Tafelbild: Partitionierung, ext2, Beispiel-Programme: Netzwerkprogrammierung

20170707/client.c

+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <unistd.h>
+#include <netdb.h>
+#include <sys/socket.h>
+#include <arpa/inet.h>
+
+#define TARGET_HOST "localhost"
+#define PORT 1234
+#define MESSAGE "Hello, world!\n"
+
+void error (char *msg)
+{
+  fprintf (stderr, "%s\n", msg);
+  exit (1);
+}
+
+int main (void)
+{
+  int s;
+  struct sockaddr_in name;
+  if ((s = socket (PF_INET, SOCK_STREAM, 0)) < 0)
+    error ("cannot create socket");
+  memset (&name, 0, sizeof (name));
+  name.sin_family = AF_INET;
+  name.sin_port = htons (PORT);
+  name.sin_addr.s_addr = htonl (INADDR_ANY);
+  struct hostent *ho = gethostbyname (TARGET_HOST);
+  if (!ho)
+    {
+      close (s);
+      error ("name server lookup error");
+    }
+  if (ho->h_length > (int) sizeof (name.sin_addr))
+    ho->h_length = sizeof (name.sin_addr);
+  memcpy (&name.sin_addr, ho->h_addr, ho->h_length);
+  if (connect (s, (struct sockaddr *) &name, sizeof (name)) < 0)
+    {
+      close (s);
+      error ("cannot connect to socket");
+    }
+  send (s, MESSAGE, strlen (MESSAGE), 0);
+  shutdown (s, SHUT_RDWR);
+  close (s);
+  return 0;
+}

20170707/server.c

+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <unistd.h>
+#include <netdb.h>
+#include <sys/socket.h>
+#include <arpa/inet.h>
+
+#define PORT 1234
+#define MESSAGE "Hello, world!\n"
+
+void error (char *msg)
+{
+  fprintf (stderr, "%s\n", msg);
+  exit (1);
+}
+
+int main (void)
+{
+  int s;
+  struct sockaddr_in name;
+  if ((s = socket (PF_INET, SOCK_STREAM, 0)) < 0)
+    error ("cannot create socket");
+  memset (&name, 0, sizeof (name));
+  name.sin_family = AF_INET;
+  name.sin_port = htons (PORT);
+  name.sin_addr.s_addr = htonl (INADDR_ANY);
+  int on = 1;
+  setsockopt (s, SOL_SOCKET, SO_REUSEADDR, (void *) &on, sizeof (on));
+  if (bind (s, (struct sockaddr *) &name, sizeof (name)) < 0)
+    {
+      close (s);
+      error ("cannot bind socket");
+    }
+  if (listen (s, 16) < 0)
+    {
+      close (s);
+      error ("cannot listen on socket");
+    }
+  struct sockaddr_in clientname;
+  size_t size = sizeof (clientname);
+  s = accept (s, (struct sockaddr *) &clientname, &size);
+  if (s < 0)
+    error ("cannot accept connection");
+  char *host_address = inet_ntoa (clientname.sin_addr);
+  char *host_name;
+  struct hostent *hp = gethostbyaddr ((void *) &clientname.sin_addr, sizeof (clientname.sin_addr), clientname.sin_family);
+  if (hp)
+    host_name = hp->h_name;
+  else
+    host_name = inet_ntoa (clientname.sin_addr);
+  int remote_port = ntohs (clientname.sin_port);
+  printf ("connection from %s [%s], port %d\n",
+          host_name, host_address, remote_port);
+  send (s, MESSAGE, strlen (MESSAGE), 0);
+  shutdown (s, SHUT_RDWR);
+  close (s);
+  return 0;
+}