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Code Issues Releases Wiki Activity

Fix overall checksum calculation

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This commit is contained in:
Matias Fontanini
2015-12-29 09:57:42 -03:00
parent afe778d03c
commit 67d31fd62c
7 changed files with 148 additions and 72 deletions
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78
src/udp.cpp
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@@ -74,6 +74,43 @@ uint32_t UDP::header_size() const {
return sizeof(udphdr);
}
uint32_t sum_range(const uint8_t *start, const uint8_t *end) {
uint32_t checksum(0);
const uint8_t *last = end;
uint16_t buffer = 0;
uint16_t padding = 0;
const uint8_t *ptr = start;
if(((end - start) & 1) == 1) {
last = end - 1;
padding = Endian::host_to_le<uint16_t>(*(end - 1));
}
while(ptr < last) {
memcpy(&buffer, ptr, sizeof(uint16_t));
checksum += buffer;
ptr += sizeof(uint16_t);
}
checksum += padding;
return checksum;
}
uint32_t pseudoheader_checksum(IPv4Address source_ip, IPv4Address dest_ip, uint32_t len, uint32_t flag) {
uint32_t checksum(0);
uint8_t buffer[sizeof(uint32_t) * 3];
OutputMemoryStream stream(buffer, sizeof(buffer));
stream.write(source_ip);
stream.write(dest_ip);
stream.write(Endian::host_to_be<uint16_t>(flag));
stream.write(Endian::host_to_be<uint16_t>(len));
uint16_t *ptr = (uint16_t*)buffer, *end = (uint16_t*)(buffer + sizeof(buffer));
while (ptr < end) {
checksum += *ptr++;
}
return checksum;
}
void UDP::write_serialization(uint8_t *buffer, uint32_t total_sz, const PDU *parent) {
OutputMemoryStream stream(buffer, total_sz);
// Set checksum to 0, we'll calculate it at the end
@@ -85,36 +122,31 @@ void UDP::write_serialization(uint8_t *buffer, uint32_t total_sz, const PDU *par
length(static_cast<uint16_t>(sizeof(udphdr)));
}
stream.write(_udp);
const Tins::IP *ip_packet = tins_cast<const Tins::IP*>(parent);
if(ip_packet) {
uint32_t checksum = Utils::pseudoheader_checksum(
uint32_t checksum = 0;
if (const Tins::IP *ip_packet = tins_cast<const Tins::IP*>(parent)) {
checksum = Utils::pseudoheader_checksum(
ip_packet->src_addr(),
ip_packet->dst_addr(),
size(),
Constants::IP::PROTO_UDP
) + Utils::do_checksum(buffer, buffer + total_sz);
while (checksum >> 16) {
checksum = (checksum & 0xffff)+(checksum >> 16);
}
_udp.check = Endian::host_to_be<uint16_t>(~checksum);
((udphdr*)buffer)->check = _udp.check;
) + Utils::sum_range(buffer, buffer + total_sz);
}
else if (const Tins::IPv6 *ip6_packet = tins_cast<const Tins::IPv6*>(parent)) {
checksum = Utils::pseudoheader_checksum(
ip6_packet->src_addr(),
ip6_packet->dst_addr(),
size(),
Constants::IP::PROTO_UDP
) + Utils::sum_range(buffer, buffer + total_sz);
}
else {
const Tins::IPv6 *ip6_packet = tins_cast<const Tins::IPv6*>(parent);
if(ip6_packet) {
uint32_t checksum = Utils::pseudoheader_checksum(
ip6_packet->src_addr(),
ip6_packet->dst_addr(),
size(),
Constants::IP::PROTO_UDP
) + Utils::do_checksum(buffer, buffer + total_sz);
while (checksum >> 16) {
checksum = (checksum & 0xffff)+(checksum >> 16);
}
_udp.check = Endian::host_to_be<uint16_t>(~checksum);
((udphdr*)buffer)->check = _udp.check;
}
return;
}
while (checksum >> 16) {
checksum = (checksum & 0xffff)+(checksum >> 16);
}
_udp.check = ~checksum;
((udphdr*)buffer)->check = _udp.check;
}
bool UDP::matches_response(const uint8_t *ptr, uint32_t total_sz) const {