid(pid_tpid, int *status, int options);
参数pid=-1时,等待任何一个子进程退出,没有任何限制,此时waitpid和wait的作用一模一样。
参数 status我们设置为NULL。
参数options提供了一些额外的选项来控制waitpid,WNOHANG常量表示,即使没有子进程退出,它也会立即返回,不会像wait那样永远等下去。
我们希望只有给waitpid()信号时,才使用它!
这时,我们需要另外一个函数sigaction()。
sigaction函数原型:
#include<signal.h>
int sigaction(int signum, const struct sigaction *act, struct sigaction *oldact);
参数 signum=SIGCHLD时,只有子进程停止或者退出才进行调用。
参数 act是一个指向sigaction结构的指针。
参数 oldact一般废止不用。
我们主要设置结构sigaction的sa_handler、sa_mask和sa_flags三个成员变量即可!
下面是示例:
- /**
- * Version: 0.2
- *
- * Description: Add signal
- *
- */
- #include <stdio.h>
- #include <string.h>
- #include <sys/types.h>
- #include <sys/socket.h>
- #include <netdb.h>
- #include <arpa/inet.h>
- #include <signal.h>
- #include <sys/wait.h>
- #include <stdlib.h> /* exit declare */
- #include <unistd.h> /* fork declare */
- #define SERVPORT "2349"
- void sigchild_handler()
- {
- while (waitpid(-1, NULL, WNOHANG) > 0);
- }
- int main(int argc,char *argv[])
- {
- struct addrinfo hints, *res;
- int status;
- int sockfd;
- int connFd;
- /* struct sockaddr_in cliAddr; Only IPv4 */
- struct sockaddr_storage clientAddr;/* both IPv4 and IPv6 */
- struct sigaction sa;
- int sendSta;
- char *msg;
- if (argc != 2) {
- fprintf(stderr, "Usage: Not found Read File");
- return 1;
- }
- memset(&hints, 0, sizeof(hints));
- hints.ai_family = AF_UNSPEC;
- hints.ai_socktype = SOCK_STREAM;
- hints.ai_flags = AI_PASSIVE;
- status = getaddrinfo(NULL, SERVPORT, &hints, &res);
- if (status != 0) {
- fprintf(stderr, "getaddrinfo, fail!");
- return 2;
- }
- sockfd = socket(res->ai_family, res->ai_socktype, res->ai_protocol);
- bind(sockfd, res->ai_addr, res->ai_addrlen);
- listen(sockfd, 5);
- printf("======== Please Wait Client =========\n");
- /* struct sigaction notes from POSIX:
- *
- * (1) Routines stored in sa_handler should take a single int as
- * their argument although the POSIX standard does not require this.
- * (2) The fields sa_handler and sa_sigaction may overlap, and a conforming
- * application should not use both simultaneously.
- */
- sa.sa_handler = sigchild_handler;
- sigemptyset(&sa.sa_mask); /* Additional set of signals to be blocked */
- /* during execution of signal-catching function. */
- sa.sa_flags = SA_RESTART; /* Special flags to affect behavior of signal */
- /* SA_RESTART 0x10000000 // Restart syscall on signal return */
- if (sigaction(SIGCHLD, &sa, NULL) == -1) {/* SIGCHLD 20 // to parent on child stop or exit */
- fprintf(stderr, "sigaction fail!");
- exit(3);
- }
- while(1) { // loop forever!
- char ipstr[INET_ADDRSTRLEN];
- void *addr;
- int len = sizeof(clientAddr);
- connFd = accept(sockfd, (struct sockaddr *)&clientAddr, &len);
- /* View Client IP */
- struct sockaddr_in *ipv4 = (struct sockaddr_in *)&clientAddr;
- addr = &(ipv4->sin_addr);
- inet_ntop(AF_INET, addr, ipstr, sizeof(ipstr));
- printf("client: %s\n", ipstr);
- if (!fork()) {
- close(sockfd); /* child doesn't need the listener */
- /* Copy Data */
- msg = "The server simply displays a message!";
- sendSta = send(connFd, msg, strlen(msg), 0);
- if (sendSta == -1)
- fprintf(stderr, "send fail!");
- close(connFd);
- exit(0);
- }
- close(connFd);
- }
- close(sockfd);
- return 0;
- }
/** * Version: 0.2 * * Description: Add signal * */#include <stdio.h>#include <string.h>#include <sys/types.h>#include <sys/socket.h>#include <netdb.h>#include <arpa/inet.h>#include <signal.h>#include <sys/wait.h>#include <stdlib.h>/* exit declare */#include <unistd.h>/* fork declare */#define SERVPORT "2349"void sigchild_handler(){while (waitpid(-1, NULL, WNOHANG) > 0);}int main(int argc, char *argv[]){struct addrinfo hints, *res;int status;int sockfd;int connFd;/* struct sockaddr_in cliAddr; Only IPv4 */struct sockaddr_storage clientAddr;/* both IPv4 and IPv6 */struct sigaction sa;int sendSta;char *msg;if (argc != 2) {fprintf(stderr, "Usage: Not found Read File");return 1;}memset(&hints, 0, sizeof(hints));hints.ai_family = AF_UNSPEC;hints.ai_socktype = SOCK_STREAM;hints.ai_flags = AI_PASSIVE;status = getaddrinfo(NULL, SERVPORT, &hints, &res);if (status != 0) {fprintf(stderr, "getaddrinfo, fail!");return 2;}sockfd = socket(res->ai_family, res->ai_socktype, res->ai_protocol);bind(sockfd, res->ai_addr, res->ai_addrlen);listen(sockfd, 5);printf("======== Please Wait Client =========\n");/* struct sigaction notes from POSIX: * * (1) Routines stored in sa_handler should take a single int as * their argument although the POSIX standard does not require this. * (2) The fields sa_handler and sa_sigaction may overlap, and a conforming * application should not use both simultaneously. */sa.sa_handler = sigchild_handler;sigemptyset(&sa.sa_mask);/* Additional set of signals to be blocked */ /* during execution of signal-catching function. */sa.sa_flags = SA_RESTART;/* Special flags to affect behavior of signal *//* SA_RESTART 0x10000000 // Restart syscall on signal return */if (sigaction(SIGCHLD, &sa, NULL) == -1) {/* SIGCHLD 20// to parent on child stop or exit */fprintf(stderr, "sigaction fail!");exit(3);}while(1) { // loop forever!char ipstr[INET_ADDRSTRLEN];void *addr;int len = sizeof(clientAddr);connFd = accept(sockfd, (struct sockaddr *)&clientAddr, &len);/* View Client IP */struct sockaddr_in *ipv4 = (struct sockaddr_in *)&clientAddr;addr = &(ipv4->sin_addr);inet_ntop(AF_INET, addr, ipstr, sizeof(ipstr));printf("client: %s\n", ipstr);if (!fork()) {close(sockfd);/* child doesn't need the listener *//* Copy Data */msg = "The server simply displays a message!";sendSta = send(connFd, msg, strlen(msg), 0);if (sendSta == -1)fprintf(stderr, "send fail!");close(connFd);exit(0);}close(connFd);}close(sockfd);return 0;}
End.
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