如何在C中通过HTTP协议发送图像？

Question

我是一名学生正在进行网络服务器练习,我需要一些帮助.

我的网络服务器可以正常用于文本页面,但只要浏览器发送---GET /img.jpg HTTP/1.1请求,我就不知道如何处理它.我听说HTTP协议是基于文本的,那么如何在HTTP响应中发送图像？

这是我创建正常HTTP响应的一个段,我打算用它readresult == 2来表示图像.

if(readresult == 1){
    sprintf(toreturn, "%s\r\n%s\r\n%s\r\n\r\n%s", "HTTP/1.1 200 OK", "Content-Type: text/html", "Connection: close", readpagestring);
    returnflag = 1;
}
else if(readresult == 2){
    returnflag = 2;
}
else{
    sprintf(toreturn, "%s\r\n%s\r\n%s\r\n\r\n%s", "HTTP/1.1 404 Not Found", "Content-Type: text/html", "Connection: close", readpagestring);
    returnflag = 0;
}

它所调用的功能

int readpage(char *readaddress, char *pagereturn){
    FILE *inputfile = (FILE *)calloc(1,sizeof(FILE));
    int flag;
    int c;
    int n = 0;
    readaddress++;
    inputfile=fopen(readaddress,"r");
    if (inputfile==NULL){
        FILE *missingfile;
        missingfile=fopen("404.html","r");
        while ((c = fgetc (missingfile)) != EOF){
            *(pagereturn+n) = c;
            n++;
        }
        flag = 0;
        fclose (missingfile);
    }
    else{
        while ((c = fgetc (inputfile)) != EOF){
            *(pagereturn+n) = c;
            n++;
        }
        flag = 1;
        fclose (inputfile);
    }
    return flag;
}

Answer 1

您必须返回HTTP response如下:(非常小,您可以添加所需的所有标题)

HTTP/1.1 200 OK\r\n
Content-Type: image/gif\r\n
Content-Length: [length in bytes of the image]\r\n
\r\n
[binary data of your image]

显然,您还必须根据图像类型设置内容类型.

您可以使用a构建标题sprintf,然后memcpy在最后一个之后构建图像的二进制数据\r\n

确保toreturn缓冲区足够大.