From e827b45821614f693e38bc30f680f67d171d227d Mon Sep 17 00:00:00 2001
From: Christopher Faulet <cfaulet@haproxy.com>
Date: Fri, 4 Aug 2023 14:28:23 +0200
Subject: [PATCH] BUG/MINOR: http-client: Don't forget to commit changes on HTX
 message

In the http-client I/O handler, HTX request and response are loaded from the
channels buffer. Some changes are preformed in these messages. So, we must
take care to commit changes into the underlying buffer by calling
htx_to_buf().

It is especially important when the HTX message becoms empty to be able to
quickly release the buffer.

This patch should be backported as far as 2.6.
---
 src/http_client.c | 33 +++++++++++++++++++++------------
 1 file changed, 21 insertions(+), 12 deletions(-)

diff --git a/src/http_client.c b/src/http_client.c
index 2c33c85a2..46cdbdb5d 100644
--- a/src/http_client.c
+++ b/src/http_client.c
@@ -760,12 +760,11 @@ static void httpclient_applet_io_handler(struct appctx *appctx)
 						/* call the request callback */
 						hc->ops.req_payload(hc);
 
-						hc_htx = htx_from_buf(&hc->req.buf);
-						htx = htx_from_buf(&req->buf);
-
+						hc_htx = htxbuf(&hc->req.buf);
 						if (htx_is_empty(hc_htx))
 							goto out;
 
+						htx = htx_from_buf(&req->buf);
 						if (htx_is_empty(htx)) {
 							size_t data = hc_htx->data;
 
@@ -795,9 +794,7 @@ static void httpclient_applet_io_handler(struct appctx *appctx)
 							b_free(&hc->req.buf);
 					}
 
-					htx = htx_from_buf(&req->buf);
-					if (!htx)
-						goto out;
+					htx = htxbuf(&req->buf);
 
 					/* if the request contains the HTX_FL_EOM, we finished the request part. */
 					if (htx->flags & HTX_FL_EOM)
@@ -815,7 +812,7 @@ static void httpclient_applet_io_handler(struct appctx *appctx)
 				if (!co_data(res))
 					goto out;
 				htx = htxbuf(&res->buf);
-				if (!htx)
+				if (htx_is_empty(htx))
 					goto out;
 				blk = htx_get_head_blk(htx);
 				if (blk && (htx_get_blk_type(blk) == HTX_BLK_RES_SL))
@@ -834,12 +831,15 @@ static void httpclient_applet_io_handler(struct appctx *appctx)
 				if (hc->ops.res_stline)
 					hc->ops.res_stline(hc);
 
+				htx_to_buf(htx, &res->buf);
+
 				/* if there is no HTX data anymore and the EOM flag is
 				 * set, leave (no body) */
 				if (htx_is_empty(htx) && htx->flags & HTX_FL_EOM)
 					appctx->st0 = HTTPCLIENT_S_RES_END;
 				else
 					appctx->st0 = HTTPCLIENT_S_RES_HDR;
+
 				break;
 
 			case HTTPCLIENT_S_RES_HDR:
@@ -854,7 +854,7 @@ static void httpclient_applet_io_handler(struct appctx *appctx)
 					if (!co_data(res))
 						goto out;
 					htx = htxbuf(&res->buf);
-					if (!htx)
+					if (htx_is_empty(htx))
 						goto out;
 
 					hdr_num = 0;
@@ -879,6 +879,7 @@ static void httpclient_applet_io_handler(struct appctx *appctx)
 						}
 						blk = htx_remove_blk(htx, blk);
 					}
+					htx_to_buf(htx, &res->buf);
 
 					if (hdr_num) {
 						/* alloc and copy the headers in the httpclient struct */
@@ -911,7 +912,7 @@ static void httpclient_applet_io_handler(struct appctx *appctx)
 					goto out;
 
 				htx = htxbuf(&res->buf);
-				if (!htx || htx_is_empty(htx))
+				if (htx_is_empty(htx))
 					goto out;
 
 				if (!b_alloc(&hc->res.buf))
@@ -934,8 +935,10 @@ static void httpclient_applet_io_handler(struct appctx *appctx)
 					vlen = MIN(count, blksz);
 					vlen = MIN(vlen, room);
 
-					if (vlen == 0)
+					if (vlen == 0) {
+						htx_to_buf(htx, &res->buf);
 						goto process_data;
+					}
 
 					if (type == HTX_BLK_DATA) {
 						struct ist v = htx_get_blk_value(htx, blk);
@@ -953,11 +956,15 @@ static void httpclient_applet_io_handler(struct appctx *appctx)
 							hc->ops.res_payload(hc);
 
 						/* cannot copy everything, need to process */
-						if (vlen != blksz)
+						if (vlen != blksz) {
+							htx_to_buf(htx, &res->buf);
 							goto process_data;
+						}
 					} else {
-						if (vlen != blksz)
+						if (vlen != blksz) {
+							htx_to_buf(htx, &res->buf);
 							goto process_data;
+						}
 
 						/* remove any block which is not a data block */
 						c_rew(res, blksz);
@@ -965,6 +972,8 @@ static void httpclient_applet_io_handler(struct appctx *appctx)
 					}
 				}
 
+				htx_to_buf(htx, &res->buf);
+
 				/* if not finished, should be called again */
 				if (!(htx_is_empty(htx) && (htx->flags & HTX_FL_EOM)))
 					goto out;