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" // the port client will be connecting to
  14
  15 #define MAXDATASIZE 100 // max number of bytes we can get at once
  16
  17 // get sockaddr, IPv4 or IPv6:
  18 void *get_in_addr(struct sockaddr *sa)
  19 {
  20         if (sa->sa_family == AF_INET) {
  21                 return &(((struct sockaddr_in*)sa)->sin_addr);
  22         }
  23
  24         return &(((struct sockaddr_in6*)sa)->sin6_addr);
  25 }
  26
  27 int main(int argc, char *argv[])
  28 {
  29         int sockfd, numbytes;
  30         char buf[MAXDATASIZE];
  31         struct addrinfo hints, *servinfo, *p;
  32         int rv;
  33         char s[INET6_ADDRSTRLEN];
  34
  35         if (argc != 3) {
  36             fprintf(stderr,"usage: client hostname 'message'\n");
  37             exit(1);
  38         }
  39
  40         memset(&hints, 0, sizeof hints);
  41         hints.ai_family = AF_UNSPEC;
  42         hints.ai_socktype = SOCK_STREAM;
  43
  44         if ((rv = getaddrinfo(argv[1], PORT, &hints, &servinfo)) != 0) {
  45                 fprintf(stderr, "getaddrinfo: %s\n", gai_strerror(rv));
  46                 return 1;
  47         }
  48
  49         // loop through all the results and connect to the first we can
  50         for(p = servinfo; p != NULL; p = p->ai_next) {
  51                 if ((sockfd = socket(p->ai_family, p->ai_socktype,
  52                                 p->ai_protocol)) == -1) {
  53                         perror("client: socket");
  54                         continue;
  55                 }
  56
  57                 if (connect(sockfd, p->ai_addr, p->ai_addrlen) == -1) {
  58                         close(sockfd);
  59                         perror("client: connect");
  60                         continue;
  61                 }
  62
  63                 break;
  64         }
  65
  66         if (p == NULL) {
  67                 fprintf(stderr, "client: failed to connect\n");
  68                 return 2;
  69         }
  70
  71     if (send(sockfd, argv[2], strlen(argv[2])+1, 0) == -1)
  72         perror("send");
  73
  74         close(sockfd);
  75
  76         return 0;
  77 }