1 files changed, 89 insertions, 10 deletions

diff --git a/domain2name.c b/domain2name.c
index 46fd2a3..7c84fbb 100644
--- a/domain2name.c
+++ b/domain2name.c
@@ -1,8 +1,8 @@
-int domain2name_len (const char * s, int l) {
-	int r = 1; /* ending terminator */
-	int o = 0; /* label offset */
-	for (int i = 0; i < l; i++) {
-		if (s[i] == '.') {
+int domain2name_len (const char * s, int l) {	/* TODO	make domain2name FAIL at empty label (..) */
+	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 (!o) /* double period or starting period, label is empty */
 				break;
 			o = 0;
@@ -15,9 +15,9 @@ int domain2name_len (const char * s, int l) {
 	}
 	return r;
 }
-int domain2name (char * d, const char * s, int l) { /* l is length of s */
-	char * c = d; /* where to write the label size when done with label */
-	char * w = d;
+int domain2name (char * n /* at least _len bytes */, const char * s, int l) { /* l is length of s */
+	char * c = n; /* where to write the label size when done with label */
+	char * w = n;
 	int o = 0; /* label offset */
 	for (int i = 0; i <= l /* yes, we go one more ... */; i++) {
 		if (i == l /* ... here */ || s[i] == '.') { /* end of label or end of last label */
@@ -36,5 +36,84 @@ int domain2name (char * d, const char * s, int l) { /* l is length of s */
 			*c = 63; /* it at 63 bytes */
 	}
 	*w++ = '\0'; /* luckily this makes domain2name kind of safe for handling as a string (: */
-	return w-d; /* we return number of bytes written */
-} /* d must be allocated for at least _len. */
+	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 r = 0;
+	if (n < u+512 && *n == '\0') {
+		return 2;
+	}
+	while (n < u+512) {
+		if (*n & 1 << 7) {
+			if (!(*n & 1 << 6))
+				return -1; /* 10xx xxxx not implemented - reserved for future use */
+			n = u + N2DO(*n);
+			continue;
+		}
+		if (*n & 1 << 6)
+			return -2; /* 01xx xxxx not implemented - reserved for future use */
+		if (!*n)
+			return r+1;
+		r += *n+1;
+		n += *n+1;
+	}
+	return -3; /* 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) {
+	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') {
+		*w++ = '.';
+		*w++ = '\0';
+		return n;
+	}
+	while (n < u+512) {
+		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;
+			continue;
+		}
+		if (*n & 1 << 6)
+			return NULL; /* 01xx xxxx N/I - reserved for future use as per RFC */
+		if (!*n) { /* end of name */
+			if (w)
+				*w++ = '\0';
+			return r ? r : n;
+		}
+		const char * x = n+*n;
+		n++;
+		if (!(x < u+512))
+			return NULL; /* malformed packet */
+		while (n <= x)
+			if (w)
+				*w++ = *n++;
+			else
+				n++;
+		if (w)
+			*w++ = '.';
+	}
+	return NULL; /* malformed packet */
+} /* Returns ptr to last byte of name - '\0' or dnsptr. Ret. NULL on fail (_len also returned < 0) */
+int normalizedomain_len (const char * s, int l) {
+	int ž = domain2name_len(s, l);
+	if (ž < 0)
+		return -4;
+	char * b = alloca(ž);
+	if (domain2name(b, s, l) != ž)
+		return -5;
+	return name2domain_len(b, 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;
+	char * b = alloca(ž);
+	if (domain2name(b, s, l) != ž)
+		return -5;
+	if (!name2domain(d, b, b))
+		return -6;
+	return 0;
+}