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// Copyright (C) 1999-2015
// Smithsonian Astrophysical Observatory, Cambridge, MA, USA
// For conditions of distribution and use, see copyright notice in "copyright"
#include <string.h>
#include <stdlib.h>
#include <unistd.h>
#include <signal.h>
#include <setjmp.h>
#include <netdb.h>
#include <iostream>
#include <sstream>
#include <iomanip>
using namespace std;
#include <tcl.h>
#define SZ_LINE 2048
static int debug =0;
// alarm signal handler
static sigjmp_buf alarmbuf;
static void alarmHandler(int dummy)
{
siglongjmp(alarmbuf, 1);
}
extern "C" {
int Tclcheckdns_Init(void *vinterp);
};
static int checkdns(char *name, int delay, int cflag)
{
int result =0;
// get temp name, look for port
char tbuf[SZ_LINE];
unsigned int port=80;
if (name && *name) {
char* ss=NULL;
strncpy(tbuf, name, SZ_LINE-1);
if ((ss=strchr(tbuf, ':'))) {
*ss = '\0';
port = atoi(ss+1);
}
}
else
*tbuf = '\0';
// start the alarm, if necessary
struct sigaction sigact, osigact;
if (delay>0) {
if (sigsetjmp(alarmbuf, 1)) {
if (debug)
cerr << "alarm activated" << endl;
result= 1;
goto done;
}
else {
sigact.sa_handler = alarmHandler;
sigemptyset(&sigact.sa_mask);
sigact.sa_flags = 0;
sigaction(SIGALRM, &sigact, &osigact);
alarm(delay);
}
}
// get name of host we are interested in
char host[SZ_LINE];
if (*tbuf)
strncpy(host, tbuf, SZ_LINE-1);
else {
// use current host
if (gethostname(host, SZ_LINE) < 0) {
result =2;
goto done;
}
else if (debug)
cerr << "gethostname: " << host << endl;
}
// try to get info on this host
struct hostent* h;
if (!(h=gethostbyname(host))) {
result =3;
goto done;
}
else if (debug)
cerr << "gethostbyname: " << h->h_name << '(' << port << ')' << endl;
// connect, if necessary
if (cflag) {
unsigned int ip;
memcpy(&ip, h->h_addr_list[0], (size_t)h->h_length);
ip = ntohl(ip);
int fd;
if ((fd = socket(AF_INET, SOCK_STREAM, 0)) < 0) {
result =4;
goto done;
}
struct sockaddr_in sock_in;
memset((char *)&sock_in, 0, sizeof(sock_in));
sock_in.sin_family = AF_INET;
sock_in.sin_addr.s_addr = htonl(ip);
sock_in.sin_port = htons(port);
int got = connect(fd, (struct sockaddr *)&sock_in, sizeof(sock_in));
close(fd);
if (got < 0) {
result =5;
goto done;
}
else if (debug)
cerr << "connect succeeded" << endl;
}
done:
if (delay) {
alarm(0);
sigaction(SIGALRM, &osigact, NULL);
}
return result;
}
static int TclcheckdnsCmd(ClientData clientData, Tcl_Interp *interp,
int objc, Tcl_Obj *CONST objv[])
{
if (objc < 3) {
Tcl_WrongNumArgs(interp, 1, objv, "host delay [connect]");
return TCL_ERROR;
}
char* host =NULL;
char* ss = Tcl_GetStringFromObj(objv[1], NULL);
if (ss && *ss)
host = ss;
int delay=5;
char* tt = Tcl_GetStringFromObj(objv[2], NULL);
if (tt && *tt)
delay = atoi(tt);
int cflag=0;
if (objc >= 4) {
char* uu = Tcl_GetStringFromObj(objv[3], NULL);
if (uu && *uu)
cflag = atoi(uu);
}
ostringstream str;
str << checkdns(host, delay, cflag) << ends;
Tcl_AppendResult(interp, str.str().c_str(), NULL);
return TCL_OK;
}
int Tclcheckdns_Init(void *vinterp)
{
Tcl_Interp *interp = (Tcl_Interp *)vinterp;
if (Tcl_InitStubs(interp, TCL_PATCH_LEVEL, 0) == NULL)
return TCL_ERROR;
Tcl_CreateObjCommand(interp, "checkdns", TclcheckdnsCmd,
(ClientData)NULL, (Tcl_CmdDeleteProc *)NULL);
if (Tcl_PkgProvide(interp, PACKAGE_NAME, PACKAGE_VERSION) != TCL_OK)
return TCL_ERROR;
return TCL_OK;
}
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