请用C语言实现一个http服务器

实现一个http服务器需要涉及到socket编程、HTTP协议的解析和文件读写等技术。下面是一个简单的使用C语言实现的http服务器的代码，仅供参考：

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

#define BUFSIZE 8096

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

int main(int argc, char *argv[]) {
    int sockfd, newsockfd, portno, pid;
    socklen_t clilen;
    char buffer[BUFSIZE];
    struct sockaddr_in serv_addr, cli_addr;
    int n;

    if (argc < 2) {
        fprintf(stderr, "Usage: %s <port>\n", argv[0]);
        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);

    while (1) {
        newsockfd = accept(sockfd, (struct sockaddr *) &cli_addr, &clilen);
        if (newsockfd < 0)
            error("ERROR on accept");

        pid = fork();
        if (pid < 0)
            error("ERROR on fork");

        if (pid == 0) {
            close(sockfd);

            memset(buffer, 0, BUFSIZE);
            n = read(newsockfd, buffer, BUFSIZE - 1);
            if (n < 0)
                error("ERROR reading from socket");

            if (strncmp(buffer, "GET /", 5) != 0) {
                write(newsockfd, "HTTP/1.0 400 Bad Request\n", 25);
            } else {
                char *filename = buffer + 5;
                char *end = strchr(filename, ' ');
                if (end != NULL)
                    *end = '\0';

                if (strlen(filename) == 0)
                    filename = "index.html";

                FILE *file = fopen(filename, "r");
                if (file == NULL) {
                    write(newsockfd, "HTTP/1.0 404 Not Found\n", 23);
                } else {
                    write(newsockfd, "HTTP/1.0 200 OK\n", 16);
                    write(newsockfd, "Content-Type: text/html\n", 25);
                    write(newsockfd, "\n", 1);

                    while ((n = fread(buffer, 1, BUFSIZE, file)) > 0) {
                        write(newsockfd, buffer, n);
                    }
                    fclose(file);
                }
            }

            close(newsockfd);
            exit(0);
        } else {
            close(newsockfd);
        }
    }

    close(sockfd);
    return 0;
}

这段代码实现了一个简单的http服务器，只支持GET请求，只能读取当前目录下的html文件。在终端输入 `./http_server 8080` 即可启动服务器，其中8080是端口号，可以根据需要进行修改。