kqclient.c

   1 #include <netinet/in.h>
   2 #include <sys/event.h>
   3 #include <sys/socket.h>
   4 #include <sys/time.h>
   5 #include <netdb.h>
   6 #include <stdio.h>
   7 #include <stdlib.h>
   8 #include <string.h>
   9 #include <unistd.h>
  10
  11 #define BUFSIZE 1024
  12
  13 /* function prototypes */
  14 void diep(const char *s);
  15 int tcpopen(const char *host, int port);
  16 void sendbuftosck(int sckfd, const char *buf, int len);
  17
  18 int main(int argc, char *argv[])
  19 {
  20     struct kevent chlist[2];   /* events we want to monitor */
  21     struct kevent evlist[2];   /* events that were triggered */
  22     char buf[BUFSIZE];
  23     int sckfd, kq, nev, i;
  24
  25     /* check argument count */
  26     if (argc != 3) {
  27         fprintf(stderr, "usage: %s host port\n", argv[0]);
  28         exit(EXIT_FAILURE);
  29     }
  30
  31     /* open a connection to a host:port pair */
  32     sckfd = tcpopen(argv[1], atoi(argv[2]));
  33
  34     /* create a new kernel event queue */
  35     if ((kq = kqueue()) == -1)
  36         diep("kqueue()");
  37
  38     /* initialise kevent structures */
  39     EV_SET(&chlist[0], sckfd, EVFILT_READ, EV_ADD | EV_ENABLE, 0, 0, 0);
  40     EV_SET(&chlist[1], fileno(stdin), EVFILT_READ, EV_ADD | EV_ENABLE, 0, 0, 0);
  41
  42     /* loop forever */
  43     for (;;) {
  44         nev = kevent(kq, chlist, 2, evlist, 2, NULL);
  45
  46         if (nev < 0)
  47             diep("kevent()");
  48
  49         else if (nev > 0) {
  50             if (evlist[0].flags & EV_EOF)                       /* read direction of socket has shutdown */
  51                 exit(EXIT_FAILURE);
  52
  53             for (i = 0; i < nev; i++) {
  54                 if (evlist[i].flags & EV_ERROR) {                /* report errors */
  55                     fprintf(stderr, "EV_ERROR: %s\n", strerror(evlist[i].data));
  56                     exit(EXIT_FAILURE);
  57                 }
  58
  59                 if (evlist[i].ident == sckfd) {                  /* we have data from the host */
  60                     memset(buf, 0, BUFSIZE);
  61                     if (read(sckfd, buf, BUFSIZE) < 0)
  62                         diep("read()");
  63                     fputs(buf, stdout);
  64                 }
  65
  66                 else if (evlist[i].ident == fileno(stdin)) {     /* we have data from stdin */
  67                     memset(buf, 0, BUFSIZE);
  68                     fgets(buf, BUFSIZE, stdin);
  69                     sendbuftosck(sckfd, buf, strlen(buf));
  70                 }
  71             }
  72         }
  73     }
  74
  75     close(kq);
  76     return EXIT_SUCCESS;
  77 }
  78
  79 void diep(const char *s)
  80 {
  81     perror(s);
  82     exit(EXIT_FAILURE);
  83 }
  84
  85 int tcpopen(const char *host, int port)
  86 {
  87     struct sockaddr_in server;
  88     struct hostent *hp;
  89     int sckfd;
  90
  91     if ((hp = gethostbyname(host)) == NULL)
  92         diep("gethostbyname()");
  93
  94     if ((sckfd = socket(PF_INET, SOCK_STREAM, 0)) < 0)
  95         diep("socket()");
  96
  97     server.sin_family = AF_INET;
  98     server.sin_port = htons(port);
  99     server.sin_addr = *((struct in_addr *)hp->h_addr);
 100     memset(&(server.sin_zero), 0, 8);
 101
 102     if (connect(sckfd, (struct sockaddr *)&server, sizeof(struct sockaddr)) < 0)
 103         diep("connect()");
 104
 105     return sckfd;
 106 }
 107
 108 void sendbuftosck(int sckfd, const char *buf, int len)
 109 {
 110     int bytessent, pos;
 111
 112     pos = 0;
 113     do {
 114         if ((bytessent = send(sckfd, buf + pos, len - pos, 0)) < 0)
 115             diep("send()");
 116         pos += bytessent;
 117     } while (bytessent > 0);
 118 }