源码

  1. #include <stdio.h>
  2. #include <stdlib.h>
  3. #include <string.h>
  4. #include <unistd.h>
  5. #include <sys/socket.h>
  6. #include <netinet/in.h>
  7. #include <arpa/inet.h>
  9. void start() {
  11.     struct sockaddr_in my_addr;
  12.     my_addr.sin_family = AF_INET;
  13.     my_addr.sin_port = htons(8080);
  14.     my_addr.sin_addr.s_addr = htonl(INADDR_ANY);
  16.     struct sockaddr_in client_addr;
  17.     char client_ip[INET_ADDRSTRLEN] = "";
  18.     int clientfd = 0;
  20.     int listenfd = socket(AF_INET, SOCK_STREAM, 0);
  21.     bind(listenfd, (struct sockaddr*)&my_addr, sizeof(my_addr));
  22.     listen(listenfd, 128);
  23.     printf("listen client @port=%d...\n", 8080);
  25.     int lastfd = listenfd;
  26.     int i;
  27.     fd_set read_set, total_set;
  28.     FD_ZERO(&read_set);
  29.     FD_SET(listenfd, &total_set);
  31.     while(1) {
  32.         read_set = total_set;
  33.         int z = select(lastfd + 1, &read_set, NULL, NULL, NULL);
  34.         if (z > 0) {
  35.             if (FD_ISSET(listenfd, &read_set)) {
  36.                 socklen_t client_len = sizeof(client_addr);
  37.                 clientfd = accept(listenfd, (struct sockaddr*)&client_addr, &client_len);
  38.                 inet_ntop(AF_INET, &client_addr.sin_addr, client_ip, INET_ADDRSTRLEN);
  39.                 printf("----------------------------------\n");
  40.                 printf("client ip=%s, port=%d\n", client_ip, ntohs(client_addr.sin_port));
  41.                 FD_SET(clientfd, &total_set);
  42.                 lastfd = clientfd;
  43.                 if (0 == --z) {
  44.                     continue;
  45.                 }
  46.             }
  48.             for (i = listenfd + 1; i <= lastfd; i++) {
  49.                 if (FD_ISSET(i, &read_set)) {
  50.                     char recv_buf[1024] = "";
  51.                     int rs = read(i, recv_buf, sizeof(recv_buf));
  52.                     if (rs == 0) {
  53.                         close(i);
  54.                         FD_CLR(i, &total_set);
  55.                     } else {
  56.                         printf("%s\n", recv_buf);
  57.                         // write(0, recv_buf, rs);
  58.                     } 
  59.                 }
  60.             }
  61.         }
  62.     }
  64. }
  66. int main() {
  67.     start();
  68.     return 0;
  69. }

编译

  1. gcc -o select select.c

测试

  1. eric@LEGION:~/study_java$ ./select
  2. listen client @port=8080...
  3. ----------------------------------
  4. client ip=127.0.0.1, port=10966
  5. ----------------------------------
  6. client ip=127.0.0.1, port=10975
  7. 111
  8. 222