notify.c

   1 #include <stdio.h>
   2 #include <stdlib.h>
   3 #include <unistd.h>
   4 #include <errno.h>
   5 #include <string.h>
   6 #include <netdb.h>
   7 #include <sys/types.h>
   8 #include <netinet/in.h>
   9 #include <sys/socket.h>
  10
  11 #include <arpa/inet.h>
  12
  13 #define PORT "3490"
  14 #define MAX_MSG_ACCEPT_BYTES 100
  15
  16 // look for an IPv4/6 host:port in an address structure
  17 void *get_in_addr(struct sockaddr *sa)
  18 {
  19         if (sa->sa_family == AF_INET) {
  20                 return &(((struct sockaddr_in*)sa)->sin_addr);
  21         }
  22         return &(((struct sockaddr_in6*)sa)->sin6_addr);
  23 }
  24
  25 int main(int argc, char *argv[])
  26 {
  27         int sockfd, numbytes;
  28         struct addrinfo hints, *servinfo, *port;
  29         char s[INET6_ADDRSTRLEN];
  30         int rv;
  31         char buf[MAX_MSG_ACCEPT_BYTES];
  32
  33         if (argc != 3) {
  34             fprintf(stderr, "usage: client hostname 'message'\n");
  35             exit(1);
  36         }
  37
  38         memset(&hints, 0, sizeof hints);
  39         hints.ai_family = AF_UNSPEC;
  40         hints.ai_socktype = SOCK_STREAM;
  41
  42     // look up local address information
  43         if ((rv = getaddrinfo(argv[1], PORT, &hints, &servinfo)) != 0) {
  44                 fprintf(stderr, "getaddrinfo: %s\n", gai_strerror(rv));
  45                 return 1;
  46         }
  47
  48         // loop over available interfaces and try to bind to port
  49         for(port = servinfo; port != NULL; port = port->ai_next) {
  50                 if ((sockfd = socket(port->ai_family, port->ai_socktype,
  51                                 port->ai_protocol)) == -1) {
  52                         perror("client: socket");
  53                         continue;
  54                 }
  55                 if (connect(sockfd, port->ai_addr, port->ai_addrlen) == -1) {
  56                         close(sockfd);
  57                         perror("client: connect");
  58                         continue;
  59                 }
  60                 break;
  61         }
  62
  63         if (port == NULL) {
  64                 fprintf(stderr, "client: failed to connect\n");
  65                 return 2;
  66         }
  67
  68     if (send(sockfd, argv[2], strlen(argv[2])+1, 0) == -1)
  69         perror("send");
  70
  71         close(sockfd);
  72
  73         return 0;
  74 }