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Code Issues Releases Wiki Activity

Fixed bug on ICMP checksum calculation when using timestamp request/replies.

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This commit is contained in:
Matias Fontanini
2013-12-14 13:42:12 -03:00
parent 1cec0f106d
commit 81a947e3b3
2 changed files with 23 additions and 5 deletions
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13
src/icmp.cpp
View File

@@ -57,10 +57,14 @@ ICMP::ICMP(const uint8_t *buffer, uint32_t total_sz)
buffer += sizeof(icmphdr);
total_sz -= sizeof(icmphdr);
if(type() == TIMESTAMP_REQUEST || type() == TIMESTAMP_REPLY) {
if(total_sz < sizeof(uint32_t) * 3)
throw malformed_packet();
const uint32_t *ptr = reinterpret_cast<const uint32_t*>(buffer);
original_timestamp(*ptr++);
receive_timestamp(*ptr++);
transmit_timestamp(*ptr++);
total_sz -= sizeof(uint32_t) * 3;
buffer += sizeof(uint32_t) * 3;
}
if(total_sz)
inner_pdu(new RawPDU(buffer, total_sz));
@@ -183,17 +187,16 @@ void ICMP::write_serialization(uint8_t *buffer, uint32_t total_sz, const PDU *)
*ptr++ = receive_timestamp();
*ptr++ = transmit_timestamp();
}
// checksum calc
_icmp.check = 0;
uint32_t checksum = Utils::do_checksum(buffer + ICMP::header_size(), buffer + total_sz) +
Utils::do_checksum((uint8_t*)&_icmp, ((uint8_t*)&_icmp) + ICMP::header_size());
memcpy(buffer, &_icmp, sizeof(icmphdr));
uint32_t checksum = Utils::do_checksum(buffer, buffer + total_sz);
while (checksum >> 16)
checksum = (checksum & 0xffff) + (checksum >> 16);
_icmp.check = Endian::host_to_be<uint16_t>(~checksum);
memcpy(buffer, &_icmp, sizeof(icmphdr));
((icmphdr*)buffer)->check = _icmp.check;
}
bool ICMP::matches_response(const uint8_t *ptr, uint32_t total_sz) const {

15
tests/src/icmp.cpp
View File

@@ -3,6 +3,8 @@
#include <string>
#include <stdint.h>
#include "icmp.h"
#include "ip.h"
#include "ethernetII.h"
#include "utils.h"
using namespace std;
@@ -67,6 +69,19 @@ TEST_F(ICMPTest, FlagConstructor) {
EXPECT_EQ(icmp.type(), ICMP::ECHO_REPLY);
}
TEST_F(ICMPTest, ChecksumOnTimestamp) {
const uint8_t raw_pkt[] = {
0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 8, 0, 69, 0, 0, 45, 0, 1, 0,
0, 128, 1, 185, 25, 192, 168, 0, 100, 192, 168, 0, 1, 13, 0, 237,
141, 0, 0, 0, 0, 159, 134, 1, 0, 151, 134, 1, 0, 152, 134, 1, 0,
98, 111, 105, 110, 103, 0
};
EthernetII pkt(raw_pkt, sizeof(raw_pkt));
pkt.serialize();
EXPECT_EQ(0xb919, pkt.rfind_pdu<IP>().checksum());
EXPECT_EQ(0xed8d, pkt.rfind_pdu<ICMP>().check());
}
TEST_F(ICMPTest, Code) {
ICMP icmp;
icmp.code(0x7a);