From: Willy Tarreau <w@1wt.eu>
Date: Thu, 17 Apr 2014 19:14:47 +0000 (+0200)
Subject: MAJOR: http: reset msg->sov after headers are forwarded
X-Git-Tag: v1.5-dev23~23
X-Git-Url: http://git.ipfire.org/?a=commitdiff_plain;h=1234f4a21028051d0249d3b34fd8b3360a2f2318;p=thirdparty%2Fhaproxy.git

MAJOR: http: reset msg->sov after headers are forwarded

In order to avoid abusively relying on buf->o to guess how many bytes to
rewind during a redispatch, we now clear msg->sov. Thus the meaning of this
field is exactly "how many bytes of headers are left to be forwarded". It
is still possible to rewind because msg->eoh + msg->eol equal that value
before scheduling the forwarding, so we can always subtract them.
---

diff --git a/include/proto/proto_http.h b/include/proto/proto_http.h
index 53f0eca04c..2c8b062a99 100644
--- a/include/proto/proto_http.h
+++ b/include/proto/proto_http.h
@@ -134,10 +134,13 @@ enum http_meth_t find_http_meth(const char *str, const int len);
 /* Return the amount of bytes that need to be rewound before buf->p to access
  * the current message's headers. The purpose is to be able to easily fetch
  * the message's beginning before headers are forwarded, as well as after.
+ * The principle is that msg->eoh and msg->eol are immutable while msg->sov
+ * equals the sum of the two before forwarding and is zero after forwarding,
+ * so the difference cancels the rewinding.
  */
 static inline int http_hdr_rewind(const struct http_msg *msg)
 {
-	return msg->chn->buf->o;
+	return msg->eoh + msg->eol - msg->sov;
 }
 
 /* Return the amount of bytes that need to be rewound before buf->p to access
@@ -179,7 +182,7 @@ static inline int http_body_bytes(const struct http_msg *msg)
 {
 	int len;
 
-	len = buffer_len(msg->chn->buf) - msg->sov - msg->sol;
+	len = msg->chn->buf->i - msg->sov - msg->sol;
 	if (len > msg->body_len)
 		len = msg->body_len;
 	return len;
diff --git a/src/proto_http.c b/src/proto_http.c
index 0c30d0e018..328f28b51b 100644
--- a/src/proto_http.c
+++ b/src/proto_http.c
@@ -5064,6 +5064,7 @@ int http_request_forward_body(struct session *s, struct channel *req, int an_bit
 			msg->chunk_len += msg->next;
 			msg->chunk_len -= channel_forward(req, msg->chunk_len);
 			msg->next       = 0;
+			msg->sov        = 0;
 		}
 
 		if (msg->msg_state == HTTP_MSG_DATA) {
@@ -6188,6 +6189,7 @@ int http_response_forward_body(struct session *s, struct channel *res, int an_bi
 		 */
 		channel_forward(res, msg->sov);
 		msg->next = 0;
+		msg->sov  = 0;
 
 		if (msg->flags & HTTP_MSGF_TE_CHNK)
 			msg->msg_state = HTTP_MSG_CHUNK_SIZE;
@@ -6213,6 +6215,7 @@ int http_response_forward_body(struct session *s, struct channel *res, int an_bi
 				msg->chunk_len += msg->next;
 				msg->chunk_len -= channel_forward(res, msg->chunk_len);
 				msg->next       = 0;
+				msg->sov        = 0;
 			}
 		}
 
@@ -6302,6 +6305,7 @@ int http_response_forward_body(struct session *s, struct channel *res, int an_bi
 				/* forwarding trailers */
 				channel_forward(res, msg->next);
 				msg->next = 0;
+				msg->sov  = 0;
 			}
 			/* we're in HTTP_MSG_DONE now, but we might still have
 			 * some data pending, so let's loop over once.
@@ -6373,6 +6377,7 @@ int http_response_forward_body(struct session *s, struct channel *res, int an_bi
 			msg->chunk_len += msg->next;
 			msg->chunk_len -= channel_forward(res, msg->chunk_len);
 			msg->next       = 0;
+			msg->sov        = 0;
 		}
 	}