大家都知道各類網絡服務器程序的編寫步驟,並且都知道網絡服務器就兩大類:循環服務和併發服務。這裏附上源代碼來個小結吧。
下面是一個TCP循環服務器源程序,因爲用fork()進行多進程服務,父進程負責監聽和連接,子進程負責與客戶端進行通信,所以這種服務現實中也有用。源代碼如下:
- /*----------------------源代碼開始--------------------------------------------*/
- #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>
- /*********************************************************************
- *filename: cycletcpserver.c
- *purpose: 循環tcp服務端程序
- *tidied by: zhoulifa([email protected]) 周立發(http://zhoulifa.9999mb.com)
- Linux愛好者 Linux知識傳播者 SOHO族 開發者 最擅長C語言
- *date time:2006-07-04 22:00:00
- *Note: 任何人可以任意複製代碼並運用這些文檔,當然包括你的商業用途
- * 但請遵循GPL
- *Thanks to: Google.com
- *********************************************************************/
- int main(int argc, char ** argv)
- {
- int sockfd,new_fd; /* 監聽socket: sock_fd,數據傳輸socket: new_fd */
- struct sockaddr_in my_addr; /* 本機地址信息 */
- struct sockaddr_in their_addr; /* 客戶地址信息 */
- unsigned int sin_size, myport, lisnum;
- if(argv[1]) myport = atoi(argv[1]);
- else myport = 7838;
- if(argv[2]) lisnum = atoi(argv[2]);
- else lisnum = 2;
- if ((sockfd = socket(PF_INET, SOCK_STREAM, 0)) == -1) {
- perror("socket");
- exit(1);
- }
- my_addr.sin_family=PF_INET;
- my_addr.sin_port=htons(myport);
- my_addr.sin_addr.s_addr = INADDR_ANY;
- bzero(&(my_addr.sin_zero), 0);
- if (bind(sockfd, (struct sockaddr *)&my_addr, sizeof(struct sockaddr)) == -1) {
- perror("bind");
- exit(1);
- }
- if (listen(sockfd, lisnum) == -1) {
- perror("listen");
- exit(1);
- }
- while(1) {
- sin_size = sizeof(struct sockaddr_in);
- if ((new_fd = accept(sockfd, (struct sockaddr *)&their_addr, &sin_size)) == -1) {
- perror("accept");
- continue;
- }
- printf("server: got connection from %s\n",inet_ntoa(their_addr.sin_addr));
- if (!fork()) { /* 子進程代碼段 */
- if (send(new_fd, "Hello, world!\n", 14, 0) == -1) {
- perror("send");
- close(new_fd);
- exit(0);
- }
- }
- close(new_fd); /*父進程不再需要該socket*/
- waitpid(-1,NULL,WNOHANG);/*等待子進程結束,清除子進程所佔用資源*/
- }
- }
- /*----------------------源代碼結束--------------------------------------------*/
下面是一個演示I/O多路複用的源程序,是一個端口轉發程序,但它的用處相當大,實際應用中的各類代理軟件或端口映射軟件都是基於這樣的代碼的,比如Windows下的WinGate、WinProxy等都是在此基礎上實現的。源代碼如下:
- /*----------------------源代碼開始--------------------------------------------*/
- #include <stdlib.h>
- #include <stdio.h>
- #include <unistd.h>
- #include <sys/time.h>
- #include <sys/types.h>
- #include <string.h>
- #include <signal.h>
- #include <sys/socket.h>
- #include <netinet/in.h>
- #include <arpa/inet.h>
- #include <errno.h>
- static int forward_port;
- #undef max
- #define max(x,y) ((x) > (y) ? (x) : (y))
- /*************************關於本文檔************************************
- *filename: tcpforwardport.c
- *purpose: 演示了select的用法,這是一個極好的代理軟件核心,專門作端口映射用
