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#ifndef PACKETPP_DNS_LAYER
#define PACKETPP_DNS_LAYER
#include "DnsLayerEnums.h"
#include "DnsResource.h"
#include "DnsResourceData.h"
#include "Layer.h"
/// @file
/**
* \namespace pcpp
* \brief The main namespace for the PcapPlusPlus lib
*/
namespace pcpp
{
/**
* @struct dnshdr
* Represents the fixed part of the DNS header, meaning the part that doesn't include the DNS data (queries, answers, authorities
* and additional records)
*/
#pragma pack(push, 1)
struct dnshdr
{
/** DNS query identification */
uint16_t transactionID;
#if (BYTE_ORDER == LITTLE_ENDIAN)
uint16_t
/** Recursion desired flag */
recursionDesired:1,
/** Truncated flag */
truncation:1,
/** Authoritative answer flag */
authoritativeAnswer:1,
/** Operation Code */
opcode:4,
/** Query/Response flag */
queryOrResponse:1,
/** Return Code */
responseCode:4,
/** Checking disabled flag */
checkingDisabled:1,
/** Authenticated data flag */
authenticData:1,
/** Zero flag (Reserved) */
zero:1,
/** Recursion available flag */
recursionAvailable:1;
#elif (BYTE_ORDER == BIG_ENDIAN)
uint16_t
/** Query/Response flag */
queryOrResponse:1,
/** Operation Code */
opcode:4,
/** Authoritative answer flag */
authoritativeAnswer:1,
/** Truncated flag */
truncation:1,
/** Recursion desired flag */
recursionDesired:1,
/** Recursion available flag */
recursionAvailable:1,
/** Zero flag (Reserved) */
zero:1,
/** Authenticated data flag */
authenticData:1,
/** Checking disabled flag */
checkingDisabled:1,
/** Return Code */
responseCode:4;
#endif
/** Number of DNS query records in packet */
uint16_t numberOfQuestions;
/** Number of DNS answer records in packet */
uint16_t numberOfAnswers;
/** Number of authority records in packet */
uint16_t numberOfAuthority;
/** Number of additional records in packet */
uint16_t numberOfAdditional;
};
#pragma pack(pop)
// forward declarations
class DnsQuery;
class IDnsResource;
class DnsResource;
class IDnsResourceData;
/**
* @class DnsLayer
* Represents the DNS protocol layer
*/
class DnsLayer : public Layer
{
friend class IDnsResource;
friend class DnsQuery;
friend class DnsResource;
public:
/**
* A constructor that creates the layer from an existing packet raw data
* @param[in] data A pointer to the raw data
* @param[in] dataLen Size of the data in bytes
* @param[in] prevLayer A pointer to the previous layer
* @param[in] packet A pointer to the Packet instance where layer will be stored in
*/
DnsLayer(uint8_t* data, size_t dataLen, Layer* prevLayer, Packet* packet);
/**
* A constructor that creates an empty DNS layer: all members of dnshdr are set to 0 and layer will contain no records
*/
DnsLayer();
/**
* A copy constructor for this layer
* @param[in] other The DNS layer to copy from
*/
DnsLayer(const DnsLayer& other);
/**
* An assignment operator for this layer
* @param[in] other The DNS layer to assign
* @return A reference to the assignee
*/
DnsLayer& operator=(const DnsLayer& other);
virtual ~DnsLayer();
/**
* Get a pointer to the DNS header (as opposed to the DNS data which is the queries, answers, etc. Data can be retrieved through the
* other methods of this layer. Notice the return value points directly to the data, so every change will change the actual packet data
* @return A pointer to the @ref dnshdr
*/
dnshdr* getDnsHeader() const;
/**
* Searches for a DNS query by its name field. Notice this method returns only a query which its name equals to the requested name. If
* several queries match the requested name, the first one will be returned. If no queries match the requested name, NULL will be returned
* @param[in] name The name of the query to search
* @param[in] exactMatch Indicate whether to match the whole name or just a part of it
* @return The first matching DNS query or NULL if no queries were found
*/
DnsQuery* getQuery(const std::string& name, bool exactMatch) const;
/**
* @return The first DNS query in the packet or NULL if packet doesn't contain any queries
*/
DnsQuery* getFirstQuery() const;
/**
* Get the DNS query following a certain query
* @param[in] query A pointer to a DNS query that exist in the packet
* @return The DNS query following 'query'. If 'query' is NULL or 'query' is the last query in the packet NULL will be returned
*/
DnsQuery* getNextQuery(DnsQuery* query) const;
/**
* @return The number of DNS queries in the packet
*/
size_t getQueryCount() const;
/**
* Add a new DNS query to the layer
