From a5c6f93fa25cce2fbe689ca4d4949d10dd49d350 Mon Sep 17 00:00:00 2001
From: Erik Ekman <yarrick@kryo.se>
Date: Sun, 20 Sep 2009 15:41:24 +0000
Subject: [PATCH] Fix data length in encoding dns queries

---
 src/dns.c   | 73 +++++++++++++++++++++++++----------------------------
 tests/dns.c |  6 +++--
 2 files changed, 38 insertions(+), 41 deletions(-)

diff --git a/src/dns.c b/src/dns.c
index a11e130..8f6cae8 100644
--- a/src/dns.c
+++ b/src/dns.c
@@ -90,47 +90,41 @@ dns_encode(char *buf, size_t buflen, struct query *q, qr_t qr, char *data, size_
 		putshort(&p, C_IN);
 		putlong(&p, 0);		/* TTL */
 
-	      if (q->type == T_CNAME || q->type == T_A || q->type == T_MX)
-	      {
-		/* data is expected to be like "Hblabla.host.name.com\0" */
+		if (q->type == T_CNAME || q->type == T_A || q->type == T_MX) {
+			/* data is expected to be like "Hblabla.host.name.com\0" */
 
-		char *startp = p;
-		int namelen;
+			char *startp = p;
+			int namelen;
 
-		p += 2;			/* skip 2 bytes length */
-		CHECKLEN(2);
-		if (q->type == T_MX)
-			putshort(&p, 10);	/* preference */
-		putname(&p, buflen - (p - buf), data);
-		CHECKLEN(0);
-		namelen = p - startp;
-		namelen -= 2;
-		putshort(&startp, namelen);
-	      }
-	      else if (q->type == T_TXT)
-	      {
-		/* TXT has binary or base-X data */
-		char *startp = p;
-		int txtlen;
-
-		p += 2;			/* skip 2 bytes length */
-		puttxtbin(&p, buflen - (p - buf), data, datalen);
-		CHECKLEN(0);
-		txtlen = p - startp;
-		txtlen -= 2;
-		putshort(&startp, txtlen);
-	      }
-	      else
-	      {
-		/* NULL has raw binary data */
-		datalen = MIN(datalen, buflen - (p - buf));
-		CHECKLEN(2);
-		putshort(&p, datalen);
-		CHECKLEN(datalen);
-		putdata(&p, data, datalen);
-		CHECKLEN(0);
-	      }
+			p += 2;			/* skip 2 bytes length */
+			CHECKLEN(2);
+			if (q->type == T_MX)
+				putshort(&p, 10);	/* preference */
+			putname(&p, buflen - (p - buf), data);
+			CHECKLEN(0);
+			namelen = p - startp;
+			namelen -= 2;
+			putshort(&startp, namelen);
+		} else if (q->type == T_TXT) {
+			/* TXT has binary or base-X data */
+			char *startp = p;
+			int txtlen;
 
+			p += 2;			/* skip 2 bytes length */
+			puttxtbin(&p, buflen - (p - buf), data, datalen);
+			CHECKLEN(0);
+			txtlen = p - startp;
+			txtlen -= 2;
+			putshort(&startp, txtlen);
+		} else {
+			/* NULL has raw binary data */
+			datalen = MIN(datalen, buflen - (p - buf));
+			CHECKLEN(2);
+			putshort(&p, datalen);
+			CHECKLEN(datalen);
+			putdata(&p, data, datalen);
+			CHECKLEN(0);
+		}
 		break;
 	case QR_QUERY:
 		/* Note that iodined also uses this for forward queries */
@@ -138,7 +132,8 @@ dns_encode(char *buf, size_t buflen, struct query *q, qr_t qr, char *data, size_
 		header->qdcount = htons(1);
 		header->arcount = htons(1);
 	
-		putname(&p, buflen - (p - buf), data);
+		datalen = MIN(datalen, buflen - (p - buf));
+		putname(&p, datalen, data);
 
 		CHECKLEN(4);
 		putshort(&p, q->type);
diff --git a/tests/dns.c b/tests/dns.c
index 55e753b..21745c7 100644
--- a/tests/dns.c
+++ b/tests/dns.c
@@ -69,8 +69,9 @@ START_TEST(test_encode_query)
 	char *d;
 	size_t len;
 	int ret;
+	int enclen;
 
-	len = sizeof(buf);
+	enclen = sizeof(resolv);
 	memset(&buf, 0, sizeof(buf));
 	memset(&resolv, 0, sizeof(resolv));
 	memset(&q, 0, sizeof(struct query));
@@ -80,12 +81,13 @@ START_TEST(test_encode_query)
 	enc = get_base32_encoder();
 
 	*d++ = 'A';
-	enc->encode(d, &len, innerData, strlen(innerData));
+	enc->encode(d, &enclen, innerData, strlen(innerData));
 	d = resolv + strlen(resolv);
 	if (*d != '.') {
 		*d++ = '.';
 	}
 	strcpy(d, topdomain);
+	len = sizeof(buf);
 	ret = dns_encode(buf, len, &q, QR_QUERY, resolv, strlen(resolv));
 	len = sizeof(query_packet) - 1; /* Skip extra null character */