void reassemble()

in src/filtration/filtration_processor.h [188:263]
57 lines of code
14 McCabe index (conditional complexity)

        void reassemble(PacketInfo& info)
        {
            uint32_t seq{info.tcp->seq()};
            uint32_t len{info.dlen};

            if(sequence == 0) // this is the first time we have seen this src's sequence number
            {
                sequence = seq + len;
                if(info.tcp->is(tcp_header::SYN))
                {
                    sequence++;
                }

                if(len > 0)
                {
                    reader.push(info); // write out the packet data
                }

                return;
            }

            // if we are here, we have already seen this src, let's
            // try and figure out if this packet is in the right place
            if(LT_SEQ(seq, sequence))
            {
                // this sequence number seems dated, but
                // check the end to make sure it has no more
                // info than we have already seen
                uint32_t newseq{seq + len};
                if(GT_SEQ(newseq, sequence))
                {
                    // this one has more than we have seen. let's get the
                    // payload that we have not seen
                    uint32_t new_len{sequence - seq};

                    if(info.dlen <= new_len)
                    {
                        info.data = nullptr;
                        info.dlen = 0;
                    }
                    else
                    {
                        assert(info.dlen >= new_len);
                        info.data += new_len;
                        info.dlen -= new_len;
                    }

                    seq = sequence;
                    len = newseq - sequence;

                    // this will now appear to be right on time :)
                }
            }

            if(EQ_SEQ(seq, sequence)) // right on time
            {
                sequence += len;
                if(info.tcp->is(tcp_header::SYN)) sequence++;

                if(info.data && info.dlen > 0)
                {
                    reader.push(info);
                }
                // done with the packet, see if it caused a fragment to fit
                while(check_fragments(0))
                    ;
            }
            else // out of order packet
            {
                if(info.dlen > 0 && GT_SEQ(seq, sequence))
                {
                    //TRACE("ADD FRAGMENT seq: %u dlen: %u sequence: %u", seq, info.dlen, sequence);
                    fragments = Packet::create(info, fragments);
                }
            }
        }