* @param[in] name The value that shall be set in the name field of the query
* @param[in] dnsType The value that shall be set in the DNS type field of the query
* @param[in] dnsClass The value that shall be set in the DNS class field of the query
* @return A pointer to the newly created DNS query or NULL if query could not be created (an appropriate error log message will be
* printed in this case)
*/
DnsQuery* addQuery(const std::string& name, DnsType dnsType, DnsClass dnsClass);
/**
* Add a new DNS query similar to an already existing DNS query. All query fields will be copied from the existing query
* @param[in] copyQuery The record to create the new record from. copyQuery won't be changed in any way
* @return A pointer to the newly created DNS query or NULL if query could not be created (an appropriate error log message will be
* printed in this case)
*/
DnsQuery* addQuery(DnsQuery* const copyQuery);
/**
* Remove an existing query by name. If several queries matches the name, the first match will be removed
* @param[in] queryNameToRemove The name of the query to remove
* @param[in] exactMatch Indicate whether to match the whole name or just a part of it
* @return True if query was found and successfully removed or false if query was not found or couldn't be removed
*/
bool removeQuery(const std::string& queryNameToRemove, bool exactMatch);
/**
* Remove an existing query
* @param[in] queryToRemove A pointer to the query to remove
* @return True if query was found and successfully removed or false if query was not found or couldn't be removed
*/
bool removeQuery(DnsQuery* queryToRemove);
/**
* Searches for a DNS answer by its name field. Notice this method returns only an answer which its name equals to the requested name. If
* several answers match the requested name, the first one will be returned. If no answers match the requested name, NULL will be returned
* @param[in] name The name of the answer to search
* @param[in] exactMatch Indicate whether to match the whole name or just a part of it
* @return The first matching DNS answer or NULL if no answers were found
*/
DnsResource* getAnswer(const std::string& name, bool exactMatch) const;
/**
* @return The first DNS answer in the packet or NULL if packet doesn't contain any answers
*/
DnsResource* getFirstAnswer() const;
/**
* Get the DNS answer following a certain answer
* @param[in] answer A pointer to a DNS answer that exist in the packet
* @return The DNS answer following 'answer'. If 'answer' is NULL or 'answer' is the last answer in the packet NULL will be returned
*/
DnsResource* getNextAnswer(DnsResource* answer) const;
/**
* @return The number of DNS answers in the packet
*/
size_t getAnswerCount() const;
/**
* Add a new DNS answer to the layer
* @param[in] name The value that shall be set in the name field of the answer
* @param[in] dnsType The value that shall be set in the DNS type field of the answer
* @param[in] dnsClass The value that shall be set in the DNS class field of the answer
* @param[in] ttl The value that shall be set in the 'time-to-leave' field of the answer
* @param[in] data The answer data to be set. The type of the data should match the type of the DNS record
* (for example: DNS record of type A should have data of type IPv4DnsResourceData. Please see DnsResource#setData()
* for more info on this
* @return A pointer to the newly created DNS answer or NULL if answer could not be created (an appropriate error log message will be
* printed in this case)
*/
DnsResource* addAnswer(const std::string& name, DnsType dnsType, DnsClass dnsClass, uint32_t ttl, IDnsResourceData* data);
/**
* Add a new DNS answer similar to an already existing DNS answer. All answer fields will be copied from the existing answer
* @param[in] copyAnswer The record to create the new record from. copyAnswer won't be changed in any way
* @return A pointer to the newly created DNS answer or NULL if query could not be created (an appropriate error log message will be
* printed in this case)
*/
DnsResource* addAnswer(DnsResource* const copyAnswer);
/**
* Remove an existing answer by name. If several answers matches the name, the first match will be removed
* @param[in] answerNameToRemove The name of the answer to remove
* @param[in] exactMatch Indicate whether to match the whole name or just a part of it
* @return True if answer was found and successfully removed or false if answer was not found or couldn't be removed
*/
