dns

3 files changed, 448 insertions, 2 deletions

diff --git a/src/libndb/mkfile b/src/libndb/mkfile
index a49cd5e0..b7c9ee96 100644
--- a/src/libndb/mkfile
+++ b/src/libndb/mkfile
@@ -21,6 +21,7 @@ OFILES=\
 	ndbparse.$O\
 	ndbreorder.$O\
 	ndbsubstitute.$O\
+	sysdnsquery.$O\
 
 HFILES=\
 	$PLAN9/include/ndb.h\
@@ -28,5 +29,6 @@ HFILES=\
 
 <$PLAN9/src/mksyslib
 
-$O.out: testipinfo.$O
-	$LD $prereq
+testdns: testdns.$O $LIBDIR/$LIB
+	$LD -o $target $prereq
+
diff --git a/src/libndb/sysdnsquery.c b/src/libndb/sysdnsquery.c
new file mode 100644
index 00000000..1561c4dd
--- /dev/null
+++ b/src/libndb/sysdnsquery.c
@@ -0,0 +1,409 @@
+#include <u.h>
+#include <netinet/in.h>
+#include <arpa/nameser.h>
+#include <resolv.h>
+#include <netdb.h>
+#include <libc.h>
+#include <ip.h>
+#include <bio.h>
+#include <ndb.h>
+#include "ndbhf.h"
+
+static void nstrcpy(char*, char*, int);
+static void mkptrname(char*, char*, int);
+static Ndbtuple *doquery(char*, char*);
+
+/*
+ * Run a DNS lookup for val/type on net.
+ */
+Ndbtuple*
+dnsquery(char *net, char *val, char *type)
+{
+	static int init;
+	char rip[128];	
+	Ndbtuple *t;
+
+	USED(net);
+	
+	if(!init){
+		init = 1;
+		fmtinstall('I', eipfmt);
+	}
+	/* give up early on stupid questions - vwhois */
+	if(strcmp(val, "::") == 0 || strcmp(val, "0.0.0.0") == 0)
+		return nil;
+	
+	/* zero out the error string */
+	werrstr("");
+	
+	/* if this is a reverse lookup, first look up the domain name */
+	if(strcmp(type, "ptr") == 0){
+		mkptrname(val, rip, sizeof rip);
+		t = doquery(rip, "ptr");
+	}else
+		t = doquery(val, type);
+	
+	return t;
+}
+
+/*
+ *  convert address into a reverse lookup address
+ */
+static void
+mkptrname(char *ip, char *rip, int rlen)
+{
+	char buf[128];
+	char *p, *np;
+	int len;
+
+	if(strstr(ip, "in-addr.arpa") || strstr(ip, "IN-ADDR.ARPA")){
+		nstrcpy(rip, ip, rlen);
+		return;
+	}
+
+	nstrcpy(buf, ip, sizeof buf);
+	for(p = buf; *p; p++)
+		;
+	*p = '.';
+	np = rip;
+	len = 0;
+	while(p >= buf){
+		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");
+}
+
+static void
+nstrcpy(char *to, char *from, int len)
+{
+	strncpy(to, from, len);
+	to[len-1] = 0;
+}
+
+/*
+ * Disgusting, ugly interface to libresolv,
+ * which everyone seems to have.
+ */
+enum
+{
+	MAXRR = 100,
+	MAXDNS = 4096,
+};
+
+static int name2type(char*);
+static uchar *skipquestion(uchar*, uchar*, uchar*, int);
+static uchar *unpack(uchar*, uchar*, uchar*, Ndbtuple**, int);
+static uchar *rrnext(uchar*, uchar*, uchar*, Ndbtuple**);
+static Ndbtuple *rrunpack(uchar*, uchar*, uchar**, char*, ...);
+
+static Ndbtuple*
+doquery(char *name, char *type)
+{
+	int n, nstype;
+	uchar *buf, *p;
+	HEADER *h;
+	Ndbtuple *t;
+
+	if((nstype = name2type(type)) < 0){
+		werrstr("unknown dns type %s", type);
+		return nil;
+	}
+
+	buf = malloc(MAXDNS);
+	if(buf == nil)
+		return nil;
+
+	if((n = res_search(name, ns_c_in, nstype, buf, MAXDNS)) < 0){
+		free(buf);
+		return nil;
+	}
+	if(n >= MAXDNS){
