workshop:sockets

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workshop:sockets [2010-09-29 17:47] – angelegt equinoxworkshop:sockets [2025-11-09 09:25] (current) – external edit 127.0.0.1
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-====== Vortrag/Workshop Einführung in Einführung Unix Socket Programmierung ======+====== Vortrag/Workshop Einführung in Unix Socket Programmierung ======
  
   * by Christian Pointner   * 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 ====
 +
 +<file>
 +/*
 + *  udpclient
 + *
 + *  This is a very basic UDP client example to show the usage of
 + *  sockets. 
 + *  
 + *  Copyright (C) 2010 Christian Pointner <equinox@realraum.at>
 + *
 + *  udpclient 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.
 + *
 + *  udpclient 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 udpclient. 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>
 +
 +int main(int argc, char** argv)
 +{
 +  if(argc <= 2) {
 +    fprintf(stderr,"too few arguments\n");
 +    exit(1);
 +  }
 +  printf("starting UDP Client\n");
 +
 +  int sock = socket(AF_INET, SOCK_DGRAM, 0);
 +  if(sock < 0) { 
 +    perror("socket() call failed");
 +    exit(-1);
 +  }
 +    
 +  struct sockaddr_in remote_addr;
 +  int alen, len;
 +  alen = sizeof(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);
 +  }
 +
 +  uint8_t buffer[1500];
 +  for (;;) {
 +    if((len = read(0, buffer, 1500))==-1) {
 +      perror("read() call failed");
 +      exit(-1);
 +    }
 +
 +    if((len = sendto(sock, buffer, len, 0, (struct sockaddr *)&remote_addr, alen))==-1) {
 +      perror("sendto() call failed");
 +      exit(-1);
 +    }
 +  }
 +
 +  close(sock);
 +  
 +  printf("exiting UDP Client\n");
 +
 +  return 0;
 +}
 +</file>
 +
 +==== Beispiel: udpserver ====
 +
 +<file>
 +/*
 + *  udpserver
 + *
 + *  This is a very basic UDP client example to show the usage of
 + *  sockets. 
 + *  
 + *  Copyright (C) 2010 Christian Pointner <equinox@realraum.at>
 + *
 + *  udpserver 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.
 + *
 + *  udpserver 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 udpserver. 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>
 +
 +int main(int argc, char** argv)
 +{
 +  printf("starting UDP Server\n");
 +
 +  int sock = socket(AF_INET, SOCK_DGRAM, 0);
 +  if(sock < 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(sock, (struct sockaddr *)&local_addr, sizeof(local_addr))==-1) { 
 +    perror("bind() call failed");
 +    exit(-1);
 +  }
 +
 +  struct sockaddr_in remote_addr;
 +  int alen, len;
 +  alen = sizeof(remote_addr);
 +  uint8_t buffer[1500];
 +  for (;;) {
 +    if((len = recvfrom(sock, buffer, 1500, 0, (struct sockaddr *)&remote_addr, &alen))==-1) {
 +      perror("recvfrom() call failed");
 +      exit(-1);
 +    }
 +
 +    printf("Received %d Bytes from %s:%d\n", len, inet_ntoa(remote_addr.sin_addr), ntohs(remote_addr.sin_port));
 +  }
 +
 +  close(sock);
 +  
 +  printf("exiting UDP Server\n");
 +
 +  return 0;
 +}
 +</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/>.
 + */
 +
 +#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>
 +
  
 ---- ----
 {{tag>workshop}} {{tag>workshop}}
  
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