harvey/sys/src/cmd/ndb/dnsquery.c

#include <u.h>
#include <libc.h>
#include <bio.h>
#include <ctype.h>
#include <ndb.h>
#include "dns.h"
#include "ip.h"

static int domount;
static char *mtpt, *dns, *srv;

static int
setup(int argc, char **argv)
{
	int fd;

	if(argc == 1){
		domount = 0;
		mtpt = argv[0];
	}

	fd = open(dns, ORDWR);
	if(fd < 0){
		if(domount == 0){
			fprint(2, "can't open %s: %r\n", mtpt);
			exits(0);
		}
		fd = open(srv, ORDWR);
		if(fd < 0){
			print("can't open %s: %r\n", srv);
			exits(0);
		}
		if(mount(fd, -1, mtpt, MBEFORE, "") < 0){
			print("can't mount(%s, %s): %r\n", srv, mtpt);
			exits(0);
		}
		fd = open(mtpt, ORDWR);
		if(fd < 0){
			print("can't open %s: %r\n", mtpt);
			exits(0);
		}
	}
	return fd;
}

static void
querydns(int fd, char *line, int n)
{
	char buf[1024];

	seek(fd, 0, 0);
	if(write(fd, line, n) != n) {
		print("!%r\n");
		return;
	}
	seek(fd, 0, 0);
	buf[0] = '\0';
	while((n = read(fd, buf, sizeof(buf))) > 0){
		buf[n] = '\0';
		print("%s\n", buf);
	}
}

static void
query(int fd)
{
	int n, len;
	char *lp, *p, *np;
	char buf[1024], line[1024];
	Biobuf in;

	Binit(&in, 0, OREAD);
	for(print("> "); lp = Brdline(&in, '\n'); print("> ")){
		n = Blinelen(&in) -1;
		while(isspace(lp[n]))
			lp[n--] = 0;
		n++;
		while(isspace(*lp)){
			lp++;
			n--;
		}
		if(!*lp)
			continue;
		strcpy(line, lp);

		/* default to an "ip" request if alpha, "ptr" if numeric */
		if(strchr(line, ' ') == nil)
			if(strcmp(ipattr(line), "ip") == 0) {
				strcat(line, " ptr");
				n += 4;
			} else {
				strcat(line, " ip");
				n += 3;
			}

		/* inverse queries may need to be permuted */
		if(n > 4 && strcmp("ptr", &line[n-3]) == 0 &&
		    cistrstr(line, ".arpa") == nil){
			/* TODO: reversing v6 addrs is harder */
			for(p = line; *p; p++)
				if(*p == ' '){
					*p = '.';
					break;
				}
			np = buf;
			len = 0;
			while(p >= line){
				len++;
				p--;
				if(*p == '.'){
					memmove(np, p+1, len);
					np += len;
					len = 0;
				}
			}
			memmove(np, p+1, len);
			np += len;
			strcpy(np, "in-addr.arpa ptr");	/* TODO: ip6.arpa for v6 */
			strcpy(line, buf);
			n = strlen(line);
		}

		querydns(fd, line, n);
	}
	Bterm(&in);
}

void
main(int argc, char *argv[])
{
	mtpt = "/net";
	dns = "/net/dns";
	srv = "/srv/dns";
	domount = 1;
	ARGBEGIN {
	case 'x':
		mtpt = "/net.alt";
		dns = "/net.alt/dns";
		srv = "/srv/dns_net.alt";
		break;
	default:
		fprint(2, "usage: %s [-x] [dns-mount-point]\n", argv0);
		exits("usage");
	} ARGEND;

	query(setup(argc, argv));
	exits(0);
}