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network-programming-example
/
httpd.c

#include <stdio.h>
#include <stdlib.h> //malloc
#include <string.h> //memset
#include <sys/types.h>
#include <sys/socket.h>
#include <netinet/ip.h> //sockaddr_in
#include <arpa/inet.h> //inet_ntop
#include <signal.h>
#include <unistd.h> //chroot

//解析请求头，返回请求路径
char* parse_request(char *line)
{
    char method[10];
	char protocol[10];
    char* path = NULL;

	puts(line);
    //%ms会自动分配内存
	sscanf(line, "%9s %ms %9s", method, &path, protocol);

    printf("method = %s\n", method);
    printf("path = %s\n", path);
	printf("protocol = %s\n", protocol);

    return path;
}

int main()
{
    signal(SIGPIPE, SIG_IGN);
    int listenfd = socket(AF_INET, SOCK_STREAM, 0);
    if (listenfd < 0)
    {
        perror("socket");
        return 1;
    }

    int opt = 1;
    setsockopt(listenfd, SOL_SOCKET, SO_REUSEADDR, &opt, sizeof(opt));

    struct sockaddr_in saddr;
    memset(&saddr, 0, sizeof(saddr));

    saddr.sin_family = AF_INET;
    saddr.sin_addr.s_addr = htonl(INADDR_ANY);
    saddr.sin_port = htons(80);
    if (bind(listenfd, (struct sockaddr *)&saddr, sizeof(saddr)) < 0)
    {
        perror("bind");
        return 1;
    }

    if (listen(listenfd, 64) < 0)
    {
        perror("listen");
        return 1;
    }

    chroot(".");

    puts("web server start");

    while (1)
    {
        struct sockaddr_in caddr;
        socklen_t addrlen = sizeof(caddr);
        int connfd;
        connfd = accept(listenfd, (struct sockaddr *)&caddr, &addrlen);

        char ipstr[INET_ADDRSTRLEN];
        inet_ntop(AF_INET, &caddr.sin_addr, ipstr, sizeof ipstr);
        printf("client %s connected\n", ipstr);
        if (connfd < 0)
        {
            perror("accept");
            continue;
        }

        FILE* sfp = fdopen(connfd, "r+");
        if (!sfp)
        {
            perror("fdopen");
            continue;
        }

        char buf[BUFSIZ];

        fgets(buf, BUFSIZ, sfp);
        char* path = parse_request(buf);
        puts(path);

        //读到空行结束
        while(fgets(buf, BUFSIZ, sfp) && strlen(buf) > 2)
        {
            printf(buf);
        }

        FILE* fp = fopen(path, "r+");
        if (!fp)
        {
            //文件不存在，返回404
            perror("fopen");
            fprintf(sfp, "HTTP/1.1 404 Page Not Found\r\n");
            fprintf(sfp, "Content-Type: text/html\r\n");
            fprintf(sfp, "Content-Length: 36\r\n");
            fprintf(sfp, "\r\n");
            fprintf(sfp, "<html><body><p>Nothing</p></body></html>");
        }
        else
        {
            //获取文件大小（标准IO）
            fseek(fp, 0, SEEK_END);
            long file_size = ftell(fp);
            fseek(fp, 0, SEEK_SET);

            printf("file size: %ld\n", file_size);

            //分配内存并读取文件到内存
            char* file_buf = (char*)malloc(file_size);
            if (!file_buf)
            {
                perror("malloc");
                return 1;
            }
            fread(file_buf, 1, file_size, fp);
            //发送响应消息
            fprintf(sfp, "HTTP/1.1 200 OK\r\n");
            fprintf(sfp, "Content-Type: text/plain\r\n");
            fprintf(sfp, "Content-Length: %ld\r\n", file_size);
            fprintf(sfp, "\r\n");
            fwrite(file_buf, 1, file_size, sfp);

            free(file_buf);
            fclose(fp);
        }

        free(path);
        fclose(sfp);
    }
}