Kea 2.7.4
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Light-weight Accessor to Name data. More...
#include <labelsequence.h>
Static Public Attributes | |
static const size_t | MAX_SERIALIZED_LENGTH |
Max possible size of serialized image generated by serialize . | |
Friends | |
std::string | Name::toText (bool) const |
Well-known LabelSequence constants | |
static const LabelSequence & | WILDCARD () |
Wildcard label ("*") | |
LabelSequence (const Name &name) | |
Constructs a LabelSequence for the given name. | |
LabelSequence (const void *buf) | |
Constructor from serialized image. | |
LabelSequence (const LabelSequence &src, uint8_t buf[MAX_SERIALIZED_LENGTH]) | |
Construct 'extendable' LabelSequence. | |
LabelSequence (const LabelSequence &ls) | |
Copy constructor. | |
LabelSequence & | operator= (const LabelSequence &other) |
Assignment operator. | |
const uint8_t * | getData (size_t *len) const |
Return the wire-format data for this LabelSequence. | |
size_t | getDataLength () const |
Return the length of the wire-format data of this LabelSequence. | |
size_t | getSerializedLength () const |
Return the size of serialized image of the LabelSequence . | |
void | serialize (void *buf, size_t buf_len) const |
Serialize the LabelSequence object in to a buffer. | |
bool | equals (const LabelSequence &other, bool case_sensitive=false) const |
Compares two label sequences for equality. | |
bool | operator== (const LabelSequence &other) const |
Compares two label sequences for equality (case ignored). | |
NameComparisonResult | compare (const LabelSequence &other, bool case_sensitive=false) const |
Compares two label sequences. | |
void | stripLeft (size_t i) |
Remove labels from the front of this LabelSequence. | |
void | stripRight (size_t i) |
Remove labels from the end of this LabelSequence. | |
size_t | getLabelCount () const |
Returns the current number of labels for this LabelSequence. | |
std::string | toText () const |
Convert the LabelSequence to a string. | |
std::string | toRawText (bool omit_final_dot) const |
Convert the LabelSequence to a string without escape sequences. | |
void | extend (const LabelSequence &labels, uint8_t buf[MAX_SERIALIZED_LENGTH]) |
Extend this LabelSequence with the given labelsequence. | |
size_t | getHash (bool case_sensitive) const |
Calculate a simple hash for the label sequence. | |
bool | isAbsolute () const |
Checks whether the label sequence is absolute. | |
Light-weight Accessor to Name data.
The purpose of this class is to easily match Names and parts of Names, without needing to copy the underlying data on each label strip.
It can only work on existing Name objects, or data as provided by the Name object or another LabelSequence, and the data or Name MUST remain in scope during the entire lifetime of its associated LabelSequence(s).
Upon creation of a LabelSequence, it records the offsets of the labels in the wireformat data of the Name. When stripLeft() or stripRight() is called on the LabelSequence, no changes in the original data occur, but the internal pointers of the LabelSequence are modified.
LabelSequences can be compared to other LabelSequences, and their data can be requested (which then points to part of the original data of the original Name object).
Definition at line 35 of file labelsequence.h.
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inlineexplicit |
Constructs a LabelSequence for the given name.
name | The Name to construct a LabelSequence for |
Definition at line 64 of file labelsequence.h.
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explicit |
Constructor from serialized image.
This constructor restores a LabelSequence
object from a serialized binary image previously generated by serialize()
. Any other input to this constructor will result in undefined behavior.
The binary data passed to this constructor MUST remain in scope and MUST NOT be modified during the lifetime of this LabelSequence.
As long as the data were previously generated by a call to serialize()
on a valid LabelSequence
object, this constructor should succeed. While any other case is undefined, this constructor may perform some validity checks internally for safety. Nevertheless, applications must not rely on such checks.
buf | Pointer to the serialized image generated by serialize() . |
Definition at line 21 of file labelsequence.cc.
References isc_throw, isc::dns::Name::MAX_LABELLEN, and isc::dns::Name::MAX_LABELS.
isc::dns::LabelSequence::LabelSequence | ( | const LabelSequence & | src, |
uint8_t | buf[MAX_SERIALIZED_LENGTH] ) |
Construct 'extendable' LabelSequence.
This form of LabelSequence copies the data from the given labelsequence into the given external buffer, which is subsequently extendable by calling extend()
The data is placed into the given buffer as follows:
src | LabelSequence to copy the initial data from |
buf | external buffer to store this labelsequence's data in |
Definition at line 63 of file labelsequence.cc.
References isc::dns::Name::MAX_WIRE.
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inline |
Copy constructor.
ls | The LabelSequence to construct a LabelSequence from |
Definition at line 125 of file labelsequence.h.
