dns/resource: fix nsec for 63 char names

src/dns.c

@@ -2222,16 +2222,28 @@ hsk_dns_name_serialize(
   int size;
   int i;
   char *s;
-  int size_byte = 0;
+  int size_adjust = 0;
 
   for (s = (char *)name, i = 0; *s; s++, i++) {
+    if (name[i] == '\\') {
+      if (!isdigit(name[++i]) ||
+          !isdigit(name[++i]) ||
+          !isdigit(name[++i])) {
+        *len = off;
+        return false;
+      }
+
+      size_adjust += 3;
+      s += 3;
+    }
+
     if (name[i] == '.') {
       if (i > 0 && name[i - 1] == '.') {
         *len = off;
         return false;
       }
 
-      size = i - begin;
+      size = i - begin - size_adjust;
 
       if (size > HSK_DNS_MAX_LABEL) {
         *len = off;
@@ -2243,8 +2255,7 @@ hsk_dns_name_serialize(
           *len = off;
           return false;
         }
-        // Size will be written here once we know what size is
-        size_byte = off;
+        data[off] = size;
       }
 
       if (cmp) {
@@ -2274,13 +2285,6 @@ hsk_dns_name_serialize(
           char ch = name[j];
           if (ch == '\\') {
             // Read the next three digits and form a single byte
-            if (!isdigit(name[j + 1]) ||
-                !isdigit(name[j + 2]) ||
-                !isdigit(name[j + 3])) {
-              *len = off;
-              return false;
-            }
-
             uint16_t value = (name[++j] - 0x30) * 100;
             value += (name[++j] - 0x30) * 10;
             value += (name[++j] - 0x30);
@@ -2305,13 +2309,12 @@ hsk_dns_name_serialize(
 
           data[off++] = ch;
         }
-
-        data[size_byte] = size;
       } else {
         off += size;
       }
 
       begin = i + 1;
+      size_adjust = 0;
     }
   }
 

src/resource.c

@@ -929,6 +929,9 @@ hsk_resource_to_dns(const hsk_resource_t *rs, const char *name, uint16_t type) {
   hsk_dns_rrs_t *ns = &msg->ns; // authority
   hsk_dns_rrs_t *ar = &msg->ar; // additional
 
+  // Even though the name here is a single label (the TLD)
+  // we use a larger buffer size of 255 (instead of 63)
+  // to allow escaped byte codes like /000
   char next[HSK_DNS_MAX_NAME];
   next_name(tld, next);
 
@@ -1160,7 +1163,10 @@ hsk_resource_to_nx(const char *tld) {
   hsk_dns_rr_t *rr1 = hsk_dns_rrs_pop(ns);
   hsk_dns_rr_t *rr2 = hsk_dns_rrs_pop(ns);
 
-  // Prove the name doesn't exist
+  // Prove the name doesn't exist.
+  // Even though the name here is a single label (the TLD)
+  // we use a larger buffer size of 255 (instead of 63)
+  // to allow escaped byte codes like /000
   char next[HSK_DNS_MAX_NAME];
   char prev[HSK_DNS_MAX_NAME];
   next_name(tld, next);
@@ -1245,6 +1251,7 @@ next_name(const char *name, char *next) {
     memcpy(&next[len], "\\000.", 6);
   } else {
     next[len - 1]++;
+    memcpy(&next[len], ".", 2);
   }
 }
 

test/data/name_serialization_vectors.h

@@ -50,17 +50,15 @@ static const name_serializtion_vector_t name_serializtion_vectors[7] = {
   {
     "abcdef\\256.",
     {
-      0x00, 0x61, 0x62, 0x63, 0x64, 0x65, 0x66
+      0x07, 0x61, 0x62, 0x63, 0x64, 0x65, 0x66
     },
     7,
     false
   },
   {
     "abcdef\\LOL.",
-    {
-      0x00, 0x61, 0x62, 0x63, 0x64, 0x65, 0x66
-    },
-    7,
+    {},
+    0,
     false
   },
   {