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Fix blockwise response logic #376

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merged 3 commits into from
Mar 26, 2024
Merged

Fix blockwise response logic #376

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3c34e45
Update blockwise tests to catch edge-cases
edrose Dec 17, 2023
ec1c126
Update automatic blockwise transfer logic
edrose Dec 16, 2023
0a11715
Perform extra checks on CoAP message size
edrose Dec 16, 2023
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14 changes: 11 additions & 3 deletions lib/parameters.ts
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Original file line number Diff line number Diff line change
Expand Up @@ -131,9 +131,16 @@ const NON_LIFETIME = 145
const COAP_PORT = 5683

/**
* Default max packet size based on IP MTU.
* Maximum total size of the CoAP application layer message, as
* recommended by the CoAP specification
*/
const IP_MTU = 1280
const MAX_MESSAGE_SIZE = 1152

/**
* Default max payload size recommended in the CoAP specification
* For more info see RFC 7252 Section 4.6
*/
const MAX_PAYLOAD_SIZE = 1024

/* Custom default parameters */

Expand Down Expand Up @@ -176,7 +183,8 @@ const p: Parameters = {
maxLatency: MAX_LATENCY,
nonLifetime: NON_LIFETIME,
coapPort: COAP_PORT,
maxPacketSize: IP_MTU,
maxPayloadSize: MAX_PAYLOAD_SIZE,
maxMessageSize: MAX_MESSAGE_SIZE,
sendAcksForNonConfirmablePackets,
piggybackReplyMs,
pruneTimerPeriod
Expand Down
40 changes: 23 additions & 17 deletions lib/server.ts
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Original file line number Diff line number Diff line change
Expand Up @@ -144,11 +144,13 @@ class CoAPServer extends EventEmitter {

// We use an LRU cache for the responses to avoid
// DDOS problems.
// max packet size is 1280
// 32 MB / 1280 = 26214
// The max lifetime is roughly 200s per packet.
// Which gave us 131 packets/second guarantee
let maxSize = 32768 * 1024
// total cache size is 32MiB
// max message size is 1152 bytes
// 32 MiB / 1152 = 29127 messages total

// The max lifetime is roughly 200s per message.
// Which gave us 145 messages/second guarantee
let maxSize = 32768 * 1024 // Maximum cache size is 32 MiB

if (typeof this._options.cacheSize === 'number' && this._options.cacheSize >= 0) {
maxSize = this._options.cacheSize
Expand Down Expand Up @@ -211,7 +213,7 @@ class CoAPServer extends EventEmitter {
payload,
messageId: packet != null ? packet.messageId : undefined,
token: packet != null ? packet.token : undefined
})
}, parameters.maxMessageSize)

if (this._sock instanceof Socket) {
this._sock.send(message, 0, message.length, rsinfo.port)
Expand All @@ -222,7 +224,7 @@ class CoAPServer extends EventEmitter {
const url = new URL(proxyUri)
const host = url.hostname
const port = parseInt(url.port)
const message = generate(removeProxyOptions(packet))
const message = generate(removeProxyOptions(packet), parameters.maxMessageSize)

if (this._sock instanceof Socket) {
this._sock.send(message, port, host, callback)
Expand All @@ -232,7 +234,7 @@ class CoAPServer extends EventEmitter {
_sendReverseProxied (packet: ParsedPacket, rsinfo: AddressInfo, callback?: (error: Error | null, bytes: number) => void): void {
const host = rsinfo.address
const port = rsinfo.port
const message = generate(packet)
const message = generate(packet, parameters.maxMessageSize)

if (this._sock instanceof Socket) {
this._sock.send(message, port, host, callback)
Expand Down Expand Up @@ -450,7 +452,7 @@ class CoAPServer extends EventEmitter {
const sender = new RetrySend(sock, rsinfo.port, rsinfo.address)

try {
buf = generate(packet)
buf = generate(packet, parameters.maxMessageSize)
} catch (err) {
response.emit('error', err)
return
Expand Down Expand Up @@ -630,13 +632,17 @@ class CoAPServer extends EventEmitter {
}
}

// maxBlock2 is in formular 2**(i+4), and must <= 2**(6+4)
let maxBlock2 = Math.pow(
2,
Math.floor(Math.log(parameters.maxPacketSize) / Math.log(2))
)
if (maxBlock2 > Math.pow(2, 6 + 4)) {
maxBlock2 = Math.pow(2, 6 + 4)
// Max block size defined in the protocol is 2^(6+4) = 1024
let maxBlock2 = 1024

