// Copyright (c) Microsoft. All rights reserved. // Licensed under the MIT license. See LICENSE file in the project root for full license information. #include #include #include #include "azure_c_shared_utility/gballoc.h" #include "azure_c_shared_utility/gb_rand.h" #include "azure_c_shared_utility/uws_frame_encoder.h" #include "azure_c_shared_utility/xlogging.h" #include "azure_c_shared_utility/buffer_.h" #include "azure_c_shared_utility/uniqueid.h" BUFFER_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) { BUFFER_HANDLE result; if (reserved > 7) { /* 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. ]*/ LogError("Bad reserved value: 0x%02x", reserved); result = NULL; } else if (opcode > 0x0F) { /* Codes_SRS_UWS_FRAME_ENCODER_01_006: [ If an unknown opcode is received, the receiving endpoint MUST _Fail the WebSocket Connection_. ]*/ LogError("Invalid opcode: 0x%02x", opcode); result = NULL; } else if ((length > 0) && (payload == NULL)) { /* 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. ]*/ LogError("Invalid arguments: NULL payload and length=%u", (unsigned int)length); result = NULL; } else { size_t needed_bytes = 2; size_t header_bytes; /* Codes_SRS_UWS_FRAME_ENCODER_01_044: [ On success uws_frame_encoder_encode shall return a non-NULL handle to the result buffer. ]*/ /* Codes_SRS_UWS_FRAME_ENCODER_01_048: [ The newly created buffer shall be created by calling BUFFER_new. ]*/ result = BUFFER_new(); if (result == NULL) { /* Codes_SRS_UWS_FRAME_ENCODER_01_049: [ If BUFFER_new fails then uws_frame_encoder_encode shall fail and return NULL. ]*/ LogError("Cannot create new buffer"); } else { /* 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.]*/ if (length > 65535) { needed_bytes += 8; } else if (length > 125) { needed_bytes += 2; } if (is_masked) { needed_bytes += 4; } header_bytes = needed_bytes; needed_bytes += length; /* Codes_SRS_UWS_FRAME_ENCODER_01_046: [ The result buffer shall be resized accordingly using BUFFER_enlarge. ]*/ if (BUFFER_enlarge(result, needed_bytes) != 0) { /* Codes_SRS_UWS_FRAME_ENCODER_01_047: [ If BUFFER_enlarge fails then uws_frame_encoder_encode shall fail and return NULL. ]*/ LogError("Cannot allocate memory for encoded frame"); BUFFER_delete(result); result = NULL; } else { /* Codes_SRS_UWS_FRAME_ENCODER_01_050: [ The allocated memory shall be accessed by calling BUFFER_u_char. ]*/ unsigned char* buffer = BUFFER_u_char(result); if (buffer == NULL) { /* Codes_SRS_UWS_FRAME_ENCODER_01_051: [ If BUFFER_u_char fails then uws_frame_encoder_encode shall fail and return a NULL. ]*/ LogError("Cannot get encoded buffer pointer"); BUFFER_delete(result); result = NULL; } else { /* Codes_SRS_UWS_FRAME_ENCODER_01_007: [ * %x0 denotes a continuation frame ]*/ /* Codes_SRS_UWS_FRAME_ENCODER_01_008: [ * %x1 denotes a text frame ]*/ /* Codes_SRS_UWS_FRAME_ENCODER_01_009: [ * %x2 denotes a binary frame ]*/ /* Codes_SRS_UWS_FRAME_ENCODER_01_010: [ * %x3-7 are reserved for further non-control frames ]*/ /* Codes_SRS_UWS_FRAME_ENCODER_01_011: [ * %x8 denotes a connection close ]*/ /* Codes_SRS_UWS_FRAME_ENCODER_01_012: [ * %x9 denotes a ping ]*/ /* Codes_SRS_UWS_FRAME_ENCODER_01_013: [ * %xA denotes a pong ]*/ /* Codes_SRS_UWS_FRAME_ENCODER_01_014: [ * %xB-F are reserved for further control frames ]*/ buffer[0] = (unsigned char)opcode; /* Codes_SRS_UWS_FRAME_ENCODER_01_002: [ Indicates that this is the final fragment in a message. ]*/ /* Codes_SRS_UWS_FRAME_ENCODER_01_003: [ The first fragment MAY also be the final fragment. ]*/ if (is_final) { buffer[0] |= 0x80; } /* Codes_SRS_UWS_FRAME_ENCODER_01_004: [ MUST be 0 unless an extension is negotiated that defines meanings for non-zero values. ]*/ buffer[0] |= reserved << 4; /* 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. ]*/ /* Codes_SRS_UWS_FRAME_ENCODER_01_018: [ The length of the "Payload data", in bytes: ]*/ /* Codes_SRS_UWS_FRAME_ENCODER_01_023: [ The payload length is the length of the "Extension data" + the length of the "Application data". ]*/ /* 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. ]*/ if (length > 65535) { /* 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. ]*/ buffer[1] = 127; /* Codes_SRS_UWS_FRAME_ENCODER_01_021: [ Multibyte length quantities are expressed in network byte order. ]*/ buffer[2] = (unsigned char)((uint64_t)length >> 56) & 0xFF; buffer[3] = (unsigned char)((uint64_t)length >> 48) & 0xFF; buffer[4] = (unsigned char)((uint64_t)length >> 40) & 0xFF; buffer[5] = (unsigned char)((uint64_t)length >> 32) & 0xFF; buffer[6] = (unsigned char)((uint64_t)length >> 24) & 0xFF; buffer[7] = (unsigned char)((uint64_t)length >> 16) & 0xFF; buffer[8] = (unsigned char)((uint64_t)length >> 8) & 0xFF; buffer[9] = (unsigned char)(length & 0xFF); } else if (length > 125) { /* Codes_SRS_UWS_FRAME_ENCODER_01_019: [ If 126, the following 2 bytes interpreted as a 16-bit unsigned integer are the payload length. ]*/ buffer[1] = 126; /* Codes_SRS_UWS_FRAME_ENCODER_01_021: [ Multibyte length quantities are expressed in network byte order. ]*/ buffer[2] = (unsigned char)(length >> 8); buffer[3] = (unsigned char)(length & 0xFF); } else { /* Codes_SRS_UWS_FRAME_ENCODER_01_043: [ if 0-125, that is the payload length. ]*/ buffer[1] = (unsigned char)length; } if (is_masked) { /* Codes_SRS_UWS_FRAME_ENCODER_01_015: [ Defines whether the "Payload data" is masked. ]*/ /* 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. ]*/ buffer[1] |= 0x80; /* 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). ]*/ /* 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. ]*/ /* 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. ]*/ /* 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. ]*/ /* Codes_SRS_UWS_FRAME_ENCODER_01_036: [ The masking key is a 32-bit value chosen at random by the client. ]*/ /* 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. ]*/ /* 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. ]*/ buffer[header_bytes - 4] = (unsigned char)gb_rand(); buffer[header_bytes - 3] = (unsigned char)gb_rand(); buffer[header_bytes - 2] = (unsigned char)gb_rand(); buffer[header_bytes - 1] = (unsigned char)gb_rand(); } if (length > 0) { if (is_masked) { size_t i; /* 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". ]*/ /* Codes_SRS_UWS_FRAME_ENCODER_01_039: [ To convert masked data into unmasked data, or vice versa, the following algorithm is applied. ]*/ /* 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. ]*/ for (i = 0; i < length; i++) { /* 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"): ]*/ buffer[header_bytes + i] = ((unsigned char*)payload)[i] ^ buffer[header_bytes - 4 + (i % 4)]; } } else { (void)memcpy(buffer + header_bytes, payload, length); } } } } } } return result; }