3rd-party/libtins
1
0
Fork 0
mirror of https://github.com/mfontanini/libtins synced 2026-01-23 02:35:57 +01:00
Code Issues Releases Wiki Activity

Parse and serialize MX preference field correctly

Browse Source
This commit is contained in:
Matias Fontanini
2016-01-11 15:48:03 -08:00
parent 75add84741
commit ca56cc10dd
3 changed files with 89 additions and 21 deletions
Download Patch File Download Diff File Expand all files Collapse all files

63
include/tins/dns.h
View File

@@ -236,11 +236,16 @@ public:
* \param rclass The class of this record.
* \param ttl The time-to-live of this record.
*/
Resource(const std::string& dname, const std::string& data,
uint16_t type, uint16_t rclass, uint32_t ttl)
: dname_(dname), data_(data), type_(type), qclass_(rclass), ttl_(ttl) {}
Resource(const std::string& dname,
const std::string& data,
uint16_t type,
uint16_t rclass,
uint32_t ttl,
uint16_t preference = 0)
: dname_(dname), data_(data), type_(type), qclass_(rclass),
ttl_(ttl), preference_(preference) {}
Resource() : type_(), qclass_(), ttl_() {}
Resource() : type_(), qclass_(), ttl_(), preference_() {}
/**
* \brief Getter for the domain name field.
@@ -248,27 +253,46 @@ public:
* This returns the domain name for which this record
* provides an answer.
*/
const std::string& dname() const { return dname_; }
const std::string& dname() const {
return dname_;
}
/**
* Getter for the data field.
*/
const std::string& data() const { return data_; }
const std::string& data() const {
return data_;
}
/**
* Getter for the query type field.
*/
uint16_t type() const { return type_; }
uint16_t type() const {
return type_;
}
/**
* Getter for the query class field.
*/
uint16_t query_class() const { return qclass_; }
uint16_t query_class() const {
return qclass_;
}
/**
* Getter for the type field.
* Getter for the time-to-live field.
*/
uint32_t ttl() const { return ttl_; }
uint32_t ttl() const {
return ttl_;
}
/**
* \brief Getter for the preferece field.
*
* This field is only valid for MX resources.
*/
uint16_t preference() const {
return preference_;
}
/**
* Setter for the domain name field.
@@ -313,10 +337,20 @@ public:
void ttl(uint32_t data) {
ttl_ = data;
}
/**
* \brief Setter for the preference field.
*
* This field is only valid for MX resources.
*/
void preference(uint16_t data) {
preference_ = data;
}
private:
std::string dname_, data_;
uint16_t type_, qclass_;
uint32_t ttl_;
uint16_t preference_;
};
typedef std::list<Query> queries_type;
@@ -711,11 +745,16 @@ private:
typedef std::vector<std::pair<uint32_t*, uint32_t> > sections_type;
uint32_t compose_name(const uint8_t* ptr, char* out_ptr) const;
void convert_records(const uint8_t* ptr, const uint8_t* end, resources_type& res) const;
void convert_records(const uint8_t* ptr,
const uint8_t* end,
resources_type& res) const;
void skip_to_section_end(Memory::InputMemoryStream& stream,
const uint32_t num_records) const;
void skip_to_dname_end(Memory::InputMemoryStream& stream) const;
void update_records(uint32_t& section_start, uint32_t num_records, uint32_t threshold, uint32_t offset);
void update_records(uint32_t& section_start,
uint32_t num_records,
uint32_t threshold,
uint32_t offset);
uint8_t* update_dname(uint8_t* ptr, uint32_t threshold, uint32_t offset);
static void inline_convert_v4(uint32_t value, char* output);
static bool contains_dname(uint16_t type);

