From: Willy Tarreau <w@1wt.eu>
Date: Thu, 13 Mar 2014 14:48:45 +0000 (+0100)
Subject: MINOR: http: make msg->eol carry the last CRLF length
X-Git-Tag: v1.5-dev23~31
X-Git-Url: http://git.ipfire.org/?a=commitdiff_plain;h=0558a02eb141a8f6d9e894834547cb64213e4ed4;p=thirdparty%2Fhaproxy.git

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

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.
---

diff --git a/include/types/proto_http.h b/include/types/proto_http.h
index 53e9fb4e83..95860c05e5 100644
--- a/include/types/proto_http.h
+++ b/include/types/proto_http.h
@@ -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
diff --git a/src/proto_http.c b/src/proto_http.c
index a1b064abdf..7c0b7fe735 100644
--- a/src/proto_http.c
+++ b/src/proto_http.c
@@ -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;