C TCP/IP Echo Server——绑定(bind)和接受函数出错

Question

我在绑定(bind)套接字时遇到问题。当我编译这段代码时:

#include <stdio.h>
#include <sys/socket.h>
#include <sys/types.h>
#include <netinet/in.h>
#include <stdlib.h> 
#include <string.h>

int main(int argc, char *argv[])
{
    if (argc != 2)
    {
        printf("Error. Please enter the right amount of arguments (2)");
        exit(1);
    }

    int sock, port, clientlen, connection, readfd, writefd;
    char buffer[255];
    struct sockaddr_in server, clientaddr;

     if (sock = socket(AF_INET, SOCK_STREAM, IPPROTO_TCP) < 0)
     {
         printf("Socket was not made.");
         exit(1);
     }

    bzero((char *) &server, sizeof(server));
    port = atoi(argv[1]);

    server.sin_family = AF_INET;
    server.sin_addr.s_addr = INADDR_ANY;
    server.sin_port = htons(port);

    if ((bind(socket, (struct sockaddr *) &server, sizeof(server))) < 0)
    {
        printf("Could not bind socket to address\n");
        exit(1);
    }

    listen(socket, 5);

    clientlen = sizeof(clientaddr);

    if (connection = accept(socket, (struct sockaddr *) &clientaddr, &clientlen) < 0)
    {
        printf("Could not accept connection");
        exit(1);
    }       

    if (readfd = read(connection, buffer, 255) < 0)
    {
        printf("Could not read from socket");
        exit(1);
    }

    printf("!---THIS IS A TEST---! \n BUFFER: %s", buffer);

    if (writefd = write(connection, buffer, 255) < 0)
    {
        printf("Could not write to socket");
        exit(1);
    }

    return 0;
}   

我收到错误:

a3server.c: In function ‘main’:
a3server.c:33:28: warning: passing argument 1 of ‘bind’ makes integer from pointer without a cast [enabled by default]
  if ((bind(socket, (struct sockaddr *) &server, sizeof(server))) < 0)
                        ^
In file included from a3server.c:2:0:
/usr/include/x86_64-linux-gnu/sys/socket.h:123:12: note: expected ‘int’ but argument is of type ‘int (*)(int,  int,  int)’
 extern int bind (int __fd, __CONST_SOCKADDR_ARG __addr, socklen_t __len)
        ^
a3server.c:39:2: warning: passing argument 1 of ‘listen’ makes integer from pointer without a cast [enabled by default]
  listen(socket, 5);
  ^
In file included from a3server.c:2:0:
/usr/include/x86_64-linux-gnu/sys/socket.h:233:12: note: expected ‘int’ but argument is of type ‘int (*)(int,  int,  int)’
 extern int listen (int __fd, int __n) __THROW;
        ^
a3server.c:43:42: warning: passing argument 1 of ‘accept’ makes integer from pointer without a cast [enabled by default]
  if (connection = accept(socket, (struct sockaddr *) &clientaddr, &clientlen) < 0)
                                      ^
In file included from a3server.c:2:0:
/usr/include/x86_64-linux-gnu/sys/socket.h:243:12: note: expected ‘int’ but argument is of type ‘int (*)(int,  int,  int)’
 extern int accept (int __fd, __SOCKADDR_ARG __addr,

我在这里遵循了本指南:http://www.cs.rpi.edu/~moorthy/Courses/os98/Pgms/socket.html而且我不太确定我哪里出错了。

此外，这是我编译“gcc a3server.c -g -o server”时的命令(如果与此有关)。

Answer 1

您在bind()、listen() 和accept() 中使用的“socket”变量未定义。 socket() 返回的文件描述符保存在“sock”变量中。您必须将出现的“socket”替换为“sock”。

正确的方法是:

bind (sock, (struct sockaddr *) &server, sizeof (server))
...
listen (sock, 5);
...
accept (sock, ...