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--- workshop:sockets [2010-09-29 17:50] – equinox
+++ workshop:sockets [2025-11-09 09:25] (current) – external edit 127.0.0.1
@@ Line 1: / Line 1: @@
-====== Vortrag/Workshop Einführung in Einführung Unix Socket Programmierung ======
+====== Vortrag/Workshop Einführung in Unix Socket Programmierung ======
   * by Christian Pointner
+===== Beispielcode =====
+Es folgen ein paar simple Beispielprogramme die die Verwendung von Sockets unter Unix zeigen. Alle Beispiele und ein kleines Makefile können auch direkt per unten stehendem Link heruntergeladen werden:
+{{workshop:socket-examples.tar.gz|socket-examples.tar.gz}}
+Es folgt noch der Code für einen sehr simplen Chat Server anhand dessen die Verwendung des Resolvers (DNS etc.) gezeigt wird.
 ==== Beispiel: udpclient ====
@@ Line 53: / Line 64: @@
   }
-  struct sockaddr_in local_addr;
-  memset((char *) &local_addr, 0, sizeof(local_addr));
-  local_addr.sin_family = AF_INET;
-  local_addr.sin_port = htons(4321);
-  local_addr.sin_addr.s_addr = htonl(INADDR_ANY);
-  if(bind(sock, (struct sockaddr *)&local_addr, sizeof(local_addr))==-1) {
-    perror("bind() call failed");
-    exit(-1);
-  }
   struct sockaddr_in remote_addr;
   int alen, len;
@@ Line 93: / Line 93: @@
   return 0;
 }
-</file>/*
+</file>
+==== Beispiel: udpserver ====
+<file>
+/*
  *  udpserver
  *
@@ Line 168: / Line 173: @@
 </file>
+==== Beispiel: tcpclient ====
+<file>
+/*
+ *  tcpclient
+ *
+ *  This is a very basic TCP client example to show the usage of
+ *  sockets.
+ *
+ *  Copyright (C) 2010 Christian Pointner <equinox@realraum.at>
+ *
+ *  tcpclient is free software: you can redistribute it and/or modify
+ *  it under the terms of the GNU General Public License as published by
+ *  the Free Software Foundation, either version 3 of the License, or
+ *  any later version.
+ *
+ *  tcpclient is distributed in the hope that it will be useful,
+ *  but WITHOUT ANY WARRANTY; without even the implied warranty of
+ *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ *  GNU General Public License for more details.
+ *
+ *  You should have received a copy of the GNU General Public License
+ *  along with tcpclient. If not, see <http://www.gnu.org/licenses/>.
+ */
-==== Beispiel: udpserver ====
+#include <stdio.h>
+#include <stdlib.h>
+#include <unistd.h>
+#include <errno.h>
+#include <string.h>
+#include <sys/types.h>
+#include <sys/socket.h>
+#include <arpa/inet.h>
+int main(int argc, char** argv)
+{
+  if(argc <= 2) {
+    fprintf(stderr,"too few arguments\n");
+    exit(1);
+  }
+  printf("starting TCP Client\n");
+  int sock = socket(AF_INET, SOCK_STREAM, 0);
+  if(sock < 0) {
+    perror("socket() call failed");
+    exit(-1);
+  }
+  struct sockaddr_in remote_addr;
+  remote_addr.sin_family = AF_INET;
+  remote_addr.sin_port = htons(atoi(argv[2]));
+  if (inet_aton(argv[1], &remote_addr.sin_addr)==0) {
+    perror("inet_aton() call failed");
+    exit(-1);
+  }
+  if(connect(sock, (struct sockaddr *)&remote_addr, sizeof(remote_addr))==-1) {
+    perror("connect() call failed");
+    exit(-1);
+  }
+  int len;
+  uint8_t buffer[1500];
+  for (;;) {
+    if((len = read(0, buffer, 1500))==-1) {
+      perror("read() call failed");
+      exit(-1);
+    }
+    int offset = 0;
+    int wlen;
+    for(;;) {
+      wlen = send(sock, &buffer[offset], len - offset, 0);
+      if(wlen == -1) {
+        if(errno != EINTR) {
+          perror("write() call failed");
+          exit(-1);
+        }
+        wlen = 0;
+      }
+      offset += wlen;
+      if(offset+1 >= len)
+        break;
+    }
+  }
+  close(sock);
+  printf("exiting TCP Client\n");
+  return 0;
+}
+</file>
+==== Beispiel: tcpserver ====
 <file>
+/*
+ *  tcpserver
+ *
+ *  This is a very basic TCP server example to show the usage of
+ *  sockets.
+ *
+ *  Copyright (C) 2010 Christian Pointner <equinox@realraum.at>
+ *
+ *  tcpserver is free software: you can redistribute it and/or modify
+ *  it under the terms of the GNU General Public License as published by
+ *  the Free Software Foundation, either version 3 of the License, or
+ *  any later version.
+ *
+ *  tcpserver is distributed in the hope that it will be useful,
+ *  but WITHOUT ANY WARRANTY; without even the implied warranty of
+ *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ *  GNU General Public License for more details.
+ *
+ *  You should have received a copy of the GNU General Public License
+ *  along with tcpserver. If not, see <http://www.gnu.org/licenses/>.
+ */
+#include <stdio.h>
+#include <stdlib.h>
+#include <unistd.h>
+#include <errno.h>
+#include <string.h>
+#include <sys/types.h>
+#include <sys/socket.h>
+#include <arpa/inet.h>
+#include <sys/select.h>
+int main(int argc, char** argv)
+{
+  printf("starting TCP Server\n");
+  int server = socket(AF_INET, SOCK_STREAM, 0);
+  if(server < 0) {
+    perror("socket() call failed");
+    exit(-1);
+  }
+  struct sockaddr_in local_addr;
+  memset((char *) &local_addr, 0, sizeof(local_addr));
+  local_addr.sin_family = AF_INET;
+  local_addr.sin_port = htons(1234);
+  local_addr.sin_addr.s_addr = htonl(INADDR_ANY);
+  if(bind(server, (struct sockaddr *)&local_addr, sizeof(local_addr))==-1) {
+    perror("bind() call failed");
+    exit(-1);
+  }
+  if(listen(server, 5)==-1) {
+    perror("listen() call failed");
+    exit(-1);
+  }
+  fd_set readfds, tmpfds;
+  FD_ZERO(&readfds);
+  FD_SET(server, &readfds);
+  int max_fd = server;
+  uint8_t buffer[1500];
+  struct sockaddr_in remote_addr;
+  memset (&remote_addr, 0, sizeof(remote_addr));
+  int len, alen=sizeof(remote_addr);
+  for (;;) {
+    memcpy(&tmpfds, &readfds, sizeof(tmpfds));
+    int num = select(max_fd+1, &tmpfds, NULL, NULL, NULL);
+    if(num == -1 && errno != EINTR) {
+      perror("select() call failed");
+      exit(-1);
+    }
+    if(num == -1 || !num)
+      continue;
+    if(FD_ISSET(server, &tmpfds)) {
+      int new_client = accept(server, (struct sockaddr *)&remote_addr, &alen);
+      if(new_client==-1) {
+        perror("accept() call failed");
+        exit(-1);
+      }
+      printf("new connection %s:%d (fd=%d)\n", inet_ntoa(remote_addr.sin_addr), ntohs(remote_addr.sin_port), new_client);
+      FD_SET(new_client, &readfds);
+      max_fd = (max_fd < new_client) ? new_client : max_fd;
+      FD_CLR(server, &tmpfds);
+    }
+    int fd;
+    for(fd=0; fd<=max_fd; ++fd) {
+      if(FD_ISSET(fd, &tmpfds)) {
+        len = recv(fd, buffer, 1500, 0);
+        if(len <= 0) {
+          if(len < 0) perror("recv() call failed");
+          else fprintf(stderr, "client closed connection\n");
+          printf("removing client (fd=%d)\n", fd);
+          FD_CLR(fd, &readfds);
+          close(fd);
+        }
+        else
+          printf("Received %d Bytes from client (fd=%d)\n", len, fd);
+      }
+    }
+  }
+  close(server);
+  printf("exiting TCP Server\n");
+  return 0;
+}
+</file>