Question

我修改了beej的网络示例指南（如下所示），将html响应传回浏览器。我每次刷新都会“重置连接”，似乎无法找出原因？就像它在发出html响应之前关闭连接一样。

任何想法或调试建议？

编辑：它有时会将正确的数据传递给浏览器。

以下是代码：

/*
 ** server.c -- a stream socket server demo
 */

#include <iostream>
#include <string>
#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
#include <errno.h>
#include <string.h>
#include <sys/types.h>
#include <sys/socket.h>
#include <netinet/in.h>
#include <netdb.h>
#include <arpa/inet.h>
#include <sys/wait.h>
#include <signal.h>

#define PORT "8080"  // the port users will be connecting to

#define BACKLOG 10000    // how many pending connections queue will hold

using namespace std;

void sigchld_handler(int s)
{
    while(waitpid(-1, NULL, WNOHANG) > 0);
}

// get sockaddr, IPv4 or IPv6:
void *get_in_addr(struct sockaddr *sa)
{
    if (sa->sa_family == AF_INET) {
        return &(((struct sockaddr_in*)sa)->sin_addr);
    }

    return &(((struct sockaddr_in6*)sa)->sin6_addr);
}

int main(void)
{
    int sockfd, new_fd;  // listen on sock_fd, new connection on new_fd
    struct addrinfo hints, *servinfo, *p;
    struct sockaddr_storage their_addr; // connector's address information
    socklen_t sin_size;
    struct sigaction sa;
    int yes=1;
    char s[INET6_ADDRSTRLEN];
    int rv;

    memset(&hints, 0, sizeof hints);
    hints.ai_family = AF_UNSPEC;
    hints.ai_socktype = SOCK_STREAM;
    hints.ai_flags = AI_PASSIVE; // use my IP

    if ((rv = getaddrinfo(NULL, PORT, &hints, &servinfo)) != 0) {
        fprintf(stderr, "getaddrinfo: %s\n", gai_strerror(rv));
        return 1;
    }

    // loop through all the results and bind to the first we can
    for(p = servinfo; p != NULL; p = p->ai_next) {
        if ((sockfd = socket(p->ai_family, p->ai_socktype,
                        p->ai_protocol)) == -1) {
            perror("server: socket");
            continue;
        }

        if (setsockopt(sockfd, SOL_SOCKET, SO_REUSEADDR, &yes,
                    sizeof(int)) == -1) {
            perror("setsockopt");
            exit(1);
        }

        if (bind(sockfd, p->ai_addr, p->ai_addrlen) == -1) {
            close(sockfd);
            perror("server: bind");
            continue;
        }

        break;
    }

    if (p == NULL)  {
        fprintf(stderr, "server: failed to bind\n");
        return 2;
    }

    freeaddrinfo(servinfo); // all done with this structure

    if (listen(sockfd, BACKLOG) == -1) {
        perror("listen");
        exit(1);
    }

    sa.sa_handler = sigchld_handler; // reap all dead processes
    sigemptyset(&sa.sa_mask);
    sa.sa_flags = SA_RESTART;
    if (sigaction(SIGCHLD, &sa, NULL) == -1) {
        perror("sigaction");
        exit(1);
    }

    printf("server: waiting for connections...\n");

    while(1) {  // main accept() loop
        sin_size = sizeof their_addr;
        new_fd = accept(sockfd, (struct sockaddr *)&their_addr, &sin_size);
        if (new_fd == -1) {
            cout << "accept fail" << endl;
            continue;
        }

        inet_ntop(their_addr.ss_family,
                get_in_addr((struct sockaddr *)&their_addr),
                s, sizeof s);
        printf("server: got connection from %s\n", s);

        if (!fork()) { // this is the child process
            close(sockfd); // child doesn't need the listener
            string response = "HTTP/1.0 200 OK\r\n\r\n<html><head><title>Test</title></head><body>ok!</body></html>";
            if (send(new_fd, response.c_str(), response.length(), 0) == -1)
                cout << "error" << endl;
            close(new_fd);
            cout << "sent." << endl;
            exit(0);
        }
        close(new_fd);  // parent doesn't need this
    }

    return 0;
}

Answer 1

所以这里有2个错误（实际上有3个错误，最后一个是如果你想与浏览器交谈，你必须正确地实现HTTP，这是非常重要的）

您在接受客户时立即发送回复。有点慢的浏览器可能会在它发送完请求之前收到响应 - 这会使浏览器感到困惑。
您没有阅读请求。这意味着当你关闭套接字时，会有未读数据，这将导致在关闭套接字时发送TCP RST（导致“连接重置......”错误）。在某些情况下，浏览器会在此之前读取响应，在其他情况下可能没有，（在某些情况下，我猜它会因为没有Content-Length：标题而混淆，所以浏览器不会不知道它是否应该在遇到TCP RST时接收更多数据。这种特殊情况更好地描述了here

C服务器 - “连接已重置”

1 个答案: