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Implement async DNS resolution using c-ares

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fix #2533
This commit is contained in:
Florent Le Coz
2015-02-23 13:56:08 +01:00
parent a17135720e
commit b86547dc1e
11 changed files with 499 additions and 13 deletions
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src/network/tcp_socket_handler.cpp
+161 -5
View File
@@ -1,4 +1,5 @@
#include <network/tcp_socket_handler.hpp>
#include <network/dns_handler.hpp>
#include <utils/timed_events.hpp>
#include <utils/scopeguard.hpp>
@@ -42,8 +43,22 @@ TCPSocketHandler::TCPSocketHandler(std::shared_ptr<Poller> poller):
use_tls(false),
connected(false),
connecting(false)
#ifdef CARES_FOUND
,resolved(false),
resolved4(false),
resolved6(false),
cares_addrinfo(nullptr),
cares_error()
#endif
{}
TCPSocketHandler::~TCPSocketHandler()
{
#ifdef CARES_FOUND
this->free_cares_addrinfo();
#endif
}
void TCPSocketHandler::init_socket(const struct addrinfo* rp)
{
if ((this->socket = ::socket(rp->ai_family, rp->ai_socktype, rp->ai_protocol)) == -1)
@@ -72,9 +87,35 @@ void TCPSocketHandler::connect(const std::string& address, const std::string& po
if (!this->connecting)
{
// Get the addrinfo from getaddrinfo (or ares_gethostbyname), only if
// this is the first call of this function.
#ifdef CARES_FOUND
if (!this->resolved)
{
log_info("Trying to connect to " << address << ":" << port);
// Start the asynchronous process of resolving the hostname. Once
// the addresses have been found and `resolved` has been set to true
// (but connecting will still be false), TCPSocketHandler::connect()
// needs to be called, again.
DNSHandler::instance.gethostbyname(address, this, AF_INET6);
DNSHandler::instance.gethostbyname(address, this, AF_INET);
return;
}
else
{
// The c-ares resolved the hostname and the available addresses
// where saved in the cares_addrinfo linked list. Now, just use
// this list to try to connect.
addr_res = this->cares_addrinfo;
if (!addr_res)
{
this->close();
this->on_connection_failed(this->cares_error);
return ;
}
}
#else
log_info("Trying to connect to " << address << ":" << port);
// Get the addrinfo from getaddrinfo, only if this is the first call
// of this function.
struct addrinfo hints;
memset(&hints, 0, sizeof(struct addrinfo));
hints.ai_flags = 0;
@@ -94,6 +135,7 @@ void TCPSocketHandler::connect(const std::string& address, const std::string& po
// Make sure the alloced structure is always freed at the end of the
// function
sg.add_callback([&addr_res](){ freeaddrinfo(addr_res); });
#endif
}
else
{ // This function is called again, use the saved addrinfo structure,
@@ -144,9 +186,9 @@ void TCPSocketHandler::connect(const std::string& address, const std::string& po
// If the connection has not succeeded or failed in 5s, we consider
// it to have failed
TimedEventsManager::instance().add_event(
TimedEvent(std::chrono::steady_clock::now() + 5s,
std::bind(&TCPSocketHandler::on_connection_timeout, this),
"connection_timeout"s + std::to_string(this->socket)));
TimedEvent(std::chrono::steady_clock::now() + 5s,
std::bind(&TCPSocketHandler::on_connection_timeout, this),
"connection_timeout"s + std::to_string(this->socket)));
return ;
}
log_info("Connection failed:" << strerror(errno));
@@ -321,7 +363,11 @@ bool TCPSocketHandler::is_connected() const
bool TCPSocketHandler::is_connecting() const
{
#ifdef CARES_FOUND
return this->connecting || !this->resolved;
#else
return this->connecting;
#endif
}
void* TCPSocketHandler::get_receive_buffer(const size_t) const
@@ -413,4 +459,114 @@ void TCPSocketHandler::on_tls_activated()
{
this->send_data("");
}
#endif // BOTAN_FOUND
#ifdef CARES_FOUND
void TCPSocketHandler::on_hostname4_resolved(int status, struct hostent* hostent)
{
this->resolved4 = true;
if (status == ARES_SUCCESS)
this->fill_ares_addrinfo4(hostent);
else
this->cares_error = ::ares_strerror(status);
if (this->resolved4 && this->resolved6)
{
this->resolved = true;
this->connect();
}
}
void TCPSocketHandler::on_hostname6_resolved(int status, struct hostent* hostent)
{
this->resolved6 = true;
if (status == ARES_SUCCESS)
this->fill_ares_addrinfo6(hostent);
else
this->cares_error = ::ares_strerror(status);
if (this->resolved4 && this->resolved6)
{
this->resolved = true;
this->connect();
}
}
void TCPSocketHandler::fill_ares_addrinfo4(const struct hostent* hostent)
{
struct addrinfo* prev = this->cares_addrinfo;
struct in_addr** address = reinterpret_cast<struct in_addr**>(hostent->h_addr_list);
while (*address)
{
// Create a new addrinfo list element, and fill it
struct addrinfo* current = new struct addrinfo;
current->ai_flags = 0;
current->ai_family = hostent->h_addrtype;
current->ai_socktype = SOCK_STREAM;
current->ai_protocol = 0;
current->ai_addrlen = sizeof(struct sockaddr_in);
struct sockaddr_in* addr = new struct sockaddr_in;
addr->sin_family = hostent->h_addrtype;
addr->sin_port = htons(strtoul(this->port.data(), nullptr, 10));
addr->sin_addr.s_addr = (*address)->s_addr;
current->ai_addr = reinterpret_cast<struct sockaddr*>(addr);
current->ai_next = nullptr;
current->ai_canonname = nullptr;
current->ai_next = prev;
this->cares_addrinfo = current;
prev = current;
++address;
}
}
void TCPSocketHandler::fill_ares_addrinfo6(const struct hostent* hostent)
{
struct addrinfo* prev = this->cares_addrinfo;
struct in6_addr** address = reinterpret_cast<struct in6_addr**>(hostent->h_addr_list);
while (*address)
{
// Create a new addrinfo list element, and fill it
struct addrinfo* current = new struct addrinfo;
current->ai_flags = 0;
current->ai_family = hostent->h_addrtype;
current->ai_socktype = SOCK_STREAM;
current->ai_protocol = 0;
current->ai_addrlen = sizeof(struct sockaddr_in6);
struct sockaddr_in6* addr = new struct sockaddr_in6;
addr->sin6_family = hostent->h_addrtype;
addr->sin6_port = htons(strtoul(this->port.data(), nullptr, 10));
::memcpy(addr->sin6_addr.s6_addr, (*address)->s6_addr, 16);
addr->sin6_flowinfo = 0;
addr->sin6_scope_id = 0;
current->ai_addr = reinterpret_cast<struct sockaddr*>(addr);
current->ai_next = nullptr;
current->ai_canonname = nullptr;
current->ai_next = prev;
this->cares_addrinfo = current;
prev = current;
++address;
}
}
void TCPSocketHandler::free_cares_addrinfo()
{
while (this->cares_addrinfo)
{
delete this->cares_addrinfo->ai_addr;
auto next = this->cares_addrinfo->ai_next;
delete this->cares_addrinfo;
this->cares_addrinfo = next;
}
}
#endif // CARES_FOUND