Question

现在，我的代码允许多个客户端连接到服务器并向服务器发送消息，然后将消息发送回发送它的客户端。我试图弄清楚如何让服务器将收到的消息发送给所有客户端。

我考虑将sd存储在一个数组中，然后写入每个sd，但我先打印了sd，它总是相同的数字（4），所以我不确定我是什么应该做

我目前的代码：

server.c

#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>

#include "networking.h"

void process( char * s );
void sub_server( int sd );

int main() {

  int sd, connection;

  sd = server_setup();

  while (1) {

    connection = server_connect( sd );

    int f = fork();
    if ( f == 0 ) {

      close(sd);
      sub_server( connection );

      exit(0);
    }
    else {
      close( connection );
    }
  }
  return 0;
}


void sub_server( int sd ) {

  char buffer[MESSAGE_BUFFER_SIZE];
  while (read( sd, buffer, sizeof(buffer) )) {

    printf("[SERVER %d] received: %s\n", getpid(), buffer );
    process( buffer );
    write( sd, buffer, sizeof(buffer));    
  }

}
void process( char * s ) {

  while ( *s ) {
    *s = (*s - 'a' + 13) % 26 + 'a';
    s++;
  }
}

client.c

#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>

#include "networking.h"

int main( int argc, char *argv[] ) {

  char *host;
  if (argc != 2 ) {
    printf("host not specified, conneting to 127.0.0.1\n");
    host = "127.0.0.1";
  }
  else
    host = argv[1];

  int sd;

  sd = client_connect( host );

  char buffer[MESSAGE_BUFFER_SIZE];

  while (1) {
    printf("enter message: ");
    fgets( buffer, sizeof(buffer), stdin );
    char *p = strchr(buffer, '\n');
    *p = 0;

    write( sd, buffer, sizeof(buffer) );
    read( sd, buffer, sizeof(buffer) );
    printf( "received: %s\n", buffer );
  }

  return 0;
}

networking.c

#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <errno.h>

#include <sys/socket.h>
#include <sys/types.h>
#include <netinet/in.h>
#include <unistd.h>
#include <arpa/inet.h>

void error_check( int i, char *s ) {
  if ( i < 0 ) {
    printf("%d\n", i);
    printf("[%s] error %d: %s\n", s, errno, strerror(errno) );
    exit(1);
  }
}

int server_setup() {

  int sd;
  int i;

  sd = socket( AF_INET, SOCK_STREAM, 0 );
  error_check( sd, "server socket" );

  struct sockaddr_in sock;
  sock.sin_family = AF_INET;
  sock.sin_addr.s_addr = INADDR_ANY;
  sock.sin_port = htons(9001);
  i = bind( sd, (struct sockaddr *)&sock, sizeof(sock) );
  error_check( i, "server bind" );

  return sd;
}

int server_connect(int sd) {
  int connection, i;

  i = listen(sd, 1);
  error_check( i, "server listen" );

  struct sockaddr_in sock1;
  unsigned int sock1_len = sizeof(sock1);
  connection = accept( sd, (struct sockaddr *)&sock1, &sock1_len );
  error_check( connection, "server accept" );

  printf("[server] connected to %s\n", inet_ntoa( sock1.sin_addr ) );

  return connection;
}


int client_connect( char *host ) {
  int sd, i;

  sd = socket( AF_INET, SOCK_STREAM, 0 );
  error_check( sd, "client socket" );

  struct sockaddr_in sock;
  sock.sin_family = AF_INET;
  inet_aton( host, &(sock.sin_addr));
  sock.sin_port = htons(9001);

  printf("[client] connecting to: %s\n", host );
  i = connect( sd, (struct sockaddr *)&sock, sizeof(sock) );
  error_check( i, "client connect");

  return sd;
}

非常感谢帮助和解释（我也是C的新手，所以请尝试解释）

C：如何将发送到服务器的客户端消息发送给所有客户端？

0 个答案: