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1// Copyright 2015 Joyent, Inc.
2
3module.exports = SSHBuffer;
4
5var assert = require('assert-plus');
6var Buffer = require('safer-buffer').Buffer;
7
8function SSHBuffer(opts) {
9	assert.object(opts, 'options');
10	if (opts.buffer !== undefined)
11		assert.buffer(opts.buffer, 'options.buffer');
12
13	this._size = opts.buffer ? opts.buffer.length : 1024;
14	this._buffer = opts.buffer || Buffer.alloc(this._size);
15	this._offset = 0;
16}
17
18SSHBuffer.prototype.toBuffer = function () {
19	return (this._buffer.slice(0, this._offset));
20};
21
22SSHBuffer.prototype.atEnd = function () {
23	return (this._offset >= this._buffer.length);
24};
25
26SSHBuffer.prototype.remainder = function () {
27	return (this._buffer.slice(this._offset));
28};
29
30SSHBuffer.prototype.skip = function (n) {
31	this._offset += n;
32};
33
34SSHBuffer.prototype.expand = function () {
35	this._size *= 2;
36	var buf = Buffer.alloc(this._size);
37	this._buffer.copy(buf, 0);
38	this._buffer = buf;
39};
40
41SSHBuffer.prototype.readPart = function () {
42	return ({data: this.readBuffer()});
43};
44
45SSHBuffer.prototype.readBuffer = function () {
46	var len = this._buffer.readUInt32BE(this._offset);
47	this._offset += 4;
48	assert.ok(this._offset + len <= this._buffer.length,
49	    'length out of bounds at +0x' + this._offset.toString(16) +
50	    ' (data truncated?)');
51	var buf = this._buffer.slice(this._offset, this._offset + len);
52	this._offset += len;
53	return (buf);
54};
55
56SSHBuffer.prototype.readString = function () {
57	return (this.readBuffer().toString());
58};
59
60SSHBuffer.prototype.readCString = function () {
61	var offset = this._offset;
62	while (offset < this._buffer.length &&
63	    this._buffer[offset] !== 0x00)
64		offset++;
65	assert.ok(offset < this._buffer.length, 'c string does not terminate');
66	var str = this._buffer.slice(this._offset, offset).toString();
67	this._offset = offset + 1;
68	return (str);
69};
70
71SSHBuffer.prototype.readInt = function () {
72	var v = this._buffer.readUInt32BE(this._offset);
73	this._offset += 4;
74	return (v);
75};
76
77SSHBuffer.prototype.readInt64 = function () {
78	assert.ok(this._offset + 8 < this._buffer.length,
79	    'buffer not long enough to read Int64');
80	var v = this._buffer.slice(this._offset, this._offset + 8);
81	this._offset += 8;
82	return (v);
83};
84
85SSHBuffer.prototype.readChar = function () {
86	var v = this._buffer[this._offset++];
87	return (v);
88};
89
90SSHBuffer.prototype.writeBuffer = function (buf) {
91	while (this._offset + 4 + buf.length > this._size)
92		this.expand();
93	this._buffer.writeUInt32BE(buf.length, this._offset);
94	this._offset += 4;
95	buf.copy(this._buffer, this._offset);
96	this._offset += buf.length;
97};
98
99SSHBuffer.prototype.writeString = function (str) {
100	this.writeBuffer(Buffer.from(str, 'utf8'));
101};
102
103SSHBuffer.prototype.writeCString = function (str) {
104	while (this._offset + 1 + str.length > this._size)
105		this.expand();
106	this._buffer.write(str, this._offset);
107	this._offset += str.length;
108	this._buffer[this._offset++] = 0;
109};
110
111SSHBuffer.prototype.writeInt = function (v) {
112	while (this._offset + 4 > this._size)
113		this.expand();
114	this._buffer.writeUInt32BE(v, this._offset);
115	this._offset += 4;
116};
117
118SSHBuffer.prototype.writeInt64 = function (v) {
119	assert.buffer(v, 'value');
120	if (v.length > 8) {
121		var lead = v.slice(0, v.length - 8);
122		for (var i = 0; i < lead.length; ++i) {
123			assert.strictEqual(lead[i], 0,
124			    'must fit in 64 bits of precision');
125		}
126		v = v.slice(v.length - 8, v.length);
127	}
128	while (this._offset + 8 > this._size)
129		this.expand();
130	v.copy(this._buffer, this._offset);
131	this._offset += 8;
132};
133
134SSHBuffer.prototype.writeChar = function (v) {
135	while (this._offset + 1 > this._size)
136		this.expand();
137	this._buffer[this._offset++] = v;
138};
139
140SSHBuffer.prototype.writePart = function (p) {
141	this.writeBuffer(p.data);
142};
143
144SSHBuffer.prototype.write = function (buf) {
145	while (this._offset + buf.length > this._size)
146		this.expand();
147	buf.copy(this._buffer, this._offset);
148	this._offset += buf.length;
149};
150