bool removeAnswer(const std::string& answerNameToRemove, bool exactMatch);
/**
* Remove an existing answer
* @param[in] answerToRemove A pointer to the answer to remove
* @return True if answer was found and successfully removed or false if answer was not found or couldn't be removed
*/
bool removeAnswer(DnsResource* answerToRemove);
/**
* Searches for a DNS authority by its name field. Notice this method returns only an authority which its name equals to the requested name. If
* several authorities match the requested name, the first one will be returned. If no authorities match the requested name, NULL will be returned
* @param[in] name The name of the authority to search
* @param[in] exactMatch Indicate whether to match the whole name or just a part of it
* @return The first matching DNS authority or NULL if no authorities were found
*/
DnsResource* getAuthority(const std::string& name, bool exactMatch) const;
/**
* @return The first DNS authority in the packet or NULL if packet doesn't contain any authorities
*/
DnsResource* getFirstAuthority() const;
/**
* Get the DNS authority following a certain authority
* @param[in] authority A pointer to a DNS authority that exist in the packet
* @return The DNS authority following 'authority'. If 'authority' is NULL or 'authority' is the last authority in the packet NULL will be returned
*/
DnsResource* getNextAuthority(DnsResource* authority) const;
/**
* @return The number of DNS authorities in the packet
*/
size_t getAuthorityCount() const;
/**
* Add a new DNS authority to the layer
* @param[in] name The value that shall be set in the name field of the authority
* @param[in] dnsType The value that shall be set in the DNS type field of the authority
* @param[in] dnsClass The value that shall be set in the DNS class field of the authority
* @param[in] ttl The value that shall be set in the 'time-to-leave' field of the authority
* @param[in] data The authority data to be set. The type of the data should match the type of the DNS record
* (for example: DNS record of type A should have data of type IPv4DnsResourceData. Please see DnsResource#setData()
* for more info on this
* @return A pointer to the newly created DNS authority or NULL if authority could not be created (an appropriate error log message will be
* printed in this case)
*/
DnsResource* addAuthority(const std::string& name, DnsType dnsType, DnsClass dnsClass, uint32_t ttl, IDnsResourceData* data);
/**
* Add a new DNS authority similar to an already existing DNS authority. All authority fields will be copied from the existing authority
* @param[in] copyAuthority The record to create the new record from. copyAuthority won't be changed in any way
* @return A pointer to the newly created DNS authority or NULL if query could not be created (an appropriate error log message will be
* printed in this case)
*/
DnsResource* addAuthority(DnsResource* const copyAuthority);
/**
* Remove an existing authority by name. If several authorities matches the name, the first match will be removed
* @param[in] authorityNameToRemove The name of the authority to remove
* @param[in] exactMatch Indicate whether to match the whole name or just a part of it
* @return True if authority was found and successfully removed or false if authority was not found or couldn't be removed
*/
bool removeAuthority(const std::string& authorityNameToRemove, bool exactMatch);
/**
* Remove an existing authority
* @param[in] authorityToRemove A pointer to the authority to remove
* @return True if authority was found and successfully removed or false if authority was not found or couldn't be removed
*/
bool removeAuthority(DnsResource* authorityToRemove);
/**
* Searches for a DNS additional record by its name field. Notice this method returns only an additional record which its name equals to
* the requested name. If several additional records match the requested name, the first one will be returned. If no additional records
* match the requested name, NULL will be returned
* @param[in] name The name of the additional record to search
* @param[in] exactMatch Indicate whether to match the whole name or just a part of it
* @return The first matching DNS additional record or NULL if no additional records were found
*/
DnsResource* getAdditionalRecord(const std::string& name, bool exactMatch) const;
/**
* @return The first DNS additional record in the packet or NULL if packet doesn't contain any additional records
*/
