nim-libp2p/libp2p/protocols/secure/secio.nim

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## Nim-LibP2P
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## Copyright (c) 2019 Status Research & Development GmbH
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## Licensed under either of
## * Apache License, version 2.0, ([LICENSE-APACHE](LICENSE-APACHE))
## * MIT license ([LICENSE-MIT](LICENSE-MIT))
## at your option.
## This file may not be copied, modified, or distributed except according to
## those terms.
import options
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import chronos, chronicles
import nimcrypto/[sysrand, hmac, sha2, sha, hash, rijndael, twofish, bcmode]
import secure,
../../connection,
../../peerinfo,
../../stream/lpstream,
../../crypto/crypto,
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../../crypto/ecnist,
../../protobuf/minprotobuf,
../../peer,
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../../stream/bufferstream
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export hmac, sha2, sha, hash, rijndael, bcmode
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logScope:
topic = "secio"
const
SecioCodec* = "/secio/1.0.0"
SecioMaxMessageSize = 8 * 1024 * 1024 ## 8mb
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SecioMaxMacSize = sha512.sizeDigest
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SecioNonceSize = 16
SecioExchanges = "P-256,P-384,P-521"
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SecioCiphers = "TwofishCTR,AES-256,AES-128"
SecioHashes = "SHA256,SHA512"
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type
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Secio = ref object of Secure
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localPrivateKey: PrivateKey
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localPublicKey: PublicKey
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remotePublicKey: PublicKey
SecureCipherType {.pure.} = enum
Aes128, Aes256, Twofish
SecureMacType {.pure.} = enum
Sha1, Sha256, Sha512
SecureCipher = object
case kind: SecureCipherType
of SecureCipherType.Aes128:
ctxaes128: CTR[aes128]
of SecureCipherType.Aes256:
ctxaes256: CTR[aes256]
of SecureCipherType.Twofish:
ctxtwofish256: CTR[twofish256]
SecureMac = object
case kind: SecureMacType
of SecureMacType.Sha256:
ctxsha256: HMAC[sha256]
of SecureMacType.Sha512:
ctxsha512: HMAC[sha512]
of SecureMacType.Sha1:
ctxsha1: HMAC[sha1]
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SecureConnection = ref object of Connection
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writerMac: SecureMac
readerMac: SecureMac
writerCoder: SecureCipher
readerCoder: SecureCipher
SecioError* = object of CatchableError
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proc init(mac: var SecureMac, hash: string, key: openarray[byte]) =
if hash == "SHA256":
mac = SecureMac(kind: SecureMacType.Sha256)
mac.ctxsha256.init(key)
elif hash == "SHA512":
mac = SecureMac(kind: SecureMacType.Sha512)
mac.ctxsha512.init(key)
elif hash == "SHA1":
mac = SecureMac(kind: SecureMacType.Sha1)
mac.ctxsha1.init(key)
proc update(mac: var SecureMac, data: openarray[byte]) =
case mac.kind
of SecureMacType.Sha256:
update(mac.ctxsha256, data)
of SecureMacType.Sha512:
update(mac.ctxsha512, data)
of SecureMacType.Sha1:
update(mac.ctxsha1, data)
proc sizeDigest(mac: SecureMac): int {.inline.} =
case mac.kind
of SecureMacType.Sha256:
result = int(mac.ctxsha256.sizeDigest())
of SecureMacType.Sha512:
result = int(mac.ctxsha512.sizeDigest())
of SecureMacType.Sha1:
result = int(mac.ctxsha1.sizeDigest())
proc finish(mac: var SecureMac, data: var openarray[byte]) =
case mac.kind
of SecureMacType.Sha256:
discard finish(mac.ctxsha256, data)
of SecureMacType.Sha512:
discard finish(mac.ctxsha512, data)
of SecureMacType.Sha1:
discard finish(mac.ctxsha1, data)
proc reset(mac: var SecureMac) =
case mac.kind
of SecureMacType.Sha256:
reset(mac.ctxsha256)
of SecureMacType.Sha512:
reset(mac.ctxsha512)
of SecureMacType.Sha1:
reset(mac.ctxsha1)
proc init(sc: var SecureCipher, cipher: string, key: openarray[byte],
iv: openarray[byte]) {.inline.} =
if cipher == "AES-128":
sc = SecureCipher(kind: SecureCipherType.Aes128)
sc.ctxaes128.init(key, iv)
elif cipher == "AES-256":
sc = SecureCipher(kind: SecureCipherType.Aes256)
sc.ctxaes256.init(key, iv)
elif cipher == "TwofishCTR":
sc = SecureCipher(kind: SecureCipherType.Twofish)
sc.ctxtwofish256.init(key, iv)
proc encrypt(cipher: var SecureCipher, input: openarray[byte],
output: var openarray[byte]) {.inline.} =
case cipher.kind
of SecureCipherType.Aes128:
cipher.ctxaes128.encrypt(input, output)
of SecureCipherType.Aes256:
cipher.ctxaes256.encrypt(input, output)
of SecureCipherType.Twofish:
cipher.ctxtwofish256.encrypt(input, output)
proc decrypt(cipher: var SecureCipher, input: openarray[byte],
output: var openarray[byte]) {.inline.} =
case cipher.kind
of SecureCipherType.Aes128:
cipher.ctxaes128.decrypt(input, output)
of SecureCipherType.Aes256:
cipher.ctxaes256.decrypt(input, output)
of SecureCipherType.Twofish:
cipher.ctxtwofish256.decrypt(input, output)
