LIBSSH2 C++ with dual stack IPv4 and IPv6 - c++

Question

I am working on a C++ project that needs to establish a connection via SSH to a remote server and execute some commands and transfer files via SFTP. However, I need this application to work in dual stack mode (e.g., with IPv6 and IPv4) mode.
In the snippet below, my program initially receives an host-name, IPv6 or IPv4 address. In the IPv4 input the connection is successful. However, I am having strange problems in the IPv6 mode that I am noticing that the connection is established via socket and the SSH session fails to start.
Currently, I believe it could be something related to the inet_ntop() method. Please notice that remoteHost variable is an char* type and the remotePort is uint16_t type.
// Initialize some important variables
uint32_t hostaddr = 0, hostaddr6 = 0;
struct sockaddr_in sin = {};
struct sockaddr_in6 sinV6 = {};
int rc = 0, sock = 0, i = 0, auth_pw = 0;
// Here we will initialize our base class with username and password
this->username = usrName;
this->password = usrPassword;
// Firstly, we need to translate the hostname into an IPv4 or IPv6 address
struct addrinfo hints={}, *sAdrInfo = {};
char addrstr[100]={};
void *ptr= nullptr;
char addrParsed[50]={};
memset (&hints, 0, sizeof (hints));
hints.ai_family = PF_UNSPEC;
hints.ai_socktype = SOCK_STREAM;
hints.ai_flags |= AI_CANONNAME;
// Now we need to get some address info from the one supplied that remoteHost parameter
int errcode = getaddrinfo (remoteHost, nullptr, &hints, &sAdrInfo);
if (errcode != 0) {
SERVER_ERROR("[SSH] Error while getaddrinfo at SSHConnect() code %d", errno);
return -4;
}
inet_ntop(sAdrInfo->ai_family, sAdrInfo->ai_addr->sa_data, addrstr, 100);
// Here we need to determine if we are using IPv6 or IPv4
switch (sAdrInfo->ai_family) {
case AF_INET6:
ptr = &((struct sockaddr_in6 *) sAdrInfo->ai_addr)->sin6_addr;
break;
case AF_INET:
ptr = &((struct sockaddr_in *) sAdrInfo->ai_addr)->sin_addr;
break;
}
inet_ntop(sAdrInfo->ai_family, ptr, addrstr, 100);
sprintf(addrParsed, "%s", addrstr);
//This part is responsible for creating the socket and establishing the connection
// Now if we have an IPv4 based host
if (sAdrInfo->ai_family == AF_INET) {
this->hostaddr = inet_addr(addrParsed);
sock = socket(AF_INET, SOCK_STREAM, 0);
sin.sin_family = AF_INET;
// Now we need to set these (address and port to our sockaddr_in variable sin)
sin.sin_port = htons(remotePort);
memcpy(&sin.sin_addr, &hostaddr, sizeof(hostaddr));
}
// Now if we have an IPv6 based host
else if (sAdrInfo->ai_family == AF_INET6) {
this->hostaddr6 = inet_addr(addrParsed);
sock = socket(AF_INET6, SOCK_STREAM, 0);
sin.sin_family = AF_INET6;
// Now we need to set these (address and port to our sockaddr_in variable sin)
sinV6.sin6_port = htons(remotePort);
memcpy(&sinV6.sin6_addr.s6_addr32, &hostaddr6, sizeof(this->hostaddr6));
}
// Now we need to connect to our socket :D
if (sAdrInfo->ai_family == AF_INET) {
int resCon = connect(sock, (struct sockaddr*)(&sin), sizeof(struct sockaddr_in));
if (resCon != 0){
SERVER_ERROR("[SSH] failed to connect with error code: %d!\n", errno);
return -1;
}
}
else if (sAdrInfo->ai_family == AF_INET6) {
int resCon = connect(sock, (struct sockaddr*)(&sinV6), sizeof(struct sockaddr_in6));
if (resCon != 0){
SERVER_ERROR("[SSH] failed to connect with error code: %d!\n", errno);
return -1;
}
}
// Free our result variables
freeaddrinfo(sAdrInfo);
// Create a session instance
session = libssh2_session_init();
if(!session) {
return -2;
}
/* Now to start the session. Here will trade welcome banners, exchange keys and setup crypto, compression,
* and MAC layers */
rc = libssh2_session_handshake(session, sock);
if(rc) {
SERVER_ERROR("Failure establishing SSH session: %d\n", rc);
return -3;
}
What is wrong with the implementation that is generating the "Failure establishing SSH session" message with IPv6 stack?
Best regards,