114 lines
4.0 KiB
JavaScript
114 lines
4.0 KiB
JavaScript
//
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// Created by Mingliang Chen on 17/8/1.
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// illuspas[a]gmail.com
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// Copyright (c) 2018 Nodemedia. All rights reserved.
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//
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// const Logger = require('./node_core_logger');
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const Crypto = require('crypto');
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const MESSAGE_FORMAT_0 = 0;
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const MESSAGE_FORMAT_1 = 1;
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const MESSAGE_FORMAT_2 = 2;
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const RTMP_SIG_SIZE = 1536;
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const SHA256DL = 32;
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const RandomCrud = Buffer.from([
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0xf0, 0xee, 0xc2, 0x4a, 0x80, 0x68, 0xbe, 0xe8,
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0x2e, 0x00, 0xd0, 0xd1, 0x02, 0x9e, 0x7e, 0x57,
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0x6e, 0xec, 0x5d, 0x2d, 0x29, 0x80, 0x6f, 0xab,
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0x93, 0xb8, 0xe6, 0x36, 0xcf, 0xeb, 0x31, 0xae
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])
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const GenuineFMSConst = 'Genuine Adobe Flash Media Server 001';
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const GenuineFMSConstCrud = Buffer.concat([Buffer.from(GenuineFMSConst, 'utf8'), RandomCrud]);
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const GenuineFPConst = 'Genuine Adobe Flash Player 001';
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const GenuineFPConstCrud = Buffer.concat([Buffer.from(GenuineFPConst, 'utf8'), RandomCrud]);
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function calcHmac(data, key) {
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let hmac = Crypto.createHmac('sha256', key);
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hmac.update(data);
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return hmac.digest();
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}
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function GetClientGenuineConstDigestOffset(buf) {
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let offset = buf[0] + buf[1] + buf[2] + buf[3];
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offset = (offset % 728) + 12;
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return offset;
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}
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function GetServerGenuineConstDigestOffset(buf) {
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let offset = buf[0] + buf[1] + buf[2] + buf[3];
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offset = (offset % 728) + 776;
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return offset;
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}
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function detectClientMessageFormat(clientsig) {
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let computedSignature, msg, providedSignature, sdl;
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sdl = GetServerGenuineConstDigestOffset(clientsig.slice(772, 776));
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msg = Buffer.concat([clientsig.slice(0, sdl), clientsig.slice(sdl + SHA256DL)], 1504);
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computedSignature = calcHmac(msg, GenuineFPConst);
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providedSignature = clientsig.slice(sdl, sdl + SHA256DL);
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if (computedSignature.equals(providedSignature)) {
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return MESSAGE_FORMAT_2;
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}
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sdl = GetClientGenuineConstDigestOffset(clientsig.slice(8, 12));
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msg = Buffer.concat([clientsig.slice(0, sdl), clientsig.slice(sdl + SHA256DL)], 1504);
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computedSignature = calcHmac(msg, GenuineFPConst);
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providedSignature = clientsig.slice(sdl, sdl + SHA256DL);
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if (computedSignature.equals(providedSignature)) {
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return MESSAGE_FORMAT_1;
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}
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return MESSAGE_FORMAT_0;
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}
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function generateS1(messageFormat) {
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let randomBytes = Crypto.randomBytes(RTMP_SIG_SIZE - 8);
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let handshakeBytes = Buffer.concat([Buffer.from([0, 0, 0, 0, 1, 2, 3, 4]), randomBytes], RTMP_SIG_SIZE);
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let serverDigestOffset
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if (messageFormat === 1) {
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serverDigestOffset = GetClientGenuineConstDigestOffset(handshakeBytes.slice(8, 12));
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} else {
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serverDigestOffset = GetServerGenuineConstDigestOffset(handshakeBytes.slice(772, 776));
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}
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msg = Buffer.concat([handshakeBytes.slice(0, serverDigestOffset), handshakeBytes.slice(serverDigestOffset + SHA256DL)], RTMP_SIG_SIZE - SHA256DL);
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hash = calcHmac(msg, GenuineFMSConst);
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hash.copy(handshakeBytes, serverDigestOffset, 0, 32);
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return handshakeBytes;
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}
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function generateS2(messageFormat, clientsig, callback) {
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let randomBytes = Crypto.randomBytes(RTMP_SIG_SIZE - 32);
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let challengeKeyOffset;
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if (messageFormat === 1) {
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challengeKeyOffset = GetClientGenuineConstDigestOffset(clientsig.slice(8, 12));
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} else {
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challengeKeyOffset = GetServerGenuineConstDigestOffset(clientsig.slice(772, 776));
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}
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let challengeKey = clientsig.slice(challengeKeyOffset, challengeKeyOffset + 32);
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let hash = calcHmac(challengeKey, GenuineFMSConstCrud);
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let signature = calcHmac(randomBytes, hash);
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let s2Bytes = Buffer.concat([randomBytes, signature], RTMP_SIG_SIZE);
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return s2Bytes
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}
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function generateS0S1S2(clientsig) {
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let clientType = Buffer.alloc(1, 3);
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let messageFormat = detectClientMessageFormat(clientsig);
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let allBytes;
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if (messageFormat === MESSAGE_FORMAT_0) {
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// Logger.debug('[rtmp handshake] using simple handshake.');
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allBytes = Buffer.concat([clientType, clientsig, clientsig]);
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} else {
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// Logger.debug('[rtmp handshake] using complex handshake.');
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allBytes = Buffer.concat([clientType, generateS1(messageFormat), generateS2(messageFormat, clientsig)]);
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}
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return allBytes;
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}
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module.exports = { generateS0S1S2 };
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