proc macCheckAndDecode(sconn: SecureConnection, data: var seq[byte]): bool =
## This procedure checks MAC of recieved message ``data`` and if message is
## authenticated, then decrypt message.
##
## Procedure returns ``false`` if message is too short or MAC verification
## failed.
var macData: array[SecioMaxMacSize, byte]
let macsize = sconn.readerMac.sizeDigest()
if len(data) < macsize:
trace "Message is shorter then MAC size", message_length = len(data),
mac_size = macsize
return false
let mark = len(data) - macsize
sconn.readerMac.update(data.toOpenArray(0, mark - 1))
sconn.readerMac.finish(macData)
sconn.readerMac.reset()
if not equalMem(addr data[mark], addr macData[0], macsize):
trace "Invalid MAC",
calculated = toHex(macData.toOpenArray(0, macsize - 1)),
stored = toHex(data.toOpenArray(mark, len(data) - 1))
return false
sconn.readerCoder.decrypt(data.toOpenArray(0, mark - 1),
data.toOpenArray(0, mark - 1))
data.setLen(mark)
result = true
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proc readMessage(sconn: SecureConnection): Future[seq[byte]] {.async.} =
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## Read message from channel secure connection ``sconn``.
try:
var buf = newSeq[byte](4)
await sconn.readExactly(addr buf[0], 4)
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let length = (int(buf[0]) shl 24) or (int(buf[1]) shl 16) or
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(int(buf[2]) shl 8) or (int(buf[3]))
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trace "Recieved message header", header = toHex(buf), length = length
if length <= SecioMaxMessageSize:
buf.setLen(length)
await sconn.readExactly(addr buf[0], length)
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trace "Received message body", length = length,
buffer = toHex(buf)
if sconn.macCheckAndDecode(buf):
result = buf
else:
trace "Message MAC verification failed", buf = toHex(buf)
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else:
trace "Received message header size is more then allowed",
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length = length, allowed_length = SecioMaxMessageSize
except AsyncStreamIncompleteError:
trace "Connection dropped while reading"
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except AsyncStreamReadError:
trace "Error reading from connection"
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proc writeMessage(sconn: SecureConnection, message: seq[byte]) {.async.} =
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## Write message ``message`` to secure connection ``sconn``.
let macsize = sconn.writerMac.sizeDigest()
var msg = newSeq[byte](len(message) + 4 + macsize)
sconn.writerCoder.encrypt(message, msg.toOpenArray(4, 4 + len(message) - 1))
let mo = 4 + len(message)
sconn.writerMac.update(msg.toOpenArray(4, 4 + len(message) - 1))
sconn.writerMac.finish(msg.toOpenArray(mo, mo + macsize - 1))
sconn.writerMac.reset()
let length = len(message) + macsize
msg[0] = byte((length shr 24) and 0xFF)
msg[1] = byte((length shr 16) and 0xFF)
msg[2] = byte((length shr 8) and 0xFF)
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msg[3] = byte(length and 0xFF)
trace "Writing message", message = toHex(msg)
try:
await sconn.write(msg)
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except AsyncStreamWriteError:
trace "Could not write to connection"
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proc newSecureConnection(conn: Connection,
hash: string,
cipher: string,
secrets: Secret,
order: int,
remotePubKey: PublicKey): SecureConnection =
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## Create new secure connection, using specified hash algorithm ``hash``,
