/**
* Parses the work buffer to extract packets
*
* The work buffer should be filled in with a set of tuples (bh_hdrlen, frame, pad).
* The pad extends each packet out to BPF_WORDALIGN.
*
* If the CCNxMessage PacketLength says it is larger than the read capture length (caplen),
* then this is an invalid packet and it will be discarded. This error will result in a
* ReadWorkBufferResult_TryAgain condition.
*
* struct bpf_hdr {
* struct BPF_TIMEVAL bh_tstamp; // time stamp
* bpf_u_int32 bh_caplen; // length of captured portion
* bpf_u_int32 bh_datalen; // original length of packet
* u_short bh_hdrlen; // length of bpf header (this struct plus alignment padding)
* }
*
* @param [in] ether An allocated Darwin ethernet.
* @param [in] readbuffer A user-provided read buffer.
*
* @retval ReadWorkBufferResult_Ok A frame was moved from workbuffer to readbuffer
* @retval ReadWorkBufferResult_Empty There's not enough bytes in the workbuffer
* @retval ReadWorkBufferResult_TryAgain (likely discard) caused this call to fail, but you should try again
*
* Example:
* @code
* <#example#>
* @endcode
*/
static _ReadWorkBufferResult
_darwinEthernet_ReadWorkBuffer(MetisGenericEther *ether, PARCEventBuffer *readbuffer)
{
_ReadWorkBufferResult result = ReadWorkBufferResult_Empty;
// Make sure we have linear memory for the BPF header
struct bpf_hdr *bpfHeader = (struct bpf_hdr *) parcEventBuffer_Pullup(ether->workBuffer, sizeof(struct bpf_hdr));
// make sure we have enough bytes to process the frame
// bpfHeader may be NULL if there are not sizeof(struct bpf_hdr) bytes available.
if (bpfHeader && parcEventBuffer_GetLength(ether->workBuffer) >= bpfHeader->bh_hdrlen + bpfHeader->bh_caplen) {
// (0) Save the needed fields from the bpf header
// (1) pop off the bpf header
// (2) move the iovec from work buffer to readBuffer.
// (3) remove any BPF_WORDALIGN padding to the start of the next packet
// (0) Save the needed fields from the bpf header
uint16_t hdrlen = bpfHeader->bh_hdrlen;
uint32_t caplen = bpfHeader->bh_caplen;
// (1) pop off the bpf header
parcEventBuffer_Read(ether->workBuffer, NULL, hdrlen);
// (1a) Determine the packet length from the fixed header and only transfer that many bytes
uint16_t packetlen = _getFrameLengthFromWorkBuffer(ether);
if (packetlen <= caplen) {
// (2) move the iovec from work buffer to readBuffer.
parcEventBuffer_ReadIntoBuffer(ether->workBuffer, readbuffer, packetlen);
// (2a) drain off any trailer (i.e. FCS)
parcEventBuffer_Read(ether->workBuffer, NULL, caplen - packetlen);
result = ReadWorkBufferResult_Ok;
} else {
if (metisLogger_IsLoggable(ether->logger, MetisLoggerFacility_IO, PARCLogLevel_Warning)) {
metisLogger_Log(ether->logger, MetisLoggerFacility_IO, PARCLogLevel_Warning, __func__,
"%s reading fd %d discard packetlen %u greater than caplen %u",
__func__, ether->etherSocket, packetlen, caplen);
}
// discard all of caplen
parcEventBuffer_Read(ether->workBuffer, NULL, caplen);
// tell the caller that this read failed, but they could try again.
result = ReadWorkBufferResult_TryAgain;
}
// (3) remove any BPF_WORDALIGN padding to the start of the next packet
size_t alignedLength = BPF_WORDALIGN(hdrlen + caplen);
size_t pad = alignedLength - hdrlen - caplen;
parcEventBuffer_Read(ether->workBuffer, NULL, pad);
}
return result;
}
static void
_resetParser(MetisHopByHopFragmenter *fragmenter)
{
// throw away the re-assembly buffer and reset state to Idle
parcEventBuffer_Read(fragmenter->currentReceiveBuffer, NULL, UINT32_MAX);
fragmenter->parserState = _ParserState_Idle;
}
TransportMessage *
rtaComponent_GetMessage(PARCEventQueue *queue)
{
PARCEventBuffer *in = parcEventBuffer_GetQueueBufferInput(queue);
while (parcEventBuffer_GetLength(in) >= sizeof(TransportMessage *)) {
ssize_t len;
TransportMessage *tm;
RtaConnection *conn;
len = parcEventBuffer_Read(in, (void *)&tm, sizeof(&tm));
assertTrue(len == sizeof(TransportMessage *),
"parcEventBuffer_Read returned error");
// Is the transport message for an open connection?
conn = rtaConnection_GetFromTransport(tm);
assertNotNull(conn, "%s GetInfo returnd null connection\n", __func__);
if (DEBUG_OUTPUT) {
printf("%s queue %-12s tm %p\n",
__func__,
rtaProtocolStack_GetQueueName(rtaConnection_GetStack(conn), queue),
(void *) tm);
}
(void) rtaConnection_DecrementMessagesInQueue(conn);
if (rtaConnection_GetState(conn) != CONN_CLOSED) {
parcEventBuffer_Destroy(&in);
return tm;
}
// it's a closed connection
if (DEBUG_OUTPUT) {
printf("%s clearing connection %p reference in transport\n",
__func__, (void *) conn);
}
// should increment a drop counter (case 908)
transportMessage_Destroy(&tm);
}
parcEventBuffer_Destroy(&in);
return NULL;
}
