C UDP 套接字不工作

发布于 2024-12-28 10:05:24 字数 1706 浏览 0 评论 0原文

我在 C 中的套接字编程方面的作业之一遇到了问题。我们正在使用 UDP 做一个简单的客户端/服务器事情，而我在服务器方面遇到了麻烦。这是一个片段：

int main(int argc, char *argv[])
{
    int sockfd, newsockfd, portno;
    socklen_t clilen;
    char buffer[PACKET_DATA_LENGTH];
    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_DGRAM, 0);
    if (sockfd < 0)
        error("ERROR opening socket");

最初是 sockfd = socket(AF_NET, SOCK_DGRAM, 0) 是一个 SOCK_STREAM，但由于项目规范是在 UDP 而不是 TCP 中进行，所以我更改了STREAM 到 DGRAM。

我这样调用服务器： ./receiver 1234

并且收到错误： 接受时出错：套接字上不支持操作

但是，如果我将其从 改回来DGRAM 到 STREAM 它编译并且 ./receiver 1234 工作正常。

帮助？

谢谢！ -kstruct

编辑这就是 error() 的样子（这是预先给定的代码，我没有编写它，它是项目的一部分）

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

EDIT2 这是我的更多代码（紧随我发布的第一块代码之后的代码）..我猜样板代码确实调用了accept()，但这不应该触发不同的输出消息吗？也就是说，它不应该说ERROR opening socket而不是ERROR on Accept吗？

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");

原文

I'm having a problem with one of my homework assignments on socket programming in C.. we're doing a simple client/server thing with UDP and I'm having trouble with the server.. here's a snippet:

int main(int argc, char *argv[])
{
    int sockfd, newsockfd, portno;
    socklen_t clilen;
    char buffer[PACKET_DATA_LENGTH];
    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_DGRAM, 0);
    if (sockfd < 0)
        error("ERROR opening socket");

Originally the sockfd = socket(AF_NET, SOCK_DGRAM, 0) was a SOCK_STREAM, but since the project specification was to do it in UDP and not TCP I changed STREAM to DGRAM.

I call the server like: ./receiver 1234

And I get the error: ERROR on accept: Operation not supported on socket

However, if I change it back from DGRAM to STREAM it compiles and ./receiver 1234 works fine.

Help?

Thanks!
-kstruct

EDIT
This is what error() looks like (this is pre-given code, I did not write it, it came as part of the project)

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

EDIT2
Here's more of my code (what follows immediately after the first block of code I posted).. I guess the boilerplate code does call accept(), but shouldn't that trigger a different output message? Namely, shouldn't it say ERROR opening socket rather than ERROR on accept?

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");

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