Merge pull request #30 from kostaleonard/blockchain-verify

Adds blockchain serialization and deserialization

.gitignore

@@ -3,6 +3,7 @@
 
 build
 scrap
+tests/output
 
 ### C ###
 # Prerequisites

CMakeLists.txt

@@ -22,9 +22,13 @@ target_link_libraries(main hash)
 add_library(base64 src/base64.c)
 target_link_libraries(base64 OpenSSL::Crypto)
 target_link_libraries(main base64)
+add_library(endian src/endian.c)
+target_link_libraries(main endian)
 include_directories(${CMOCKA_INCLUDE_DIR})
 find_package(cmocka REQUIRED)
 add_executable(tests tests/main.c)
+add_library(test_file_paths tests/file_paths.c)
+target_link_libraries(tests test_file_paths)
 add_library(test_linked_list tests/test_linked_list.c)
 target_link_libraries(test_linked_list linked_list)
 target_link_libraries(tests test_linked_list)
@@ -41,4 +45,7 @@ target_link_libraries(tests test_transaction)
 add_library(test_base64 tests/test_base64.c)
 target_link_libraries(test_base64 base64)
 target_link_libraries(tests test_base64)
+add_library(test_endian tests/test_endian.c)
+target_link_libraries(test_endian endian)
+target_link_libraries(tests test_endian)
 target_link_libraries(tests cmocka)

include/block.h

@@ -17,8 +17,9 @@
  * 
  * @param created_at The datetime at which the user created this block.
  * @param transaction_list A list of the transactions this block contains.
- * @param proof_of_work A number p' such that hash(pp') contains some number of
- * leading zeros, where p is the previous block's proof of work.
+ * @param proof_of_work A number such that the hash of the block_t contains
+ * some number of leading zeros. It has no meaning other than as part of the
+ * hash.
  * @param previous_block_hash The hash of the previous block.
  */
 typedef struct block_t {
@@ -33,8 +34,9 @@ typedef struct block_t {
  * 
  * @param block The pointer to fill with the new block.
  * @param transaction_list A list of the transactions this block contains.
- * @param proof_of_work A number p' such that hash(pp') contains some number of
- * leading zeros, where p is the previous block's proof of work.
+ * @param proof_of_work A number such that the hash of the block_t contains
+ * some number of leading zeros. It has no meaning other than as part of the
+ * hash.
  * @param previous_block_hash The hash of the previous block.
  * @return return_code_t A return code indicating success or failure.
  */

include/blockchain.h

@@ -89,4 +89,61 @@ return_code_t blockchain_mine_block(
  */
 void blockchain_print(blockchain_t *blockchain);
 
+/**
+ * @brief Serializes the blockchain into a buffer for file or network I/O.
+ * 
+ * @param blockchain The blockchain.
+ * @param buffer A pointer to fill with the bytes representing the blockchain.
+ * Callers can write the bytes to a file or send on the network and reconstruct
+ * the original blockchain with blockchain_deserialize. Callers are responsible
+ * for freeing the buffer.
+ * @param buffer_size A pointer to fill with the final size of the buffer.
+ * @return return_code_t A return code indicating success or failure.
+ */
+return_code_t blockchain_serialize(
+    blockchain_t *blockchain,
+    unsigned char **buffer,
+    uint64_t *buffer_size
+);
+
+/**
+ * @brief Reconstructs the blockchain from a buffer.
+ * 
+ * @param blockchain A pointer to fill with the reconstructed blockchain.
+ * Callers are responsible for calling blockchain_destroy when finished.
+ * @param buffer An array containing the serialized blockchain.
+ * @param buffer_size The length of the serialized blockchain.
+ * @return return_code_t A return code indicating success or failure.
+ */
+return_code_t blockchain_deserialize(
+    blockchain_t **blockchain,
+    unsigned char *buffer,
+    uint64_t buffer_size
+);
+
+/**
+ * @brief Saves the blockchain to a file.
+ * 
+ * @param blockchain The blockchain.
+ * @param outfile The path to the file to which to write the blockchain.
+ * @return return_code_t A return code indicating success or failure.
+ */
+return_code_t blockchain_write_to_file(
+    blockchain_t *blockchain,
+    char *outfile
+);
+
+/**
+ * @brief Reads the blockchain from a file.
+ * 
+ * @param blockchain A pointer to fill with the reconstructed blockchain.
+ * Callers are responsible for calling blockchain_destroy when finished.
+ * @param infile The path to the file from which to read the blockchain.
+ * @return return_code_t A return code indicating success or failure.
+ */
+return_code_t blockchain_read_from_file(
+    blockchain_t **blockchain,
+    char *infile
+);
+
 #endif  // INCLUDE_BLOCKCHAIN_H_

