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Code Issues Releases Wiki Activity

Add ICMP extensions to ICMP PDU

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This commit is contained in:
Matias Fontanini
2015-12-14 21:18:42 -08:00
parent 6e026fcb66
commit fb43cb738b
3 changed files with 86 additions and 9 deletions
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33
include/tins/icmp.h
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@@ -46,6 +46,7 @@
#include "pdu.h"
#include "endianness.h"
#include "ip_address.h"
#include "icmp_extension.h"
namespace Tins {
@@ -297,12 +298,19 @@ namespace Tins {
return address_type(Endian::be_to_host(_icmp.un.gateway));
}
/**
* \brief Getter for the pointer field.
*
* \return Returns the pointer field value.
*/
uint8_t pointer() const { return this->_icmp.un.pointer; }
/**
* \brief Getter for the pointer field.
*
* \return Returns the pointer field value.
*/
uint8_t pointer() const { return this->_icmp.un.rfc4884.pointer; }
/**
* \brief Getter for the length field.
*
* \return Returns the length field value.
*/
uint8_t length() const { return this->_icmp.un.rfc4884.length; }
/**
* \brief Getter for the mtu field.
@@ -358,6 +366,8 @@ namespace Tins {
*/
bool matches_response(const uint8_t *ptr, uint32_t total_sz) const;
const ICMPExtensionsStructure& extensions() { return extensions_; }
/**
* \brief Getter for the PDU's type.
*
@@ -372,6 +382,8 @@ namespace Tins {
return new ICMP(*this);
}
private:
static const uint32_t EXTENSION_PAYLOAD_LIMIT;
TINS_BEGIN_PACK
struct icmphdr {
uint8_t type;
@@ -387,7 +399,11 @@ namespace Tins {
uint16_t unused;
uint16_t mtu;
} frag;
uint8_t pointer;
struct {
uint8_t pointer;
uint8_t length;
uint16_t unused;
} rfc4884;
} un;
} TINS_END_PACK;
@@ -400,8 +416,11 @@ namespace Tins {
*/
void write_serialization(uint8_t *buffer, uint32_t total_sz, const PDU *parent);
void try_parse_extensions(const uint8_t* buffer, uint32_t& total_sz);
icmphdr _icmp;
uint32_t _orig_timestamp_or_address_mask, _recv_timestamp, _trans_timestamp;
ICMPExtensionsStructure extensions_;
};
}

42
src/icmp.cpp
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@@ -41,6 +41,9 @@
#include "icmp.h"
namespace Tins {
const uint32_t ICMP::EXTENSION_PAYLOAD_LIMIT = 128;
ICMP::ICMP(Flags flag)
: _orig_timestamp_or_address_mask(), _recv_timestamp(), _trans_timestamp()
{
@@ -76,8 +79,11 @@ ICMP::ICMP(const uint8_t *buffer, uint32_t total_sz)
total_sz -= sizeof(uint32_t);
buffer += sizeof(uint32_t);
}
if(total_sz)
// Attempt to parse ICMP extensions
try_parse_extensions(buffer, total_sz);
if (total_sz) {
inner_pdu(new RawPDU(buffer, total_sz));
}
}
void ICMP::code(uint8_t new_code) {
@@ -109,7 +115,7 @@ void ICMP::mtu(uint16_t new_mtu) {
}
void ICMP::pointer(uint8_t new_pointer) {
_icmp.un.pointer = new_pointer;
_icmp.un.rfc4884.pointer = new_pointer;
}
void ICMP::original_timestamp(uint32_t new_timestamp) {
@@ -222,6 +228,38 @@ void ICMP::write_serialization(uint8_t *buffer, uint32_t total_sz, const PDU *)
memcpy(buffer + 2, &_icmp.check, sizeof(uint16_t));
}
void ICMP::try_parse_extensions(const uint8_t* buffer, uint32_t& total_sz) {
if (total_sz == 0) {
return;
}
// Check if this is one of the types defined in RFC 4884
if (type() == DEST_UNREACHABLE || type() == TIME_EXCEEDED || type() == PARAM_PROBLEM) {
uint32_t actual_length = length() * sizeof(uint32_t);
// Check if we actually have this amount of data and whether it's more than
// the minimum encapsulated packet size
const uint8_t* extensions_ptr;
uint32_t extensions_size;
if (actual_length < total_sz && actual_length >= EXTENSION_PAYLOAD_LIMIT) {
extensions_ptr = buffer + actual_length;
extensions_size = total_sz - actual_length;
}
else if (total_sz > EXTENSION_PAYLOAD_LIMIT) {
// This packet might be non-rfc compliant. In that case the length
// field can contain garbage.
extensions_ptr = buffer + EXTENSION_PAYLOAD_LIMIT;
extensions_size = total_sz - EXTENSION_PAYLOAD_LIMIT;
}
else {
// No more special cases, this doesn't have extensions
return;
}
if (ICMPExtensionsStructure::validate_extensions(extensions_ptr, extensions_size)) {
extensions_ = ICMPExtensionsStructure(extensions_ptr, extensions_size);
total_sz -= extensions_size;
}
}
}
bool ICMP::matches_response(const uint8_t *ptr, uint32_t total_sz) const {
if(total_sz < sizeof(icmphdr))
return false;

20
tests/src/icmp.cpp
View File

@@ -6,6 +6,7 @@
#include "ip.h"
#include "ethernetII.h"
#include "utils.h"
#include "rawpdu.h"
using namespace std;
using namespace Tins;
@@ -286,3 +287,22 @@ TEST_F(ICMPTest, ConstructorFromBuffer) {
test_equals(icmp1, icmp2);
}
}
TEST_F(ICMPTest, ExtensionsParsingWithoutALengthField) {
const uint8_t packet[] = { 11, 0, 205, 4, 0, 0, 0, 0, 69, 0, 0, 40, 165, 76, 0, 0, 1, 17, 247, 111, 12, 4, 4, 4, 12, 1, 1, 1, 165, 75, 130, 155, 0, 20, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 32, 0, 197, 95, 0, 8, 1, 1, 24, 150, 1, 1 };
const uint8_t encapsulated[] = { 69, 0, 0, 40, 165, 76, 0, 0, 1, 17, 247, 111, 12, 4, 4, 4, 12, 1, 1, 1, 165, 75, 130, 155, 0, 20, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0 };
const uint8_t ext[] = { 0, 8, 1, 1, 24, 150, 1, 1 };
ICMP icmp(packet, sizeof(packet));
ICMPExtensionsStructure extensions = icmp.extensions();
ASSERT_EQ(1, extensions.extensions().size());
EXPECT_EQ(
ICMPExtension::payload_type(ext, ext + sizeof(ext)),
extensions.extensions().begin()->serialize()
);
const RawPDU* raw = icmp.find_pdu<RawPDU>();
ASSERT_TRUE(raw != 0);
EXPECT_EQ(
RawPDU::payload_type(encapsulated, encapsulated + sizeof(encapsulated)),
raw->payload()
);
}