24
src/dns.cpp
View File

@@ -203,7 +203,8 @@ void DNS::add_record(const Resource& resource, const sections_type& sections) {
// will end up being inconsistent.
IPv4Address v4_addr;
IPv6Address v6_addr;
string buffer = encode_domain_name(resource.dname()), encoded_data;
string buffer = encode_domain_name(resource.dname()),
encoded_data;
// By default the data size is the length of the data field.
size_t data_size = resource.data().size();
if (resource.type() == A) {
@@ -220,13 +221,17 @@ void DNS::add_record(const Resource& resource, const sections_type& sections) {
}
size_t offset = buffer.size() + sizeof(uint16_t) * 3 + sizeof(uint32_t) + data_size,
threshold = sections.empty() ? records_data_.size() :* sections.front().first;
// Skip the preference field
// Take into account the MX preference field
if (resource.type() == MX) {
offset += sizeof(uint16_t);
}
for (size_t i = 0; i < sections.size(); ++i) {
update_records(*sections[i].first, sections[i].second,
static_cast<uint32_t>(threshold), static_cast<uint32_t>(offset));
update_records(
*sections[i].first,
sections[i].second,
static_cast<uint32_t>(threshold),
static_cast<uint32_t>(offset)
);
}
records_data_.insert(
@@ -241,7 +246,7 @@ void DNS::add_record(const Resource& resource, const sections_type& sections) {
stream.write_be(resource.ttl());
stream.write_be<uint16_t>(data_size + (resource.type() == MX ? 2 : 0));
if (resource.type() == MX) {
stream.skip(sizeof(uint16_t));
stream.write_be(resource.preference());
}
if (resource.type() == A) {
stream.write(v4_addr);
@@ -380,15 +385,15 @@ void DNS::convert_records(const uint8_t* ptr,
// Retrieve the record's domain name.
stream.skip(compose_name(stream.pointer(), dname));
// Retrieve the following fields.
uint16_t type, qclass, data_size;
uint16_t type, qclass, data_size, preference = 0;
uint32_t ttl;
type = stream.read_be<uint16_t>();
qclass = stream.read_be<uint16_t>();
ttl = stream.read_be<uint32_t>();
data_size = stream.read_be<uint16_t>();
// Skip the preference field if it's MX
// Read the preference field if it's MX
if (type == MX) {
stream.skip(sizeof(uint16_t));
preference = stream.read_be<uint16_t>();
data_size -= sizeof(uint16_t);
}
if (!stream.can_read(data_size)) {
@@ -431,7 +436,8 @@ void DNS::convert_records(const uint8_t* ptr,
(used_small_buffer) ? small_addr_buf : addr,
type,
qclass,
ttl
ttl,
preference
)
);
}

23
tests/src/dns.cpp
View File

@@ -118,6 +118,7 @@ TEST_F(DNSTest, ConstructorFromBuffer2) {
}
DNS::resources_type resources = dns.answers();
size_t resource_index = 0;
for(DNS::resources_type::const_iterator it = resources.begin(); it != resources.end(); ++it) {
EXPECT_EQ("google.com", it->dname());
EXPECT_EQ(DNS::MX, it->type());
@@ -130,6 +131,13 @@ TEST_F(DNSTest, ConstructorFromBuffer2) {
it->data() == "alt5.aspmx.l.google.com" ||
it->data() == "aspmx.l.google.com"
);
if (resource_index == 0) {
EXPECT_EQ(50, it->preference());
}
else if (resource_index == 1) {
EXPECT_EQ(40, it->preference());
}
resource_index++;
}
// Add some stuff and see if something gets broken
if(i == 0) {
@@ -450,3 +458,18 @@ TEST_F(DNSTest, ItAintGonnaCorrupt) {
EXPECT_EQ(it->query_class(), DNS::IN);
}
}
TEST_F(DNSTest, MXPreferenceField) {
DNS dns1;
dns1.add_answer(
DNS::Resource("example.com", "mail.example.com", DNS::MX, DNS::IN, 0x762, 42)
);
DNS::serialization_type buffer = dns1.serialize();
DNS dns2(&buffer[0], buffer.size());
DNS::resources_type answers = dns1.answers();
ASSERT_EQ(1, answers.size());
const DNS::Resource& resource = *answers.begin();
EXPECT_EQ(42, resource.preference());
EXPECT_EQ("example.com", resource.dname());
}