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mysever.c

+
+#include <errno.h>
+#include <stdio.h>
+#include <stdlib.h>
+
+#include <netinet/in.h>
+#include <ctype.h>
+#include <arpa/inet.h>
+
+#include <fcntl.h>
+#include <netdb.h>
+
+#include <string.h>
+#include <strings.h>
+#include <sys/socket.h>
+#include <sys/types.h>
+#include <unistd.h>
+#define MAXFD 2
+
+int main(int argc, char ** argv)
+{
+    int sockfd, newsockfd, portno; // clilen;
+    char buffer[256];
+    struct sockaddr_in serv_addr, cli_addr;
+    socklen_t clilen;
+    int n;
+    char * c;//
+
+    if (argc < 3)
+    {
+        fprintf(stderr, "usage: %s ip port\n", argv[0]);
+        return 0;
+    }
+
+    /* Create TCP socket */
+    sockfd = socket(AF_INET, SOCK_STREAM, 0);
+    if (sockfd < 0)
+    {
+        perror("ERROR opening socket");
+        exit(EXIT_FAILURE);
+    }
+
+    // reuse the socket if possible
+    int const reuse = 1;
+    if (setsockopt(sockfd, SOL_SOCKET, SO_REUSEADDR, &reuse, sizeof(int)) < 0)
+    {
+        perror("setsockopt");
+        exit(EXIT_FAILURE);
+    }
+
+    portno = atoi(argv[2]);
+
+    /* Create address we're going to listen on (given port number)
+     - converted to network byte order & any IP address for this machine */
+    bzero((char *)&serv_addr, sizeof(serv_addr));
+    serv_addr.sin_family = AF_INET;
+    serv_addr.sin_addr.s_addr = INADDR_ANY;//differ
+    serv_addr.sin_port = htons(portno); // store in machine-neutral format
+
+    /* Bind address to the socket */
+    if (bind(sockfd, (struct sockaddr *)&serv_addr, sizeof(serv_addr)) < 0)
+    {
+        perror("ERROR on binding");
+        exit(EXIT_FAILURE);
+    }
+
+    /* Listen on socket - means we're ready to accept connections -
+     incoming connection requests will be queued */
+    listen(sockfd, 5);
+
+    clilen = sizeof(cli_addr);
+
+    /* Accept a connection - block until a connection is ready to
+     be accepted. Get back a new file descriptor to communicate on. */
+    /*newsockfd = accept(sockfd, (struct sockaddr *)&cli_addr, &clilen);
+    if (newsockfd < 0)
+    {
+        perror("ERROR on accept");
+        exit(EXIT_FAILURE);
+    }*/
+
+    // initialise an active file descriptors set
+    fd_set masterfds;
+    FD_ZERO(&masterfds);
+    FD_SET(sockfd, &masterfds);
+    // record the maximum socket number
+    int maxfd = sockfd;
+
+    while (1)
+    {
+      // monitor file descriptors
+      fd_set readfds = masterfds;
+      if (select(FD_SETSIZE, &readfds, NULL, NULL, NULL) < 0)
+      {
+          perror("select");
+          exit(EXIT_FAILURE);
+      }
+
+      // loop all possible descriptor
+      for (int i = 0; i <= maxfd; ++i)
+          // determine if the current file descriptor is active
+          if (FD_ISSET(i, &readfds))
+          {
+              // create new socket if there is new incoming connection request
+              if (i == sockfd)
+              {
+                  int newsockfd = accept(sockfd, (struct sockaddr *)&cliaddr, &clilen);
+                  if (newsockfd < 0)
+                      perror("accept");
+                  else
+                  {
+                      // add the socket to the set
+                      FD_SET(newsockfd, &masterfds);
+                      // update the maximum tracker
+                      if (newsockfd > maxfd)
+                          maxfd = newsockfd;
+                      // print out the IP and the socket number
+                      /*char ip[INET_ADDRSTRLEN];
+                      printf(
+                          "new connection from %s on socket %d\n",
+                          // convert to human readable string
+                          inet_ntop(cliaddr.sin_family, &cliaddr.sin_addr, ip, INET_ADDRSTRLEN),
+                          newsockfd
+                      );*/
+                  }
+              }
+              // a message is sent from the client
+              else
+              {   /* Read characters from the connection, then process */
+                  char buff[256];
+                  int n = read(i, buff, 256);
+                  if (n <= 0)
+                  {
+                      if (n < 0)
+                          perror("read");
+                      else
+                          printf("socket %d close the connection\n", i);
+                      close(i);
+                      FD_CLR(i, &masterfds);
+                  }
+                  // write back to the client
+                  else if (write(i, buff, n) < 0)
+                  {
+                      perror("write");
+                      close(i);
+                      FD_CLR(i, &masterfds);
+                  }
+              }
+          }
+
+
+
+        if (!strncmp(buffer, "GOODBYE-CLOSE-TCP", 17))
+            break;
+
+        /*c = buffer;
+        while (*c)
+        {
+            *c = toupper(*c);
+            ++c;
+        }*/
+
+
+
+    /* close socket */
+    //close(sockfd);
+
+    return 0;
+}