DnsResource* getFirstAdditionalRecord() const;
/**
* Get the DNS additional record following a certain additional record
* @param[in] additionalRecord A pointer to a DNS additional record that exist in the packet
* @return The DNS additional record following 'additionalRecord'. If 'additionalRecord' is NULL or 'additionalRecord' is the
* last additional record in the packet NULL will be returned
*/
DnsResource* getNextAdditionalRecord(DnsResource* additionalRecord) const;
/**
* @return The number of DNS additional records in the packet
*/
size_t getAdditionalRecordCount() const;
/**
* Add a new DNS additional record to the layer
* @param[in] name The value that shall be set in the name field of the additional record
* @param[in] dnsType The value that shall be set in the DNS type field of the additional record
* @param[in] dnsClass The value that shall be set in the DNS class field of the additional record
* @param[in] ttl The value that shall be set in the 'time-to-leave' field of the additional record
* @param[in] data The additional record data to be set. The type of the data should match the type of the DNS record
* (for example: DNS record of type A should have data of type IPv4DnsResourceData. Please see DnsResource#setData()
* for more info on this
* @return A pointer to the newly created DNS additional record or NULL if additional record could not be created (an appropriate error
* log message will be printed in this case)
*/
DnsResource* addAdditionalRecord(const std::string& name, DnsType dnsType, DnsClass dnsClass, uint32_t ttl, IDnsResourceData* data);
/**
* Add a new DNS additional record to the layer that doesn't have DNS class and TTL. Instead these bytes may contains some arbitrary
* data. In the future I may add support for these kinds of additional data records. For now, these bytes are set as raw
* @param[in] name The value that shall be set in the name field of the additional record
* @param[in] dnsType The value that shall be set in the DNS type field of the additional record
* @param[in] customData1 Two bytes of the arbitrary data that will be set in the offset usually used for the DNS class
* @param[in] customData2 Four bytes of the arbitrary data that will be set in the offset usually used for the TTL
* @param[in] data The additional record data to be set. The type of the data should match the type of the DNS record.
* (for example: DNS record of type A should have data of type IPv4DnsResourceData. Please see DnsResource#setData()
* for more info on this
* @return A pointer to the newly created DNS additional record or NULL if additional record could not be created (an appropriate error
* log message will be printed in this case)
*/
DnsResource* addAdditionalRecord(const std::string& name, DnsType dnsType, uint16_t customData1, uint32_t customData2, IDnsResourceData* data);
/**
* Add a new DNS additional record similar to an already existing DNS additional record. All additional record fields will be copied from the
* existing additional record
* @param[in] copyAdditionalRecord The record to create the new record from. copyAdditionalRecord won't be changed in any way
* @return A pointer to the newly created DNS additional record or NULL if query could not be created (an appropriate error log message will
* be printed in this case)
*/
DnsResource* addAdditionalRecord(DnsResource* const copyAdditionalRecord);
/**
* Remove an existing additional record by name. If several additional records matches the name, the first match will be removed
* @param[in] additionalRecordNameToRemove The name of the additional record to remove
* @param[in] exactMatch Indicate whether to match the whole name or just a part of it
* @return True if additional record was found and successfully removed or false if additional record was not found or couldn't be removed
*/
bool removeAdditionalRecord(const std::string& additionalRecordNameToRemove, bool exactMatch);
/**
* Remove an existing additional record
* @param[in] additionalRecordToRemove A pointer to the additional record to remove
* @return True if additional record was found and successfully removed or false if additional record was not found or couldn't be removed
*/
bool removeAdditionalRecord(DnsResource* additionalRecordToRemove);
// implement abstract methods
/**
* Does nothing for this layer (DnsLayer is always last)
*/
void parseNextLayer() {}
/**
