diff options
Diffstat (limited to 'lib/pure/asyncnet.nim')
| -rw-r--r-- | lib/pure/asyncnet.nim | 51 |
1 files changed, 43 insertions, 8 deletions
diff --git a/lib/pure/asyncnet.nim b/lib/pure/asyncnet.nim index 334f95baa..3b64c278f 100644 --- a/lib/pure/asyncnet.nim +++ b/lib/pure/asyncnet.nim @@ -159,7 +159,9 @@ when defineSsl: await socket.fd.AsyncFd.send(data, flags) proc appeaseSsl(socket: AsyncSocket, flags: set[SocketFlag], - sslError: cint) {.async.} = + sslError: cint): Future[bool] {.async.} = + ## Returns ``true`` if ``socket`` is still connected, otherwise ``false``. + result = true case sslError of SSL_ERROR_WANT_WRITE: await sendPendingSslData(socket, flags) @@ -173,6 +175,7 @@ when defineSsl: elif length == 0: # connection not properly closed by remote side or connection dropped SSL_set_shutdown(socket.sslHandle, SSL_RECEIVED_SHUTDOWN) + result = false else: raiseSSLError("Cannot appease SSL.") @@ -180,13 +183,27 @@ when defineSsl: op: expr) = var opResult {.inject.} = -1.cint while opResult < 0: + # Call the desired operation. opResult = op # Bit hackish here. # TODO: Introduce an async template transformation pragma? + + # Send any remaining pending SSL data. yield sendPendingSslData(socket, flags) + + # If the operation failed, try to see if SSL has some data to read + # or write. if opResult < 0: let err = getSslError(socket.sslHandle, opResult.cint) - yield appeaseSsl(socket, flags, err.cint) + let fut = appeaseSsl(socket, flags, err.cint) + yield fut + if not fut.read(): + # Socket disconnected. + if SocketFlag.SafeDisconn in flags: + break + else: + raiseSSLError("Socket has been disconnected") + proc connect*(socket: AsyncSocket, address: string, port: Port) {.async.} = ## Connects ``socket`` to server at ``address:port``. @@ -388,7 +405,7 @@ proc accept*(socket: AsyncSocket, return retFut proc recvLineInto*(socket: AsyncSocket, resString: FutureVar[string], - flags = {SocketFlag.SafeDisconn}) {.async.} = + flags = {SocketFlag.SafeDisconn}, maxLength = MaxLineLength) {.async.} = ## Reads a line of data from ``socket`` into ``resString``. ## ## If a full line is read ``\r\L`` is not @@ -401,13 +418,14 @@ proc recvLineInto*(socket: AsyncSocket, resString: FutureVar[string], ## is read) then line will be set to ``""``. ## The partial line **will be lost**. ## + ## The ``maxLength`` parameter determines the maximum amount of characters + ## that can be read before a ``ValueError`` is raised. This prevents Denial + ## of Service (DOS) attacks. + ## ## **Warning**: The ``Peek`` flag is not yet implemented. ## ## **Warning**: ``recvLineInto`` on unbuffered sockets assumes that the ## protocol uses ``\r\L`` to delimit a new line. - ## - ## **Warning**: ``recvLineInto`` currently uses a raw pointer to a string for - ## performance reasons. This will likely change soon to use FutureVars. assert SocketFlag.Peek notin flags ## TODO: assert(not resString.mget.isNil(), "String inside resString future needs to be initialised") @@ -454,6 +472,12 @@ proc recvLineInto*(socket: AsyncSocket, resString: FutureVar[string], else: resString.mget.add socket.buffer[socket.currPos] socket.currPos.inc() + + # Verify that this isn't a DOS attack: #3847. + if resString.mget.len > maxLength: + let msg = "recvLine received more than the specified `maxLength` " & + "allowed." + raise newException(ValueError, msg) else: var c = "" while true: @@ -475,10 +499,17 @@ proc recvLineInto*(socket: AsyncSocket, resString: FutureVar[string], resString.complete() return resString.mget.add c + + # Verify that this isn't a DOS attack: #3847. + if resString.mget.len > maxLength: + let msg = "recvLine received more than the specified `maxLength` " & + "allowed." + raise newException(ValueError, msg) resString.complete() proc recvLine*(socket: AsyncSocket, - flags = {SocketFlag.SafeDisconn}): Future[string] {.async.} = + flags = {SocketFlag.SafeDisconn}, + maxLength = MaxLineLength): Future[string] {.async.} = ## Reads a line of data from ``socket``. Returned future will complete once ## a full line is read or an error occurs. ## @@ -492,6 +523,10 @@ proc recvLine*(socket: AsyncSocket, ## is read) then line will be set to ``""``. ## The partial line **will be lost**. ## + ## The ``maxLength`` parameter determines the maximum amount of characters + ## that can be read before a ``ValueError`` is raised. This prevents Denial + ## of Service (DOS) attacks. + ## ## **Warning**: The ``Peek`` flag is not yet implemented. ## ## **Warning**: ``recvLine`` on unbuffered sockets assumes that the protocol @@ -501,7 +536,7 @@ proc recvLine*(socket: AsyncSocket, # TODO: Optimise this var resString = newFutureVar[string]("asyncnet.recvLine") resString.mget() = "" - await socket.recvLineInto(resString, flags) + await socket.recvLineInto(resString, flags, maxLength) result = resString.mget() proc listen*(socket: AsyncSocket, backlog = SOMAXCONN) {.tags: [ReadIOEffect].} = |