source: azure_iot_hub_f767zi/trunk/azure_iot_sdk/c-utility/src/uws_frame_encoder.c@ 457

Last change on this file since 457 was 457, checked in by coas-nagasima, 4 years ago

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1 // Copyright (c) Microsoft. All rights reserved.
2// Licensed under the MIT license. See LICENSE file in the project root for full license information.
3
4#include <stdlib.h>
5#include <stdint.h>
6#include <stdbool.h>
7#include "azure_c_shared_utility/gballoc.h"
8#include "azure_c_shared_utility/gb_rand.h"
9#include "azure_c_shared_utility/uws_frame_encoder.h"
10#include "azure_c_shared_utility/xlogging.h"
11#include "azure_c_shared_utility/buffer_.h"
12#include "azure_c_shared_utility/uniqueid.h"
13
14BUFFER_HANDLE uws_frame_encoder_encode(WS_FRAME_TYPE opcode, const unsigned char* payload, size_t length, bool is_masked, bool is_final, unsigned char reserved)
15{
16 BUFFER_HANDLE result;
17
18 if (reserved > 7)
19 {
20 /* Codes_SRS_UWS_FRAME_ENCODER_01_052: [ If reserved has any bits set except the lowest 3 then uws_frame_encoder_encode shall fail and return NULL. ]*/
21 LogError("Bad reserved value: 0x%02x", reserved);
22 result = NULL;
23 }
24 else if (opcode > 0x0F)
25 {
26 /* Codes_SRS_UWS_FRAME_ENCODER_01_006: [ If an unknown opcode is received, the receiving endpoint MUST _Fail the WebSocket Connection_. ]*/
27 LogError("Invalid opcode: 0x%02x", opcode);
28 result = NULL;
29 }
30 else if ((length > 0) &&
31 (payload == NULL))
32 {
33 /* Codes_SRS_UWS_FRAME_ENCODER_01_054: [ If length is greater than 0 and payload is NULL, then uws_frame_encoder_encode shall fail and return NULL. ]*/
34 LogError("Invalid arguments: NULL payload and length=%u", (unsigned int)length);
35 result = NULL;
36 }
37 else
38 {
39 size_t needed_bytes = 2;
40 size_t header_bytes;
41
42 /* Codes_SRS_UWS_FRAME_ENCODER_01_044: [ On success uws_frame_encoder_encode shall return a non-NULL handle to the result buffer. ]*/
43 /* Codes_SRS_UWS_FRAME_ENCODER_01_048: [ The newly created buffer shall be created by calling BUFFER_new. ]*/
44 result = BUFFER_new();
45 if (result == NULL)
46 {
47 /* Codes_SRS_UWS_FRAME_ENCODER_01_049: [ If BUFFER_new fails then uws_frame_encoder_encode shall fail and return NULL. ]*/
48 LogError("Cannot create new buffer");
49 }
50 else
51 {
52 /* Codes_SRS_UWS_FRAME_ENCODER_01_001: [ uws_frame_encoder_encode shall encode the information given in opcode, payload, length, is_masked, is_final and reserved according to the RFC6455 into a new buffer.]*/
53 if (length > 65535)
54 {
55 needed_bytes += 8;
56 }
57 else if (length > 125)
58 {
59 needed_bytes += 2;
60 }
61
62 if (is_masked)
63 {
64 needed_bytes += 4;
65 }
66
67 header_bytes = needed_bytes;
68 needed_bytes += length;
69
70 /* Codes_SRS_UWS_FRAME_ENCODER_01_046: [ The result buffer shall be resized accordingly using BUFFER_enlarge. ]*/
71 if (BUFFER_enlarge(result, needed_bytes) != 0)
72 {
73 /* Codes_SRS_UWS_FRAME_ENCODER_01_047: [ If BUFFER_enlarge fails then uws_frame_encoder_encode shall fail and return NULL. ]*/
74 LogError("Cannot allocate memory for encoded frame");
75 BUFFER_delete(result);
76 result = NULL;
77 }
78 else
79 {
