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Code Issues Releases Wiki Activity

Use first IP fragment as base for reassembly

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Fixes #225 for good
This commit is contained in:
Matias Fontanini
2017-12-03 13:50:02 -08:00
parent e16fe46d7a
commit a3dd057147
3 changed files with 20 additions and 16 deletions
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1
include/tins/ip_reassembler.h
View File

@@ -86,7 +86,6 @@ private:
size_t total_size_;
IP first_fragment_;
bool received_end_;
uint8_t transport_proto_;
};
} // namespace Internals

29
src/ip_reassembler.cpp
View File

@@ -38,19 +38,13 @@ namespace Tins {
namespace Internals {
IPv4Stream::IPv4Stream()
: received_size_(), total_size_(), received_end_(false), transport_proto_(0xff) {
: received_size_(), total_size_(), received_end_(false) {
}
void IPv4Stream::add_fragment(IP* ip) {
if (fragments_.empty()) {
// Release the inner PDU, store this first fragment and restore the inner PDU
PDU* inner_pdu = ip->release_inner_pdu();
first_fragment_ = *ip;
ip->inner_pdu(inner_pdu);
}
const uint16_t offset = extract_offset(ip);
fragments_type::iterator it = fragments_.begin();
uint16_t offset = extract_offset(ip);
while (it != fragments_.end() && offset > it->offset()) {
++it;
}
@@ -66,28 +60,37 @@ void IPv4Stream::add_fragment(IP* ip) {
received_end_ = true;
}
if (offset == 0) {
transport_proto_ = ip->protocol();
// Release the inner PDU, store this first fragment and restore the inner PDU
PDU* inner_pdu = ip->release_inner_pdu();
first_fragment_ = *ip;
ip->inner_pdu(inner_pdu);
}
}
bool IPv4Stream::is_complete() const {
return received_end_ && received_size_ == total_size_;
// If we haven't received the last chunk of we haven't received all the data,
// then we're not complete
if (!received_end_ || received_size_ != total_size_) {
return false;
}
// Make sure the first fragment has offset 0
return fragments_.begin()->offset() == 0;
}
PDU* IPv4Stream::allocate_pdu() const {
PDU::serialization_type buffer;
buffer.reserve(total_size_);
// Check if we actually have all the data we need. Otherwise return nullptr;
uint16_t expected = 0;
size_t expected = 0;
for (fragments_type::const_iterator it = fragments_.begin(); it != fragments_.end(); ++it) {
if (expected != it->offset()) {
return 0;
}
expected = static_cast<uint16_t>(it->offset() + it->payload().size());
expected = it->offset() + it->payload().size();
buffer.insert(buffer.end(), it->payload().begin(), it->payload().end());
}
return Internals::pdu_from_flag(
static_cast<Constants::IP::e>(transport_proto_),
static_cast<Constants::IP::e>(first_fragment_.protocol()),
buffer.empty() ? 0 :& buffer[0],
static_cast<uint32_t>(buffer.size())
);

6
tests/src/ip_reassembler_test.cpp
View File

@@ -51,7 +51,9 @@ void IPv4ReassemblerTest::test_packets(const vector<pair<const uint8_t*, size_t>
IPv4Reassembler reassembler;
for(size_t i = 0; i < vt.size(); ++i) {
EthernetII eth(vt[i].first, (uint32_t)vt[i].second);
if (i != 0) {
// Set the TTL for the first fragment to 32 so we can make sure the right "base"
// packet was used to build the reassembled one
if (eth.rfind_pdu<IP>().fragment_offset() == 0) {
eth.rfind_pdu<IP>().ttl(32);
}
IPv4Reassembler::PacketStatus status = reassembler.process(eth);
@@ -60,7 +62,7 @@ void IPv4ReassemblerTest::test_packets(const vector<pair<const uint8_t*, size_t>
ASSERT_EQ(static_cast<size_t>(vt.size() - 1), i);
ASSERT_TRUE(eth.find_pdu<UDP>() != NULL);
const IP& ip = eth.rfind_pdu<IP>();
EXPECT_EQ(64, ip.ttl());
EXPECT_EQ(32, ip.ttl());
RawPDU* raw = eth.find_pdu<RawPDU>();
ASSERT_TRUE(raw != NULL);