隨意抓的一個HTTP包，以做參考
代碼分析：
int read_header(request * req)
{
int bytes, buf_bytes_left;
char *check, *buffer;
/*
client_stream：是用來裝HTTP數據報文的buffer。
parse_pos：已經解析字符數。
client_stream_pos：從socket中讀取的字符數。
*/
check = req->client_stream + req->parse_pos;
buffer = req->client_stream;
bytes = req->client_stream_pos;
#ifdef VERY_FASCIST_LOGGING
if (check < (buffer + bytes)) {
buffer[bytes] = '\0';
log_error_time();
fprintf(stderr, "%s:%d - Parsing headers (\"%s\")\n",
__FILE__, __LINE__, check);
}
#endif
while (check < (buffer + bytes)) {
switch (req->status) {
case READ_HEADER:
if (*check == '\r') {
req->status = ONE_CR;
req->header_end = check;
} else if (*check == '\n') {
req->status = ONE_LF;
req->header_end = check;
}
break;
/* HTTP數據包，每條信息結尾都以\r\n結尾，
但一些較老的客戶端可能仍然用\n結尾，
所以我們的WEB服務器一般都有一定的容錯能力，
當直接檢測到結尾是\n時，直接跳到ONE_LF狀態，
絲毫不影響對HTTP包頭的解析。*/
case ONE_CR:
if (*check == '\n')
req->status = ONE_LF;
else if (*check != '\r')
req->status = READ_HEADER;
break;
case ONE_LF:
/* if here, we've found the end (for sure) of a header */
if (*check == '\r') /* could be end o headers */
req->status = TWO_CR;
else if (*check == '\n')
req->status = BODY_READ;
else
req->status = READ_HEADER;
break;
/*HTTP 以單獨的一行\r\n 結尾所以當連續出現\r\n 時說明HTTP頭解析完成*/
case TWO_CR:
if (*check == '\n')
req->status = BODY_READ;
else if (*check != '\r')
req->status = READ_HEADER;
break;
default:
break;
}
#ifdef VERY_FASCIST_LOGGING
log_error_time();
fprintf(stderr, "status, check: %d, %d\n", req->status, *check);
#endif
req->parse_pos++; /* update parse position */
check++;
if (req->status == ONE_LF) {
*req->header_end = '\0';
/* terminate string that begins at req->header_line */
if (req->logline) {
if (process_option_line(req) == 0) {//解析HTTP頭部信息並放入結構體內
return 0;
}
} else {
if (process_logline(req) == 0)//解析HTTP 頭的第一行，確定訪問方式GET POST HEAD
return 0;
if (req->simple)
return process_header_end(req);
}
/* set header_line to point to beginning of new header */
req->header_line = check;
} else if (req->status == BODY_READ) {//處理HTTP 主體部分
#ifdef VERY_FASCIST_LOGGING
int retval;
log_error_time();
fprintf(stderr, "%s:%d -- got to body read.\n",
__FILE__, __LINE__);
retval = process_header_end(req);
#else
int retval = process_header_end(req);////調用CGI之前做最後的處理
#endif
/* process_header_end inits non-POST cgi's */
if (retval && req->method == M_POST) {
/* for body_{read,write}, set header_line to start of data,
and header_end to end of data */
req->header_line = check;
req->header_end =
req->client_stream + req->client_stream_pos;
req->status = BODY_WRITE;
/* so write it */
/* have to write first, or read will be confused
* because of the special case where the
* filesize is less than we have already read.
*/
/*
As quoted from RFC1945:
A valid Content-Length is required on all HTTP/1.0 POST requests. An
HTTP/1.0 server should respond with a 400 (bad request) message if it
cannot determine the length of the request message's content.
*/
if (req->content_length) {
int content_length;
content_length = boa_atoi(req->content_length);
/* Is a content-length of 0 legal? */
if (content_length <= 0) {
log_error_time();
fprintf(stderr, "Invalid Content-Length [%s] on POST!\n",
req->content_length);
send_r_bad_request(req);
return 0;
}
if (single_post_limit && content_length > single_post_limit) {
log_error_time();
fprintf(stderr, "Content-Length [%d] > SinglePostLimit [%d] on POST!\n",
content_length, single_post_limit);
send_r_bad_request(req);
return 0;
}
req->filesize = content_length;
req->filepos = 0;
if (req->header_end - req->header_line > req->filesize) {
req->header_end = req->header_line + req->filesize;
}
} else {
log_error_time();
fprintf(stderr, "Unknown Content-Length POST!\n");
send_r_bad_request(req);
return 0;
}
} /* either process_header_end failed or req->method != POST */
return retval; /* 0 - close it done, 1 - keep on ready */
} /* req->status == BODY_READ */
} /* done processing available buffer */
#ifdef VERY_FASCIST_LOGGING
log_error_time();
fprintf(stderr, "%s:%d - Done processing buffer. Status: %d\n",
__FILE__, __LINE__, req->status);
#endif
/* 在分析主體部分之前，
也就是在分析HTTP所承載的數據之前不斷的從socket中讀取HTTP頭數據進行解析。*/
if (req->status < BODY_READ) {
/* only reached if request is split across more than one packet */
buf_bytes_left = CLIENT_STREAM_SIZE - req->client_stream_pos;
if (buf_bytes_left < 1) {
log_error_time();
fputs("buffer overrun - read.c, read_header - closing\n",
stderr);
req->status = DEAD;
return 0;
}
bytes = read(req->fd, buffer + req->client_stream_pos, buf_bytes_left);
if (bytes < 0) {
if (errno == EINTR)
return 1;
if (errno == EAGAIN || errno == EWOULDBLOCK) /* request blocked */
return -1;
/*
else if (errno == EBADF || errno == EPIPE) {
req->status = DEAD;
return 0;
*/
log_error_doc(req);
perror("header read"); /* don't need to save errno because log_error_doc does */
return 0;
} else if (bytes == 0) {
/*
log_error_time();
fputs("unexpected end of headers\n", stderr);
*/
return 0;
}
/* bytes is positive */
req->client_stream_pos += bytes;
#ifdef FASCIST_LOGGING1
log_error_time();
req->client_stream[req->client_stream_pos] = '\0';
fprintf(stderr, "%s:%d -- We read %d bytes: \"%s\"\n",
__FILE__, __LINE__, bytes,
#ifdef VERY_FASCIST_LOGGING2
req->client_stream + req->client_stream_pos - bytes);
#else
"");
#endif
#endif
return 1;
}
return 1;
}