80 /* Codes_SRS_UWS_FRAME_ENCODER_01_050: [ The allocated memory shall be accessed by calling BUFFER_u_char. ]*/
81 unsigned char* buffer = BUFFER_u_char(result);
82 if (buffer == NULL)
83 {
84 /* Codes_SRS_UWS_FRAME_ENCODER_01_051: [ If BUFFER_u_char fails then uws_frame_encoder_encode shall fail and return a NULL. ]*/
85 LogError("Cannot get encoded buffer pointer");
86 BUFFER_delete(result);
87 result = NULL;
88 }
89 else
90 {
91 /* Codes_SRS_UWS_FRAME_ENCODER_01_007: [ * %x0 denotes a continuation frame ]*/
92 /* Codes_SRS_UWS_FRAME_ENCODER_01_008: [ * %x1 denotes a text frame ]*/
93 /* Codes_SRS_UWS_FRAME_ENCODER_01_009: [ * %x2 denotes a binary frame ]*/
94 /* Codes_SRS_UWS_FRAME_ENCODER_01_010: [ * %x3-7 are reserved for further non-control frames ]*/
95 /* Codes_SRS_UWS_FRAME_ENCODER_01_011: [ * %x8 denotes a connection close ]*/
96 /* Codes_SRS_UWS_FRAME_ENCODER_01_012: [ * %x9 denotes a ping ]*/
97 /* Codes_SRS_UWS_FRAME_ENCODER_01_013: [ * %xA denotes a pong ]*/
98 /* Codes_SRS_UWS_FRAME_ENCODER_01_014: [ * %xB-F are reserved for further control frames ]*/
99 buffer[0] = (unsigned char)opcode;
100
101 /* Codes_SRS_UWS_FRAME_ENCODER_01_002: [ Indicates that this is the final fragment in a message. ]*/
102 /* Codes_SRS_UWS_FRAME_ENCODER_01_003: [ The first fragment MAY also be the final fragment. ]*/
103 if (is_final)
104 {
105 buffer[0] |= 0x80;
106 }
107
108 /* Codes_SRS_UWS_FRAME_ENCODER_01_004: [ MUST be 0 unless an extension is negotiated that defines meanings for non-zero values. ]*/
109 buffer[0] |= reserved << 4;
110
111 /* Codes_SRS_UWS_FRAME_ENCODER_01_022: [ Note that in all cases, the minimal number of bytes MUST be used to encode the length, for example, the length of a 124-byte-long string can't be encoded as the sequence 126, 0, 124. ]*/
112 /* Codes_SRS_UWS_FRAME_ENCODER_01_018: [ The length of the "Payload data", in bytes: ]*/
113 /* Codes_SRS_UWS_FRAME_ENCODER_01_023: [ The payload length is the length of the "Extension data" + the length of the "Application data". ]*/
114 /* Codes_SRS_UWS_FRAME_ENCODER_01_042: [ The payload length, indicated in the framing as frame-payload-length, does NOT include the length of the masking key. ]*/
115 if (length > 65535)
116 {
117 /* Codes_SRS_UWS_FRAME_ENCODER_01_020: [ If 127, the following 8 bytes interpreted as a 64-bit unsigned integer (the most significant bit MUST be 0) are the payload length. ]*/
118 buffer[1] = 127;
119
120 /* Codes_SRS_UWS_FRAME_ENCODER_01_021: [ Multibyte length quantities are expressed in network byte order. ]*/
121 buffer[2] = (unsigned char)((uint64_t)length >> 56) & 0xFF;
122 buffer[3] = (unsigned char)((uint64_t)length >> 48) & 0xFF;
123 buffer[4] = (unsigned char)((uint64_t)length >> 40) & 0xFF;
124 buffer[5] = (unsigned char)((uint64_t)length >> 32) & 0xFF;
125 buffer[6] = (unsigned char)((uint64_t)length >> 24) & 0xFF;
126 buffer[7] = (unsigned char)((uint64_t)length >> 16) & 0xFF;
127 buffer[8] = (unsigned char)((uint64_t)length >> 8) & 0xFF;
128 buffer[9] = (unsigned char)(length & 0xFF);
129 }
130 else if (length > 125)
131 {
132 /* Codes_SRS_UWS_FRAME_ENCODER_01_019: [ If 126, the following 2 bytes interpreted as a 16-bit unsigned integer are the payload length. ]*/
133 buffer[1] = 126;
134
