nameinfo.c

#include <stdio.h>
#include <stdlib.h>
#include <rdma/fabric.h>
#include <rdma/fi_eq.h>
#include <rdma/fi_endpoint.h>
#include <rdma/fi_cm.h>
#include <rdma/fi_errno.h>
#include <string.h>
#include <netinet/in.h>
#include <netdb.h>
#include <arpa/inet.h>
#include <sys/socket.h>
#include <sys/epoll.h>

#define ERROR(x, ...) \
do { \
  fprintf(stderr, "error: "x"\n", __VA_ARGS__);\
  exit(EXIT_FAILURE);\
} while(0)

union sockaddr_any {
  struct sockaddr   sa;
  struct sockaddr_in  sin;
  struct sockaddr_in6 sin6;
  struct sockaddr_storage ss;
};


struct listen_socket
{
  struct fi_info* fi;
  struct fid_fabric *fabric;
  struct fid_eq *eq;
  struct fid_pep *pep;
  int fd;
};



static const char *
sockaddrstr(const union sockaddr_any *addr, socklen_t len, char *buf, size_t buflen, unsigned short* port)
{
  static char namebuf[BUFSIZ];
  static char servbuf[BUFSIZ];
  int errcode;

  if ((errcode = getnameinfo(&addr->sa, len, namebuf, BUFSIZ,
    servbuf, BUFSIZ,
    NI_NUMERICHOST | NI_NUMERICSERV)))
  {
    if (errcode != EAI_SYSTEM) {
      ERROR("getnameinfo failed: %s", gai_strerror(errcode));
    } else {
      ERROR("getnameinfo failed: %s", strerror(errno));
    }
  }

  snprintf(buf, buflen, "%s", namebuf);
  *port = atoi(servbuf);
  return buf;
}



static void
print_endpoint(struct listen_socket* socket)
{
  union sockaddr_any addr;
  memset(&addr, 0, sizeof(addr));
  size_t addrlen = sizeof(addr);

  int ret;
  if((ret = fi_getname(&socket->pep->fid, &addr, &addrlen)))
  {
    ERROR("fi_getname failed: %d '%s'", ret, fi_strerror(-ret));
  }

  char buf[128];
  unsigned short port;
  const char* straddr = sockaddrstr(&addr, addrlen, buf, 128, &port);

  printf("endpoint = %s:%d\n", straddr, port);
}





void listen_server(struct listen_socket* socket, const char* address)
{
  int ret;
  struct epoll_event ev;
  struct fi_info* hints;
  struct fi_eq_attr eq_attr = {
    .wait_obj = FI_WAIT_FD
  };

  hints = fi_allocinfo();
  hints->ep_attr->type  = FI_EP_MSG;
  hints->caps = FI_MSG;
  hints->mode = FI_LOCAL_MR;

  if(ret = fi_getinfo(FI_VERSION(1, 0), address, "0", FI_SOURCE, hints, &socket->fi)) {
    ERROR("fi_getinfo failed: %d '%s'", ret, fi_strerror(-ret));
  }

  //printf("info: %s\n", fi_tostr(socket->fi, FI_TYPE_INFO));

  if(ret = fi_fabric(socket->fi->fabric_attr, &socket->fabric, NULL)) {
    ERROR("fi_fabric failed: %d", ret);
  }

  if(ret = fi_eq_open(socket->fabric, &eq_attr, &socket->eq, NULL)) {
    ERROR("fi_eq_open failed: %d", ret);
  }

  if(ret = fi_passive_ep(socket->fabric, socket->fi, &socket->pep, NULL)) {
    ERROR("fi_passive_ep failed: %d", ret);
  }

  if(ret = fi_pep_bind(socket->pep, &socket->eq->fid, 0)) {
    ERROR("fi_pep_bind failed: %d", ret);
  }
  
  if(ret = fi_listen(socket->pep)) {
    ERROR("fi_listen failed: %d '%s'", ret, fi_strerror(-ret));
  }  

  print_endpoint(socket);
}



int main()
{
  int ret;
  struct listen_socket lsocket;

  listen_server(&lsocket, "127.0.0.1");
  listen_server(&lsocket, "0.0.0.0");

  return 0;
}

Output of the above program:

endpoint = 127.0.0.1:46542
endpoint = 137.138.90.204:0

The first time with the fixed IP address the port gets auto-assigned, but the second time not.