NameComparisonResult isc::dns::LabelSequence::compare | ( | const LabelSequence & | other, |
bool | case_sensitive = false ) const |
Compares two label sequences.
Performs a (optionally case-insensitive) comparison between this LabelSequence and another LabelSequence.
other | The LabelSequence to compare with |
case_sensitive | If true, comparison is case-insensitive |
NameComparisonResult
object representing the comparison result. Definition at line 167 of file labelsequence.cc.
References isc::dns::NameComparisonResult::COMMONANCESTOR, isc::dns::NameComparisonResult::EQUAL, getLabelCount(), isc_throw_assert, isc::dns::name::internal::maptolower, isc::dns::Name::MAX_LABELLEN, isc::dns::NameComparisonResult::NONE, isc::dns::NameComparisonResult::SUBDOMAIN, and isc::dns::NameComparisonResult::SUPERDOMAIN.
bool isc::dns::LabelSequence::equals | ( | const LabelSequence & | other, |
bool | case_sensitive = false ) const |
Compares two label sequences for equality.
Performs a (optionally case-sensitive) comparison between this LabelSequence and another LabelSequence for equality.
other | The LabelSequence to compare with |
case_sensitive | If true, comparison is case-sensitive |
Definition at line 140 of file labelsequence.cc.
References getData(), and isc::dns::name::internal::maptolower.
Referenced by operator==().
void isc::dns::LabelSequence::extend | ( | const LabelSequence & | labels, |
uint8_t | buf[MAX_SERIALIZED_LENGTH] ) |
Extend this LabelSequence with the given labelsequence.
The given labels are appended to the name data, and internal offset data is updated accordingly.
The data from the given LabelSequence is copied into the buffer associated with this LabelSequence; the appended LabelSequence (the 'labels' argument) can be released if it is not needed for other operations anymore.
If this LabelSequence is absolute, its root label will be stripped before the given LabelSequence is appended; after extend(), this LabelSequence will be absolute if, and only if, the appended LabelSequence was. A side-effect of this property is that adding the root label to an absolute LabelSequence has no effect (the root label is stripped, then added again).
Some minimal checking is done on the data, but internal integrity is not assumed. Do NOT modify the given buffer except through calls to this method, and do NOT call this method if the buffer is associated to another LabelSequence (behaviour of the other LabelSequence is undefined in that scenario).
BadValue | If the buffer does not appear to be associated with this LabelSequence, or if the maximum wire length or maximum number of labels would be exceeded by this operation |
labels | The labels to append to this LabelSequence |
buf | The buffer associated with this LabelSequence |
Definition at line 417 of file labelsequence.cc.
References isAbsolute(), isc_throw, isc::dns::Name::MAX_LABELS, and isc::dns::Name::MAX_WIRE.
const uint8_t * isc::dns::LabelSequence::getData | ( | size_t * | len | ) | const |
Return the wire-format data for this LabelSequence.
The data is returned as a pointer to (the part of) the original wireformat data, from either the original Name object, or the raw data given in the constructor, and the given len value is set to the number of octets that match this labelsequence.
len | Pointer to a size_t where the length of the data will be stored (in number of octets) |
Definition at line 82 of file labelsequence.cc.
References getDataLength().
Referenced by equals(), and getHash().
size_t isc::dns::LabelSequence::getDataLength | ( | ) | const |
Return the length of the wire-format data of this LabelSequence.
This method returns the number of octets for the data that would be returned by the getData()
method.
Note that the return value of this method is always positive. Note also that if the return value of this method is 1, it means the sequence consists of the null label, i.e., a single "dot", and vice versa.
Definition at line 88 of file labelsequence.cc.
Referenced by getData(), getSerializedLength(), serialize(), and toRawText().
size_t isc::dns::LabelSequence::getHash | ( | bool | case_sensitive | ) | const |
Calculate a simple hash for the label sequence.
This method calculates a hash value for the label sequence as binary data. If case_sensitive
is false, it ignores the case stored in the labels; specifically, it normalizes the labels by converting all upper case characters to lower case ones and calculates the hash value for the result.
This method is intended to provide a lightweight way to store a relatively small number of label sequences in a hash table. For this reason it only takes into account data up to 16 octets (16 was derived from BIND 9's implementation). Also, the function does not provide any unpredictability; a specific sequence will always have the same hash value. It should therefore not be used in the context where an untrusted third party can mount a denial of service attack by forcing the application to create a very large number of label sequences that have the same hash value and expected to be stored in a hash table.
None |
case_sensitive |
Definition at line 263 of file labelsequence.cc.
References getData(), and isc::dns::name::internal::maptolower.
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inline |
Returns the current number of labels for this LabelSequence.
Definition at line 308 of file labelsequence.h.
