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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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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;