IBM MQ MQCONN from host to Docker container - c

Question

Trying to connect from a C application running as an IBM MQ client on a host to an MQ server running as a docker container.
The client code taken from an IBM example is provided below.
The questions is which protocol is used when MQCONN is called as no IP/port is provided? I can only guess it is some kind of an IPC.
For this reason I'm running the docker container with --ipc="host" option, but it still fails with CompCode=2, Reason=2058
#include <cmqc.h>
⋮
static char Parm1[MQ_Q_MGR_NAME_LENGTH] ;
⋮
int main(int argc, char *argv[] )
{
/* */
/* Variables for MQ calls */
/* */
MQHCONN Hconn; /* Connection handle */
MQLONG CompCode; /* Completion code */
MQLONG Reason; /* Qualifying reason */
⋮
/* Copy the queue manager name, passed in the */
/* parm field, to Parm1 */
strncpy(Parm1,argv[1],MQ_Q_MGR_NAME_LENGTH);
⋮
/* */
/* Connect to the specified queue manager. */
/* Test the output of the connect call. If the */
/* call fails, print an error message showing the */
/* completion code and reason code, then leave the */
/* program. */
/* */
MQCONN(Parm1,
&Hconn,
&CompCode,
&Reason);
if ((CompCode != MQCC_OK) | (Reason != MQRC_NONE))
{
sprintf(pBuff, MESSAGE_4_E,
ERROR_IN_MQCONN, CompCode, Reason);
PrintLine(pBuff);
RetCode = CSQ4_ERROR;
goto AbnormalExit2;
}
⋮
}

Answer 1

If your program will be running on the same server as the queue manager then it is best to link it with 'mqm.lib' (bindings mode) rather than 'mqic.lib' (client mode).
In the MQ KnowLedge Center, there are examples on how to compile and link your C program. The examples are listed as: 'C client application' (client mode) and 'C server application' (bindings mode).
If in the future, your C program needs to connect to a remote queue manager then you need to link it for 'client mode'.
To configure your C program to handle proper MQ security, change the MQCONN API call to MQCONNX API call.
i.e.
MQCNO cno = {MQCNO_DEFAULT};
MQCD cd = {MQCD_CLIENT_CONN_DEFAULT};
MQCSP csp = {MQCSP_DEFAULT};
strncpy(cd.ConnectionName, hostname, MQ_CONN_NAME_LENGTH);
strncpy(cd.ChannelName, channelName, MQ_CHANNEL_NAME_LENGTH);
csp.AuthenticationType = MQCSP_AUTH_USER_ID_AND_PWD;
csp.CSPUserIdPtr = &myUserId;
csp.CSPUserIdOffset = 0;
csp.CSPUserIdLength = strlen(myUserId);
csp.CSPPasswordPtr = &myPassword;
csp.CSPPasswordOffset = 0;
csp.CSPPasswordLength = strlen(myPassword);
cno.cdPtr = &cd;
cno.Version = MQCNO_CURRENT_VERSION;
cno.SecurityParmsPtr = &csp;
cno.SecurityParmsOffset = 0;
MQCONNX(QMgrName, &cno, &Hcon, &CompCode, &Reason);
A few years ago, I wrote a blog posting called: MQ API Verbs that IBM Forgot!!. I created wraps for MQCONN and MQCONNX that will allow the program to pass UserId & Password for MQCONN and MQCONNX API calls. You may find it easier to simply use the wrappers.