## cipher algorithm ``cipher``, stretched keys ``secrets`` and order
## ``order``.
new result
result.stream = conn
result.closeEvent = newAsyncEvent()
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let i0 = if order < 0: 1 else: 0
let i1 = if order < 0: 0 else: 1
trace "Writer credentials", mackey = toHex(secrets.macOpenArray(i0)),
enckey = toHex(secrets.keyOpenArray(i0)),
iv = toHex(secrets.ivOpenArray(i0))
trace "Reader credentials", mackey = toHex(secrets.macOpenArray(i1)),
enckey = toHex(secrets.keyOpenArray(i1)),
iv = toHex(secrets.ivOpenArray(i1))
result.writerMac.init(hash, secrets.macOpenArray(i0))
result.readerMac.init(hash, secrets.macOpenArray(i1))
result.writerCoder.init(cipher, secrets.keyOpenArray(i0),
secrets.ivOpenArray(i0))
result.readerCoder.init(cipher, secrets.keyOpenArray(i1),
secrets.ivOpenArray(i1))
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result.peerInfo = PeerInfo.init(remotePubKey)
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proc transactMessage(conn: Connection,
msg: seq[byte]): Future[seq[byte]] {.async.} =
var buf = newSeq[byte](4)
try:
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trace "Sending message", message = toHex(msg), length = len(msg)
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await conn.write(msg)
await conn.readExactly(addr buf[0], 4)
let length = (int(buf[0]) shl 24) or (int(buf[1]) shl 16) or
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(int(buf[2]) shl 8) or (int(buf[3]))
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trace "Recieved message header", header = toHex(buf), length = length
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if length <= SecioMaxMessageSize:
buf.setLen(length)
await conn.readExactly(addr buf[0], length)
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trace "Received message body", conn = conn,
length = length,
buff = buf
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result = buf
else:
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trace "Received size of message exceed limits", conn = conn,
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length = length
except AsyncStreamIncompleteError:
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trace "Connection dropped while reading", conn = conn
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except AsyncStreamReadError:
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trace "Error reading from connection", conn = conn
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except AsyncStreamWriteError:
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trace "Could not write to connection", conn = conn
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proc handshake(s: Secio, conn: Connection): Future[SecureConnection] {.async.} =
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var
localNonce: array[SecioNonceSize, byte]
remoteNonce: seq[byte]
remoteBytesPubkey: seq[byte]
remoteEBytesPubkey: seq[byte]
remoteEBytesSig: seq[byte]
remotePubkey: PublicKey
remoteEPubkey: PublicKey = PublicKey(scheme: ECDSA)
remoteESignature: Signature
remoteExchanges: string
remoteCiphers: string
remoteHashes: string
remotePeerId: PeerID
localPeerId: PeerID
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localBytesPubkey = s.localPublicKey.getBytes()
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if randomBytes(localNonce) != SecioNonceSize:
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raise newException(CatchableError, "Could not generate random data")
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var request = createProposal(localNonce,
localBytesPubkey,
SecioExchanges,
SecioCiphers,
SecioHashes)
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localPeerId = PeerID.init(s.localPublicKey)
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trace "Local proposal", schemes = SecioExchanges, ciphers = SecioCiphers,
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hashes = SecioHashes,
pubkey = toHex(localBytesPubkey),
peer = localPeerId
var answer = await transactMessage(conn, request)
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if len(answer) == 0:
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trace "Proposal exchange failed", conn = conn
raise newException(SecioError, "Proposal exchange failed")
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if not decodeProposal(answer, remoteNonce, remoteBytesPubkey, remoteExchanges,
remoteCiphers, remoteHashes):
trace "Remote proposal decoding failed", conn = conn
raise newException(SecioError, "Remote proposal decoding failed")
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if not remotePubkey.init(remoteBytesPubkey):
trace "Remote public key incorrect or corrupted", pubkey = remoteBytesPubkey
raise newException(SecioError, "Remote public key incorrect or corrupted")
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remotePeerId = PeerID.init(remotePubkey)
# TODO: PeerID check against supplied PeerID
let order = getOrder(remoteBytesPubkey, localNonce, localBytesPubkey,
remoteNonce)
trace "Remote proposal", schemes = remoteExchanges, ciphers = remoteCiphers,
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hashes = remoteHashes,
pubkey = toHex(remoteBytesPubkey), order = order,
peer = remotePeerId
let scheme = selectBest(order, SecioExchanges, remoteExchanges)
let cipher = selectBest(order, SecioCiphers, remoteCiphers)
let hash = selectBest(order, SecioHashes, remoteHashes)
if len(scheme) == 0 or len(cipher) == 0 or len(hash) == 0:
trace "No algorithms in common", peer = remotePeerId
raise newException(SecioError, "No algorithms in common")
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trace "Encryption scheme selected", scheme = scheme, cipher = cipher,
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hash = hash
var ekeypair = ephemeral(scheme)
# We need EC public key in raw binary form
var epubkey = ekeypair.pubkey.eckey.getRawBytes()
