服务器读取传递给客户端的命令行参数

Question

我想将参数传递给客户端，将其发送到服务器，然后在那里打印，目前我没有得到任何输出。

当前代码：

客户：

#include <stdio.h> 
#include <sys/socket.h> 
#include <arpa/inet.h> 
#include <unistd.h> 
#include <string.h> 
#include <stdlib.h>
#include<errno.h>

#define PORT 8080 

int main(int argc, char const *argv[]) 
{ 
    int sock = 0, valread; 
    struct sockaddr_in serv_addr; 

    char buffer[1024] = {0}; 
    if ((sock = socket(AF_INET, SOCK_STREAM, 0)) < 0) 
    { 
        printf("\n Socket creation error \n"); 
        return -1; 
    } 

    serv_addr.sin_family = AF_INET; 
    serv_addr.sin_port = htons(PORT); 


    if(inet_pton(AF_INET, "127.0.0.1", &serv_addr.sin_addr)<=0)  
    { 
        printf("Invalid address \n"); 
        return -1; 
    } 

    if (connect(sock, (struct sockaddr *)&serv_addr, sizeof(serv_addr)) < 0) 
    { 
        printf("Connection Failed \n"); 
        return -1; 
    } 
      int i;
     if(argc>=2){
     for(i=0; i<argc; i++) {
    if(write( sock, argv[i], 1 + strlen( argv[i] ))<0)
    {
    printf("Error in write() ! %s\n", strerror(errno));
        return -1; 
    }
}
}
    return 0; 
} 

服务器：

#include <unistd.h> 
#include <stdio.h> 
#include <sys/socket.h> 
#include <stdlib.h> 
#include <netinet/in.h> 
#include <string.h> 
#include<errno.h>
#define PORT 8080 
int main(int argc, char const *argv[]) 
{ 
    int server_fd, new_socket, valread; 
    struct sockaddr_in address; 
    int opt = 1; 
    int addrlen = sizeof(address); 
    char buffer[1024] = {0}; 
    char *hello = "Hello from server"; 


    if ((server_fd = socket(AF_INET, SOCK_STREAM, 0)) == 0) 
    { 
        perror("socket failed"); 
        exit(EXIT_FAILURE); 
    } 


    if (setsockopt(server_fd, SOL_SOCKET, SO_REUSEADDR , &opt, sizeof(opt))) 
    { 
        perror("setsockopt"); 
        exit(EXIT_FAILURE); 
    } 
    address.sin_family = AF_INET; 
    address.sin_addr.s_addr = INADDR_ANY; 
    address.sin_port = htons( PORT ); 


    if (bind(server_fd, (struct sockaddr *)&address,  
                                 sizeof(address))<0) 
    { 
        perror("bind failed"); 
        exit(EXIT_FAILURE); 
    } 
    if (listen(server_fd, 3) < 0) 
    { 
        perror("listen"); 
        exit(EXIT_FAILURE); 
    } 
    if ((new_socket = accept(server_fd, (struct sockaddr *)&address,  
                       (socklen_t*)&addrlen))<0) 
    { 
        perror("accept"); 
        exit(EXIT_FAILURE); 
    } 

valread = read(new_socket , buffer, 1024); 
puts("The client sent the value: ");
int* valuerec=(int *)buffer;
int val2=*valuerec;

    return 0; 
} 

目前我没有得到任何数字作为输出，我该如何解决这个问题？最终我的目标是发送和接收多个参数，但现在我只发送一个。

Answer 1

以下建议的代码：

1. 干净编译
2. 执行所需的服务器功能
3. 正确检查错误
4. 正确处理错误
5. 为函数使用适当的签名：main()
6. 不包括那些内容没有使用的头文件
7. 使用有意义的名称而不是“神奇的”数字
8. 使用适当的水平间距以提高可读性
9. NUL 正确终止输入缓冲区
10. 注意功能：atoi()不表示何时发生错误，建议改用strtol()
11. 在设置某些字段之前正确清除结构address

现在建议的代码：

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



#define PORT 8080 
#define MAX_BUFFER_LEN 1025

int main( void ) 
{ 
    int server_fd, new_socket;

    struct sockaddr_in address; 

    if ( ( server_fd = socket( AF_INET, SOCK_STREAM, 0 ) ) < 0 ) 
    { 
        perror( "socket failed" ); 
        exit( EXIT_FAILURE ); 
    } 

    int opt = 1; 
    if ( setsockopt( server_fd, SOL_SOCKET, SO_REUSEADDR , &opt, sizeof(opt) ) ) 
    { 
        perror("setsockopt failed" ); 
        exit( EXIT_FAILURE ); 
    } 

    memset( &address, 0, sizeof( address ) );
    address.sin_family      = AF_INET; 
    address.sin_addr.s_addr = htonl( INADDR_ANY ); 
    address.sin_port        = htons( PORT ); 

    socklen_t addrlen = sizeof( address );
    if ( bind( server_fd, (struct sockaddr *)&address, addrlen ) < 0 ) 
    { 
        perror( "bind failed" ); 
        exit( EXIT_FAILURE ); 
    } 

    if ( listen( server_fd, 3 ) < 0 ) 
    { 
        perror( "listen failed" ); 
        exit( EXIT_FAILURE ); 
    } 

    if (( new_socket = accept(server_fd, (struct sockaddr *)&address,  
                       (socklen_t*)&addrlen ) ) < 0 ) 
    { 
        perror( "accept failed" ); 
        exit( EXIT_FAILURE ); 
    } 

    ssize_t valread; 
    char buffer[ MAX_BUFFER_LEN ] = { 0 };

    if( ( valread = read( new_socket, buffer, MAX_BUFFER_LEN -1 ) ) > 0 )
    {  // then read successful
        buffer[ valread ] = '\0';
        int value = atoi( buffer );
        printf( "The client sent the string: %s, which began with integer value: %d\n", buffer, value );
    }

    else if( ! valread )
    {
        puts( "client hungup" );
    }

    else
    {
        perror( "read failed" );
    }

    return 0; 
}