Reworked HTTP1 -> HTTP2 message transformation.

This patch introduce another approach to HTTP1 -> HTTP2 message
transformation. We had following problems with inplace transformation:
Each added header was added to new skb fragment, that caused skb
fragmentation. Appending value to existing in message header
was limited by size which remains after transformation. We could
use mixed approach, encode headers inplace while message has room
and then expand skb by new fragments, but maintain both approaches
and code complexity not worth it.

Now transformation consist of following steps:
1. Find skb and fragment contains body or last crlf, if body not exists.
2. Delete found data from skb. Keep skb.
3. Hpack encode headers then add to skb from previous step. Headers adds
as paged fragments, now we don't use headroom. HTTP2_MAX_OFFSET not used
anymore during HTTP1 -> HTTP2 transformation without cache. All paged
data in skb allocates from response's TfwPool.
4. Forward message to client.
5. Cleanup all data that was deleted from skbs in first step.

TfwPool was patched to statisfy new requirments. Now we use compound
pages for order above zero and `put_page` insted of `free_pages`,
because during free pages might be still used by skbs.

Fixed CONTINUATION frame.

Author: const-t

fw/cache.c

@@ -2519,6 +2519,8 @@ tfw_cache_build_resp(TfwHttpReq *req, TfwCacheEntry *ce, long lifetime,
 
 	h_len += mit->acc_len;
 
+	/* @TODO: Temporary solution */
+	resp->mit.frame_head = it->skb_head->data;
 	/*
 	 * Split response to h2 frames. Don't write body with generic function,
 	 * just indicate that we have body for correct framing.

fw/hpack.c

@@ -3578,12 +3578,12 @@ tfw_hpack_str_expand(TfwHttpTransIter *mit, TfwMsgIter *it,
  */
 static int
 tfw_hpack_hdr_add(TfwHttpResp *__restrict resp, TfwStr *__restrict hdr,
-		  TfwHPackInt *__restrict idx, bool name_indexed)
+		  TfwHPackInt *__restrict idx, bool name_indexed, bool inplace)
 {
 	int r;
-	TfwStr *c, *end;
+	TfwHPackInt vlen;
 	TfwHttpTransIter *mit = &resp->mit;
-	TfwStr s_val;
+	TfwStr s_name = {}, s_val = {}, s_vlen = {};
 	const TfwStr s_idx = {
 		.data = idx->buf,
 		.len = idx->sz,
@@ -3592,43 +3592,53 @@ tfw_hpack_hdr_add(TfwHttpResp *__restrict resp, TfwStr *__restrict hdr,
 	T_DBG3("%s: s_idx->len=%lu, s_idx->data='%.*s'\n",
 	       __func__, s_idx.len, (int)s_idx.len, s_idx.data);
 
-	r = tfw_h2_msg_rewrite_data(mit, &s_idx, mit->bnd);
+	r = tfw_http_msg_expand_from_pool(mit, resp->pool, &s_idx);
 	if (unlikely(r))
 		return r;
 
 	if (!hdr)
 		return 0;
 
-	if (WARN_ON_ONCE(TFW_STR_PLAIN(hdr)))
+	if (WARN_ON_ONCE(TFW_STR_PLAIN(hdr) || TFW_STR_DUP(hdr)))
 		return -EINVAL;
 
+	tfw_http_hdr_split(hdr, &s_name, &s_val, inplace);
+
 	if (unlikely(!name_indexed)) {
-		r = tfw_hpack_str_add(mit, TFW_STR_CHUNK(hdr, 0), resp->pool);
+		TfwHPackInt nlen;
+		TfwStr s_nlen = {};
+
+		write_int(s_name.len, 0x7F, 0, &nlen);
+		s_nlen.data = nlen.buf;
+		s_nlen.len = nlen.sz;
+
+		r = tfw_http_msg_expand_from_pool(mit, resp->pool, &s_nlen);
+		if (unlikely(r))
+			return r;
+
+		if (inplace)
+			r = tfw_http_msg_expand_from_pool_lc(mit, resp->pool,
+							     &s_name);
+		else
+			r = tfw_http_msg_expand_from_pool(mit, resp->pool,
+							  &s_name);
 		if (unlikely(r))
 			return r;
 	}
 
-	/*
-	 * During headers addition into the message the source @hdr must have
-	 * the following chunk structure (without the OWS):
-	 *
-	 *	{ name [S_DLM] value1 [value2 [value3 ...]] }.
-	 *
-	 */
-	c = TFW_STR_CHUNK(hdr, 1);
-	if (WARN_ON_ONCE(!c))
-		return -EINVAL;
+	write_int(s_val.len, 0x7F, 0, &vlen);
+	s_vlen.data = vlen.buf;
+	s_vlen.len = vlen.sz;
 