var localCorpus = request[4..^1] & answer & epubkey
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var signature = s.localPrivateKey.sign(localCorpus)
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var localExchange = createExchange(epubkey, signature.getBytes())
var remoteExchange = await transactMessage(conn, localExchange)
if len(remoteExchange) == 0:
trace "Corpus exchange failed", conn = conn
raise newException(SecioError, "Corpus exchange failed")
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if not decodeExchange(remoteExchange, remoteEBytesPubkey, remoteEBytesSig):
trace "Remote exchange decoding failed", conn = conn
raise newException(SecioError, "Remote exchange decoding failed")
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if not remoteESignature.init(remoteEBytesSig):
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trace "Remote signature incorrect or corrupted", signature = toHex(remoteEBytesSig)
raise newException(SecioError, "Remote signature incorrect or corrupted")
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var remoteCorpus = answer & request[4..^1] & remoteEBytesPubkey
if not remoteESignature.verify(remoteCorpus, remotePubkey):
trace "Signature verification failed", scheme = remotePubkey.scheme,
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signature = remoteESignature,
pubkey = remotePubkey,
corpus = remoteCorpus
raise newException(SecioError, "Signature verification failed")
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trace "Signature verified", scheme = remotePubkey.scheme
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if not remoteEPubkey.eckey.initRaw(remoteEBytesPubkey):
trace "Remote ephemeral public key incorrect or corrupted",
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pubkey = toHex(remoteEBytesPubkey)
raise newException(SecioError, "Remote ephemeral public key incorrect or corrupted")
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var secret = getSecret(remoteEPubkey, ekeypair.seckey)
if len(secret) == 0:
trace "Shared secret could not be created",
pubkeyScheme = remoteEPubkey.scheme,
seckeyScheme = ekeypair.seckey.scheme
raise newException(SecioError, "Shared secret could not be created")
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trace "Shared secret calculated", secret = toHex(secret)
var keys = stretchKeys(cipher, hash, secret)
trace "Authenticated encryption parameters",
iv0 = toHex(keys.ivOpenArray(0)), key0 = toHex(keys.keyOpenArray(0)),
mac0 = toHex(keys.macOpenArray(0)),
iv1 = toHex(keys.ivOpenArray(1)), key1 = toHex(keys.keyOpenArray(1)),
mac1 = toHex(keys.macOpenArray(1))
# Perform Nonce exchange over encrypted channel.
result = newSecureConnection(conn, hash, cipher, keys, order, remotePubkey)
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await result.writeMessage(remoteNonce)
var res = await result.readMessage()
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if res != @localNonce:
trace "Nonce verification failed", receivedNonce = toHex(res),
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localNonce = toHex(localNonce)
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raise newException(CatchableError, "Nonce verification failed")
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else:
trace "Secure handshake succeeded"
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proc readLoop(sconn: SecureConnection, stream: BufferStream) {.async.} =
try:
while not sconn.closed:
let msg = await sconn.readMessage()
if msg.len == 0:
trace "stream EOF"
return
await stream.pushTo(msg)
except CatchableError as exc:
trace "exception occured", exc = exc.msg
finally:
if not sconn.closed:
await sconn.close()
trace "ending secio readLoop", isclosed = sconn.closed()
proc handleConn(s: Secio, conn: Connection): Future[Connection] {.async, gcsafe.} =
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var sconn = await s.handshake(conn)
proc writeHandler(data: seq[byte]) {.async, gcsafe.} =
trace "sending encrypted bytes", bytes = data.toHex()
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await sconn.writeMessage(data)
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var stream = newBufferStream(writeHandler)
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asyncCheck readLoop(sconn, stream)
result = newConnection(stream)
result.closeEvent.wait()
.addCallback do (udata: pointer):
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trace "wrapped connection closed, closing upstream"
if not isNil(sconn) and not sconn.closed:
asyncCheck sconn.close()
result.peerInfo = PeerInfo.init(sconn.peerInfo.publicKey.get())
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method init(s: Secio) {.gcsafe.} =
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proc handle(conn: Connection, proto: string) {.async, gcsafe.} =
trace "handling connection"
try:
discard await s.handleConn(conn)
trace "connection secured"
except CatchableError as exc:
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if not conn.closed():
warn "securing connection failed", msg = exc.msg
await conn.close()
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s.codec = SecioCodec
s.handler = handle
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method secure*(s: Secio, conn: Connection): Future[Connection] {.async, gcsafe.} =
try:
result = await s.handleConn(conn)
except CatchableError as exc:
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warn "securing connection failed", msg = exc.msg
if not conn.closed():
await conn.close()
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proc newSecio*(localPrivateKey: PrivateKey): Secio =
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new result
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result.localPrivateKey = localPrivateKey
result.localPublicKey = localPrivateKey.getKey()
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result.init()