From: Christopher Faulet <cfaulet@haproxy.com>
Date: Tue, 25 Feb 2020 14:21:02 +0000 (+0100)
Subject: MINOR: lua: Add a function to get a filter attached to a channel class
X-Git-Tag: v2.5-dev4~28
X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=9f55a5012efbffda5ae80ec5825fd58384bb8c3f;p=thirdparty%2Fhaproxy.git

MINOR: lua: Add a function to get a filter attached to a channel class

For now, there is no support for filters written in lua. So this function,
if called, will always return NULL. But when it will be called in a filter
context, it will return the filter structure attached to a channel
class. This function is also responsible to set the offset of data that may
be processed and the length of these data. When called outside a filter
context (so from an action), the offset is the input data position and the
length is the input data length. From a filter, the offset and the length of
data that may be filtered are retrieved the filter context.
---

diff --git a/src/hlua.c b/src/hlua.c
index a7ad97984d..f2ed684a3b 100644
--- a/src/hlua.c
+++ b/src/hlua.c
@@ -196,6 +196,8 @@ lua_State *hlua_init_state(int thread_id);
  */
 static lua_State *hlua_states[MAX_THREADS + 1];
 
+#define HLUA_FLT_CTX_FL_PAYLOAD  0x00000001
+
 struct hlua_reg_filter  {
 	char *name;
 	int flt_ref[MAX_THREADS + 1];
@@ -219,6 +221,8 @@ struct hlua_flt_ctx {
 
 DECLARE_STATIC_POOL(pool_head_hlua_flt_ctx, "hlua_flt_ctx", sizeof(struct hlua_flt_ctx));
 
+static int hlua_filter_from_payload(struct filter *filter);
+
 /* This is the chained list of struct hlua_flt referenced
  * for haproxy filters. It is used for a post-initialisation control.
  */
@@ -3000,6 +3004,30 @@ static int hlua_channel_new(lua_State *L, struct channel *channel)
 	return 1;
 }
 
+/* Helper function returning a filter attached to a channel at the position <ud>
+ * in the stack, filling the current offset and length of the filter. If no
+ * filter is attached, NULL is returned and <offet> and <len> are not
+ * initialized.
+ */
+static __maybe_unused struct filter *hlua_channel_filter(lua_State *L, int ud, struct channel *chn, size_t *offset, size_t *len)
+{
+	struct filter *filter = NULL;
+
+	if (lua_getfield(L, ud, "__filter") == LUA_TLIGHTUSERDATA) {
+		struct hlua_flt_ctx *flt_ctx;
+
+		filter  = lua_touserdata (L, -1);
+		flt_ctx = filter->ctx;
+		if (hlua_filter_from_payload(filter)) {
+			*offset  = flt_ctx->cur_off[CHN_IDX(chn)];
+			*len     = flt_ctx->cur_len[CHN_IDX(chn)];
+		}
+	}
+
+	lua_pop(L, 1);
+	return filter;
+}
+
 /* Copies <len> bytes of data present in the channel's buffer, starting at the
 * offset <offset>, and put it in a LUA string variable. It is the caller
 * responsibility to ensure <len> and <offset> are valid. It always return the
@@ -8812,6 +8840,13 @@ static void hlua_filter_delete(struct stream *s, struct filter *filter)
 	filter->ctx = NULL;
 }
 
+static int hlua_filter_from_payload(struct filter *filter)
+{
+	struct hlua_flt_ctx *flt_ctx = filter->ctx;
+
+	return (flt_ctx && !!(flt_ctx->flags & HLUA_FLT_CTX_FL_PAYLOAD));
+}
+
 static int hlua_filter_parse_fct(char **args, int *cur_arg, struct proxy *px,
 				 struct flt_conf *fconf, char **err, void *private)
 {