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有人能帮我理解为什么我的C Web服务器正在抛出SIGABRT吗

sigabrt webserver pthreads sockets c

Jacob · 技术社区 · 1 年前

我是C语言的新手,试图构建一个非常简单的Web服务器作为启动项目,但由于某种原因,在处理完一个请求(并正确返回HTML文件)后,我在handleClient函数中得到了SIGABRT

当我介绍Posix线程时,它就出现了,我认为这与多线程和错误的内存处理有关。有人能给我指明正确的方向吗?或者帮助我找出代码的哪一部分可能是错误的?

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

void serveFile(int socket, const char* filename) {
    char buffer[1024];
    int fd;
    int readBytes;

    fd = open(filename, O_RDONLY);

    if (fd == -1) {
        perror("File open failed");
        return;
    }

    while ((readBytes = read(fd, buffer, sizeof(buffer))) > 0) {
        write(socket, buffer, readBytes);
    }

    close(fd);
}

void *handleClient(void *arg) {
    int socket = *(int*)arg;
    char buffer[1024];
    int readBytes;

    readBytes = read(socket, buffer, sizeof(buffer));

    buffer[readBytes] = '\0';
    printf("Received: %s\n", buffer);

    char *header = "HTTP/1.1 200 OK\nContent-Type: text/html\n\n";
    write(socket, header, strlen(header));

    serveFile(socket, "./helloworld.html");

    close(socket);

    free(arg);

    return NULL;
}

int main() {
    int server_fd, new_socket;
    struct sockaddr_in address;
    int opt = 1;
    int addrlen = sizeof(address);

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

    address.sin_family = AF_INET;
    address.sin_addr.s_addr = INADDR_ANY;
    address.sin_port = htons(8080);

    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);
    }

    while(1) {
        printf("Waiting for connections...\n");

        int *client_fd = malloc(sizeof(int));

        if ((*client_fd = accept(server_fd, (struct sockaddr *)&address, (socklen_t*)&addrlen))<0) {
            perror("accept");
            continue;
        }
        
        pthread_t thread_id;

        if(pthread_create(&thread_id, NULL, handleClient, (void *)client_fd)) {
            perror("Could not create thread");
            continue;
        }

        pthread_detach(thread_id);        
    }

    return 0;
}

edit:这是服务器从客户端接收的内容:

Received: GET / HTTP/1.1
Host: localhost:8080
Connection: keep-alive
Cache-Control: max-age=0
sec-ch-ua: "Google Chrome";v="123", "Not:A-Brand";v="8", "Chromium";v="123"
sec-ch-ua-mobile: ?0
sec-ch-ua-platform: "macOS"
Upgrade-Insecure-Requests: 1
User-Agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10_15_7) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/123.0.0.0 Safari/537.36
Accept: text/html,application/xhtml+xml,application/xml;q=0.9,image/avif,image/webp,image/apng,*/*;q=0.8,application/signed-exchange;v=b3;q=0.7
Sec-Fetch-Site: none
Sec-Fetch-Mode: navigate
Sec-Fetch-User: ?1
Sec-Fetch-Dest: document
Accept-Encoding: gzip, deflate, br, zstd
Accept-Language: en-US,en;q=0.9,sv-SE;q=0.8,sv;q=0.7
Cookie: access_token="token"

我使用m3芯片在macOS上运行和编译。我正在使用最新版本的Chrome进行测试,这就是错误消息在终端中的样子

zsh: abort      ./http_server

1 回复 | 直到 1 年前

Andrew Henle 1 年前

您的代码中有几个问题对我来说很明显。

首先,这是一个潜在的缓冲区溢出:

char buffer[1024];
int readBytes;

readBytes = read(socket, buffer, sizeof(buffer));

buffer[readBytes] = '\0';

如果你读了整整1024个字节,就会溢出 buffer .

如果你想将数据读取为以nul结尾的字符串,你必须考虑必须自己添加它:

char buffer[1024];
int readBytes;

readBytes = read(socket, buffer, sizeof(buffer) - 1);

buffer[readBytes] = '\0';

此铸造到 socklen_t 可能完全错误:

    if ((*client_fd = accept(server_fd, (struct sockaddr *)&address, (socklen_t*)&addrlen))<0) {
        ...

如果 addrlen 不是 socklen_t 这个 accept() 可以覆盖内存,如果 socklen_t 大于 int addrlen . 从不扔掉警告。

可能还有其他问题——我很快就注意到了这些问题。