Beispiel-Programme und Tafelbild 30.6.2017

20170630/bs-20170630.txt

+30.06.2017
+ - Quelltexte RP6 und Linux-Scheduler
+ - Signale
+ - Netzwerk-Interfaces
+
+Signale, 23.05.2016, 09:29:58
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+Prozeßkontrolle von bash aus: ^C, ^Z, jobs, kill -INT %3, fg, bg
+Prozeßkontrolle: ps, ps aux, pstree, kill
+Signal-Handler schreiben: signals-*.c
+Aufgabe: "Timer-Interrupt" programmieren
+
+Netzwerk-Interfaces, 30.05.2016, 10:36:28
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+Loopback-Treiber:
+Datei: ~/bo/2016ss/bs/20160509/linux-source-3.16/drivers/net/loopback.c
+Suchbegriff: struct net_device_ops
+
+drivers/net: Netzwerkkarten.
+net: Protokolle.
+
+Datei: ~/bo/2016ss/bs/20160509/linux-source-3.16/net/
+Suchbegriff: ether_setup
+
+Netzwerk-Treiber: früher auch unter /dev, jetzt nicht mehr
+ - "keine klassischen Datei-Operationen" --> serielle Schnittstellen
+ - historisch: Hot-Plug-Fähigkeit --> udev [--> systemd]
+
+Netzwerke in der Praxis:
+Datei: ~/bo/2013ss/net/script/net-2013ss.pdf
+
+SMTP-Sitzung: E-Mail versenden
+
+  $ nc 88.198.170.60 25
+  220 mx1.gerwinski.de ESMTP Exim 4.84_2 Mon, 30 May 2016 12:39:01 +0200
+  HELO microsoft.com
+  250 mx1.gerwinski.de Hello office.g-n-u.de [82.207.128.254]
+  MAIL FROM: <korbinian.moeller@hs-bochum.de>
+  250 OK
+  RCPT TO: <peter@gerwinski.de>
+  250 Accepted
+  DATA
+  354 Enter message, ending with "." on a line by itself
+  Subject: Test
+  From: Bill Gates <gates@microsoft.com>
+  To: Steve Jobs <jobs@apple.com>
+
+  Hi! B-)
+  .
+  250 OK id=1b7Kbi-0003Ut-CZ
+  QUIT
+  221 mx1.gerwinski.de closing connection
+  $

20170630/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;
+}

20170630/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;
+}

20170630/signals-0.c

+#include <signal.h>
+#include <stdio.h>
+
+static void signal_handler (int signo)
+{
+  printf ("Hello, world!\n");
+}
+
+int main (void)
+{
+  signal (SIGINT, signal_handler);
+  while (1);
+  return 0;
+}

20170630/signals-1.c

+#include <signal.h>
+#include <stdio.h>
+
+static void signal_handler (int signo)
+{
+  printf ("Hello, world!\n");
+}
+
+int main (void)
+{
+  if (signal (SIGINT, signal_handler) == SIG_ERR)
+    {
+      fputs ("Error installing signal handler.\n", stderr);
+      return 1;
+    }
+  while (1);
+  return 0;
+}

20170630/signals-2.c

+#include <signal.h>
+#include <stdio.h>
+
+static void signal_handler (int signo)
+{
+  printf ("Hello, world!\n");
+}
+
+int main (void)
+{
+  if (signal (SIGUSR1, signal_handler) == SIG_ERR)
+    {
+      fputs ("Error installing signal handler.\n", stderr);
+      return 1;
+    }
+  while (1);
+  return 0;
+}

20170630/signals-3.c

+#include <signal.h>
+#include <stdio.h>
+#include <sys/time.h>
+
+static void signal_handler (int signo)
+{
+  printf ("Hello, world!\n");
+}
+
+int main (void)
+{
+  if (signal (SIGVTALRM, signal_handler) == SIG_ERR)
+    {
+      fputs ("Error installing signal handler.\n", stderr);
+      return 1;
+    }
+
+  struct itimerval timer;
+  timer.it_value.tv_sec = 1;
+  timer.it_value.tv_usec = 0;
+  timer.it_interval.tv_sec = 1;
+  timer.it_interval.tv_usec = 0;
+  setitimer (ITIMER_VIRTUAL, &timer, NULL);
+
+  while (1);
+  return 0;
+}

20170630/signals-4.c

+#include <signal.h>
+#include <stdio.h>
+#include <sys/time.h>
+#include <unistd.h>
+
+static void signal_handler (int signo)
+{
+  printf ("Hello, world!\n");
+}
+
+int main (void)
+{
+  if (signal (SIGVTALRM, signal_handler) == SIG_ERR)
+    {
+      fputs ("Error installing signal handler.\n", stderr);
+      return 1;
+    }
+
+  struct itimerval timer;
+  timer.it_value.tv_sec = 1;
+  timer.it_value.tv_usec = 0;
+  timer.it_interval.tv_sec = 1;
+  timer.it_interval.tv_usec = 0;
+  setitimer (ITIMER_VIRTUAL, &timer, NULL);
+
+  while (1)
+    sleep (10);
+  return 0;
+}

20170630/signals-5.c

+#include <signal.h>
+#include <stdio.h>
+#include <sys/time.h>
+#include <unistd.h>
+
+static void signal_handler (int signo)
+{
+  printf ("Hello, world!\n");
+}
+
+int main (void)
+{
+  if (signal (SIGALRM, signal_handler) == SIG_ERR)
+    {
+      fputs ("Error installing signal handler.\n", stderr);
+      return 1;
+    }
+
+  struct itimerval timer;
+  timer.it_value.tv_sec = 1;
+  timer.it_value.tv_usec = 0;
+  timer.it_interval.tv_sec = 1;
+  timer.it_interval.tv_usec = 0;
+  setitimer (ITIMER_REAL, &timer, NULL);
+
+  while (1)
+    sleep (10);
+  return 0;
+}

20170630/signals-6.c

+#include <signal.h>
+#include <stdio.h>
+#include <unistd.h>
+
+static void signal_handler (int signo)
+{
+  printf ("Hello, world!\n");
+  alarm (1);
+}
+
+int main (void)
+{
+  if (signal (SIGALRM, signal_handler) == SIG_ERR)
+    {
+      fputs ("Error installing signal handler.\n", stderr);
+      return 1;
+    }
+  alarm (1);
+  while (1)
+    sleep (10);
+  return 0;
+}