Referenced by compare(), getSerializedLength(), serialize(), stripLeft(), stripRight(), and toRawText().
size_t isc::dns::LabelSequence::getSerializedLength | ( | ) | const |
Return the size of serialized image of the LabelSequence
.
This method calculates the size of necessary storage to store serialized image of this LabelSequence
(which would be dumped by serialize()
) and returns it. The size is in bytes.
none. |
LabelSequence
. Definition at line 94 of file labelsequence.cc.
References getDataLength(), and getLabelCount().
Referenced by serialize().
bool isc::dns::LabelSequence::isAbsolute | ( | ) | const |
Checks whether the label sequence is absolute.
Definition at line 258 of file labelsequence.cc.
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inline |
Assignment operator.
other | The LabelSequence to assign a LabelSequence from |
Definition at line 141 of file labelsequence.h.
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inline |
Compares two label sequences for equality (case ignored).
This is equivalent to this->equals(other)
.
The operator version is convenient some specific cases such as in unit tests.
Definition at line 267 of file labelsequence.h.
References equals().
void isc::dns::LabelSequence::serialize | ( | void * | buf, |
size_t | buf_len ) const |
Serialize the LabelSequence
object in to a buffer.
This method dumps a serialized image of this LabelSequence
that would be restored by the corresponding constructor into the given buffer. The buffer size must be at least equal to the value returned by getSerializedLength() (it can be larger than that).
Be careful about where the buffer is located; due to the nature of the buffer, it's quite possible that the memory region is being used to construct another active LabelSequence
. In such a case the serialization would silently break that sequence object, and it will be very difficult to identify the cause. This method has minimal level checks to avoid such disruption: If the serialization would break "this" LabelSequence
object, it doesn't write anything to the given buffer and throw a isc::BadValue
exception.
In general, it should be safe to call this method on a LabelSequence
object constructed from a Name
object or a copy of such LabelSequence
. When you construct LabelSequence
from pre-serialized data, calling this method on it can be unsafe. One safe (but a bit less efficient) way in such a case is to make the source LabelSequence
temporary and immediately create a local copy using an explicit buffer, and call this method on the latter:
The serialized image would be as follows:
Applications must use the resulting image as opaque value and must not use it for other purposes than input to the corresponding constructor to restore it. Application behavior that assumes the specific organization of the image is not guaranteed.
isc::BadValue | buf_len is too short (this method never throws otherwise) or the serialization would override internal data of of the source LabelSequence. |
buf | Pointer to the placeholder to dump the serialized image |
buf_len | The size of available region in buf |
Definition at line 111 of file labelsequence.cc.
References getDataLength(), getLabelCount(), getSerializedLength(), isc_throw, and isc_throw_assert.
void isc::dns::LabelSequence::stripLeft | ( | size_t | i | ) |
Remove labels from the front of this LabelSequence.
OutOfRange | if i is greater than or equal to the number of labels currently pointed to by this LabelSequence |
i | The number of labels to remove. |
Definition at line 240 of file labelsequence.cc.
References getLabelCount(), and isc_throw.
void isc::dns::LabelSequence::stripRight | ( | size_t | i | ) |
Remove labels from the end of this LabelSequence.
OutOfRange | if i is greater than or equal to the number of labels currently pointed to by this LabelSequence |
i | The number of labels to remove. |
Definition at line 249 of file labelsequence.cc.
References getLabelCount(), and isc_throw.
std::string isc::dns::LabelSequence::toRawText | ( | bool | omit_final_dot | ) | const |
Convert the LabelSequence to a string without escape sequences.
The string returned will contain a single character value for any escape sequences in the label(s).
omit_final_dot | whether to omit the trailing dot in the output. |
LabelSequence
that does not contain escape sequences. Definition at line 281 of file labelsequence.cc.
References getDataLength(), getLabelCount(), isc_throw, isc_throw_assert, and isc::dns::Name::MAX_LABELLEN.
std::string isc::dns::LabelSequence::toText | ( | ) | const |
Convert the LabelSequence to a string.
This method returns a std::string
object representing the LabelSequence as a string. The returned string ends with a dot '.' if the label sequence is absolute.
This function assumes the underlying data is in proper uncompressed wire format. If it finds an unexpected label character including compression pointer, an exception of class BadLabelType
will be thrown. In addition, if resource allocation for the result string fails, a corresponding standard exception will be thrown.
LabelSequence
. Definition at line 412 of file labelsequence.cc.
References isAbsolute(), and Name::toText.
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inlinestatic |
Wildcard label ("*")
Definition at line 443 of file labelsequence.h.
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friend |
Referenced by toText().
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static |
Max possible size of serialized image generated by serialize
.
A fixed length buffer of this size can be always passed to serialize()
safely. (But the application shouldn't use the specific size value; it must use this constant variable).
Definition at line 45 of file labelsequence.h.