Reducing buffer_ext module with most of the API now in the SDK

diff --git a/src/boilerplate/dispatcher.c b/src/boilerplate/dispatcher.c
index 405e863..da9ff6c 100644
--- a/src/boilerplate/dispatcher.c
+++ b/src/boilerplate/dispatcher.c
@@ -24,7 +24,6 @@
 #include "buffer.h"
 
 /* Local headers */
-#include "buffer_ext.h"
 #include "constants.h"
 #include "globals.h"
 #include "io_ext.h"
diff --git a/src/common/buffer_ext.c b/src/common/buffer_ext.c
index 6344474..65ee2f1 100644
--- a/src/common/buffer_ext.c
+++ b/src/common/buffer_ext.c
@@ -13,12 +13,6 @@
  *  See the License for the specific language governing permissions and
  *  limitations under the License.
  *****************************************************************************/
-
-/*
- * NOTE: The SDK's buffer_t type uses `const uint8_t *ptr` for both read and write.
- * Write functions cast away const; callers must ensure underlying memory is mutable.
- */
-
 #include <stdbool.h>
 #include <stddef.h>
 #include <stdint.h>
@@ -33,98 +27,6 @@
 #include "varint.h"
 #include "write.h"
 
-bool buffer_peek(const buffer_t *buffer, uint8_t *value) {
-    return buffer_peek_n(buffer, 0, value);
-}
-
-bool buffer_peek_n(const buffer_t *buffer, size_t n, uint8_t *value) {
-    if (!buffer_can_read(buffer, n + 1)) {
-        return false;
-    }
-
-    *value = buffer->ptr[buffer->offset + n];
-
-    return true;
-}
-
-bool buffer_read_bytes(buffer_t *buffer, uint8_t *out, size_t n) {
-    if (buffer->size - buffer->offset < n) {
-        return false;
-    }
-
-    memmove(out, buffer->ptr + buffer->offset, n);
-    buffer_seek_cur(buffer, n);
-
-    return true;
-}
-
-bool buffer_write_u8(buffer_t *buffer, uint8_t value) {
-    if (!buffer_can_read(buffer, 1)) {
-        return false;
-    }
-
-    ((uint8_t *) buffer->ptr)[buffer->offset] = value;
-    buffer_seek_cur(buffer, 1);
-
-    return true;
-}
-
-bool buffer_write_u16(buffer_t *buffer, uint16_t value, endianness_t endianness) {
-    if (!buffer_can_read(buffer, 2)) {
-        return false;
-    }
-
-    if (endianness == BE) {
-        write_u16_be((uint8_t *) buffer->ptr, buffer->offset, value);
-    } else {
-        write_u16_le((uint8_t *) buffer->ptr, buffer->offset, value);
-    }
-    buffer_seek_cur(buffer, 2);
-
-    return true;
-}
-
-bool buffer_write_u32(buffer_t *buffer, uint32_t value, endianness_t endianness) {
-    if (!buffer_can_read(buffer, 4)) {
-        return false;
-    }
-
-    if (endianness == BE) {
-        write_u32_be((uint8_t *) buffer->ptr, buffer->offset, value);
-    } else {
-        write_u32_le((uint8_t *) buffer->ptr, buffer->offset, value);
-    }
-    buffer_seek_cur(buffer, 4);
-
-    return true;
-}
-
-bool buffer_write_u64(buffer_t *buffer, uint64_t value, endianness_t endianness) {
-    if (!buffer_can_read(buffer, 8)) {
-        return false;
-    }
-
-    if (endianness == BE) {
-        write_u64_be((uint8_t *) buffer->ptr, buffer->offset, value);
-    } else {
-        write_u64_le((uint8_t *) buffer->ptr, buffer->offset, value);
-    }
-
-    buffer_seek_cur(buffer, 8);
-
-    return true;
-}
-
-bool buffer_write_bytes(buffer_t *buffer, const uint8_t *data, size_t n) {
-    if (!buffer_can_read(buffer, n)) {
-        return false;
-    }
-
-    memmove((uint8_t *) (buffer->ptr + buffer->offset), data, n);
-    buffer_seek_cur(buffer, n);
-    return true;
-}
-
 void *buffer_alloc(buffer_t *buffer, size_t size, bool aligned) {
     size_t padding_size = 0;
 
diff --git a/src/common/buffer_ext.h b/src/common/buffer_ext.h
index 19ccf66..27d7a61 100644
--- a/src/common/buffer_ext.h
+++ b/src/common/buffer_ext.h
@@ -7,168 +7,6 @@
 /* SDK headers */
 #include "buffer.h"
 