135 /* Codes_SRS_UWS_FRAME_ENCODER_01_021: [ Multibyte length quantities are expressed in network byte order. ]*/
136 buffer[2] = (unsigned char)(length >> 8);
137 buffer[3] = (unsigned char)(length & 0xFF);
138 }
139 else
140 {
141 /* Codes_SRS_UWS_FRAME_ENCODER_01_043: [ if 0-125, that is the payload length. ]*/
142 buffer[1] = (unsigned char)length;
143 }
144
145 if (is_masked)
146 {
147 /* Codes_SRS_UWS_FRAME_ENCODER_01_015: [ Defines whether the "Payload data" is masked. ]*/
148 /* Codes_SRS_UWS_FRAME_ENCODER_01_033: [ A masked frame MUST have the field frame-masked set to 1, as defined in Section 5.2. ]*/
149 buffer[1] |= 0x80;
150
151 /* Codes_SRS_UWS_FRAME_ENCODER_01_053: [ In order to obtain a 32 bit value for masking, gb_rand shall be used 4 times (for each byte). ]*/
152 /* Codes_SRS_UWS_FRAME_ENCODER_01_016: [ If set to 1, a masking key is present in masking-key, and this is used to unmask the "Payload data" as per Section 5.3. ]*/
153 /* Codes_SRS_UWS_FRAME_ENCODER_01_026: [ This field is present if the mask bit is set to 1 and is absent if the mask bit is set to 0. ]*/
154 /* Codes_SRS_UWS_FRAME_ENCODER_01_034: [ The masking key is contained completely within the frame, as defined in Section 5.2 as frame-masking-key. ]*/
155 /* Codes_SRS_UWS_FRAME_ENCODER_01_036: [ The masking key is a 32-bit value chosen at random by the client. ]*/
156 /* Codes_SRS_UWS_FRAME_ENCODER_01_037: [ When preparing a masked frame, the client MUST pick a fresh masking key from the set of allowed 32-bit values. ]*/
157 /* Codes_SRS_UWS_FRAME_ENCODER_01_038: [ The masking key needs to be unpredictable; thus, the masking key MUST be derived from a strong source of entropy, and the masking key for a given frame MUST NOT make it simple for a server/proxy to predict the masking key for a subsequent frame. ]*/
158 buffer[header_bytes - 4] = (unsigned char)gb_rand();
159 buffer[header_bytes - 3] = (unsigned char)gb_rand();
160 buffer[header_bytes - 2] = (unsigned char)gb_rand();
161 buffer[header_bytes - 1] = (unsigned char)gb_rand();
162 }
163
164 if (length > 0)
165 {
166 if (is_masked)
167 {
168 size_t i;
169
170 /* Codes_SRS_UWS_FRAME_ENCODER_01_035: [ It is used to mask the "Payload data" defined in the same section as frame-payload-data, which includes "Extension data" and "Application data". ]*/
171 /* Codes_SRS_UWS_FRAME_ENCODER_01_039: [ To convert masked data into unmasked data, or vice versa, the following algorithm is applied. ]*/
172 /* Codes_SRS_UWS_FRAME_ENCODER_01_040: [ The same algorithm applies regardless of the direction of the translation, e.g., the same steps are applied to mask the data as to unmask the data. ]*/
173 for (i = 0; i < length; i++)
174 {
175 /* Codes_SRS_UWS_FRAME_ENCODER_01_041: [ Octet i of the transformed data ("transformed-octet-i") is the XOR of octet i of the original data ("original-octet-i") with octet at index i modulo 4 of the masking key ("masking-key-octet-j"): ]*/
176 buffer[header_bytes + i] = ((unsigned char*)payload)[i] ^ buffer[header_bytes - 4 + (i % 4)];
177 }
178 }
179 else
180 {
181 (void)memcpy(buffer + header_bytes, payload, length);
182 }
183 }
184 }
185 }
186 }
187 }
188
189 return result;
190}
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