commit c0968f59b723dfa9effa63ac28b59642b11c6b8b
Author: Richard Russo <russor@whatsapp.com>
Date:   Wed Jul 31 11:45:56 2019 -0700

    BUG/MAJOR: http/sample: use a static buffer for raw -> htx conversion
    
    Multiple calls to smp_fetch_fhdr use the header context to keep track of
    header parsing position; however, when using header sampling on a raw
    connection, the raw buffer is converted into an HTX structure each time, and
    this was done in the trash areas; so the block reference would be invalid on
    subsequent calls.
    
    This patch must be backported to 2.0 and 1.9.
    
    (cherry picked from commit 458eafb36df88932a02d1ce7ca31832abf11b8b3)
    Signed-off-by: Christopher Faulet <cfaulet@haproxy.com>

diff --git a/src/http_fetch.c b/src/http_fetch.c
index 67ea2094..e372a122 100644
--- a/src/http_fetch.c
+++ b/src/http_fetch.c
@@ -46,10 +46,40 @@
 /* this struct is used between calls to smp_fetch_hdr() or smp_fetch_cookie() */
 static THREAD_LOCAL struct hdr_ctx static_hdr_ctx;
 static THREAD_LOCAL struct http_hdr_ctx static_http_hdr_ctx;
+/* this is used to convert raw connection buffers to htx */
+static THREAD_LOCAL struct buffer static_raw_htx_chunk;
+static THREAD_LOCAL char *static_raw_htx_buf;
 
 #define SMP_REQ_CHN(smp) (smp->strm ? &smp->strm->req : NULL)
 #define SMP_RES_CHN(smp) (smp->strm ? &smp->strm->res : NULL)
 
+/* This function returns the static htx chunk, where raw connections get
+ * converted to HTX as needed for samplxsing.
+ */
+struct buffer *get_raw_htx_chunk(void)
+{
+	chunk_reset(&static_raw_htx_chunk);
+	return &static_raw_htx_chunk;
+}
+
+static int alloc_raw_htx_chunk_per_thread()
+{
+	static_raw_htx_buf = malloc(global.tune.bufsize);
+	if (!static_raw_htx_buf)
+		return 0;
+	chunk_init(&static_raw_htx_chunk, static_raw_htx_buf, global.tune.bufsize);
+	return 1;
+}
+
+static void free_raw_htx_chunk_per_thread()
+{
+	free(static_raw_htx_buf);
+	static_raw_htx_buf = NULL;
+}
+
+REGISTER_PER_THREAD_ALLOC(alloc_raw_htx_chunk_per_thread);
+REGISTER_PER_THREAD_FREE(free_raw_htx_chunk_per_thread);
+
 /*
  * Returns the data from Authorization header. Function may be called more
  * than once so data is stored in txn->auth_data. When no header is found
@@ -265,7 +295,7 @@ struct htx *smp_prefetch_htx(struct sample *smp, struct channel *chn, int vol)
 		else if (h1m.flags & H1_MF_CLEN)
 			flags |= HTX_SL_F_CLEN;
 
-		htx = htx_from_buf(get_trash_chunk());
+		htx = htx_from_buf(get_raw_htx_chunk());
 		sl = htx_add_stline(htx, HTX_BLK_REQ_SL, flags, h1sl.rq.m, h1sl.rq.u, h1sl.rq.v);
 		if (!sl || !htx_add_all_headers(htx, hdrs))
 			return NULL;