1 /*
2 *
3 * Copyright 2015 gRPC authors.
4 *
5 * Licensed under the Apache License, Version 2.0 (the "License");
6 * you may not use this file except in compliance with the License.
7 * You may obtain a copy of the License at
8 *
9 * http://www.apache.org/licenses/LICENSE-2.0
10 *
11 * Unless required by applicable law or agreed to in writing, software
12 * distributed under the License is distributed on an "AS IS" BASIS,
13 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
14 * See the License for the specific language governing permissions and
15 * limitations under the License.
16 *
17 */
18
19 #include <grpc/support/port_platform.h>
20
21 #include "src/core/ext/transport/chttp2/transport/frame_window_update.h"
22 #include "src/core/ext/transport/chttp2/transport/internal.h"
23
24 #include "absl/strings/str_cat.h"
25 #include "absl/strings/str_format.h"
26
27 #include <grpc/support/alloc.h>
28 #include <grpc/support/log.h>
29
grpc_chttp2_window_update_create(uint32_t id,uint32_t window_delta,grpc_transport_one_way_stats * stats)30 grpc_slice grpc_chttp2_window_update_create(
31 uint32_t id, uint32_t window_delta, grpc_transport_one_way_stats* stats) {
32 static const size_t frame_size = 13;
33 grpc_slice slice = GRPC_SLICE_MALLOC(frame_size);
34 stats->header_bytes += frame_size;
35 uint8_t* p = GRPC_SLICE_START_PTR(slice);
36
37 GPR_ASSERT(window_delta);
38
39 *p++ = 0;
40 *p++ = 0;
41 *p++ = 4;
42 *p++ = GRPC_CHTTP2_FRAME_WINDOW_UPDATE;
43 *p++ = 0;
44 *p++ = static_cast<uint8_t>(id >> 24);
45 *p++ = static_cast<uint8_t>(id >> 16);
46 *p++ = static_cast<uint8_t>(id >> 8);
47 *p++ = static_cast<uint8_t>(id);
48 *p++ = static_cast<uint8_t>(window_delta >> 24);
49 *p++ = static_cast<uint8_t>(window_delta >> 16);
50 *p++ = static_cast<uint8_t>(window_delta >> 8);
51 *p++ = static_cast<uint8_t>(window_delta);
52
53 return slice;
54 }
55
grpc_chttp2_window_update_parser_begin_frame(grpc_chttp2_window_update_parser * parser,uint32_t length,uint8_t flags)56 grpc_error* grpc_chttp2_window_update_parser_begin_frame(
57 grpc_chttp2_window_update_parser* parser, uint32_t length, uint8_t flags) {
58 if (flags || length != 4) {
59 return GRPC_ERROR_CREATE_FROM_COPIED_STRING(
60 absl::StrFormat("invalid window update: length=%d, flags=%02x", length,
61 flags)
62 .c_str());
63 }
64 parser->byte = 0;
65 parser->amount = 0;
66 return GRPC_ERROR_NONE;
67 }
68
grpc_chttp2_window_update_parser_parse(void * parser,grpc_chttp2_transport * t,grpc_chttp2_stream * s,const grpc_slice & slice,int is_last)69 grpc_error* grpc_chttp2_window_update_parser_parse(void* parser,
70 grpc_chttp2_transport* t,
71 grpc_chttp2_stream* s,
72 const grpc_slice& slice,
73 int is_last) {
74 const uint8_t* const beg = GRPC_SLICE_START_PTR(slice);
75 const uint8_t* const end = GRPC_SLICE_END_PTR(slice);
76 const uint8_t* cur = beg;
77 grpc_chttp2_window_update_parser* p =
78 static_cast<grpc_chttp2_window_update_parser*>(parser);
79
80 while (p->byte != 4 && cur != end) {
81 p->amount |= (static_cast<uint32_t>(*cur)) << (8 * (3 - p->byte));
82 cur++;
83 p->byte++;
84 }
85
86 if (s != nullptr) {
87 s->stats.incoming.framing_bytes += static_cast<uint32_t>(end - cur);
88 }
89
90 if (p->byte == 4) {
91 // top bit is reserved and must be ignored.
92 uint32_t received_update = p->amount & 0x7fffffffu;
93 if (received_update == 0) {
94 return GRPC_ERROR_CREATE_FROM_COPIED_STRING(
95 absl::StrCat("invalid window update bytes: ", p->amount).c_str());
96 }
97 GPR_ASSERT(is_last);
98
99 if (t->incoming_stream_id != 0) {
100 if (s != nullptr) {
101 s->flow_control->RecvUpdate(received_update);
102 if (grpc_chttp2_list_remove_stalled_by_stream(t, s)) {
103 grpc_chttp2_mark_stream_writable(t, s);
104 grpc_chttp2_initiate_write(
105 t, GRPC_CHTTP2_INITIATE_WRITE_FLOW_CONTROL_UNSTALLED_BY_UPDATE);
106 }
107 }
108 } else {
109 bool was_zero = t->flow_control->remote_window() <= 0;
110 t->flow_control->RecvUpdate(received_update);
111 bool is_zero = t->flow_control->remote_window() <= 0;
112 if (was_zero && !is_zero) {
113 grpc_chttp2_initiate_write(
114 t, GRPC_CHTTP2_INITIATE_WRITE_TRANSPORT_FLOW_CONTROL_UNSTALLED);
115 }
116 }
117 }
118
119 return GRPC_ERROR_NONE;
120 }
121