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MINOR: http: make msg->eol carry the last CRLF length

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One of the issues we face when we need to either forward headers only
before compressing, or rewind the stream during a redispatch is to know
the proper length of the request headers. msg->eoh always has the total
length up to the last CRLF, and we never know whether the request ended
with a single LF or a standard CRLF. This makes it hard to rewind the
headers without explicitly checking the bytes in the buffer.

Instead of doing so, we now use msg->eol to carry the length of the last
CRLF (either 1 or 2). Since it is not modified at all after HTTP_MSG_BODY,
and was only left in an undefined state, it is safe to use at any moment.

Thus, the complete header length to forward or to rewind now is always
msg->eoh + msg->eol.
This commit is contained in:
Willy Tarreau 2014-03-13 15:48:45 +01:00
parent 890988f122
commit 0558a02eb1
2 changed files with 18 additions and 3 deletions
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15
include/types/proto_http.h
View file

@ -320,11 +320,22 @@ enum {
* for states after START. When in HTTP_MSG_BODY,
* eoh points to the first byte of the last CRLF
* preceeding data. Relative to buffer's origin.
* This value then remains unchanged till the end
* so that we can rewind the buffer to change some
* headers if needed (eg: http-send-name-header).
*
* - sov : When in HTTP_MSG_BODY, will point to the first
* byte of data (relative to buffer's origin).
* - sol (start of line) : start of current line during parsing, or zero.
* - eol (End of Line) : relative offset in the buffer of the first byte
* which marks the end of the line (LF or CRLF).
*
* - eol (End of Line) : Before HTTP_MSG_BODY, relative offset in the
* buffer of the first byte which marks the end of
* the line current (LF or CRLF).
* From HTTP_MSG_BODY to the end, contains the
* length of the last CRLF (1 for a plain LF, or 2
* for a true CRLF). So eoh+eol always contain the
* exact size of the header size.
*
* Note that all offsets are relative to the origin of the buffer (buf->p)
* which always points to the beginning of the message (request or response).
* Since a message may not wrap, pointer computations may be one without any

6
src/proto_http.c
View file

@ -1731,12 +1731,16 @@ void http_msg_analyzer(struct http_msg *msg, struct hdr_idx *idx)
case HTTP_MSG_LAST_LF:
http_msg_last_lf:
/* Assumes msg->sol points to the first of either CR or LF */
/* Assumes msg->sol points to the first of either CR or LF.
* Sets ->sov and ->next to the total header length, ->eoh to
* the last CRLF, and ->eol to the last CRLF length (1 or 2).
*/
EXPECT_LF_HERE(ptr, http_msg_invalid);
ptr++;
msg->sov = msg->next = ptr - buf->p;
msg->eoh = msg->sol;
msg->sol = 0;
msg->eol = msg->sov - msg->eoh;
msg->msg_state = HTTP_MSG_BODY;
return;