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authormickeyl <mickeyl>2003-04-16 17:54:46 (UTC)
committer mickeyl <mickeyl>2003-04-16 17:54:46 (UTC)
commitfc4eab06caed9892ded036fc0dcacaf8074f00f9 (patch) (side-by-side diff)
tree663a812e2e1af9c2bbc5a1c84fb89fcf72eb4376 /libopie2
parentbe5832dc22255be38884e352917f48d5b71ae657 (diff)
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start documenting the packet class family - explain why deriving from QObject is clever
Diffstat (limited to 'libopie2') (more/less context) (ignore whitespace changes)
-rw-r--r--libopie2/opienet/opcap.h67
1 files changed, 50 insertions, 17 deletions
diff --git a/libopie2/opienet/opcap.h b/libopie2/opienet/opcap.h
index 6bf7416..fe88e68 100644
--- a/libopie2/opienet/opcap.h
+++ b/libopie2/opienet/opcap.h
@@ -68,7 +68,49 @@ class QSocketNotifier;
/*======================================================================================
* OPacket - A frame on the wire
*======================================================================================*/
-// FIXME how many OPackets do we've at a time? QObject seams to be a big for that usage
+
+/** @brief A class representing a data frame on the wire.
+ *
+ * The whole family of the packet classes are used when capturing frames from a network.
+ * Most standard network protocols in use share a common architecture, which mostly is
+ * a packet header and then the packet payload. In layered architectures, each lower layer
+ * encapsulates data from its upper layer - that is it
+ * treats the data from its upper layer as payload and prepends an own header to the packet,
+ * which - again - is treated as the payload for the layer below. The figure below is an
+ * example for how such a data frame is composed out of packets, e.g. when sending a mail.
+ *
+ * <pre>
+ * | User Data | == Mail Data
+ * | SMTP Header | User Data | == SMTP
+ * | TCP Header | SMTP Header | User Data | == TCP
+ * | IP Header | TCP Header | SMTP Header | User Data | == IP
+ * | MAC Header | IP Header | TCP Header | SMTP Header | User Data | == MAC
+ *
+ * </pre>
+ *
+ * The example is trimmed for simplicity, because the MAC (Medium Access Control) layer
+ * also contains a few more levels of encapsulation.
+ * Since the type of the payload is more or less independent from the encapsulating protocol,
+ * the header must be inspected before attempting to decode the payload. Hence, the
+ * encapsulation level varies and can't be deduced without actually looking into the packets.
+ *
+ * For actually working with captured frames, it's useful to identify the packets via names and
+ * insert them into a parent/child - relationship based on the encapsulation. This is why
+ * all packet classes derive from QObject. The amount of overhead caused by the QObject is
+ * not a problem in this case, because we're talking about a theoratical maximum of about
+ * 10 packets per captured frame. We need to stuff them into a searchable list anyway and the
+ * QObject also cares about destroying the sub-, (child-) packets.
+ *
+ * This enables us to perform a simple look for packets of a certain type:
+ * @code
+ * OPacketCapturer* pcap = new OPacketCapturer();
+ * pcap->open( "eth0" );
+ * OPacket* p = pcap->next();
+ * OIPPacket* ip = (OIPPacket*) p->child( "IP" ); // returns 0, if no such child exists
+ * odebug << "got ip packet from " << ip->fromIPAddress().toString() << " to " << ip->toIPAddress().toString() << oendl;
+ *
+ */
+
class OPacket : public QObject
{
Q_OBJECT
@@ -95,7 +137,6 @@ class OPacket : public QObject
* OEthernetPacket - DLT_EN10MB frame
*======================================================================================*/
-//FIXME same critic as above -zecke
class OEthernetPacket : public QObject
{
Q_OBJECT
@@ -116,7 +157,7 @@ class OEthernetPacket : public QObject
/*======================================================================================
* OWaveLanPacket - DLT_IEEE802_11 frame
*======================================================================================*/
-//FIXME same
+
class OWaveLanPacket : public QObject
{
Q_OBJECT
@@ -146,7 +187,7 @@ class OWaveLanPacket : public QObject
/*======================================================================================
* OWaveLanManagementPacket - type: management (T_MGMT)
*======================================================================================*/
-//FIXME same as above -zecke
+
class OWaveLanManagementPacket : public QObject
{
Q_OBJECT
@@ -175,7 +216,7 @@ class OWaveLanManagementPacket : public QObject
/*======================================================================================
* OWaveLanManagementSSID
*======================================================================================*/
-//FIXME is QObject necessary? -zecke
+
class OWaveLanManagementSSID : public QObject
{
Q_OBJECT
@@ -193,7 +234,7 @@ class OWaveLanManagementSSID : public QObject
/*======================================================================================
* OWaveLanManagementRates
*======================================================================================*/
-// FIXME same as above -zecke
+
class OWaveLanManagementRates : public QObject
{
Q_OBJECT
@@ -210,7 +251,6 @@ class OWaveLanManagementRates : public QObject
* OWaveLanManagementCF
*======================================================================================*/
-//FIXME same....
class OWaveLanManagementCF : public QObject
{
Q_OBJECT
@@ -227,7 +267,6 @@ class OWaveLanManagementCF : public QObject
* OWaveLanManagementFH
*======================================================================================*/
-//FIXME same
class OWaveLanManagementFH : public QObject
{
Q_OBJECT
@@ -243,7 +282,7 @@ class OWaveLanManagementFH : public QObject
/*======================================================================================
* OWaveLanManagementDS
*======================================================================================*/
-//FIXME same
+
class OWaveLanManagementDS : public QObject
{
Q_OBJECT
@@ -262,7 +301,6 @@ class OWaveLanManagementDS : public QObject
* OWaveLanManagementTim
*======================================================================================*/
-//FIXME guess what?
class OWaveLanManagementTim : public QObject
{
Q_OBJECT
@@ -279,7 +317,6 @@ class OWaveLanManagementTim : public QObject
* OWaveLanManagementIBSS
*======================================================================================*/
-//FIXME same as above ( Qobject )
class OWaveLanManagementIBSS : public QObject
{
Q_OBJECT
@@ -328,7 +365,7 @@ class OWaveLanDataPacket : public QObject
/*======================================================================================
* OWaveLanControlPacket - type: control (T_CTRL)
*======================================================================================*/
-// Qobject needed?
+
class OWaveLanControlPacket : public QObject
{
Q_OBJECT
@@ -345,7 +382,6 @@ class OWaveLanControlPacket : public QObject
* OLLCPacket - IEEE 802.2 Link Level Control
*======================================================================================*/
-// QObject needed?
class OLLCPacket : public QObject
{
Q_OBJECT
@@ -355,7 +391,6 @@ class OLLCPacket : public QObject
virtual ~OLLCPacket();
private:
- //FIXME how to get that header?
const struct ieee_802_11_802_2_header* _header;
};
@@ -363,7 +398,6 @@ class OLLCPacket : public QObject
* OIPPacket
*======================================================================================*/
-// Qobject as baseclass?
class OIPPacket : public QObject
{
Q_OBJECT
@@ -390,7 +424,7 @@ class OIPPacket : public QObject
/*======================================================================================
* OUDPPacket
*======================================================================================*/
-// QObject?
+
class OUDPPacket : public QObject
{
Q_OBJECT
@@ -410,7 +444,6 @@ class OUDPPacket : public QObject
* OTCPPacket
*======================================================================================*/
-// Qobect needed?
class OTCPPacket : public QObject
{
Q_OBJECT