-	if (c->len == SLEN(S_DLM) && *(short *)c->data == *(short *)S_DLM) {
-		c = TFW_STR_CHUNK(hdr, 2);
-		if (WARN_ON_ONCE(!c))
-			return -EINVAL;
-	}
+	r = tfw_http_msg_expand_from_pool(mit, resp->pool, &s_vlen);
 
-	end = hdr->chunks + hdr->nchunks;
-	tfw_str_collect_cmp(c, end, &s_val, NULL);
+	if (unlikely(r))
+		return r;
+	if (!TFW_STR_EMPTY(&s_val)) {
+		r = tfw_http_msg_expand_from_pool(mit, resp->pool, &s_val);
+	}
 
-	return tfw_hpack_str_add(mit,&s_val, resp->pool);
+	return r;
 }
 
 /*
@@ -3699,88 +3709,6 @@ tfw_hpack_hdr_expand(TfwHttpResp *__restrict resp, TfwStr *__restrict hdr,
 	return tfw_hpack_str_expand(mit, iter, skb_head, &s_val, NULL);
 }
 
-/*
- * Transform the HTTP/1.1 header @hdr in-place into HTTP/2 HPACK format in the
- * response @resp.
- */
-static int
-tfw_hpack_hdr_inplace(TfwHttpResp *__restrict resp, TfwStr *__restrict hdr,
-		      TfwHPackInt *__restrict idx, bool name_indexed,
-		      bool indexed)
-{
-	int r;
-	const char *bnd;
-	TfwHPackInt vlen;
-	TfwHttpTransIter *mit = &resp->mit;
-	TfwStr s_name = {}, s_val = {}, s_vlen = {};
-	const TfwStr s_idx = {
-		.data = idx->buf,
-		.len = idx->sz,
-	};
-
-	T_DBG3("%s: s_idx->len=%lu, s_idx->data='%.*s'\n",
-	       __func__, s_idx.len, (int)s_idx.len, s_idx.data);
-
-	if (!hdr || WARN_ON_ONCE(TFW_STR_PLAIN(hdr) || TFW_STR_DUP(hdr)))
-		return -EINVAL;
-
-	tfw_http_hdr_split(hdr, &s_name, &s_val, true);
-
-	if (unlikely(!name_indexed)) {
-		TfwHPackInt nlen;
-		TfwStr s_nlen = {};
-
-		bnd = __TFW_STR_CH(&s_name, 0)->data;
-
-		r = tfw_h2_msg_rewrite_data(mit, &s_idx, bnd);
-		if (unlikely(r))
-			return r;
-
-		write_int(s_name.len, 0x7F, 0, &nlen);
-		s_nlen.data = nlen.buf;
-		s_nlen.len = nlen.sz;
-
-		r = tfw_h2_msg_rewrite_data(mit, &s_nlen, bnd);
-		if (unlikely(r))
-			return r;
-
-		if (!TFW_STR_EMPTY(&s_val))
-			bnd = __TFW_STR_CH(&s_val, 0)->data;
-		else
-			bnd = mit->bnd;
-
-		r = tfw_h2_msg_rewrite_data_lc(mit, &s_name, bnd);
-		if (unlikely(r))
-			return r;
-	} else {
-		bnd = indexed || TFW_STR_EMPTY(&s_val)
-			? mit->bnd
-			: __TFW_STR_CH(&s_val, 0)->data;
-
-		r = tfw_h2_msg_rewrite_data(mit, &s_idx, bnd);
-		if (unlikely(r))
-			return r;
-
-		if (indexed)
-			return 0;
-	}
-
-	write_int(s_val.len, 0x7F, 0, &vlen);
-	s_vlen.data = vlen.buf;
-	s_vlen.len = vlen.sz;
-
-	r = tfw_h2_msg_rewrite_data(mit, &s_vlen, bnd);
-	if (unlikely(r))
-		return r;
-	if (!TFW_STR_EMPTY(&s_val)) {
-		r = tfw_h2_msg_rewrite_data(mit, &s_val, mit->bnd);
-		if (unlikely(r))
-			return r;
-	}
-
-	return 0;
-}
-
 /*
  * Perform encoding of the header @hdr into the HTTP/2 HPACK format. The four
  * operation types can be executed here: addition, substitution, in-place
@@ -3810,7 +3738,6 @@ tfw_hpack_encode(TfwHttpResp *__restrict resp, TfwStr *__restrict hdr,
 	TfwH2Ctx *ctx = tfw_h2_context(resp->req->conn);
 	TfwHPackETbl *tbl = &ctx->hpack.enc_tbl;
 	int r = HPACK_IDX_ST_NOT_FOUND;
-	TfwHttpTransIter mit = resp->mit;
 