- *tidied by: zhoulifa([email protected]) 周立發(http://zhoulifa.9999mb.com)
- Linux愛好者 Linux知識傳播者 SOHO族 開發者 最擅長C語言
- *date time:2006-07-05 19:00:00
- *Note: 任何人可以任意複製代碼並運用這些文檔,當然包括你的商業用途
- * 但請遵循GPL
- *Thanks to: Paul Sheer 感謝Paul Sheer在select_tut的man手冊裏提供了這份源代碼
- *Hope:希望越來越多的人貢獻自己的力量,爲科學技術發展出力
- *********************************************************************/
- static int listen_socket (int listen_port) {
- struct sockaddr_in a;
- int s;
- int yes;
- if ((s = socket (AF_INET, SOCK_STREAM, 0)) < 0) {
- perror ("socket");
- return -1;
- }
- yes = 1;
- if (setsockopt(s, SOL_SOCKET, SO_REUSEADDR, (char *) &yes, sizeof (yes)) <
- 0) {
- perror ("setsockopt");
- close (s);
- return -1;
- }
- memset (&a, 0, sizeof (a));
- a.sin_port = htons (listen_port);
- a.sin_family = AF_INET;
- if (bind(s, (struct sockaddr *) &a, sizeof (a)) < 0) {
- perror ("bind");
- close (s);
- return -1;
- }
- printf ("accepting connections on port %d\n", (int) listen_port);
- listen (s, 10);
- return s;
- }
- static int connect_socket (int connect_port, char *address) {
- struct sockaddr_in a;
- int s;
- if ((s = socket (AF_INET, SOCK_STREAM, 0)) < 0) {
- perror ("socket");
- close (s);
- return -1;
- }
- memset (&a, 0, sizeof (a));
- a.sin_port = htons (connect_port);
- a.sin_family = AF_INET;
- if (!inet_aton(address, (struct in_addr *) &a.sin_addr.s_addr)) {
- perror ("bad IP address format");
- close (s);
- return -1;
- }
- if (connect(s, (struct sockaddr *) &a, sizeof (a)) < 0) {
- perror ("connect()");
- shutdown (s, SHUT_RDWR);
- close (s);
- return -1;
- }
- return s;
- }
- #define SHUT_FD1 { \
- if (fd1 >= 0) { \
- shutdown (fd1, SHUT_RDWR); \
- close (fd1); \
- fd1 = -1; \
- } \
- }
- #define SHUT_FD2 { \
- if (fd2 >= 0) { \
- shutdown (fd2, SHUT_RDWR); \
- close (fd2); \
- fd2 = -1; \
- } \
- }
- #define BUF_SIZE 1024
- int main (int argc, char **argv) {
- int h;
- int fd1 = -1, fd2 = -1;
- char buf1[BUF_SIZE], buf2[BUF_SIZE];
- int buf1_avail, buf1_written;
- int buf2_avail, buf2_written;
- if (argc != 4) {
- fprintf (stderr, "Usage\n\tfwd \n");
- exit (1);
- }
- signal (SIGPIPE, SIG_IGN);
- forward_port = atoi (argv[2]);
- /*建立監聽socket*/
- h = listen_socket (atoi (argv[1]));
- if (h < 0) exit (1);
- for (;;) {
- int r, nfds = 0;
- fd_set rd, wr, er;
- FD_ZERO (&rd);
- FD_ZERO (&wr);
- FD_ZERO (&er);
- FD_SET (h, &rd);
- /*把監聽socket和可讀socket三個一起放入select的可讀句柄列表裏*/
- nfds = max (nfds, h);
- if (fd1 > 0 && buf1_avail < BUF_SIZE) {
- FD_SET (fd1, &rd);
- nfds = max (nfds, fd1);
- }
- if (fd2 > 0 && buf2_avail < BUF_SIZE) {
- FD_SET (fd2, &rd);
- nfds = max (nfds, fd2);
- }
- /*把可寫socket兩個一起放入select的可寫句柄列表裏*/
- if (fd1 > 0 && buf2_avail - buf2_written > 0) {
- FD_SET (fd1, &wr);