* @return The size of the DNS data in the packet including he DNS header and size of all queries, answers, authorities and additional
* records
*/
size_t getHeaderLen() const { return m_DataLen; } //No layer above DNS
/**
* Does nothing for this layer
*/
virtual void computeCalculateFields() {}
std::string toString() const;
OsiModelLayer getOsiModelLayer() const { return OsiModelApplicationLayer; }
/**
* A static method that checks whether the port is considered as DNS
* @param[in] port The port number to be checked
* @return True if the port is associated with the DNS protocol
*/
static inline bool isDnsPort(uint16_t port);
/**
* A static method that validates the input data
* @param[in] data The pointer to the beginning of a byte stream of a DNS packet
* @param[in] dataLen The length of the byte stream
* @param[in] dnsOverTcp Should be set to "true" if this is DNS is over TCP, otherwise set to "false"
* (which is also the default value)
* @return True if the data is valid and can represent a DNS packet
*/
static inline bool isDataValid(const uint8_t* data, size_t dataLen, bool dnsOverTcp = false);
protected:
DnsLayer(uint8_t* data, size_t dataLen, Layer* prevLayer, Packet* packet, size_t offsetAdjustment);
explicit DnsLayer(size_t offsetAdjustment);
private:
IDnsResource* m_ResourceList;
DnsQuery* m_FirstQuery;
DnsResource* m_FirstAnswer;
DnsResource* m_FirstAuthority;
DnsResource* m_FirstAdditional;
uint16_t m_OffsetAdjustment;
size_t getBasicHeaderSize();
void init(size_t offsetAdjustment, bool callParseResource);
void initNewLayer(size_t offsetAdjustment);
IDnsResource* getFirstResource(DnsResourceType resType) const;
void setFirstResource(DnsResourceType resType, IDnsResource* resource);
using Layer::extendLayer;
bool extendLayer(int offsetInLayer, size_t numOfBytesToExtend, IDnsResource* resource);
using Layer::shortenLayer;
bool shortenLayer(int offsetInLayer, size_t numOfBytesToShorten, IDnsResource* resource);
IDnsResource* getResourceByName(IDnsResource* startFrom, size_t resourceCount, const std::string& name, bool exactMatch) const;
void parseResources();
DnsResource* addResource(DnsResourceType resType, const std::string& name, DnsType dnsType, DnsClass dnsClass,
uint32_t ttl, IDnsResourceData* data);
bool removeResource(IDnsResource* resourceToRemove);
};
/**
* @class DnsOverTcpLayer
* Represents the DNS over TCP layer.
* DNS over TCP is described here: https://tools.ietf.org/html/rfc7766 .
* It is very similar to DNS over UDP, except for one field: TCP message length which is added in the beginning of the message
* before the other DNS data properties. The rest of the data is similar.
*
* Note: DNS over TCP can spread over more than one packet, but this implementation doesn't support this use-case and assumes
* the whole message fits in a single packet.
*/
class DnsOverTcpLayer : public DnsLayer
{
public:
/**
* A constructor that creates the layer from an existing packet raw data
* @param[in] data A pointer to the raw data
* @param[in] dataLen Size of the data in bytes
* @param[in] prevLayer A pointer to the previous layer
* @param[in] packet A pointer to the Packet instance where layer will be stored in
*/
DnsOverTcpLayer(uint8_t* data, size_t dataLen, Layer* prevLayer, Packet* packet)
: DnsLayer(data, dataLen, prevLayer, packet, sizeof(uint16_t)) {}
/**
* A constructor that creates an empty DNS layer: all members of dnshdr are set to 0 and layer will contain no records
*/
DnsOverTcpLayer() : DnsLayer(sizeof(uint16_t)) {}
/**
* A copy constructor for this layer
* @param[in] other The DNS over TCP layer to copy from
*/
DnsOverTcpLayer(const DnsOverTcpLayer& other) : DnsLayer(other) {}
/**
* @return The value of the TCP message length as described in https://tools.ietf.org/html/rfc7766#section-8
*/
uint16_t getTcpMessageLength();
/**
* Set the TCP message length value as described in https://tools.ietf.org/html/rfc7766#section-8
* @param[in] value The value to set
*/
void setTcpMessageLength(uint16_t value);
// overridden methods
/**
* Calculate the TCP message length field
*/
void computeCalculateFields();
};
// implementation of inline methods
bool DnsLayer::isDnsPort(uint16_t port)
{
switch (port)
{
case 53:
case 5353:
case 5355:
return true;
default:
return false;
}
}
bool DnsLayer::isDataValid(const uint8_t* data, size_t dataLen, bool dnsOverTcp)
{
size_t minSize = sizeof(dnshdr) + (dnsOverTcp ? sizeof(uint16_t) : 0);
return data && dataLen >= minSize;
}
} // namespace pcpp
#endif /* PACKETPP_DNS_LAYER */