+		free(buf);
+		werrstr("too much dns information");
+		return nil;
+	}
+	
+	h = (HEADER*)buf;
+	h->qdcount = ntohs(h->qdcount);
+	h->ancount = ntohs(h->ancount);
+	h->nscount = ntohs(h->nscount);
+	h->arcount = ntohs(h->arcount);
+	
+	p = buf+sizeof(HEADER);
+	p = skipquestion(buf, buf+n, p, h->qdcount);
+	p = unpack(buf, buf+n, p, &t, h->ancount);
+	USED(p);
+	return t;
+}
+
+static struct {
+	char *s;
+	int t;
+} dnsnames[] =
+{
+	"ip",		ns_t_a,
+	"ns",	ns_t_ns,
+	"md",	ns_t_md,
+	"mf",	ns_t_mf,
+	"cname",	ns_t_cname,
+	"soa",	ns_t_soa,
+	"mb",	ns_t_mb,
+	"mg",	ns_t_mg,
+	"mr",	ns_t_mr,
+	"null",	ns_t_null,
+	"ptr",	ns_t_ptr,
+	"hinfo",	ns_t_hinfo,
+	"minfo",	ns_t_minfo,
+	"mx",	ns_t_mx,
+	"txt",	ns_t_txt,
+	"rp",	ns_t_rp,
+	"key",	ns_t_key,
+	"cert",	ns_t_cert,
+	"sig",	ns_t_sig,
+	"aaaa",	ns_t_aaaa,
+	"ixfr",	ns_t_ixfr,
+	"axfr",	ns_t_axfr,
+	"all",	ns_t_any,
+};
+
+static char*
+type2name(int t)
+{
+	int i;
+	
+	for(i=0; i<nelem(dnsnames); i++)
+		if(dnsnames[i].t == t)
+			return dnsnames[i].s;
+	return nil;
+}
+
+static int
+name2type(char *name)
+{
+	int i;
+	
+	for(i=0; i<nelem(dnsnames); i++)
+		if(strcmp(name, dnsnames[i].s) == 0)
+			return dnsnames[i].t;
+	return -1;
+}
+
+static uchar*
+skipquestion(uchar *buf, uchar *ebuf, uchar *p, int n)
+{
+	int i, len;
+	char tmp[100];
+	
+	for(i=0; i<n; i++){
+		if((len = dn_expand(buf, ebuf, p, tmp, sizeof tmp)) <= 0)
+			return nil;
+		p += NS_QFIXEDSZ+len;
+	}
+	return p;
+}
+
+static uchar*
+unpack(uchar *buf, uchar *ebuf, uchar *p, Ndbtuple **tt, int n)
+{
+	int i;
+	Ndbtuple *first, *last, *t;
+
+	*tt = nil;
+	first = nil;
+	last = nil;
+	for(i=0; i<n; i++){
+		if((p = rrnext(buf, ebuf, p, &t)) == nil){
+			if(first)
+				ndbfree(first);
+			return nil;
+		}
+		if(t == nil)	/* unimplemented rr type */
+			continue;
+		if(last)
+			last->entry = t;
+		else
+			first = t;
+		for(last=t; last->entry; last=last->entry)
+			last->line = last->entry;
+		last->line = t;
+	}
+	*tt = first;
+	return p;
+}
+
+#define G2(p) nhgets(p)
+#define G4(p) nhgetl(p)
+
+static uchar*
+rrnext(uchar *buf, uchar *ebuf, uchar *p, Ndbtuple **tt)
+{
+	char tmp[Ndbvlen];
+	char b[MAXRR];
+	uchar ip[IPaddrlen];
+	int len;
+	Ndbtuple *first, *t;
+	int rrtype;
+	int rrlen;
+
+	first = nil;
+	t = nil;
+	*tt = nil;
+	if(p == nil)
+		return nil;
+
+	if((len = dn_expand(buf, ebuf, p, b, sizeof b)) < 0){
+	corrupt:
+		werrstr("corrupt dns packet");
+		if(first)
+			ndbfree(first);
+		return nil;
+	}
+	p += len;
+	
+	rrtype = G2(p);
+	rrlen = G2(p+8);
+	p += 10;
+	
+	if(rrtype == ns_t_ptr)
+		first = ndbnew("ptr", b);
+	else
+		first = ndbnew("dom", b);
+
+	switch(rrtype){
+	default:
+		goto end;
+	case ns_t_hinfo:
+		t = rrunpack(buf, ebuf, &p, "YY", "cpu", "os");
+		break;
+	case ns_t_minfo:
+		t = rrunpack(buf, ebuf, &p, "NN", "mbox", "mbox");
+		break;
+	case ns_t_mx:
+		t = rrunpack(buf, ebuf, &p, "SN", "pref", "mx");
+		break;
+	case ns_t_cname:
+	case ns_t_md:
+	case ns_t_mf:
+	case ns_t_mg:
