X-Git-Url: http://g0dil.de/git?a=blobdiff_plain;f=Packets%2FMainpage.dox;h=889aa5f43f5667697e059ef0a259477637b555da;hb=8f1a688cea76f2e76bfa0193dff9c1538929147e;hp=5bff312639bb653722c405a8dd7c4e7178e6012f;hpb=90b6130cd03023e18bf35a5f38b3df4381e1868b;p=senf.git diff --git a/Packets/Mainpage.dox b/Packets/Mainpage.dox index 5bff312..889aa5f 100644 --- a/Packets/Mainpage.dox +++ b/Packets/Mainpage.dox @@ -1,8 +1,8 @@ // $Id$ // -// Copyright (C) 2007 -// Fraunhofer Institute for Open Communication Systems (FOKUS) -// Competence Center NETwork research (NET), St. Augustin, GERMANY +// Copyright (C) 2007 +// Fraunhofer Institute for Open Communication Systems (FOKUS) +// Competence Center NETwork research (NET), St. Augustin, GERMANY // Stefan Bund // // This program is free software; you can redistribute it and/or modify @@ -105,26 +105,27 @@ eth.next().is(); // true eth.next().next() == udp; // true eth.next().is(); // false - eth.next() == udp; // true + eth.find() == udp; // true - udp.next(); // throws InvalidPacketChainException - udp.next(senf::nothrow); // a senf::Packet testing as false - udp.findNext == udp; // true - udp.first() == ip; // true + udp.find(); // throws InvalidPacketChainException + udp.find(senf::nothrow); // An in-valid() senf::Packet which tests as 'false' + udp.find == udp; // true + udp.first(); // throws InvalidPacketChainException udp.prev() == ip; // true - udp.prev() == eth // true + udp.prev(); // throws Inv \endcode - ... and so on. It is therefore not necessary to stash away a reference for every interpreter (as - each of the sub-packets are called) as long as at least one reference is available. + ... and so on. See the senf::Packet documentation for more. Using these members, the complete + chain of packet interpreters (as these sub-packets or headers are called) may be traversed from + any packet handle. These chain navigation functions are also used to parse a packet. Let's read an Ethernet packet from a packet socket handle: \code senf::PacketSocketHandle sock ("eth0"); - senf::EthernetPacket packet (senf::EthernetPacket::create(senf::Packet::noinit)); + senf::EthernetPacket packet (senf::EthernetPacket::create(senf::noinit)); sock.read(packet.data(),0u); \endcode @@ -133,17 +134,20 @@ \code try { - senf::UDPPacket udp (packet.findNext(senf::nothrow)); - if (udp && udp->destination() == 2001u) { + senf::UDPPacket udp (packet.find()); + if (udp->destination() == 2001u) { // Voila ... } - } catch (senf::TruncatedPacketException const &) { - std::cerr << "Ooops !! Broken packet received ...\n" + } catch (senf::TruncatedPacketException &) { + std::cerr << "Ooops !! Broken packet received\n"; + } catch (senf::InvalidPacketChainException &) { + std::cerr << "Not a udp packet\n"; } \endcode TruncatedPacketException is thrown by udp->destination() if that field cannot be - accessed. More generally, whenever a field cannot be accessed because it would be out of bounds + accessed (that is it would be beyond the data read which means we have read a truncated + packet). More generally, whenever a field cannot be accessed because it would be out of bounds of the data read, this exception is generated. This is only a very short introduction to the library to give a feel for the implementation. For