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/* RFC2136 DNS inform - necessary for Win2k3 DNS servers */
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#include <u.h>
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#include <libc.h>
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#include <bio.h>
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#include <ndb.h>
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#include <ip.h>
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#include "dns.h"
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enum {
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	FQDNMAX	= 255,
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};
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char *errmsgs[] = {
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	[0]  "ok",
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	[1]  "request format error",
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	[2]  "internal server error",
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	[3]  "domain name does not exist",
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	[4]  "request not supported",
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	[5]  "permission denied",
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	[6]  "domain name already exists",
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	[7]  "resource record already exists",
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	[8]  "resource record does not exist",
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	[9]  "server not authoritative",
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	[10] "domain name not in zone",
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};
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void
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usage(void)
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{
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	fprint(2, "usage: %s [-x netmtpt]\n", argv0);
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	exits("usage");
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}
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void
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ding(void *, char *msg)
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{
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	if(strstr(msg, "alarm") != nil)
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		noted(NCONT);
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	noted(NDFLT);
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}
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int
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g16(uchar **p)
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{
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	int n;
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	n  = *(*p)++ << 8;
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	n |= *(*p)++;
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	return n;
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}
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void
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p16(uchar **p, int n)
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{
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	*(*p)++ = n >> 8;
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	*(*p)++ = n;
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}
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void
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p32(uchar **p, int n)
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{
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	*(*p)++ = n >> 24;
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	*(*p)++ = n >> 16;
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	*(*p)++ = n >> 8;
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	*(*p)++ = n;
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}
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void
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pmem(uchar **p, void *v, int len)
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{
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	memmove(*p, v, len);
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	*p += len;
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}
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void
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pname(uchar **p, char *s)
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{
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	uchar *len;
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	while (*s){
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		len = (*p)++;
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		while(*s && *s != '.')
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			*(*p)++ = *s++;
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		*len = *p - len - 1;
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		if(*s == '.')
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			s++;
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	}
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	*(*p)++ = 0;
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}
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void
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main(int argc, char *argv[])
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{
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	int debug, len, fd;
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	uint err;
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	char *sysname, *dnsdomain, *dom, *inform, *ns, net[32];
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	uchar *p, buf[4096], addr[IPv4addrlen], v6addr[IPaddrlen];
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	ushort txid;
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	Ndb *db;
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	Ndbtuple *t, *tt;
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	static char *query[] = { "dom", "dnsdomain", "ns", "inform" };
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	fmtinstall('I', eipfmt);
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	fmtinstall('V', eipfmt);
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	setnetmtpt(net, sizeof net, nil);
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	debug = 0;
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	ns = nil;
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	dom = nil;
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	inform = nil;
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	dnsdomain = nil;
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	ARGBEGIN{
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	case 'd':
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		debug = 1;
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		break;
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	case 'x':
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		setnetmtpt(net, sizeof net, EARGF(usage()));
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		break;
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	default:
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		usage();
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	}ARGEND;
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	if(argc != 0)
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		usage();
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	if((sysname = getenv("sysname")) == nil)
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		sysfatal("$sysname not set");
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	if((db = ndbopen(nil)) == nil)
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		sysfatal("can't open ndb: %r");
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	tt = ndbipinfo(db, "sys", sysname, query, nelem(query));
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	for(t = tt; t; t = t->entry){
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		if(strcmp(t->attr, "ns") == 0)
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			ns = t->val;
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		else if(strcmp(t->attr, "dom") == 0)
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			dom = t->val;
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		else if(strcmp(t->attr, "dnsdomain") == 0)
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			dnsdomain = t->val;
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		else if(strcmp(t->attr, "inform") == 0)
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			inform = t->val;
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	}
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	ndbfree(tt);
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	ndbclose(db);
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	if(inform)
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		dom = inform;
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	if(!ns)
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		sysfatal("no relevant ns=");
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	if(!dom)
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		sysfatal("no relevant dom=");
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	if(!dnsdomain)
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		sysfatal("no relevant dnsdomain=");
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	myipaddr(v6addr, net);
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	memmove(addr, v6addr + IPaddrlen - IPv4addrlen, IPv4addrlen);
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	if(debug){
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		print("ip=%V\n", addr);
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		print("ns=%s\n", ns);
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		print("dnsdomain=%s\n", dnsdomain);
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		print("dom=%s\n", dom);
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	}
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	if((fd = dial(netmkaddr(ns, "udp", "dns"), 0, 0, 0)) < 0)
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		sysfatal("can't dial %s: %r", ns);
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168 
	txid = time(nil) + getpid();
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	p = buf;
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	p16(&p, txid);		/* ID */
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	p16(&p, 5<<11);		/* flags */
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	p16(&p, 1);		/* # Zones */
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	p16(&p, 0);		/* # prerequisites */
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	p16(&p, 2);		/* # updates */
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	p16(&p, 0);		/* # additionals */
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        pname(&p, dnsdomain);	/* zone */
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	p16(&p, Tsoa);		/* zone type */
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	p16(&p, Cin);		/* zone class */
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	/* delete old name */
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        pname(&p, dom);		/* name */
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	p16(&p, Ta);		/* type: v4 addr */
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	p16(&p, Call);		/* class */
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	p32(&p, 0);		/* TTL */
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	p16(&p, 0);		/* data len */
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	/* add new A record */
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	pname(&p, dom);		/* name */
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	p16(&p, Ta);		/* type: v4 addr */
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	p16(&p, Cin);		/* class */
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	p32(&p, 60*60*25);	/* TTL (25 hours) */
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	p16(&p, IPv4addrlen);	/* data len */
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	pmem(&p, addr, IPv4addrlen);	/* v4 address */
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197 
	len = p - buf;
198 
	if(write(fd, buf, len) != len)
199 
		sysfatal("write failed: %r");
200 
 
201 
	notify(ding);
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	alarm(3000);
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	do{
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		if(read(fd, buf, sizeof buf) < 0)
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			sysfatal("timeout");
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		p = buf;
207 
	}while(g16(&p) != txid);
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	alarm(0);
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	close(fd);
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212 
	err = g16(&p) & 7;
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	if(err != 0 && err != 7)	/* err==7 is just a "yes, I know" warning */
214 
		if(err < nelem(errmsgs))
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			sysfatal("%s", errmsgs[err]);
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		else
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			sysfatal("unknown dns server error %d", err);
218 
	exits(0);
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}