1 files changed, 40 insertions, 24 deletions

diff --git a/domain2name.c b/domain2name.c
index 7c84fbb..4f305fb 100644
--- a/domain2name.c
+++ b/domain2name.c
@@ -2,16 +2,18 @@ int domain2name_len (const char * s, int l) {	/* TODO	make domain2name FAIL at e
 	int r = 1; /* ending terminator */	/*	make functions FAIL at label.length > 63 */
 	int o = 0; /* label offset */		/*	currently domain2name never fails */
 	for (int i = 0; i < l; i++) {		/* NOTE when using BOTH _len, check that they are */
-		if (s[i] == '.') {		/*	NOT negative. d2n_len will fail in d future */
+		if (s[i] == '.') {		/*	NOT negative. d2n_len may fail in d future */
 			if (!o) /* double period or starting period, label is empty */
-				break;
+				break; /* we could return -1 here if r == 1 */
 			o = 0;
 			continue;
 		}
 		if (!o) /* label has started */
 			r++;
-		r++;
-		o++;
+		if (o < 63) { /* we cap label length at 64 bytes. we could return -2 here. */
+			r++;
+			o++;
+		}
 	}
 	return r;
 }
@@ -38,42 +40,56 @@ int domain2name (char * n /* at least _len bytes */, const char * s, int l) { /*
 	*w++ = '\0'; /* luckily this makes domain2name kind of safe for handling as a string (: */
 	return w-n; /* we return number of bytes written */
 } /* no compression, it's 2022, net bandwidth is unlimited. n2d OFC does decompress ptrs acc2 std. */
-int name2domain_len (const char * u /* >= 512 bytes */, const char * n /* name */) {
-#define N2DO(x) ((x) & ~(1 << 7 & 1 << 6)) /* pointer offset */
+int name2domain_len (const char * u, int s /* size of u */, const char * n /* name */) {
+#define N2DO(x) (ntohs(x) & ~(1 << 15 | 1 << 14)) /* pointer offset */
 	int r = 0;
-	if (n < u+512 && *n == '\0') {
+	char * f = alloca(s/8+1);
+	memset(f, '\0', s/8+1);
+	if (n < u+s && *n == '\0') {
 		return 2;
 	}
-	while (n < u+512) {
+	while (n < u+s) {
 		if (*n & 1 << 7) {
 			if (!(*n & 1 << 6))
 				return -1; /* 10xx xxxx not implemented - reserved for future use */
-			n = u + N2DO(*n);
+			if (n+1 >= u+s)
+				return -2; /* malformed packet */
+			if (f[(n-u)/8] & 1 << (n-u)%8)
+				return -3; /* infinite pointer loop detected */
+			f[(n-u)/8] |= 1 << (n-u)%8;
+			n = u + N2DO(*(uint16_t *) n);
 			continue;
 		}
 		if (*n & 1 << 6)
-			return -2; /* 01xx xxxx not implemented - reserved for future use */
+			return -4; /* 01xx xxxx not implemented - reserved for future use */
 		if (!*n)
 			return r+1;
 		r += *n+1;
 		n += *n+1;
 	}
-	return -3; /* malformed packet */
+	return -5; /* malformed packet */
 } /* returns number of bytes needed for buffer, passed as the first argument of name2domain(). */
-const char * name2domain (char * d /* >= _len B */, const char * u /* >= 512 B */, const char * n) {
+const char * name2domain (char * d /* >= _len B */, const char * u, int s, const char * n) {
 	char * w = d; /* if d is NULL nothing is written and last byte of name is returned */
 	const char * r = NULL;
-	if (n < u+512 && *n == '\0') {
+	char * f = alloca(s/8+1);
+	memset(f, '\0', s/8+1);
+	if (n < u+s && *n == '\0') {
 		*w++ = '.';
 		*w++ = '\0';
 		return n;
 	}
-	while (n < u+512) {
+	while (n < u+s) {
 		if (*n & 1 << 7) {
 			if (!(*n & 1 << 6))
 				return NULL; /* 10xx xxxx N/I - reserved for future use as per RFC */
-			n = u + N2DO(*n);
-			r = n;
+			if (n+1 >= u+s)
+				return NULL;
+			r = n+1;
+			if (f[(n-u)/8] & 1 << (n-u)%8)
+				return NULL; /* infinite pointer loop detected */
+			f[(n-u)/8] |= 1 << (n-u)%8;
+			n = u + N2DO(*(uint16_t *) n);
 			continue;
 		}
 		if (*n & 1 << 6)
@@ -85,7 +101,7 @@ const char * name2domain (char * d /* >= _len B */, const char * u /* >= 512 B *
 		}
 		const char * x = n+*n;
 		n++;
-		if (!(x < u+512))
+		if (!(x < u+s))
 			return NULL; /* malformed packet */
 		while (n <= x)
 			if (w)
@@ -100,20 +116,20 @@ const char * name2domain (char * d /* >= _len B */, const char * u /* >= 512 B *
 int normalizedomain_len (const char * s, int l) {
 	int ž = domain2name_len(s, l);
 	if (ž < 0)
-		return -4;
+		return -6;
 	char * b = alloca(ž);
 	if (domain2name(b, s, l) != ž)
-		return -5;
-	return name2domain_len(b, b);
+		return -7;
+	return name2domain_len(b, ž, b);
 }
 int normalizedomain (char * d /* at least _len bytes */, const char * s, int l) {
 	int ž = domain2name_len(s, l);
 	if (ž < 0)
-		return -4;
+		return -6;
 	char * b = alloca(ž);
 	if (domain2name(b, s, l) != ž)
-		return -5;
-	if (!name2domain(d, b, b))
-		return -6;
+		return -7;
+	if (!name2domain(d, b, ž, b))
+		return -8;
 	return 0;
 }