validation: check auxpow PoW before other checks

block: check parent coinbase for input

Ported from dogecoin/dogecoin@51cbc1f

src/block.c

@@ -72,6 +72,13 @@ dogecoin_bool check(void *ctx, uint256* hash, uint32_t chainid, dogecoin_chainpa
     uint256* chain_merkle_root = check_merkle_branch(hash, chain_merkle_branch, block->aux_merkle_index);
     vector_free(chain_merkle_branch, true);
 
+    // Check that there is at least one input in the parent coinbase transaction
+    if (block->parent_coinbase->vin->len == 0) {
+        printf("Aux POW coinbase has no inputs\n");
+        dogecoin_free(chain_merkle_root);
+        return false;
+    }
+
     // Convert the root hash to a human-readable format (hex)
     unsigned char vch_roothash[64]; // Make sure it's large enough to hold the hash
     memcpy(vch_roothash, hash_to_string((uint8_t*)chain_merkle_root), 64); // Copy the data

src/validation.c

@@ -95,14 +95,6 @@ dogecoin_bool check_auxpow(dogecoin_auxpow_block* block, dogecoin_chainparams* p
     }
 
     /* We have auxpow.  Check it.  */
-    uint256 block_header_hash;
-    dogecoin_block_header_hash(block->header, block_header_hash);
-    uint32_t chainid = get_chainid(block->header->version);
-    if (!block->header->auxpow->check(block, &block_header_hash, chainid, params)) {
-        printf("%s:%d:%s : AUX POW is not valid : %s\n", __FILE__, __LINE__, __func__, strerror(errno));
-        return false;
-    }
-
     uint256 parent_hash;
     cstring* s2 = cstr_new_sz(64);
     dogecoin_block_header_serialize(s2, block->parent_header);
@@ -113,5 +105,13 @@ dogecoin_bool check_auxpow(dogecoin_auxpow_block* block, dogecoin_chainparams* p
         return false;
     }
 
+    uint256 block_header_hash;
+    dogecoin_block_header_hash(block->header, block_header_hash);
+    uint32_t chainid = get_chainid(block->header->version);
+    if (!block->header->auxpow->check(block, &block_header_hash, chainid, params)) {
+        printf("%s:%d:%s : AUX POW is not valid : %s\n", __FILE__, __LINE__, __func__, strerror(errno));
+        return false;
+    }
+
     return true;
 }