// Some network stacks (e.g. 6LowPAN/Thread) might have a lower IP MTU.
// In those cases the maxPayloadSize parameter can be adjusted
if (parameters.maxPayloadSize < 1024) {
// CoAP Block2 header only has sizes of 2^(i+4) for i in 0 to 6 inclusive,
// so pick the next size down that is supported
let exponent = Math.log2(parameters.maxPayloadSize)
exponent = Math.floor(exponent)
maxBlock2 = Math.pow(2, exponent)
}

/*
Expand Down Expand Up @@ -675,7 +681,7 @@ class OutMessage extends OutgoingMessage {
// if payload is suitable for ONE message, shoot it out
if (
payload == null ||
(requestedBlockOption == null && payload.length < parameters.maxPacketSize)
(requestedBlockOption == null && payload.length < maxBlock2)
) {
return super.end(payload)
}
Expand Down
6 changes: 4 additions & 2 deletions models/models.ts
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Original file line number Diff line number Diff line change
Expand Up @@ -53,7 +53,8 @@ export interface ParametersUpdate {
probingRate?: number
maxLatency?: number
piggybackReplyMs?: number
maxPacketSize?: number
maxPayloadSize?: number
maxMessageSize?: number
sendAcksForNonConfirmablePackets?: boolean
pruneTimerPeriod?: number
}
Expand All @@ -69,7 +70,8 @@ export interface Parameters {
piggybackReplyMs: number
nonLifetime: number
coapPort: number
maxPacketSize: number
maxPayloadSize: number
maxMessageSize: number
sendAcksForNonConfirmablePackets: boolean
pruneTimerPeriod: number
maxTransmitSpan: number
Expand Down
11 changes: 9 additions & 2 deletions test/blockwise.ts
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Original file line number Diff line number Diff line change
Expand Up @@ -59,12 +59,13 @@ describe('blockwise2', function () {
}

it('should server not use blockwise in response when payload fit in one packet', function (done) {
const payload = Buffer.alloc(100) // default max packet is 1280
const payload = Buffer.alloc(100) // default max payload is 1024

request({
port
})
.on('response', (res) => {
expect(res.code).to.eq('2.05')
let blockwiseResponse = false
for (const i in res.options) {
if (res.options[i].name === 'Block2') {
Expand All @@ -82,11 +83,13 @@ describe('blockwise2', function () {
})
})

it('should use blockwise in response when payload bigger than max packet', function (done) {
it('should use blockwise in response when payload bigger than max payload', function (done) {
const payload = Buffer.alloc(1275) // 1275 produces a CoAP message (after headers) > 1280
request({
port
})
.on('response', (res) => {
expect(res.code).to.eq('2.05')
let blockwiseResponse = false
for (const i in res.options) {
if (res.options[i].name === 'Block2') {
Expand All @@ -109,6 +112,7 @@ describe('blockwise2', function () {
port
})
.on('response', (res) => {
expect(res.code).to.eq('2.05')
expect(typeof res.headers.ETag).to.eql('string')
// expect(cache.get(res._packet.token.toString())).to.not.be.undefined
setImmediate(done)
Expand All @@ -125,6 +129,7 @@ describe('blockwise2', function () {
})
.setOption('Block2', Buffer.of(0x02))
.on('response', (res) => {
expect(res.code).to.eq('2.05')
let block2
for (const i in res.options) {
if (res.options[i].name === 'Block2') {
Expand Down Expand Up @@ -184,6 +189,7 @@ describe('blockwise2', function () {
})
.setOption('Block2', Buffer.of(0x10)) // request from block 1, with size = 16
.on('response', (res) => {
expect(res.code).to.eq('2.05')
expect(res.payload).to.eql(payload.slice(1 * 16, payload.length + 1))
// expect(cache.get(res._packet.token.toString())).to.not.be.undefined
setImmediate(done)
Expand All @@ -201,6 +207,7 @@ describe('blockwise2', function () {
})
.setOption('Block2', Buffer.of(0x0)) // early negotation with block size = 16, almost 10000/16 = 63 blocks
.on('response', (res) => {
expect(res.code).to.eq('2.05')
expect(res.payload).to.eql(payload)
// expect(cache.get(res._packet.token.toString())).to.not.be.undefined
setImmediate(done)
Expand Down
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