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Diffstat (limited to 'src/lib/dns/name.cc')
| -rw-r--r-- | src/lib/dns/name.cc | 724 |
1 files changed, 724 insertions, 0 deletions
diff --git a/src/lib/dns/name.cc b/src/lib/dns/name.cc new file mode 100644 index 0000000..3f75fa0 --- /dev/null +++ b/src/lib/dns/name.cc @@ -0,0 +1,724 @@ +// Copyright (C) 2009-2019 Internet Systems Consortium, Inc. ("ISC") +// +// This Source Code Form is subject to the terms of the Mozilla Public +// License, v. 2.0. If a copy of the MPL was not distributed with this +// file, You can obtain one at http://mozilla.org/MPL/2.0/. + +#include <config.h> + +#include <cctype> +#include <iterator> +#include <functional> +#include <vector> +#include <iostream> +#include <algorithm> + +#include <exceptions/isc_assert.h> +#include <util/buffer.h> +#include <dns/exceptions.h> +#include <dns/name.h> +#include <dns/name_internal.h> +#include <dns/messagerenderer.h> +#include <dns/labelsequence.h> + +using namespace std; +using namespace isc::util; +using isc::dns::NameComparisonResult; +using namespace isc::dns::name::internal; + +namespace isc { +namespace dns { + +namespace { +/// +/// These are shortcut arrays for efficient character conversion. +/// digitvalue converts a digit character to the corresponding integer. +/// maptolower convert uppercase alphabets to their lowercase counterparts. +/// We once used a helper non-local static object to avoid hardcoding the +/// array members, but we then realized it's susceptible to static +/// initialization order fiasco: Since these constants are used in a Name +/// constructor, a non-local static Name object defined in another translation +/// unit than this file may not be initialized correctly. +/// There are several ways to address this issue, but in this specific case +/// we chose the naive but simple hardcoding approach. +/// +/// These definitions are derived from BIND 9's libdns module. +/// Note: we could use the standard tolower() function instead of the +/// maptolower array, but a benchmark indicated that the private array could +/// improve the performance of message rendering (which internally uses the +/// array heavily) about 27%. Since we want to achieve very good performance +/// for message rendering in some cases, we'll keep using it. +const signed char digitvalue[256] = { + -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, // 16 + -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, // 32 + -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, // 48 + 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, -1, -1, -1, -1, -1, -1, // 64 + -1, 10, 11, 12, 13, 14, 15, -1, -1, -1, -1, -1, -1, -1, -1, -1, // 80 + -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, // 96 + -1, 10, 11, 12, 13, 14, 15, -1, -1, -1, -1, -1, -1, -1, -1, -1, // 112 + -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, // 128 + -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, + -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, + -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, + -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, + -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, + -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, + -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, + -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, // 256 +}; +} + +namespace name { +namespace internal { +const uint8_t maptolower[] = { + 0x00, 0x01, 0x02, 0x03, 0x04, 0x05, 0x06, 0x07, + 0x08, 0x09, 0x0a, 0x0b, 0x0c, 0x0d, 0x0e, 0x0f, + 0x10, 0x11, 0x12, 0x13, 0x14, 0x15, 0x16, 0x17, + 0x18, 0x19, 0x1a, 0x1b, 0x1c, 0x1d, 0x1e, 0x1f, + 0x20, 0x21, 0x22, 0x23, 0x24, 0x25, 0x26, 0x27, + 0x28, 0x29, 0x2a, 0x2b, 0x2c, 0x2d, 0x2e, 0x2f, + 0x30, 0x31, 0x32, 0x33, 0x34, 0x35, 0x36, 0x37, + 0x38, 0x39, 0x3a, 0x3b, 0x3c, 0x3d, 0x3e, 0x3f, + 0x40, 0x61, 0x62, 0x63, 0x64, 0x65, 0x66, 0x67, // ..., 'A' - 'G' + 0x68, 0x69, 0x6a, 0x6b, 0x6c, 0x6d, 0x6e, 0x6f, // 'H' - 'O' + 0x70, 0x71, 0x72, 0x73, 0x74, 0x75, 0x76, 0x77, // 'P' - 'W' + 0x78, 0x79, 0x7a, 0x5b, 0x5c, 0x5d, 0x5e, 0x5f, // 'X' - 'Z', ... + 0x60, 0x61, 0x62, 0x63, 0x64, 0x65, 0x66, 0x67, + 0x68, 0x69, 0x6a, 0x6b, 0x6c, 0x6d, 0x6e, 0x6f, + 0x70, 0x71, 0x72, 0x73, 0x74, 0x75, 0x76, 0x77, + 0x78, 0x79, 0x7a, 0x7b, 0x7c, 0x7d, 0x7e, 0x7f, + 0x80, 0x81, 0x82, 0x83, 0x84, 0x85, 0x86, 0x87, + 0x88, 0x89, 0x8a, 0x8b, 0x8c, 0x8d, 0x8e, 0x8f, + 0x90, 0x91, 0x92, 0x93, 0x94, 0x95, 0x96, 0x97, + 0x98, 0x99, 0x9a, 0x9b, 0x9c, 0x9d, 0x9e, 0x9f, + 0xa0, 0xa1, 0xa2, 0xa3, 0xa4, 0xa5, 0xa6, 0xa7, + 0xa8, 0xa9, 0xaa, 0xab, 0xac, 0xad, 0xae, 0xaf, + 0xb0, 0xb1, 0xb2, 0xb3, 0xb4, 0xb5, 0xb6, 0xb7, + 0xb8, 0xb9, 0xba, 0xbb, 0xbc, 0xbd, 0xbe, 0xbf, + 0xc0, 0xc1, 0xc2, 0xc3, 0xc4, 0xc5, 0xc6, 0xc7, + 0xc8, 0xc9, 0xca, 0xcb, 0xcc, 0xcd, 0xce, 0xcf, + 0xd0, 0xd1, 0xd2, 0xd3, 0xd4, 0xd5, 0xd6, 0xd7, + 0xd8, 0xd9, 0xda, 0xdb, 0xdc, 0xdd, 0xde, 0xdf, + 0xe0, 0xe1, 0xe2, 0xe3, 0xe4, 0xe5, 0xe6, 0xe7, + 0xe8, 0xe9, 0xea, 0xeb, 0xec, 0xed, 0xee, 0xef, + 0xf0, 0xf1, 0xf2, 0xf3, 0xf4, 0xf5, 0xf6, 0xf7, + 0xf8, 0xf9, 0xfa, 0xfb, 0xfc, 0xfd, 0xfe, 0xff +}; +} // end of internal +} // end of name + +namespace { +/// +/// Textual name parser states. +/// +typedef enum { + ft_init = 0, // begin of the name + ft_start, // begin of a label + ft_ordinary, // parsing an ordinary label + ft_initialescape, // just found '\' + ft_escape, // begin of handling a '\'-escaped sequence + ft_escdecimal // parsing a '\DDD' octet. +} ft_state; + +// The parser of name from a string. It is a template, because +// some parameters are used with two different types, while others +// are private type aliases. +template<class Iterator, class Offsets, class Data> +void +stringParse(Iterator s, Iterator send, bool downcase, Offsets& offsets, + Data& ndata) +{ + const Iterator orig_s(s); + // + // Initialize things to make the compiler happy; they're not required. + // + unsigned int digits = 0; + unsigned int value = 0; + unsigned int count = 0; + + // + // Set up the state machine. + // + bool done = false; + bool is_root = false; + const bool empty = s == send; + ft_state state = ft_init; + + // Prepare the output buffers. + offsets.reserve(Name::MAX_LABELS); + offsets.push_back(0); + ndata.reserve(Name::MAX_WIRE); + + // should we refactor this code using, e.g, the state pattern? Probably + // not at this point, as this is based on proved code (derived from BIND9) + // and it's less likely that we'll have more variations in the domain name + // syntax. If this ever happens next time, we should consider refactor + // the code, rather than adding more states and cases below. + while (ndata.size() < Name::MAX_WIRE && s != send && !done) { + unsigned char c = *s++; + + switch (state) { + case ft_init: + // + // Is this the root name? + // + if (c == '.') { + if (s != send) { + isc_throw(EmptyLabel, + "non terminating empty label in " << + string(orig_s, send)); + } + is_root = true; + } else if (c == '@' && s == send) { + // handle a single '@' as the root name. + is_root = true; + } + + if (is_root) { + ndata.push_back(0); + done = true; + break; + } + + // FALLTHROUGH + case ft_start: + ndata.push_back(0); // placeholder for the label length field + count = 0; + if (c == '\\') { + state = ft_initialescape; + break; + } + state = ft_ordinary; + isc_throw_assert(ndata.size() < Name::MAX_WIRE); + // FALLTHROUGH + case ft_ordinary: + if (c == '.') { + if (count == 0) { + isc_throw(EmptyLabel, + "duplicate period in " << string(orig_s, send)); + } + ndata.at(offsets.back()) = count; + offsets.push_back(ndata.size()); + if (s == send) { + ndata.push_back(0); + done = true; + } + state = ft_start; + } else if (c == '\\') { + state = ft_escape; + } else { + if (++count > Name::MAX_LABELLEN) { + isc_throw(TooLongLabel, + "label is too long in " << string(orig_s, send)); + } + ndata.push_back(downcase ? maptolower[c] : c); + } + break; + case ft_initialescape: + if (c == '[') { + // This looks like a bitstring label, which was deprecated. + // Intentionally drop it. + isc_throw(BadLabelType, + "invalid label type in " << string(orig_s, send)); + } + // FALLTHROUGH + case ft_escape: + if (!isdigit(c & 0xff)) { + if (++count > Name::MAX_LABELLEN) { + isc_throw(TooLongLabel, + "label is too long in " << string(orig_s, send)); + } + ndata.push_back(downcase ? maptolower[c] : c); + state = ft_ordinary; + break; + } + digits = 0; + value = 0; + state = ft_escdecimal; + // FALLTHROUGH + case ft_escdecimal: + if (!isdigit(c & 0xff)) { + isc_throw(BadEscape, + "mixture of escaped digit and non-digit in " + << string(orig_s, send)); + } + value *= 10; + value += digitvalue[c]; + digits++; + if (digits == 3) { + if (value > 255) { + isc_throw(BadEscape, + "escaped decimal is too large in " + << string(orig_s, send)); + } + if (++count > Name::MAX_LABELLEN) { + isc_throw(TooLongLabel, + "label is too long in " << string(orig_s, send)); + } + ndata.push_back(downcase ? maptolower[value] : value); + state = ft_ordinary; + } + break; + default: + // impossible case + isc_throw_assert(false); + } + } + + if (!done) { // no trailing '.' was found. + if (ndata.size() == Name::MAX_WIRE) { + isc_throw(TooLongName, + "name is too long for termination in " << + string(orig_s, send)); + } + isc_throw_assert(s == send); + if (state != ft_ordinary) { + isc_throw(IncompleteName, + "incomplete textual name in " << + (empty ? "<empty>" : string(orig_s, send))); + } + if (state == ft_ordinary) { + isc_throw_assert(count != 0); + ndata.at(offsets.back()) = count; + + offsets.push_back(ndata.size()); + // add a trailing \0 + ndata.push_back('\0'); + } + } +} + +} + +Name::Name(const std::string &namestring, bool downcase) { + // Prepare inputs for the parser + const std::string::const_iterator s = namestring.begin(); + const std::string::const_iterator send = namestring.end(); + + // Prepare outputs + NameOffsets offsets; + NameString ndata; + + // To the parsing + stringParse(s, send, downcase, offsets, ndata); + + // And get the output + labelcount_ = offsets.size(); + isc_throw_assert(labelcount_ > 0 && labelcount_ <= Name::MAX_LABELS); + ndata_.assign(ndata.data(), ndata.size()); + length_ = ndata_.size(); + offsets_.assign(offsets.begin(), offsets.end()); +} + +Name::Name(const char* namedata, size_t data_len, const Name* origin, + bool downcase) +{ + // Check validity of data + if (namedata == NULL || data_len == 0) { + isc_throw(isc::InvalidParameter, + "No data provided to Name constructor"); + } + // If the last character is not a dot, it is a relative to origin. + // It is safe to check now, we know there's at least one character. + const bool absolute = (namedata[data_len - 1] == '.'); + // If we are not absolute, we need the origin to complete the name. + if (!absolute && origin == NULL) { + isc_throw(MissingNameOrigin, + "No origin available and name is relative"); + } + // Prepare inputs for the parser + const char* end = namedata + data_len; + + // Prepare outputs + NameOffsets offsets; + NameString ndata; + + // Do the actual parsing + stringParse(namedata, end, downcase, offsets, ndata); + + // Get the output + labelcount_ = offsets.size(); + isc_throw_assert(labelcount_ > 0 && labelcount_ <= Name::MAX_LABELS); + ndata_.assign(ndata.data(), ndata.size()); + length_ = ndata_.size(); + offsets_.assign(offsets.begin(), offsets.end()); + + if (!absolute) { + // Now, extend the data with the ones from origin. But eat the + // last label (the empty one). + + // Drop the last character of the data (the \0) and append a copy of + // the origin's data + ndata_.erase(ndata_.end() - 1); + ndata_.append(origin->ndata_); + + // Do a similar thing with offsets. However, we need to move them + // so they point after the prefix we parsed before. + size_t offset = offsets_.back(); + offsets_.pop_back(); + size_t offset_count = offsets_.size(); + offsets_.insert(offsets_.end(), origin->offsets_.begin(), + origin->offsets_.end()); + for (NameOffsets::iterator it(offsets_.begin() + offset_count); + it != offsets_.end(); ++it) { + *it += offset; + } + + // Adjust sizes. + length_ = ndata_.size(); + labelcount_ = offsets_.size(); + + // And check the sizes are OK. + if (labelcount_ > Name::MAX_LABELS || length_ > Name::MAX_WIRE) { + isc_throw(TooLongName, "Combined name is too long"); + } + } +} + +namespace { +/// +/// Wire-format name parser states. +/// +typedef enum { + fw_start = 0, // beginning of a label + fw_ordinary, // inside an ordinary (non compressed) label + fw_newcurrent // beginning of a compression pointer +} fw_state; +} + +Name::Name(InputBuffer& buffer, bool downcase) { + NameOffsets offsets; + offsets.reserve(Name::MAX_LABELS); + + /* + * Initialize things to make the compiler happy; they're not required. + */ + unsigned int n = 0; + + // + // Set up. + // + bool done = false; + unsigned int nused = 0; + bool seen_pointer = false; + fw_state state = fw_start; + + unsigned int cused = 0; // Bytes of compressed name data used + unsigned int current = buffer.getPosition(); + unsigned int pos_begin = current; + unsigned int biggest_pointer = current; + + // Make the compiler happy; this is not required. + // XXX: bad style in that we initialize it with a dummy value and define + // it far from where it's used. But alternatives seemed even worse. + unsigned int new_current = 0; + + // + // Note: The following code is not optimized for speed, but + // rather for correctness. Speed will be addressed in the future. + // + while (current < buffer.getLength() && !done) { + unsigned int c = buffer.readUint8(); + current++; + if (!seen_pointer) { + cused++; + } + + switch (state) { + case fw_start: + if (c <= MAX_LABELLEN) { + offsets.push_back(nused); + if (nused + c + 1 > Name::MAX_WIRE) { + isc_throw(DNSMessageFORMERR, "wire name is too long: " + << nused + c + 1 << " bytes"); + } + nused += c + 1; + ndata_.push_back(c); + if (c == 0) { + done = true; + } + n = c; + state = fw_ordinary; + } else if ((c & COMPRESS_POINTER_MARK8) == COMPRESS_POINTER_MARK8) { + // + // Ordinary 14-bit pointer. + // + new_current = c & ~COMPRESS_POINTER_MARK8; + n = 1; + state = fw_newcurrent; + } else { + // this case includes local compression pointer, which hasn't + // been standardized. + isc_throw(DNSMessageFORMERR, "unknown label character: " << c); + } + break; + case fw_ordinary: + if (downcase) { + c = maptolower[c]; + } + ndata_.push_back(c); + if (--n == 0) { + state = fw_start; + } + break; + case fw_newcurrent: + new_current *= 256; + new_current += c; + if (--n != 0) { + break; + } + if (new_current >= biggest_pointer) { + isc_throw(DNSMessageFORMERR, + "bad compression pointer (out of range): " << + new_current); + } + biggest_pointer = new_current; + current = new_current; + buffer.setPosition(current); + seen_pointer = true; + state = fw_start; + break; + default: + isc_throw_assert(false); + } + } + + if (!done) { + isc_throw(DNSMessageFORMERR, "incomplete wire-format name"); + } + + labelcount_ = offsets.size(); + length_ = nused; + offsets_.assign(offsets.begin(), offsets.end()); + buffer.setPosition(pos_begin + cused); +} + +void +Name::toWire(OutputBuffer& buffer) const { + buffer.writeData(ndata_.data(), ndata_.size()); +} + +void +Name::toWire(AbstractMessageRenderer& renderer) const { + renderer.writeName(*this); +} + +std::string +Name::toText(bool omit_final_dot) const { + LabelSequence ls(*this); + return (ls.toText(omit_final_dot)); +} + +std::string +Name::toRawText(bool omit_final_dot) const { + LabelSequence ls(*this); + return (ls.toRawText(omit_final_dot)); +} + +NameComparisonResult +Name::compare(const Name& other) const { + const LabelSequence ls1(*this); + const LabelSequence ls2(other); + return (ls1.compare(ls2)); +} + +bool +Name::equals(const Name& other) const { + if (length_ != other.length_ || labelcount_ != other.labelcount_) { + return (false); + } + + for (unsigned int l = labelcount_, pos = 0; l > 0; --l) { + uint8_t count = ndata_[pos]; + if (count != other.ndata_[pos]) { + return (false); + } + ++pos; + + while (count-- > 0) { + uint8_t label1 = ndata_[pos]; + uint8_t label2 = other.ndata_[pos]; + + if (maptolower[label1] != maptolower[label2]) { + return (false); + } + ++pos; + } + } + + return (true); +} + +bool +Name::leq(const Name& other) const { + return (compare(other).getOrder() <= 0); +} + +bool +Name::geq(const Name& other) const { + return (compare(other).getOrder() >= 0); +} + +bool +Name::lthan(const Name& other) const { + return (compare(other).getOrder() < 0); +} + +bool +Name::gthan(const Name& other) const { + return (compare(other).getOrder() > 0); +} + +bool +Name::isWildcard() const { + return (length_ >= 2 && ndata_[0] == 1 && ndata_[1] == '*'); +} + +Name +Name::concatenate(const Name& suffix) const { + isc_throw_assert(length_ > 0 && suffix.length_ > 0); + isc_throw_assert(labelcount_ > 0 && suffix.labelcount_ > 0); + + unsigned int length = length_ + suffix.length_ - 1; + if (length > Name::MAX_WIRE) { + isc_throw(TooLongName, "names are too long to concatenate"); + } + + Name retname; + retname.ndata_.reserve(length); + retname.ndata_.assign(ndata_, 0, length_ - 1); + retname.ndata_.insert(retname.ndata_.end(), + suffix.ndata_.begin(), suffix.ndata_.end()); + isc_throw_assert(retname.ndata_.size() == length); + retname.length_ = length; + + // + // Setup the offsets vector. Copy the offsets of this (prefix) name, + // excluding that for the trailing dot, and append the offsets of the + // suffix name with the additional offset of the length of the prefix. + // + unsigned int labels = labelcount_ + suffix.labelcount_ - 1; + isc_throw_assert(labels <= Name::MAX_LABELS); + retname.offsets_.reserve(labels); + retname.offsets_.assign(&offsets_[0], &offsets_[0] + labelcount_ - 1); + transform(suffix.offsets_.begin(), suffix.offsets_.end(), + back_inserter(retname.offsets_), + [this] (char x) { return (x + length_ - 1); }); + isc_throw_assert(retname.offsets_.size() == labels); + retname.labelcount_ = labels; + + return (retname); +} + +Name +Name::reverse() const { + Name retname; + // + // Set up offsets: The size of the string and number of labels will + // be the same in as in the original. + // + retname.offsets_.reserve(labelcount_); + retname.ndata_.reserve(length_); + + // Copy the original name, label by label, from tail to head. + NameOffsets::const_reverse_iterator rit0 = offsets_.rbegin(); + NameOffsets::const_reverse_iterator rit1 = rit0 + 1; + NameString::const_iterator n0 = ndata_.begin(); + retname.offsets_.push_back(0); + while (rit1 != offsets_.rend()) { + retname.ndata_.append(n0 + *rit1, n0 + *rit0); + retname.offsets_.push_back(retname.ndata_.size()); + ++rit0; + ++rit1; + } + retname.ndata_.push_back(0); + + retname.labelcount_ = labelcount_; + retname.length_ = length_; + + return (retname); +} + +Name +Name::split(const unsigned int first, const unsigned int n) const { + if (n == 0 || n > labelcount_ || first > labelcount_ - n) { + isc_throw(OutOfRange, "Name::split: invalid split range"); + } + + Name retname; + // If the specified range doesn't include the trailing dot, we need one + // more label for that. + unsigned int newlabels = (first + n == labelcount_) ? n : n + 1; + + // + // Set up offsets: copy the corresponding range of the original offsets + // with subtracting an offset of the prefix length. + // + retname.offsets_.reserve(newlabels); + transform(offsets_.begin() + first, offsets_.begin() + first + newlabels, + back_inserter(retname.offsets_), + [&](char x) { return (x - offsets_[first]); }); + + // + // Set up the new name. At this point the tail of the new offsets specifies + // the position of the trailing dot, which should be equal to the length of + // the extracted portion excluding the dot. First copy that part from the + // original name, and append the trailing dot explicitly. + // + retname.ndata_.reserve(retname.offsets_.back() + 1); + retname.ndata_.assign(ndata_, offsets_[first], retname.offsets_.back()); + retname.ndata_.push_back(0); + + retname.length_ = retname.ndata_.size(); + retname.labelcount_ = retname.offsets_.size(); + isc_throw_assert(retname.labelcount_ == newlabels); + + return (retname); +} + +Name +Name::split(const unsigned int level) const { + if (level >= getLabelCount()) { + isc_throw(OutOfRange, "invalid level for name split (" << level + << ") for name " << *this); + } + + return (split(level, getLabelCount() - level)); +} + +Name& +Name::downcase() { + unsigned int nlen = length_; + unsigned int labels = labelcount_; + unsigned int pos = 0; + + while (labels > 0 && nlen > 0) { + --labels; + --nlen; + + // we assume a valid name, and do abort() if the assumption fails + // rather than throwing an exception. + unsigned int count = ndata_.at(pos++); + isc_throw_assert(count <= MAX_LABELLEN); + isc_throw_assert(nlen >= count); + + while (count > 0) { + ndata_.at(pos) = + maptolower[ndata_.at(pos)]; + ++pos; + --nlen; + --count; + } + } + + return (*this); +} + +std::ostream& +operator<<(std::ostream& os, const Name& name) { + os << name.toText(); + return (os); +} + +} +} |