imap client - how to compose proper request? - c++

Question

I'm trying to make simple IMAP client using winsock/OpenSSL, is this possible without additional libraries? If so, how to send request and get responce? Server is responding only once,even without request,after that i'm sending request and application stuck at SSL_read(..) function,than timeout and BYE.How to make proper request?
bool RequestQueue(const char* serverName)
{
SOCKET hSocket = INVALID_SOCKET;
char receiveBuf[512];
ZeroMemory(receiveBuf,512);
char requestBuf[512];
ZeroMemory(requestBuf,512);
sockaddr_in sockAddr = {0};
bool bSuccess = true;
//SSL
SSL* ssl;
SSL_CTX* ctx;
try
{
//Look up hostname and fill sockaddr_in structure
cout<< "Looking up hostname "<<serverName<<"...";
FillSockAddr(&sockAddr,serverName,IMAP_SERVER_PORT);
cout<< "found.\n";
//creating socket
cout<<"Creating socket..";
if((hSocket = socket(AF_INET,SOCK_STREAM,IPPROTO_TCP)) == INVALID_SOCKET)
throw exception("could not create socket!");
cout<<"created.\n";
//Connect to server
cout<<"Attempting to connect to "<< inet_ntoa(sockAddr.sin_addr)
<<":"<<IMAP_SERVER_PORT<<" ...";
if(connect(hSocket,(sockaddr*)(&sockAddr),sizeof(sockAddr))!= 0)
throw exception("could not connect!");
cout<<"connected\n";
ctx = SSL_CTX_new(SSLv23_client_method());
if(!ctx)
throw exception("SSL_CTX_new error");
ssl = SSL_new(ctx);
SSL_CTX_free(ctx);
if(!ssl)
throw exception("ssl initializing error");
SSL_set_fd(ssl,hSocket);
if(SSL_connect(ssl) != 1)
throw exception("SSL_connect error");
int reqLen;
int retLen;
cout<<"==============\n";
cout<<"====begin=====\n";
cout<<"==============\n";
retLen = SSL_read(ssl,receiveBuf,sizeof(receiveBuf));
if(retLen<0)
throw exception("SSL_read error.");
cout<<"S: "<<receiveBuf;
strcpy(requestBuf,"a001 CAPABILITY");
reqLen = strlen(requestBuf);
SSL_write(ssl,requestBuf,reqLen);
cout<<"C: "<<requestBuf<<endl;
ZeroMemory(receiveBuf,sizeof(receiveBuf));
retLen = SSL_read(ssl,receiveBuf,sizeof(receiveBuf));
if(retLen<0)
throw exception("SSL_read error.");
cout<<"S: "<<receiveBuf;
}
catch(exception e)
{
cout<<"Error : "<<e.what()<<endl;
}
if(hSocket != INVALID_SOCKET)
{
SSL_shutdown(ssl);
closesocket(hSocket);
SSL_free(ssl);
}
return bSuccess;
}

Answer 1

I didn't analyze your code deeply, but I can see one obvious issue.
According to the RFC 3501:
All interactions transmitted by client and server are in the form of
lines, that is, strings that end with a CRLF. The protocol receiver
of an IMAP4rev1 client or server is either reading a line, or is
reading a sequence of octets with a known count followed by a line.
In your code you're not terminating the command with CRLF. Try replacing
strcpy(requestBuf,"a001 CAPABILITY");
with
strcpy(requestBuf,"a001 CAPABILITY\r\n");
Also, you'd better start without SSL and add it later - this will simplify debugging a lot (i.e. with Wireshark).