Lehrmaterialien und Beispiele 22.11.2018

20181122/Zeichen_123.pdf

+../common/Zeichen_123.pdf
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20181122/kompass-messung.png

+../common/kompass-messung.png
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20181122/kompassmodul-an-roboter.jpg

+../common/kompassmodul-an-roboter.jpg
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20181122/kompassmodul.jpg

+../common/kompassmodul.jpg
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20181122/logo-hochschule-bochum-cvh-text-v2.pdf

+../common/logo-hochschule-bochum-cvh-text-v2.pdf
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20181122/logo-hochschule-bochum.pdf

+../common/logo-hochschule-bochum.pdf
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20181122/motherboard-anschluesse.jpg

+../common/motherboard-anschluesse.jpg
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20181122/pgslides.sty

+../common/pgslides.sty
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20181122/tcpip-client-0.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 "ngc224.gerwinski.de"
+#define PORT 80
+#define COMMAND "GET /\r\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, COMMAND, strlen (COMMAND), 0);
+  ssize_t l;
+  do
+    {
+      char buffer[100];
+      l = recv (s, buffer, 100, 0);
+      if (l > 0)
+        write (1, buffer, l);
+    }
+  while (l > 0);
+  shutdown (s, SHUT_RDWR);
+  close (s);
+  return 0;
+}

20181122/tcpip-client-1.cpp

+#include <boost/asio/io_service.hpp>
+#include <boost/asio/write.hpp>
+#include <boost/asio/buffer.hpp>
+#include <boost/asio/ip/tcp.hpp>
+#include <array>
+#include <string>
+#include <iostream>
+
+using namespace boost::asio;
+using namespace boost::asio::ip;
+
+io_service ioservice;
+tcp::resolver resolv{ioservice};
+tcp::socket tcp_socket{ioservice};
+std::array<char, 4096> bytes;
+
+void read_handler(const boost::system::error_code &ec,
+  std::size_t bytes_transferred)
+{
+  if (!ec)
+  {
+    std::cout.write(bytes.data(), bytes_transferred);
+    tcp_socket.async_read_some(buffer(bytes), read_handler);
+  }
+}
+
+void connect_handler(const boost::system::error_code &ec)
+{
+  if (!ec)
+  {
+    std::string r = "GET /\n";
+    write(tcp_socket, buffer(r));
+    tcp_socket.async_read_some(buffer(bytes), read_handler);
+  }
+}
+
+void resolve_handler(const boost::system::error_code &ec,
+  tcp::resolver::iterator it)
+{
+  if (!ec)
+    tcp_socket.async_connect(*it, connect_handler);
+}
+
+int main()
+{
+  tcp::resolver::query q{"ngc224.gerwinski.de", "80"};
+  resolv.async_resolve(q, resolve_handler);
+  ioservice.run();
+}

20181122/tcpip-server-0.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;
+  socklen_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;
+}

20181122/tcpip-server-1.cpp

+#include <boost/asio/io_service.hpp>
+#include <boost/asio/write.hpp>
+#include <boost/asio/buffer.hpp>
+#include <boost/asio/ip/tcp.hpp>
+#include <string>
+
+using namespace boost::asio;
+using namespace boost::asio::ip;
+
+io_service ioservice;
+tcp::endpoint tcp_endpoint{tcp::v4(), 1234};
+tcp::acceptor tcp_acceptor{ioservice, tcp_endpoint};
+tcp::socket tcp_socket{ioservice};
+std::string data;
+
+void write_handler(const boost::system::error_code &ec,
+  std::size_t bytes_transferred)
+{
+  if (!ec)
+    tcp_socket.shutdown(tcp::socket::shutdown_send);
+}
+
+void accept_handler(const boost::system::error_code &ec)
+{
+  if (!ec)
+  {
+    std::string data = "Hello, world!\n";
+    async_write(tcp_socket, buffer(data), write_handler);
+  }
+}
+
+int main()
+{
+  tcp_acceptor.listen();
+  tcp_acceptor.async_accept(tcp_socket, accept_handler);
+  ioservice.run();
+}

README.md

@@ -21,6 +21,7 @@ Vortragsfolien:
  * [18.10.2018: Unix: Umgang mit Dateisystemen](https://gitlab.cvh-server.de/pgerwinski/es/raw/master/20181018/es-20181018.pdf)
  * [25.10.2018: Unix: grep, Ein- und Ausgabeströme, Pipes, Verzweigungen und Schleifen](https://gitlab.cvh-server.de/pgerwinski/es/raw/master/20181025/es-20181025.pdf)
  * [08.11.2018: TCP/IP in der Praxis: Netzzugang, IP-Adressen, Ports, Protokolle](https://gitlab.cvh-server.de/pgerwinski/es/raw/master/20181108/es-20181108.pdf)
+ * [22.11.2018: TCP/IP in der Praxis: SSH, X11, GNU screen, Programmierung; Bus-Systeme](https://gitlab.cvh-server.de/pgerwinski/es/raw/master/20181122/es-20181122.pdf)
  * [alle in 1 Datei](https://gitlab.cvh-server.de/pgerwinski/es/raw/master/es-slides-2018ws.pdf)
 
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