socket鐨勭己鐪佹柟寮忥紝涔熸槸鏈甯哥敤鐨勬柟寮忥紝鍗沖嚱鏁伴樆濉炵洿鍒拌皟鐢ㄥ畬姣曘?/font> 鍙兘閫犳垚闃誨鐨勫嚱鏁版湁錛歳ecvfrom() 銆乧onnect()銆乤ccept()銆佽鍐欏嚱鏁般乻elect()銆乸oll()銆乬ethostbyname()絳夈?/font> 聽聽聽聽聽聽聽聽聽聽聽聽聽聽聽聽 
#include <stdio.h>
#include <stdlib.h>
#include <errno.h>
#include <string.h>
#include <sys/types.h>
#include <netinet/in.h>
#include <sys/socket.h>
#include <sys/wait.h>
#define MYPORT 3490聽聽聽聽聽聽聽聽聽聽聽聽聽聽聽 聽
/* 鐩戝惉鐨勭鍙?*/
#define BACKLOG 10聽聽聽聽聽聽聽聽聽聽聽聽聽聽聽 聽聽
/* listen鐨勮姹傛帴鏀墮槦鍒楅暱搴?*
void main() { int sockfd, new_fd;聽聽聽聽聽聽聽聽聽聽聽 /* 鐩戝惉绔彛錛屾暟鎹鍙?*/
struct sockaddr_in sa;聽聽聽聽聽聽聽聽 /*
鑷韓鐨勫湴鍧淇℃伅 */
struct sockaddr_in their_addr; /* 榪炴帴瀵規柟鐨勫湴鍧淇℃伅 */
int sin_size;
if ((sockfd = socket(AF_INET, SOCK_STREAM, 0)) == -1) {聽聽
聽聽聽 perror("socket");
聽聽聽 exit(1);
}
sa.sin_family = AF_INET;
sa.sin_port = htons(MYPORT);聽聽聽聽聽聽聽聽
/* 緗戠粶瀛楄妭欏哄簭 */
sa.sin_addr.s_addr = INADDR_ANY;聽聽聽聽 /* 鑷姩濉湰鏈篒P
*/
bzero(&(sa.sin_zero), 8);聽聽聽聽聽聽聽聽聽聽聽聽
/* 鍏朵綑閮ㄥ垎緗? */
if (bind(sockfd, (struct sockaddr *)&sa, sizeof(sa)) == -1) {聽聽
聽聽聽 perror("bind");
聽聽聽 exit(1);
}
if (listen(sockfd, BACKLOG) == -1) {聽聽
聽聽聽 perror("listen");
聽聽聽 exit(1);
}
/* 涓誨驚鐜?*/
while(1) {
聽聽聽 sin_size = sizeof(struct sockaddr_in);
聽聽聽 new_fd = accept(sockfd, (struct sockaddr *)&their_addr,
&sin_size));
聽聽聽 if (new_fd == -1) {
聽聽聽 聽聽聽 perror("accept");
聽聽聽 聽聽聽 continue;
聽聽聽 }
聽聽聽 printf(鈥滸ot connection from %s\n",
inet_ntoa(their_addr.sin_addr));
聽聽聽 if (fork() == 0) {聽聽聽 /* 瀛愯繘紼?*/聽聽 聽聽
聽聽聽 聽聽聽 if (send(new_fd, "Hello, world!\ n", 14, 0) == -1)聽聽 聽聽
聽聽聽 聽聽聽 聽聽聽 perror("send");
聽聽聽 聽聽聽 聽聽聽 close(new_fd);
聽聽聽 聽聽聽 聽聽聽 exit(0);
聽聽聽 }
聽聽聽 close(new_fd);聽聽聽 /*娓呴櫎鎵鏈夊瓙榪涚▼ */
聽聽聽 while(waitpid(-1,NULL,WNOHANG) > 0);
聽}
}
闈為樆濉炴ā寮?/font> 紼嬪簭璋冪敤鍙兘閫犳垚闃誨鐨勫嚱鏁版椂錛?br />濡傛灉浼?font color="#ff6600">鍙戠敓闃誨錛岃繖浜?font color="#ff6600">鍑芥暟榪斿洖-1
騫跺皢errno璁劇疆涓篍AGAIN鎴朎WOULDBLOCK錛岀▼搴忓彲緇х畫鍚戜笅榪愯銆傚彲鑳介樆濉?br />鐨勫嚱鏁板搴旂殑浠誨姟瀹屾垚錛屽垯鍐嶆璋冪敤璇ュ嚱鏁版椂灝辮繑鍥?琛ㄧず榪愯緇撴潫銆?/font>闈?
