kqueue/kqclient.c

   1 /* compile with:
   2    gcc kqclient.c -o kqclient -Wall -W -Wextra -ansi -pedantic */
   3
   4 #include <netinet/in.h>
   5 #include <sys/event.h>
   6 #include <sys/socket.h>
   7 #include <sys/time.h>
   8 #include <netdb.h>
   9 #include <stdio.h>
  10 #include <stdlib.h>
  11 #include <string.h>
  12 #include <unistd.h>
  13
  14 #define BUFSIZE 1024
  15
  16 /* function prototypes */
  17 void diep(const char *s);
  18 int tcpopen(const char *host, int port);
  19 void sendbuftosck(int sckfd, const char *buf, int len);
  20
  21 int main(int argc, char *argv[])
  22 {
  23     struct kevent chlist[2];   /* events we want to monitor */
  24     struct kevent evlist[2];   /* events that were triggered */
  25     char buf[BUFSIZE];
  26     int sckfd, kq, nev, i;
  27
  28     /* check argument count */
  29     if (argc != 3) {
  30         fprintf(stderr, "usage: %s host port\n", argv[0]);
  31         exit(EXIT_FAILURE);
  32     }
  33
  34     /* open a connection to a host:port pair */
  35     sckfd = tcpopen(argv[1], atoi(argv[2]));
  36
  37     /* create a new kernel event queue */
  38     if ((kq = kqueue()) == -1)
  39         diep("kqueue()");
  40
  41     /* initialise kevent structures */
  42     EV_SET(&chlist[0], sckfd, EVFILT_READ, EV_ADD | EV_ENABLE, 0, 0, 0);
  43     EV_SET(&chlist[1], fileno(stdin), EVFILT_READ, EV_ADD | EV_ENABLE, 0, 0, 0);
  44
  45     /* loop forever */
  46     for (;;) {
  47         nev = kevent(kq, chlist, 2, evlist, 2, NULL);
  48
  49         if (nev < 0)
  50             diep("kevent()");
  51
  52         else if (nev > 0) {
  53             if (evlist[0].flags & EV_EOF)                       /* read direction of socket has shutdown */
  54                 exit(EXIT_FAILURE);
  55
  56             for (i = 0; i < nev; i++) {
  57                 if (evlist[i].flags & EV_ERROR) {                /* report errors */
  58                     fprintf(stderr, "EV_ERROR: %s\n", strerror(evlist[i].data));
  59                     exit(EXIT_FAILURE);
  60                 }
  61
  62                 if (evlist[i].ident == sckfd) {                  /* we have data from the host */
  63                     memset(buf, 0, BUFSIZE);
  64                     if (read(sckfd, buf, BUFSIZE) < 0)
  65                         diep("read()");
  66                     fputs(buf, stdout);
  67                 }
  68
  69                 else if (evlist[i].ident == fileno(stdin)) {     /* we have data from stdin */
  70                     memset(buf, 0, BUFSIZE);
  71                     fgets(buf, BUFSIZE, stdin);
  72                     sendbuftosck(sckfd, buf, strlen(buf));
  73                 }
  74             }
  75         }
  76     }
  77
  78     close(kq);
  79     return EXIT_SUCCESS;
  80 }
  81
  82 void diep(const char *s)
  83 {
  84     perror(s);
  85     exit(EXIT_FAILURE);
  86 }
  87
  88 int tcpopen(const char *host, int port)
  89 {
  90     struct sockaddr_in server;
  91     struct hostent *hp;
  92     int sckfd;
  93
  94     if ((hp = gethostbyname(host)) == NULL)
  95         diep("gethostbyname()");
  96
  97     if ((sckfd = socket(PF_INET, SOCK_STREAM, 0)) < 0)
  98         diep("socket()");
  99
 100     server.sin_family = AF_INET;
 101     server.sin_port = htons(port);
 102     server.sin_addr = *((struct in_addr *)hp->h_addr);
 103     memset(&(server.sin_zero), 0, 8);
 104
 105     if (connect(sckfd, (struct sockaddr *)&server, sizeof(struct sockaddr)) < 0)
 106         diep("connect()");
 107
 108     return sckfd;
 109 }
 110
 111 void sendbuftosck(int sckfd, const char *buf, int len)
 112 {
 113     int bytessent, pos;
 114
 115     pos = 0;
 116     do {
 117         if ((bytessent = send(sckfd, buf + pos, len - pos, 0)) < 0)
 118             diep("send()");
 119         pos += bytessent;
 120     } while (bytessent > 0);
 121 }