-typedef size_t buffer_snapshot_t;
-
-/**
- * Returns the pointer to byte in the current position of the buffer.
- *
- * @param[in] buffer
- *   Pointer to input buffer struct.
- *
- * @return the pointer to the current position.
- *
- */
-static inline uint8_t *buffer_get_cur(const buffer_t *buffer) {
-    return (uint8_t *) (buffer->ptr + buffer->offset);
-}
-
-/**
- * Read 1 byte from buffer into uint8_t.
- *
- * @param[in,out]  buffer
- *   Pointer to input buffer struct.
- * @param[out]     value
- *   Pointer to 8-bit unsigned integer read from buffer.
- *
- * @return true if success, false otherwise.
- *
- */
-bool buffer_read_u8(buffer_t *buffer, uint8_t *value);
-
-/**
- * Read 1 byte from buffer into uint8_t without advancing the current position in the buffer.
- * Returns `true` on success, `false` if the buffer was empty; `value` is not changed in case of
- * failure.
- *
- * @param[in]  buffer
- *   Pointer to input buffer struct.
- * @param[out]  value
- *   Pointer to 8-bit unsigned integer read from buffer.
- *
- * @return true if success, false otherwise.
- */
-bool buffer_peek(const buffer_t *buffer, uint8_t *value);
-
-/**
- * Read 1 byte at position `n` from buffer into uint8_t without advancing the current position in
- * the buffer. Returns `true` on success, `false` if the buffer is not large enough; `value` is not
- * changed in case of failure.
- *
- * @param[in]  buffer
- *   Pointer to input buffer struct.
- * @param[out]  n
- *   Index of the byte to read, where the immediate next byte has index 0.
- * @param[out]  value
- *   Pointer to 8-bit unsigned integer read from buffer.
- *
- * @return true if success, false otherwise.
- */
-bool buffer_peek_n(const buffer_t *buffer, size_t n, uint8_t *value);
-
-/**
- * Read n bytes from buffer, and stores them in out.
- *
- * @param[in,out]  buffer
- *   Pointer to input buffer struct.
- * @param[out]     out
- *   Pointer to output buffer. It is the responsibility of the caller to make sure that the output
- * buffer is at least n bytes long.
- * @param[in]      n
- *   Number of bytes to read from buffer.
- *
- * @return true if success, false otherwise.
- *
- */
-bool buffer_read_bytes(buffer_t *buffer, uint8_t *out, size_t n);
-
-/**
- * Write a uint8_t into a buffer.
- *
- * @param[in,out]  buffer
- *   Pointer to output buffer struct.
- * @param[out]     value
- *   Value to be written.
- *
- * @return true if success, false if not enough space left in the buffer.
- *
- */
-bool buffer_write_u8(buffer_t *buffer, uint8_t value);
-
-/**
- * Write a uint16_t into the buffer as 2 bytes, with the given endianness.
- *
- * @param[in,out]  buffer
- *   Pointer to output buffer struct.
- * @param[out]     value
- *   Value to be written.
- * @param[in]      endianness
- *   Either BE (Big Endian) or LE (Little Endian).
- *
- * @return true if success, false if not enough space left in the buffer.
- *
- */
-bool buffer_write_u16(buffer_t *buffer, uint16_t value, endianness_t endianness);
-
-/**
- * Write a uint32_t into the buffer as 4 bytes, with the given endianness.
- *
- * @param[in,out]  buffer
- *   Pointer to output buffer struct.
- * @param[out]     value
- *   Value to be written.
- * @param[in]      endianness
- *   Either BE (Big Endian) or LE (Little Endian).
- *
- * @return true if success, false if not enough space left in the buffer.
- *
- */
-bool buffer_write_u32(buffer_t *buffer, uint32_t value, endianness_t endianness);
-
-/**
- * Write a uint64_t into the buffer as 8 bytes, with the given endianness.
- *
- * @param[in,out]  buffer
- *   Pointer to output buffer struct.
- * @param[out]     value
- *   Value to be written.
- * @param[in]      endianness
- *   Either BE (Big Endian) or LE (Little Endian).
- *
- * @return true if success, false if not enough space left in the buffer.
- *
- */
-bool buffer_write_u64(buffer_t *buffer, uint64_t value, endianness_t endianness);
-
-/**
- * Write a number of bytes to a buffer.
- *
- * @param[in,out]  buffer
- *   Pointer to output buffer struct.
- * @param[in]      data
- *   Pointer to bytes to be written.
- * @param[in]      n
- *   Size of bytes to be written.
- *
- * @return true if success, false if not enough space left in the buffer.
- *
- */
-bool buffer_write_bytes(buffer_t *buffer, const uint8_t *data, size_t n);
-
-/**
- * Creates a buffer pointing at ptr and with the given size; the initial offset is 0.
- *
- * @param[in,out]  ptr
- *   Pointer to the buffer's data.
- * @param[in]  size
- *   Size of the buffer.
- *
- * @return the new buffer with the given pointer and size.
- *
- */
-static inline buffer_t buffer_create(void *ptr, size_t size) {
-    return (buffer_t){.ptr = ptr, .size = size, .offset = 0};
-}
-
 /**
  * Returns a pointer to the current position in the buffer if at least `size` bytes are available in
  * the buffer (possibly after skipping some bytes to guarantee alignment), or NULL otherwise. On
@@ -194,24 +32,3 @@ void *buffer_alloc(buffer_t *buffer, size_t size, bool aligned);
 static inline bool buffer_is_cur_aligned(const buffer_t *buffer) {
     return (size_t) (buffer->ptr + buffer->offset) % 4 == 0;
 }
-
-/**
- * Saves a snapshot of the current position within the buffer.
- *
- * @param[in] buffer The buffer whose position is saved.
- *
- * @return a snapshot that can be restored with `buffer_restore`.
- */
-static inline buffer_snapshot_t buffer_snapshot(const buffer_t *buffer) {
-    return buffer->offset;
-}
-
-/**
- * Restores a previously taken snapshot of the buffer.
- *
- * @param[in,out] snapshot The snapshot previously returned by a call to `buffer_snapshot` on the
- * same buffer. The behavior is undefined if any other value is passed as `snapshot`.
- */
-static inline void buffer_restore(buffer_t *buffer, buffer_snapshot_t snapshot) {
-    buffer->offset = snapshot;
-}
diff --git a/src/common/parser_ext.c b/src/common/parser_ext.c
index 0f54bab..767fd66 100644
--- a/src/common/parser_ext.c
+++ b/src/common/parser_ext.c
@@ -5,9 +5,6 @@
 /* SDK headers */
 #include "read.h"
 
