我是C的新手,我正在尝试在C中实现Web服务器。我可以成功地将.txt和.html文件发送到浏览器。但是,我无法发送任何图像,虽然我有正确的内容类型标题,它识别图像是.jpg。 这是我用来查找内容类型的函数:
char *find_content_type (char *filename) {
char *p; // pointer to the type found
int i;
char buf1[MAXFILENAME]; // used to store the extension of the file
char buf2[MAXFILENAME];
p = (char *)malloc(30);
strcpy(buf1, filename);
printf("name of file requested: %s \n", buf1);
/* find the extension: */
for (i = 0; i<strlen(buf1); i++) {
if ( buf1[i] == '.' ) {
strcpy(buf2, &buf1[i]);
}
}
/* find the type: */
if ( strcmp(buf2, ".html") == 0 || strcmp (buf2, ".hml") == 0) {
strcpy (buf2, "Content-Type: text/html \r\n");
}
else if ( strcmp(buf2, ".txt") == 0) {
strcpy (buf2, "Content-Type: text/plain \r\n");
}
else if ( strcmp(buf2, ".jpg") == 0 || strcmp (buf2, ".jpeg") == 0) {
strcpy (buf2, "Content-Type: image/jpeg \r\n");
}
else if ( strcmp(buf2, ".gif") == 0) {
strcpy (buf2, "Content-Type: image/gif \r\n");
}
else {
strcpy (buf2, "Content-Type: application/octet-stream \r\n");
}
p = buf2;
printf ("content-type: %s\n", p);
//return "Content-type: image/jpeg\r\n";
return p;
}
我有解析请求的函数,并返回指向所请求文件名的指针。在main中我只接受请求并写入浏览器,所有数据解析和响应构建都在main之外。下面的函数形成了将发送到浏览器的响应:
char * response_generator (char *filename) {
char *p; // pointer to the whole response
char *content_type; // pointer to the content type
char data [MAXLEN], data2[MAXLEN - 100], data3 [MAXLEN - 200];
/* vars needed for finding the length of the file */
struct stat filestat;
FILE *fp;
int fd;
off_t size;
char filesize[6], name[30];
strcpy (name, filename);
if ( ((fd = open (filename, O_RDONLY)) < -1) || (fstat(fd, &filestat) < 0) ) {
printf ("Error in measuring the size of the file");
}
if (filename == NULL) {
// I have measured the length of my 400.html file
strcpy (data, "HTTP/1.1 400 Bad Request\r\nContent-Length: 327\r\nContent-Type: text/html\r\n");
fp = fopen ("400index.html", "r");
}
sprintf (filesize, "%d", filestat.st_size); // put the file size of buffer, so we can add it to the response header
fp = fopen (name, "r");
if (fp == NULL || strcmp (name,"404") == 0 ) {
// I have measured the length of my 404.html file
strcpy (data, "HTTP/1.1 404 Not Found\r\nContent-Length: 165\r\nContent-Type: text/html\r\n");
fp = fopen ("404index.html", "r");
}
else if (fp != NULL) {
strcpy (data, "HTTP/1.1 200 OK\r\nContent-Length: ");
/* content-length: */
strcat (data, filesize);
strcat (data, "\r\n");
/* content-type: */
strcpy (data2, find_content_type (name));
printf ("content-type: %s\n", find_content_type (name));
strcat (data, data2);
}
else {
// I have measured the length of my 500.html file
strcpy (data, "HTTP/1.1 500 Internal Server Error\r\nContent-Length: 190\r\nContent-Type: text/html\r\n");
fp = fopen ("500index.html", "r");
}
strcat (data, "Connection: keep-alive\r\n\r\n");
fread (data3, sizeof(char), filestat.st_size + 150, fp); /* read the file in a data buffer: */
strcat (data, data3);
data[strlen(data)] = '\0';
p = data;
fclose(fp);
return p;
}
这是一个非常漫长而繁重的功能,但正如我所提到的,当我必须发送图像时它似乎工作得很好。当我在终端上打印要发送的请求时,我得到的是:
HTTP/1.1 200 OK
Content-Length: 49657
Content-Type: image/jpeg
Connection: keep-alive
ÿØÿà
如果您有任何想法,请告诉我我做错了什么。谢谢!
答案 0 :(得分:0)
我设法解决了这个问题。有很多问题。首先,我删除了所有(str *()),因为正如评论中所提到的,它们并不意味着处理二进制数据。我删除了不必要的缓冲区数量。现在我有两个:第一个用于存储响应头,可以安全地使用strcat / strcpy等。我一有信息就向浏览器写入标题响应。第二个缓冲区包含浏览器请求的文件数据。我从文件中读取后立即将其写入服务器,因此我避免任何可能导致问题的操作。这是我的response_generator代码:
void response_generator (int conn_fd, char *filename) {
/* vars needed for finding the length of the file */
struct stat filestat;
FILE *fp;
int fd;
char header_buff [HEADER_LEN];
char file_buff [MAXLEN];
char filesize[7];//, name[30];
if ( ((fd = open (filename, O_RDONLY)) < -1) || (fstat(fd, &filestat) < 0) ) {
printf ("Error in measuring the size of the file");
}
if (filename == NULL) {
// I have measured the length of my 400.html file
strcpy (header_buff, "HTTP/1.1 400 Bad Request\r\nContent-Length: 327\r\nContent-Type: text/html\r\n");
fp = fopen ("400index.html", "r");
}
sprintf (filesize, "%zd", filestat.st_size); // put the file size of buffer, so we can add it to the response header
fp = fopen (filename, "r");
if (fp == NULL) {
printf ("fp is null or filename = 404\n");
// I have measured the length of my 404.html file
strcpy (header_buff, "HTTP/1.1 404 Not Found\r\nContent-Length: 165\r\nContent-Type: text/html\r\n");
fp = fopen ("404index.html", "r");
}
else if (fp != NULL) {
strcpy (header_buff, "HTTP/1.1 200 OK\r\nContent-Length: ");
/* content-length: */
strcat (header_buff, filesize);
strcat (header_buff, "\r\n");
/* content-type: */
strcat (header_buff, find_content_type (filename));
printf ("%s\n", find_content_type (filename));
}
else {
// I have measured the length of my 500.html file
strcpy (header_buff, "HTTP/1.1 500 Internal Server Error\r\nContent-Length: 190\r\nContent-Type: text/html\r\n");
fp = fopen ("500index.html", "r");
}
strcat (header_buff, "Connection: keep-alive\r\n\r\n");
write (conn_fd, header_buff, strlen(header_buff));
fread (file_buff, sizeof(char), filestat.st_size + 1, fp);
fclose(fp);
write (conn_fd, file_buff, filestat.st_size);
close (conn_fd);
}
非常感谢对我的问题的评论,他们真的帮助我修复了这段代码。