Select between TCP socket and UDP socket(c)

Question

i'm making a server in c that handles both a tcp connection for an admin to change server configs and a udp connection to handle multiple clients

Here is my code:

    struct sockaddr_in si_minhaTCP,si_minhaUDP, si_outra;
    int nready, maxfdp1;
    int fdTcp;
    int fdUdp;
    fd_set rset;
    if (argc != 4) {
    printf("server {client port(udp)} {admin port(tcp)} {registry file path}\n");
    exit(-1);
  }

    fdTcp = socket(AF_INET, SOCK_STREAM, 0);
    bzero(&si_minhaTCP, sizeof(si_minhaTCP));
    si_minhaTCP.sin_family = AF_INET;
    si_minhaTCP.sin_addr.s_addr = htonl(INADDR_ANY);
    si_minhaTCP.sin_port = htons((short) atoi(argv[2]));
    bind(fdTcp, (struct sockaddr*)&si_minhaTCP, sizeof(si_minhaTCP));
    listen(fdTcp, 10);


        
    fdUdp = socket(AF_INET, SOCK_DGRAM, 0);
    si_minhaUDP.sin_family = AF_INET;
    si_minhaUDP.sin_addr.s_addr = htonl(INADDR_ANY);
    si_minhaUDP.sin_port = htons((short) atoi(argv[1]));
    bind(fdUdp, (struct sockaddr*)&si_minhaUDP, sizeof(si_minhaUDP));


    FD_ZERO(&rset);

    maxfdp1 = max(fdTcp, fdUdp) + 1;
    for (;;)
    {
      FD_SET(fdTcp, &rset);
      FD_SET(fdUdp, &rset);
      // select the ready descriptor

      nready = select(maxfdp1, &rset, NULL, NULL, NULL);
      if (FD_ISSET(fdTcp, &rset))
      {

          //handle tcp connection
      }
      if (FD_ISSET(fdUdp, &rset))
      {
          //handle udp connection
      }

    }
           

When i run this code, and try to test it with a udp client it doesnt do anything

Answer 1

However you can use ports below 1024 if you run the program as root and have no other programs running, that already use that ports...