// HostnameLookup.cpp
// Implements the cHostnameLookup class representing an in-progress hostname-to-IP lookup
#include "Globals.h"
#include "HostnameLookup.h"
#include <event2/dns.h>
#include "NetworkSingleton.h"
////////////////////////////////////////////////////////////////////////////////
// cHostnameLookup:
cHostnameLookup::cHostnameLookup(cNetwork::cResolveNameCallbacksPtr a_Callbacks):
m_Callbacks(a_Callbacks)
{
}
void cHostnameLookup::Lookup(const AString & a_Hostname)
{
// Store the hostname for the callback:
m_Hostname = a_Hostname;
// Start the lookup:
// Note that we don't have to store the LibEvent lookup handle, LibEvent will free it on its own.
evutil_addrinfo hints;
memset(&hints, 0, sizeof(hints));
hints.ai_protocol = IPPROTO_TCP;
hints.ai_socktype = SOCK_STREAM;
hints.ai_family = AF_UNSPEC;
hints.ai_flags = EVUTIL_AI_CANONNAME;
evdns_getaddrinfo(cNetworkSingleton::Get().GetDNSBase(), a_Hostname.c_str(), nullptr, &hints, Callback, this);
}
void cHostnameLookup::Callback(int a_ErrCode, evutil_addrinfo * a_Addr, void * a_Self)
{
// Get the Self class:
cHostnameLookup * Self = reinterpret_cast<cHostnameLookup *>(a_Self);
ASSERT(Self != nullptr);
// If an error has occurred, notify the error callback:
if (a_ErrCode != 0)
{
Self->m_Callbacks->OnError(a_ErrCode, evutil_socket_error_to_string(a_ErrCode));
cNetworkSingleton::Get().RemoveHostnameLookup(Self);
return;
}
// Call the success handler for each entry received:
bool HasResolved = false;
evutil_addrinfo * OrigAddr = a_Addr;
for (;a_Addr != nullptr; a_Addr = a_Addr->ai_next)
{
char IP[128];
switch (a_Addr->ai_family)
{
case AF_INET: // IPv4
{
sockaddr_in * sin = reinterpret_cast<sockaddr_in *>(a_Addr->ai_addr);
if (!Self->m_Callbacks->OnNameResolvedV4(Self->m_Hostname, sin))
{
// Callback indicated that the IP shouldn't be serialized to a string, just continue with the next address:
HasResolved = true;
continue;
}
evutil_inet_ntop(AF_INET, &(sin->sin_addr), IP, sizeof(IP));
break;
}
case AF_INET6: // IPv6
{
sockaddr_in6 * sin = reinterpret_cast<sockaddr_in6 *>(a_Addr->ai_addr);
if (!Self->m_Callbacks->OnNameResolvedV6(Self->m_Hostname, sin))
{
// Callback indicated that the IP shouldn't be serialized to a string, just continue with the next address:
HasResolved = true;
continue;
}
evutil_inet_ntop(AF_INET6, &(sin->sin6_addr), IP, sizeof(IP));
break;
}
default:
{
// Unknown address family, handle as if this entry wasn't received
continue; // for (a_Addr)
}
}
Self->m_Callbacks->OnNameResolved(Self->m_Hostname, IP);
HasResolved = true;
} // for (a_Addr)
// If only unsupported families were reported, call the Error handler:
if (!HasResolved)
{
Self->m_Callbacks->OnError(DNS_ERR_NODATA, "The name does not resolve to any known address.");
}
else
{
Self->m_Callbacks->OnFinished();
}
evutil_freeaddrinfo(OrigAddr);
cNetworkSingleton::Get().RemoveHostnameLookup(Self);
}
////////////////////////////////////////////////////////////////////////////////
// cNetwork API:
bool cNetwork::HostnameToIP(
const AString & a_Hostname,
cNetwork::cResolveNameCallbacksPtr a_Callbacks
)
{
auto Lookup = std::make_shared<cHostnameLookup>(a_Callbacks);
cNetworkSingleton::Get().AddHostnameLookup(Lookup);
Lookup->Lookup(a_Hostname);
return true;
}
