/* * udplink.c * * Given a hostname or an IP address, confirms that IP connectivity * exists to that host. * * calling: udpecho host [flag] * * host - IP address or host name of target * host * * flag - If found the code runs UNTIL it hits * a timeout * * returns: READ_TMO (100) - host echo timed out * READ_OK (101) - host echo returned or refused * */ #define MAX_TRIES 3 /* Number of tries to get a packet through */ #define MAX_WAIT 10 /* Time to read packet - maximum */ #define RETRY_TIME 1.0 /* Extra time before redoing a failed write/read */ #define READ_OK 101 /* What to return if we get ok data back */ #define READ_TMO 100 /* What to return if we don't */ #define LOOP_WAIT 120.0 /* Number of seconds to retry whole loop in */ #ifndef TRUE #define TRUE (1==1) #endif /* TRUE */ #ifndef FALSE #define FALSE !(TRUE) #endif /* FALSE */ #ifndef boolean #define boolean int #endif /* boolean */ #include "multinet_root:[multinet.include.sys]types.h" #include "multinet_root:[multinet.include.sys]socket.h" #include "multinet_root:[multinet.include.netinet]in.h" #include #include "multinet_root:[multinet.include]netdb.h" #include "multinet_root:[multinet.include]errno.h" #include "multinet_root:[multinet.include.vms]inetiodef.h" main(argc,argv) int argc; char *argv[]; { int s; /* Pointer to socket structure */ int n; /* Byte count from read/write */ int tries; /* Count of packets tried */ boolean done; /* Did we definitely succeed? */ char buf[8]; /* Outgoing data */ char buf2[8]; /* Buffer for incoming data */ struct sockaddr_in sin; /* For remote IP address */ struct hostent *hp; /* For remote IP name */ struct servent *sp; /* For echo server port */ int exit_status; /* To pass exit status */ boolean error; /* Error out or stay in */ /* * First, create an IP-family socket on which to make the connection */ s = socket(AF_INET, SOCK_DGRAM, 0); if (s < 0) { socket_perror("udplink: unable to create socket"); exit(0x10000000); } /* * Then, get the UDP port number of the "echo" server. * */ #ifndef KNOWECHO sp = getservbyname("echo", "udp"); if (sp == NULL) { fprintf(stderr, "udplink: echo/udp: unknown service\n"); exit(0x10000000); } #endif /* * Create the sockaddr_in structure. Fill in all but the address * from what we have. Based on content of argv[1] fill in using * either gethostbyname or inet_addr(). */ sin.sin_family = AF_INET; #ifndef KNOWECHO sin.sin_port = sp->s_port; #else sin.sin_port = htons(7); #endif /* KNOWECHO */ if (stringdigit(argv[1])) { /* An IP address */ if ( (sin.sin_addr.s_addr = inet_addr(argv[1])) == -1) { fprintf(stderr, "udplink: cannot translate %s \n",argv[1]); exit(0x10000000); } } else { /* A host name */ if ( (hp = gethostbyname(argv[1])) == NULL) { fprintf(stderr, "udplink: host unknown: %s\n",argv[1]); exit(0x10000000); } bcopy(hp->h_addr, &sin.sin_addr, hp->h_length); } /* * Bind to a udp port so that we can get back any responses */ n = connect(s, &sin, sizeof(sin)); if (n < 0) { socket_perror("udplink: unable to bind to udp port\n"); exit(0x10000000); } /* * Now send data out and read it until we either time out all * our retries, or succeed... */ buf[sizeof(buf)]='\n'; error = FALSE; while (!error) { tries = 0; done = FALSE; while ((tries++ < MAX_TRIES) && !(done)) { n = socket_write(s,buf,sizeof(buf)); if (n >= 0) { n = socket_read_with_timeout(s, buf2, sizeof(buf2), MAX_WAIT); if (n >= 0) { /* Read succeeded */ done = TRUE; /* Exit inner loop */ error= FALSE; exit_status = READ_OK; /* Set exit status */ } else { /* Read failed */ if (socket_errno != ECONNREFUSED) { /* Read timed out */ done = FALSE; /* Continue inner loop */ error= TRUE; exit_status = READ_TMO; /* Set exit status */ #ifdef DEBUG printf("RD tmo\n"); printf("%s \n",vms_errno_string()); #endif /* DEBUG */ lib$wait(&RETRY_TIME); } else { /* Read had other err (ECONNREFUSED) */ done = TRUE; /* exit inner loop */ error= FALSE; exit_status = READ_OK; /* set exit_status */ #ifdef DEBUG printf("RD err (ok) %d\n",socket_errno); printf("%s \n",vms_errno_string()); #endif } /* End if */ } /* end if */ } /* end if */ else { /* Write failed */ done = FALSE; error= TRUE; exit_status = READ_TMO; #ifdef DEBUG printf("WR er err dec: %d\n",socket_errno); printf("%s \n",vms_errno_string()); #endif } /* end if */ } /* end while tries */ /* * If only one argument was entered then we're not in permanent * mode. No matter what, exit after one iteration. */ if (argc != 3) { error = TRUE; } else { if (!error) lib$wait(&LOOP_WAIT); } } /* End while !(error) */ exit(exit_status); } /* * stringdigit(char *a) Return TRUE if all characters are digits */ int stringdigit(char *a) { while (*a != '\0') { if ((*a != '.') && ((*a < '0') || (*a > '9'))) return(FALSE); a++; } return(TRUE); } /* * The following routine is taken from * multinet_common_root:[multinet.examples]udpechoclient.c */ /* * This routine does a normal read using $QIO and also sets a timer. * If no data arrives within the specified time, the read is aborted. */ int socket_read_with_timeout(fd, buf, len, timeout) int fd, len, timeout; char *buf; { unsigned short IOSB[4]; int Status, TIME[2]; /* * Start the read on the socket. */ TIME[0] = -10000000 * timeout; TIME[1] = -1; Status = SYS$QIO(1, fd, IO$_RECEIVE, IOSB, 0, 0, buf, len, 0, 0, 0, 0); if (!(Status&1)) { vmserrno = Status; if (vmserrno & 0x8000) { vmserrno |= 0x4; socket_errno = (Status & 0x7fff) >> 3; } else { socket_errno = EIO; } return(-1); } /* * Start the timer */ Status = SYS$SETIMR(2, TIME, 0, 0, 0); if (!(Status&1)) { vmserrno = Status; if (vmserrno & 0x8000) { vmserrno |= 0x4; socket_errno = (Status & 0x7fff) >> 3; } else { socket_errno = EIO; } return(-1); } SYS$WFLOR(1, (1<<1)|(1<<2)); /* * Check if timer went off, or packet was received */ if (IOSB[0] == 0) { /* * Timer went off. Cancel the I/O */ SYS$CANCEL(fd); socket_errno = ETIMEDOUT; vmserrno = 0x8004 | (ETIMEDOUT << 3); return(-1); } else { /* * I/O completed, cancel the timer. */ SYS$CANTIM(0,0); /* * Check for errors */ if (!(IOSB[0] & 1)) { vmserrno = IOSB[0]; if (vmserrno & 0x8000) { vmserrno |= 0x4; socket_errno = (IOSB[0] & 0x7fff) >> 3; } else { socket_errno = EIO; } return(-1); } } /* * And the character count */ return(IOSB[1]); }