闃誨妯″紡鍙互閬垮厤紼嬪簭姝婚攣錛屼絾鏄渶瑕佺▼搴忎笉鏂鏌ュ悇涓彲鑳介樆濉炵殑鍑芥暟鐨勭姸鎬侊紝褰撲竴涓簲鐢ㄧ▼搴忎嬌鐢ㄤ簡
闈為樆濉炴ā寮忕殑濂楁帴瀛楋紝瀹冮渶瑕佷嬌鐢ㄤ竴涓驚鐜潵涓嶅惉鐨勬祴璇曟槸
鍚︿竴涓枃浠舵弿榪扮鏈夋暟鎹彲璇伙紙縐板仛polling錛夈?br />搴旂敤紼嬪簭涓嶅仠鐨刾olling鍐呮牳鏉ユ鏌ユ槸鍚/O鎿嶄綔宸茬粡灝辯華銆傝繖灝嗘槸涓涓瀬嫻垂CPU璧勬簮鐨勬搷
浣滐紝鍥犳涓嶈兘瀹為檯
搴旂敤銆備竴鑸潪闃誨妯″紡鏄笌鍚屾I/O妯″紡鍏卞悓浣跨敤鐨勩?/font> 
鑾峰緱鎴栨敼鍙榮ocket鐨処/O灞炴э細 int ioctl(int sockfd,long cmd,unsigned long* argp); cmd灞炴х被鍨嬶紝argp灞炴х殑鍙傛暟銆?br />甯哥敤鐨勬湁錛?br />FIONREAD錛岃繑鍥瀞ocket緙撳啿鍖轟腑鏈鏁版嵁鐨勫瓧鑺傛暟
FIONBIO錛宎rgp涓洪浂鏃朵負闃誨妯″紡錛岄潪闆舵椂涓洪潪闃誨妯″紡
SIOCATMARK 錛屽垽鏂槸鍚︽湁鏈鐨勫甫澶栨暟鎹紙浠呯敤浜嶵CP鍗忚錛夛紝榪斿洖true鎴杅alse
int fcntl(int fd, int cmd, long arg); F_SETFL錛宎rp涓篛_NONBLOCK鏃惰繘鍏ラ潪闃誨妯″紡錛屼負0鏃惰繘鍏ラ樆濉炴ā寮忋?br />F_GETFL錛岃幏寰楀睘鎬с?/p>
I/O澶氳礬澶嶇敤錛堝悓姝/O妯″紡錛?/font> 聽聽聽聽 浣跨敤select()銆乸oll()絳夊嚱鏁板疄鐜板澶氫釜socket鐨勫悓姝/O鎿嶄綔銆傚畠鑳藉悓鏃剁瓑寰呭涓?
socket鎻忚堪絎︼紝鑰岃繖浜泂ocket鎻忚堪絎﹀叾涓殑浠繪剰涓涓繘鍏ヨ灝辯華/鍐欏氨緇?鍑洪敊鐘舵侊紝select()
鍑芥暟灝卞彲浠ヨ繑鍥炪?/font> 聽聽聽 聽聽  聽聽聽聽聽聽 socket杞閫夋嫨錛?/font> int select(int numfds, fd_set *readfds, fd_set *writefds, fd_set
*exceptfds, struct timeval *timeout); 搴旂敤浜庡璺悓姝/O妯″紡
| FD_ZERO(*set) 娓呯┖socket闆嗗悎 |
| FD_SET(s, *set) 灝唖鍔犲叆socket闆嗗悎 |
| FD_CLR(s, *set) 浠巗ocket闆嗗悎鍘繪帀s |
| FD_ISSET(s, *set) 鍒ゆ柇s鏄惁鍦╯ocket闆嗗悎 |
聽聽聽聽 甯告暟FD_SETSIZE錛氶泦鍚堝厓绱犵殑鏈澶氫釜鏁?/font> 絳夊緟閫夋嫨鏈哄埗錛?/font> int poll(struct pollfd *ufds, unsigned int nfds, int
timeout);
鏄痵elect鏈哄埗鐨勪竴涓彉縐嶏紝搴旂敤浜庡璺悓姝/O妯″紡
ufds鏄痯ollfd緇撴瀯鐨勬暟緇勶紝鏁扮粍鍏冪礌涓暟涓簄fds銆?/font> struct pollfd {
int fd; /* file descriptor */
short events; /* requested events */
short revents; /* returned events */
};
紼嬪簭孌佃妭閫?/font>int listenfd, connfd, maxfd=0;
int nready;
fd_set rset, allset;
struct sockaddr_in cliaddr, servaddr;
int clilen;
listenfd = socket(AF_INET, SOCK_STREAM, 0);
if (listenfd > maxfd) maxfd = listenfd;
memset(&servaddr, 0, sizeof(servaddr));
servaddr.sin_family = AF_INET;
servaddr.sin_addr.s_addr = htonl(INADDR_ANY);
servaddr.sin_port = htons(4321);
bind(listenfd, (struct sockaddr *) &servaddr, sizeof(servaddr));
FD_ZERO(&allset);
FD_SET(listenfd, &allset);
listen(listenfd, 10);
/* main loop */
while (1) {
rset = allset;
nready = select(maxfd+1, &rset, NULL, NULL, NULL);
if (FD_ISSET(listenfd, &rset)) {
/* 鏈夋柊鐨勫鎴風榪炴帴璇鋒眰
clilen = sizeof(cliaddr);
connfd = accept(listenfd, (struct sockaddr*)&cliaddr,&clilen);
if (client_num == FD_SETSIZE) {
fprintf(stderr, "too many clients\n");
exit(-1);
}
FD_SET(connfd, &allset);
if (connfd > maxfd) maxfd = connfd;
if (--nready <= 0) continue;
}
//浠ヤ笅渚濇鍒ゆ柇FD_ISSET(鏌愪釜socket, &rset) 騫跺仛鐩稿簲澶勭悊
}
淇″彿椹卞姩I/O 聽 聽聽 聽聽聽聽聽聽聽聽聽聽聽聽聽
 寮傛I/O 
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