网络编程Server端 --- Linux版
之前我们已经编写了一个，我们现在增加对此类操作特性的一些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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