 	if (WARN_ON_ONCE(!hdr || TFW_STR_EMPTY(hdr)))
 		return -EINVAL;
@@ -3840,26 +3767,15 @@ tfw_hpack_encode(TfwHttpResp *__restrict resp, TfwStr *__restrict hdr,
 
 		write_int(index, 0x7F, 0x80, &idx);
 		switch (op) {
-		case TFW_H2_TRANS_SUB:
 		case TFW_H2_TRANS_ADD:
-			r = tfw_hpack_hdr_add(resp, NULL, &idx, true);
-			if (r != -ENOSPC)
-				return r;
-			resp->mit = mit;
-			break;
+			return tfw_hpack_hdr_add(resp, NULL, &idx, true, false);
+		case TFW_H2_TRANS_INPLACE:
+			return tfw_hpack_hdr_add(resp, NULL, &idx, true, true);
 		case TFW_H2_TRANS_EXPAND:
 			return tfw_hpack_hdr_expand(resp, NULL, &idx, true);
-		case TFW_H2_TRANS_INPLACE:
-			r = tfw_hpack_hdr_inplace(resp, hdr, &idx, true, true);
-			if (r != -ENOSPC)
-				return r;
-			resp->mit = mit;
-			break;
 		default:
 			BUG();
 		}
-
-		return tfw_hpack_hdr_expand(resp, NULL, &idx, true);
 	}
 
 	if (st_index || HPACK_IDX_RES(r) == HPACK_IDX_ST_NM_FOUND) {
@@ -3877,54 +3793,33 @@ tfw_hpack_encode(TfwHttpResp *__restrict resp, TfwStr *__restrict hdr,
 			write_int(index, 0x3F, 0x40, &idx);
 		else
 			write_int(index, 0xF, 0, &idx);
+
 		switch (op) {
-		case TFW_H2_TRANS_SUB:
 		case TFW_H2_TRANS_ADD:
-			r = tfw_hpack_hdr_add(resp, hdr, &idx, true);
-			if (r != -ENOSPC)
-				return r;
-			resp->mit = mit;
-			break;
+			return tfw_hpack_hdr_add(resp, hdr, &idx, true, false);
+		case TFW_H2_TRANS_INPLACE:
+			return tfw_hpack_hdr_add(resp, hdr, &idx, true, true);
 		case TFW_H2_TRANS_EXPAND:
 			return tfw_hpack_hdr_expand(resp, hdr, &idx, true);
-		case TFW_H2_TRANS_INPLACE:
-			r = tfw_hpack_hdr_inplace(resp, hdr, &idx, true, false);
-			if (r != -ENOSPC)
-				return r;
-			resp->mit = mit;
-			break;
 		default:
 			BUG();
 		}
-
-		return tfw_hpack_hdr_expand(resp, hdr, &idx, true);
 	}
 
 	WARN_ON_ONCE(index || st_index);
 
 	idx.sz = 1;
 	idx.buf[0] = (r & HPACK_IDX_FLAG_ADD) ? 0x40 : 0;
 	switch (op) {
-	case TFW_H2_TRANS_SUB:
 	case TFW_H2_TRANS_ADD:
-		r = tfw_hpack_hdr_add(resp, hdr, &idx, false);
-		if (r != -ENOSPC)
-			return r;
-		resp->mit = mit;
-		break;
+		return tfw_hpack_hdr_add(resp, hdr, &idx, false, false);
+	case TFW_H2_TRANS_INPLACE:
+		return tfw_hpack_hdr_add(resp, hdr, &idx, false, true);
 	case TFW_H2_TRANS_EXPAND:
 		return tfw_hpack_hdr_expand(resp, hdr, &idx, false);
-	case TFW_H2_TRANS_INPLACE:
-		r = tfw_hpack_hdr_inplace(resp, hdr, &idx, false, false);
-		if (r != -ENOSPC)
-			return r;
-		resp->mit = mit;
-		break;
 	default:
 		BUG();
 	}
-
-	return tfw_hpack_hdr_expand(resp, hdr, &idx, false);
 }
 
 void

fw/hpack.h

@@ -109,7 +109,6 @@ typedef struct {
 
 typedef enum {
 	TFW_H2_TRANS_INPLACE	= 0,
-	TFW_H2_TRANS_SUB,
 	TFW_H2_TRANS_ADD,
 	TFW_H2_TRANS_EXPAND,
 } TfwH2TransOp;