Creating an IPv6 Socket failed with invalid IP - seems to get truncated - c++

Question

I am currently learning C++ and I'm working on a library that will allow sockets to be created on Windows and Linux, supporting IPv4 and IPv6.
I've got it working fine on IPv4 but I'm having a problem with IPv6.
I've tried doing it so it binds to an IP address or binds to a specific IPV6 address but either fail.
Below is how I create a socket.
this->serverSocket = socket(family, socketType, 0);
if (this->serverSocket < 0)
{
stringstream logstream;
logstream << "Error opening socket. Most likely trying to bind to an ";
logstream << "invalid IP or the port is already in use";
bitsLibrary->writeToLog(logstream.str(), "LinuxSocket", "createSocket");
return false;
}
switch (family)
{
case AF_INET: {
this->serv_addr = new sockaddr();
bzero((sockaddr*)this->serv_addr, sizeof(this->serv_addr));
sockaddr_in *sin = reinterpret_cast<sockaddr_in*>(serv_addr);
sin->sin_family = family;
//sin->sin_addr.s_addr = INADDR_ANY;
//If IP Address is NULL then set to IPADDR_ANY
if (ipAddress.empty())
{
sin->sin_addr.s_addr = INADDR_ANY;
}
else
{
inet_pton(AF_INET, ipAddress.c_str(), &sin->sin_addr);
}
sin->sin_port = htons(port);
break;
}
case AF_INET6: {
this->serv_addr = new sockaddr();
bzero((sockaddr*)this->serv_addr, sizeof(this->serv_addr));
sockaddr_in6 *sin = reinterpret_cast<sockaddr_in6*>(serv_addr);
sin->sin6_family = family;
if (ipAddress.empty())
{
sin->sin6_addr = IN6ADDR_ANY_INIT;
}
else
{
inet_pton(AF_INET6, ipAddress.c_str(), &(sin->sin6_addr));
}
sin->sin6_port = htons(port);
break;
}
default:
this->bitsLibrary->writeToLog("Invalid socket family. Only AF_INET or AF_INET6 is supported");
return false;
}
Below is how I then bind the socket
stringstream logstream;
int result = bind(this->serverSocket, (sockaddr * )serv_addr, sizeof(*serv_addr));
if (result < 0)
{
logstream << "Failed to bind socket. Error: " << strerror(result);
throw SocketException(logstream.str().c_str());
close(this->serverSocket);
return false;
}
result = listen(this->serverSocket, this->socketPort);
if (result < 0)
{
logstream << "Failed to start listening. Socket Error: " << strerror(result);
throw SocketException(logstream.str().c_str());
}
logstream << "Socket " << this->socketPort << " has been successfully bound";
this->bitsLibrary->writeToLog(logstream.str(), "LinuxSocket", "bindAndStartListening");
return true;
I call the create socket function as follows
if (!socketManager.createSocket(AF_INET6, SOCK_STREAM, 500, 50, "fe80::20c:29ff:fea0:7da8"))
The bind returns -1 strerror says an unknown error occurred.
The IP address that I am passing into createSocket method is fe80::20c:29ff:fea0:7da8.
When I run my program through strace I then get the following on the bind
socket(PF_INET6, SOCK_STREAM, IPPROTO_IP) = 4
bind(4, {sa_family=AF_INET6, sin6_port=htons(500), inet_pton(AF_INET6, "fe80::", &sin6_addr), sin6_flowinfo=0, sin6_scope_id=0}, 16) = -1 EINVAL (Invalid argument)
Notice that the IP has been truncated to fe80::.
If I don't use an IP so it binds to anything the IP is then ::
Update
Below is the code I have changed for the AF_INET6 socket.
case AF_INET6: {
this->serv_addr = new sockaddr_storage();
bzero((sockaddr_in6*)this->serv_addr, sizeof(this->serv_addr));
sockaddr_in6 *sin = reinterpret_cast<sockaddr_in6*>(serv_addr);
sin->sin6_family = family;
if (ipAddress.empty())
{
sin->sin6_addr = IN6ADDR_ANY_INIT;
}
else
{
inet_pton(AF_INET6, ipAddress.c_str(), &sin->sin6_addr);
}
sin->sin6_port = htons(port);
break;
}
I've also change this->servAddr is sockaddr_storage in the header as suggested

Answer 1

At least on Windows, sizeof(sockaddr) < sizeof(sockaddr_in6). When you allocate memory for this->serv_addr, you allocate not enough, then corrupt your heap block, and then you have bugs.
It's suggested that you use sockaddr_storage which is "Large enough to accommodate all supported protocol-specific address structures". Or you can allocate different structures in different cases, which shouldn't be a problem for the rest of your code.
UPDATE 1
There still seems to be a few mistakes in your code. You need to check all references to this->serv_addr and verify types/sizeof's.
-- Example 1: You bzero() a wrong number of bytes here - not only a wrong sizeof of wrong type, but also you do sizeof on a pointer:
bzero((sockaddr_in6*)this->serv_addr, sizeof(this->serv_addr));
Should be fixed like that:
sockaddr_in6 *sin = reinterpret_cast<sockaddr_in6*>(serv_addr);
bzero(sin, sizeof(*sin));
-- Example 2: You pass wrong buffer size here:
int result = bind(this->serverSocket, (sockaddr * )serv_addr, sizeof(*serv_addr));
You should remember the actual size for this->serv_addr at the time you allocate it and pass this size to bind()