From 0213dd70c9dc5027f18d2f2b91586f0bb510a2ad Mon Sep 17 00:00:00 2001
From: Christopher Faulet <cfaulet@haproxy.com>
Date: Tue, 10 Mar 2026 08:10:29 +0100
Subject: [PATCH] MINOR: htx: Add helper functions to xfer a message to smaller
 or larger one

htx_move_to_small_buffer()/htx_move_to_large_buffer() and
htx_copy_to_small_buffer()/htx_copy_to_large_buffer() functions can now be
used to move or copy blocks from a default buffer to a small or large
buffer. The destination buffer is allocated and then each blocks are
transferred into it.

These funtions relies in htx_xfer() function.
---
 include/haproxy/htx.h |  4 +++
 src/htx.c             | 66 +++++++++++++++++++++++++++++++++++++++++++
 2 files changed, 70 insertions(+)

diff --git a/include/haproxy/htx.h b/include/haproxy/htx.h
index e22b2c073..deeacd0a9 100644
--- a/include/haproxy/htx.h
+++ b/include/haproxy/htx.h
@@ -57,6 +57,10 @@ size_t htx_add_data(struct htx *htx, const struct ist data);
 struct htx_blk *htx_add_last_data(struct htx *htx, struct ist data);
 void htx_move_blk_before(struct htx *htx, struct htx_blk **blk, struct htx_blk **ref);
 int htx_append_msg(struct htx *dst, const struct htx *src);
+struct buffer *htx_move_to_small_buffer(struct buffer *dst, struct buffer *src);
+struct buffer *htx_move_to_large_buffer(struct buffer *dst, struct buffer *src);
+struct buffer *htx_copy_to_small_buffer(struct buffer *dst, struct buffer *src);
+struct buffer *htx_copy_to_large_buffer(struct buffer *dst, struct buffer *src);
 
 #define HTX_XFER_DEFAULT           0x00000000 /* Default XFER: no partial xfer / remove blocks from source */
 #define HTX_XFER_KEEP_SRC_BLKS     0x00000001 /* Don't remove xfer blocks from source messages during xfer */
diff --git a/src/htx.c b/src/htx.c
index 695a69aac..13b6a0cbc 100644
--- a/src/htx.c
+++ b/src/htx.c
@@ -11,6 +11,7 @@
  */
 
 #include <haproxy/chunk.h>
+#include <haproxy/dynbuf.h>
 #include <haproxy/global.h>
 #include <haproxy/htx.h>
 #include <haproxy/net_helper.h>
@@ -1325,3 +1326,68 @@ int htx_append_msg(struct htx *dst, const struct htx *src)
 	htx_truncate(dst, offset);
 	return 0;
 }
+
+
+/* If possible, trasnfer HTX blocks from <src> to a small buffer. This function
+ * allocate the small buffer and makes <dst> point on it. If <dst> is not empty
+ * or if <src> contains to many data, NULL is returned. If the allocation
+ * failed, NULL is returned. Otherwise <dst> is returned.  <flags> instructs how
+ * the transfer must be performed.
+ */
+struct buffer *__htx_xfer_to_small_buffer(struct buffer *dst, struct buffer *src, unsigned int flags)
+{
+	struct htx *dst_htx;
+	struct htx *src_htx = htxbuf(src);
+	size_t sz = (sizeof(struct htx) + htx_used_space(src_htx));
+
+	if (dst->size || sz > global.tune.bufsize_small  || !b_alloc_small(dst))
+		return NULL;
+	dst_htx = htx_from_buf(dst);
+	htx_xfer(dst_htx, src_htx, src_htx->size, flags);
+	htx_to_buf(dst_htx, dst);
+	return dst;
+}
+
+/* If possible, trasnfer HTX blocks from <src> to a large buffer. This function
+ * allocate the small buffer and makes <dst> point on it. If <dst> is not empty
+ * or if <src> contains to many data, NULL is returned. If the allocation
+ * failed, NULL is returned. Otherwise <dst> is returned.  <flags> instructs how
+ * the transfer must be performed.
+ */
+struct buffer *__htx_xfer_to_large_buffer(struct buffer *dst, struct buffer *src, unsigned int flags)
+{
+	struct htx *dst_htx;
+	struct htx *src_htx = htxbuf(src);
+	size_t sz = (sizeof(struct htx) + htx_used_space(src_htx));
+
+	if (dst->size || sz > global.tune.bufsize_large || !b_alloc_large(dst))
+		return NULL;
+	dst_htx = htx_from_buf(dst);
+	htx_xfer(dst_htx, src_htx, src_htx->size, flags);
+	htx_to_buf(dst_htx, dst);
+	return dst;
+}
+
+/* Move HTX blocks from <src> to <dst>. Relies on __htx_xfer_to_small_buffer() */
+struct buffer *htx_move_to_small_buffer(struct buffer *dst, struct buffer *src)
+{
+	return __htx_xfer_to_small_buffer(dst, src, HTX_XFER_DEFAULT);
+}
+
+/* Move HTX blocks from <src> to <dst>. Relies on __htx_xfer_to_large_buffer() */
+struct buffer *htx_move_to_large_buffer(struct buffer *dst, struct buffer *src)
+{
+	return __htx_xfer_to_large_buffer(dst, src, HTX_XFER_DEFAULT);
+}
+
+/* Copy HTX blocks from <src> to <dst>. Relies on __htx_xfer_to_small_buffer() */
+struct buffer *htx_copy_to_small_buffer(struct buffer *dst, struct buffer *src)
+{
+	return __htx_xfer_to_small_buffer(dst, src, HTX_XFER_KEEP_SRC_BLKS);
+}
+
+/* Copy HTX blocks from <src> to <dst>. Relies on __htx_xfer_to_large_buffer() */
+struct buffer *htx_copy_to_large_buffer(struct buffer *dst, struct buffer *src)
+{
+	return __htx_xfer_to_large_buffer(dst, src, HTX_XFER_KEEP_SRC_BLKS);
+}