c - Amazon EC2 Socket 编程(C)

Question

我基本上是在尝试读取 Raspberry Pi(我的客户端)上的加速计数据并将它们发送到服务器(EC2 ubuntu 实例)。

这是我的客户端代码:

#include "./sensor.h"
#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
#include <string.h>
#include <sys/types.h>
#include <sys/socket.h>
#include <netinet/in.h>
#include <netdb.h> 

void error(const char *msg)
{
    perror(msg);
    exit(0);
}

int main(int argc, char *argv[])
{
    int sockfd, portno, n;
    struct sockaddr_in serv_addr;
    struct hostent *server;

    char buffer[256];
    if (argc < 4) {
       fprintf(stderr,"usage %s hostname port\n", argv[0]);
       exit(0);
    }
    int delay = atoi(argv[3]);
    portno = atoi(argv[2]);
    sockfd = socket(AF_INET, SOCK_STREAM, 0);
    if (sockfd < 0) 
        error("ERROR opening socket");
    server = gethostbyname(argv[1]);
    if (server == NULL) {
        fprintf(stderr,"ERROR, no such host\n");
        exit(0);
    }
    bzero((char *) &serv_addr, sizeof(serv_addr));
    serv_addr.sin_family = AF_INET;
    bcopy((char *)server->h_addr, 
         (char *)&serv_addr.sin_addr.s_addr,
         server->h_length);
    serv_addr.sin_port = htons(portno);
    if (connect(sockfd,(struct sockaddr *) &serv_addr,sizeof(serv_addr)) < 0) 
        error("ERROR connecting");
    int acc[6];
    enableIMU();
    while(1){
    bzero(buffer,256);
    readACC(acc);
    sprintf(buffer,"%d\t%d\t%d\t\n", acc[0], acc[1], acc[2]);
    n = write(sockfd,buffer,strlen(buffer));
    if (n < 0) 
         error("ERROR writing to socket");
    if (n < 0) 
         error("ERROR reading from socket");
    printf("%s\n",buffer);
    }
    close(sockfd);
    return 0;
}

这是我的服务器代码:

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

void error(const char *msg)
{
    perror(msg);
    exit(1);
}

int main(int argc, char *argv[])
{
     int sockfd, newsockfd, portno;
     socklen_t clilen;
     char buffer[256];
     struct sockaddr_in serv_addr, cli_addr;
     int n;
     if (argc < 2) {
         fprintf(stderr,"ERROR, no port provided\n");
         exit(1);
     }
     sockfd = socket(AF_INET, SOCK_STREAM, 0);
     if (sockfd < 0) 
        error("ERROR opening socket");
     bzero((char *) &serv_addr, sizeof(serv_addr));
     portno = atoi(argv[1]);
     serv_addr.sin_family = AF_INET;
     serv_addr.sin_addr.s_addr = INADDR_ANY;
     serv_addr.sin_port = htons(portno);
     if (bind(sockfd, (struct sockaddr *) &serv_addr,
              sizeof(serv_addr)) < 0) 
              error("ERROR on binding");
     listen(sockfd,5);
     clilen = sizeof(cli_addr);
     newsockfd = accept(sockfd, 
                 (struct sockaddr *) &cli_addr, 
                 &clilen);
     if (newsockfd < 0) 
          error("ERROR on accept");
     bzero(buffer,256);
     n = read(newsockfd,buffer,255);
     if (n < 0) error("ERROR reading from socket");
     printf("Here is the message: %s\n",buffer);
     n = write(newsockfd,"I got your message",18);
     if (n < 0) error("ERROR writing to socket");
     close(newsockfd);
     close(sockfd);
     return 0; 
}

我将其放入客户端的命令行中并查看我的加速度计读数:

./client ec2-54-187-93-10.us-west-2.compute.amazonaws.com 8000

然后我将此行放在我的服务器上，但什么也没看到:

./server 8000

这是我的实例的安全组:

Type            Protocol          Port Range               Source
HTTP              TCP                 80                  0.0.0.0/0
Custom TCP Rule   TCP                8000                 0.0.0.0/0
SSH               TCP                 22                  0.0.0.0/0

你知道我做错了什么吗？我非常感谢您的帮助。

Answer 1

查找问题的一些技巧。您可以使用它来查找您的服务器是否已启动。

fuser 8000/tcp

如果没问题的话，你可以使用telnet:

telnet localhost:8000

并尝试向您的服务器发送一些内容，在您的情况下应该会发生这种情况:

printf("Here is the message: %s\n",buffer);

如果您可以看到端口正忙，但看不到通过 telnet 发送的消息，那么您应该对客户端进行更多调试并找出问题。