- nfds = max (nfds, fd1);
- }
- if (fd2 > 0 && buf1_avail - buf1_written > 0) {
- FD_SET (fd2, &wr);
- nfds = max (nfds, fd2);
- }
- /*把有異常數據的socket兩個一起放入select的異常句柄列表裏*/
- if (fd1 > 0) {
- FD_SET (fd1, &er);
- nfds = max (nfds, fd1);
- }
- if (fd2 > 0) {
- FD_SET (fd2, &er);
- nfds = max (nfds, fd2);
- }
- /*開始select*/
- r = select (nfds + 1, &rd, &wr, &er, NULL);
- if (r == -1 && errno == EINTR) continue;
- if (r < 0) {
- perror ("select()");
- exit (1);
- }
- /*處理新連接*/
- if (FD_ISSET (h, &rd)) {
- unsigned int l;
- struct sockaddr_in client_address;
- memset (&client_address, 0, l = sizeof (client_address));
- r = accept (h, (struct sockaddr *)&client_address, &l);
- if (r < 0) {
- perror ("accept()");
- } else {
- /*關閉原有連接,把新連接作爲fd1,同時連接新的目標fd2*/
- SHUT_FD1;
- SHUT_FD2;
- buf1_avail = buf1_written = 0;
- buf2_avail = buf2_written = 0;
- fd1 = r;
- fd2 = connect_socket (forward_port, argv[3]);
- if (fd2 < 0) {
- SHUT_FD1;
- } else
- printf ("connect from %s\n", inet_ntoa(client_address.sin_addr));
- }
- }
- /* NB: read oob data before normal reads */
- if (fd1 > 0)
- if (FD_ISSET (fd1, &er)) {
- char c;
- errno = 0;
- r = recv (fd1, &c, 1, MSG_OOB);
- if (r < 1) {
- SHUT_FD1;
- } else
- send (fd2, &c, 1, MSG_OOB);
- }
- if (fd2 > 0)
- if (FD_ISSET (fd2, &er)) {
- char c;
- errno = 0;
- r = recv (fd2, &c, 1, MSG_OOB);
- if (r < 1) {
- SHUT_FD1;
- } else
- send (fd1, &c, 1, MSG_OOB);
- }
- /* NB: read data from fd1 */
- if (fd1 > 0)
- if (FD_ISSET (fd1, &rd)) {
- r = read (fd1, buf1 + buf1_avail, BUF_SIZE - buf1_avail);
- if (r < 1) {
- SHUT_FD1;
- } else
- buf1_avail += r;
- }
- /* NB: read data from fd2 */
- if (fd2 > 0)
- if (FD_ISSET (fd2, &rd)) {
- r = read (fd2, buf2 + buf2_avail, BUF_SIZE - buf2_avail);
- if (r < 1) {
- SHUT_FD2;
- } else
- buf2_avail += r;
- }
- /* NB: write data to fd1 */
- if (fd1 > 0)
- if (FD_ISSET (fd1, &wr)) {
- r = write (fd1, buf2 + buf2_written, buf2_avail - buf2_written);
- if (r < 1) {
- SHUT_FD1;
- } else
- buf2_written += r;
- }
- /* NB: write data to fd1 */
- if (fd2 > 0)
- if (FD_ISSET (fd2, &wr)) {
- r = write (fd2, buf1 + buf1_written, buf1_avail - buf1_written);
- if (r < 1) {
- SHUT_FD2;
- } else
- buf1_written += r;
- }
- /* check if write data has caught read data */
- if (buf1_written == buf1_avail) buf1_written = buf1_avail = 0;
- if (buf2_written == buf2_avail) buf2_written = buf2_avail = 0;
- /* one side has closed connection, keep writing to the other side until empty */
- if (fd1 < 0 && buf1_avail - buf1_written == 0) {
- SHUT_FD2;
- }
- if (fd2 < 0 && buf2_avail - buf2_written == 0) {
- SHUT_FD1;
- }
- }
- return 0;
- }
- /*----------------------源代碼結束--------------------------------------------*/