include/endian.h

@@ -0,0 +1,25 @@
+/**
+ * @brief Defines functions for working with endianness.
+ */
+
+#ifndef INCLUDE_ENDIAN_H_
+#define INCLUDE_ENDIAN_H_
+#include <stdint.h>
+
+/**
+ * @brief Returns the big endian representation of data.
+ * 
+ * @param data A 64 bit piece of data. Its endianness does not matter.
+ * @return uint64_t The big endian representation of data.
+ */
+uint64_t htobe64(uint64_t data);
+
+/**
+ * @brief Returns the host representation of big endian data.
+ * 
+ * @param data A 64 bit piece of data in big endian representation.
+ * @return uint64_t The host representation of data.
+ */
+uint64_t betoh64(uint64_t data);
+
+#endif  // INCLUDE_ENDIAN_H_

include/linked_list.h

@@ -6,6 +6,7 @@
 #define INCLUDE_LINKED_LIST_H_
 
 #include <stdbool.h>
+#include <stdint.h>
 #include "include/return_codes.h"
 
 /**
@@ -148,4 +149,13 @@ return_code_t linked_list_append(linked_list_t *linked_list, void *data);
  */
 return_code_t linked_list_get_last(linked_list_t *linked_list, node_t **node);
 
+/**
+ * @brief Fills length with the number of items in the linked list.
+ * 
+ * @param linked_list The linked list.
+ * @param length A pointer to fill with the length of the list.
+ * @return return_code_t A return code indicating success or failure.
+ */
+return_code_t linked_list_length(linked_list_t *linked_list, uint64_t *length);
+
 #endif  // INCLUDE_LINKED_LIST_H_

include/return_codes.h

@@ -14,6 +14,9 @@ typedef enum return_code_t {
     FAILURE_COULD_NOT_FIND_VALID_PROOF_OF_WORK,
     FAILRE_INVALID_COMMAND_LINE_ARGS,
     FAILURE_OPENSSL_FUNCTION,
+    FAILURE_FILE_IO,
+    FAILURE_SIGNATURE_TOO_LONG,
+    FAILURE_BUFFER_TOO_SMALL,
 } return_code_t;
 
 #endif  // INCLUDE_RETURN_CODES_H_

include/transaction.h

@@ -30,7 +30,7 @@ typedef struct transaction_t {
     time_t created_at;
     ssh_key_t sender_public_key;
     ssh_key_t recipient_public_key;
-    uint32_t amount;
+    uint64_t amount;
     ssh_signature_t sender_signature;
 } transaction_t;
 
@@ -51,7 +51,7 @@ return_code_t transaction_create(
     transaction_t **transaction,
     ssh_key_t *sender_public_key,
     ssh_key_t *recipient_public_key,
-    uint32_t amount,
+    uint64_t amount,
     ssh_key_t *sender_private_key
 );
 

src/block.c

@@ -88,6 +88,9 @@ return_code_t block_hash(block_t *block, sha_256_t *hash) {
         NULL != node;
         node = node->next) {
         transaction_t *transaction = (transaction_t *)node->data;
+        // We can just hash the entire transaction directly because it contains
+        // no pointers. Memory locations don't have meaning, so we can't hash
+        // pointers.
         EVP_DigestUpdate(mdctx, (void *)transaction, sizeof(*transaction));
     }
     EVP_DigestFinal_ex(mdctx, hash->digest, NULL);