+	case ns_t_mr:
+	case ns_t_mb:
+	case ns_t_ns:
+	case ns_t_ptr:
+	case ns_t_rp:
+		t = rrunpack(buf, ebuf, &p, "N", type2name(rrtype));
+		break;
+	case ns_t_a:
+		if(rrlen != IPv4addrlen)
+			goto corrupt;
+		memmove(ip, v4prefix, IPaddrlen);
+		memmove(ip+IPv4off, p, IPv4addrlen);
+		snprint(tmp, sizeof tmp, "%I", ip);
+		t = ndbnew("ip", tmp);
+		p += rrlen;
+		break;
+	case ns_t_aaaa:
+		if(rrlen != IPaddrlen)
+			goto corrupt;
+		snprint(tmp, sizeof tmp, "%I", ip);
+		t = ndbnew("ip", tmp);
+		p += rrlen;
+		break;
+	case ns_t_null:
+		snprint(tmp, sizeof tmp, "%.*H", rrlen, p);
+		t = ndbnew("null", tmp);
+		p += rrlen;
+		break;
+	case ns_t_txt:
+		t = rrunpack(buf, ebuf, &p, "Y", "txt");
+		break;
+
+	case ns_t_soa:
+		t = rrunpack(buf, ebuf, &p, "NNLLLLL", "ns", "mbox", 
+			"serial", "refresh", "retry", "expire", "ttl");
+		break;
+
+	case ns_t_key:
+		t = rrunpack(buf, ebuf, &p, "SCCY", "flags", "proto", "alg", "key");
+		break;
+	
+	case ns_t_sig:
+		t = rrunpack(buf, ebuf, &p, "SCCLLLSNY", "type", "alg", "labels",
+			"ttl", "exp", "incep", "tag", "signer", "sig");
+		break;
+	
+	case ns_t_cert:
+		t = rrunpack(buf, ebuf, &p, "SSCY", "type", "tag", "alg", "cert");
+		break;
+	}
+	if(t == nil)
+		goto corrupt;
+
+end:
+	first->entry = t;
+	*tt = first;
+	return p;
+}
+
+static Ndbtuple*
+rrunpack(uchar *buf, uchar *ebuf, uchar **pp, char *fmt, ...)
+{
+	char *name;
+	int len, n;
+	uchar *p;
+	va_list arg;
+	Ndbtuple *t, *first, *last;
+	char tmp[Ndbvlen];
+	
+	p = *pp;
+	va_start(arg, fmt);
+	first = nil;
+	last = nil;
+	for(; *fmt; fmt++){
+		name = va_arg(arg, char*);
+		switch(*fmt){
+		default:
+			return nil;
+		case 'C':
+			snprint(tmp, sizeof tmp, "%d", *p++);
+			break;
+		case 'S':
+			snprint(tmp, sizeof tmp, "%d", G2(p));
+			p += 2;
+			break;
+		case 'L':
+			snprint(tmp, sizeof tmp, "%d", G4(p));
+			p += 4;
+			break;
+		case 'N':
+			if((len = dn_expand(buf, ebuf, p, tmp, sizeof tmp)) < 0)
+				return nil;
+			p += len;
+			break;
+		case 'Y':
+			len = *p++;
+			n = len;
+			if(n >= sizeof tmp)
+				n = sizeof tmp-1;
+			memmove(tmp, p, n);
+			p += len;
+			tmp[n] = 0;
+			break;
+		}
+		t = ndbnew(name, tmp);
+		if(last)
+			last->entry = t;
+		else
+			first = t;
+		last = t;
+	}
+	*pp = p;
+	return first;
+}
diff --git a/src/libndb/testdns.c b/src/libndb/testdns.c
new file mode 100644
index 00000000..6c72c5d8
--- /dev/null
+++ b/src/libndb/testdns.c
@@ -0,0 +1,35 @@
+#include <u.h>
+#include <libc.h>
+#include <bio.h>
+#include <ndb.h>
+
+void
+main(int argc, char **argv)
+{
+	Ndbtuple *t, *t0;
+	
+	ARGBEGIN{
+	default:
+		goto usage;
+	}ARGEND
+	
+	if(argc != 2){
+	usage:
+		fprint(2, "usage: testdns name val\n");
+		exits("usage");
+	}
+	
+	quotefmtinstall();
+	if((t = dnsquery(nil, argv[0], argv[1])) == nil)
+		sysfatal("dnsquery: %r");
+	
+	for(t0=t; t; t=t->entry){
+		print("%s=%q ", t->attr, t->val);
+		if(t->line == t0){
+			print("\n");
+			t0 = t->entry;
+		}
+	}
+	exits(0);
+}
+