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  1. #include <sys/types.h>
  2. #include <sys/socket.h>
  3. #include <netdb.h>
  4. #include <unistd.h>
  5. #include <cstdio>
  6. #include <cerrno>
  7. #include <cstdlib>
  8. #include <poll.h>
  9. #include <vector>
  10. #include <arpa/inet.h>
  11.  
  12. int main (int ac, char **av) {
  13.  
  14.   if(ac != 2) {
  15.     fprintf(stderr, "Usage: %s portnumber\n", *av);
  16.     return 1;
  17.   }
  18.  
  19.   struct addrinfo *res0;
  20.   struct addrinfo hints = { 0, 0, SOCK_DGRAM };
  21.   int rc = getaddrinfo(0, av[1], &hints, &res0);
  22.   if(rc) {
  23.     fprintf(stderr, "%s/%s: %s\n", av[1], av[2], gai_strerror(rc));
  24.     return 1;
  25.   }
  26.  
  27.   char *name = res0->ai_canonname;
  28.   std::vector<pollfd> fds;
  29.   for(struct addrinfo *res = res0; res; res=res->ai_next) {
  30.     fprintf(stderr, "%s: ", name);
  31.     int fd = socket(res->ai_family, res->ai_socktype, res->ai_protocol);
  32.     if(fd < 0) {
  33.       perror("socket");
  34.       continue;
  35.     }
  36.  
  37.     rc = bind(fd, res->ai_addr, res->ai_addrlen);
  38.     if(rc < 0) {
  39.       perror("bind");
  40.       continue;
  41.     }
  42.     fprintf(stderr, "Bound (%d)\n", fd);
  43.     fds.push_back(pollfd({fd, POLLIN}));
  44.   }
  45.   freeaddrinfo(res0);
  46.  
  47.   while( (rc = poll( &fds[0], fds.size(), -1)) > 0 ) {
  48.     for(size_t i = 0; i < fds.size(); ++i) {
  49.       pollfd& pfd = fds[i];
  50.       if(!pfd.revents)
  51.         continue;
  52.       pfd.revents = 0;
  53.  
  54.       union {
  55.         sockaddr s;
  56.         sockaddr_in sin;
  57.         sockaddr_in6 sin6;
  58.       } u;
  59.       rc = recv(pfd.fd, &u, sizeof u, 0);
  60.       if(rc < 0) {
  61.         perror("recv");
  62.         continue;
  63.       }
  64.       fprintf(stderr, "Received %d bytes\n", rc);
  65.  
  66.       char str[256];
  67.       switch(ntohs(u.s.sa_family)) {
  68.       case AF_INET:
  69.         if(inet_ntop(AF_INET, &u.sin.sin_addr, str, sizeof str)) {
  70.           fprintf(stderr, "AF_INET %s\n", str);
  71.         } else {
  72.           fprintf(stderr, "AF_INET unknown\n");
  73.         }
  74.         break;
  75.       case AF_INET6:
  76.         if(inet_ntop(AF_INET6, &u.sin6.sin6_addr, str, sizeof str)) {
  77.           fprintf(stderr, "AF_INET6 %s\n", str);
  78.         } else {
  79.           fprintf(stderr, "AF_INET6 unknown\n");
  80.         }
  81.         break;
  82.       default:
  83.         fprintf(stderr, "UNKNOWN\n");
  84.         break;
  85.       }
  86.     }
  87.   }
  88. }
  89.  
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https://ideone.com/WK6St
language:
C++ (gcc 8.3)
created:
12 years ago
visibility:
public

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