-/* Local headers */
-#include "buffer_ext.h"
-
 size_t dbuffer_get_length(buffer_t *buffers[2]) {
     return (buffers[0]->size - buffers[0]->offset) + (buffers[1]->size - buffers[1]->offset);
 }
@@ -117,8 +114,8 @@ bool parser_consolidate_buffers(buffer_t *buffers[2], size_t max_size) {
         return false;
     }
 
-    memmove((uint8_t *) buffers[0]->ptr, buffers[0]->ptr + buffers[0]->offset, length0);
-    memmove((uint8_t *) buffers[0]->ptr + length0, buffers[1]->ptr + buffers[1]->offset, length1);
+    memmove(buffers[0]->ptr, buffers[0]->ptr + buffers[0]->offset, length0);
+    memmove(buffers[0]->ptr + length0, buffers[1]->ptr + buffers[1]->offset, length1);
     buffers[0]->offset = 0;
     buffers[0]->size = length0 + length1;
     return true;
diff --git a/src/handler/get_wallet_address.c b/src/handler/get_wallet_address.c
index a9aeb65..6da86b2 100644
--- a/src/handler/get_wallet_address.c
+++ b/src/handler/get_wallet_address.c
@@ -24,7 +24,6 @@
 #include "read.h"
 
 /* Local headers */
-#include "buffer_ext.h"
 #include "client_commands.h"
 #include "commands.h"
 #include "constants.h"
diff --git a/src/handler/lib/check_merkle_tree_sorted.c b/src/handler/lib/check_merkle_tree_sorted.c
index 550dcb4..3946704 100644
--- a/src/handler/lib/check_merkle_tree_sorted.c
+++ b/src/handler/lib/check_merkle_tree_sorted.c
@@ -3,7 +3,6 @@
 #include "check_merkle_tree_sorted.h"
 
 /* Local headers */
-#include "buffer_ext.h"
 #include "get_merkle_leaf_element.h"
 #include "merkle.h"
 
diff --git a/src/handler/lib/get_merkle_leaf_hash.c b/src/handler/lib/get_merkle_leaf_hash.c
index 183e14d..d791266 100644
--- a/src/handler/lib/get_merkle_leaf_hash.c
+++ b/src/handler/lib/get_merkle_leaf_hash.c
@@ -8,7 +8,6 @@
 #include "write.h"
 
 /* Local headers */
-#include "buffer_ext.h"
 #include "client_commands.h"
 #include "debug.h"
 #include "merkle.h"
diff --git a/src/handler/lib/get_merkle_preimage.c b/src/handler/lib/get_merkle_preimage.c
index 2f03645..8a7e149 100644
--- a/src/handler/lib/get_merkle_preimage.c
+++ b/src/handler/lib/get_merkle_preimage.c
@@ -6,7 +6,6 @@
 #include "buffer.h"
 
 /* Local headers */
-#include "buffer_ext.h"
 #include "client_commands.h"
 #include "crypto.h"
 #include "debug.h"
@@ -59,7 +58,7 @@ int call_get_merkle_preimage(dispatcher_context_t *dispatcher_context,
     }
 
     uint8_t *data_ptr =
-        (uint8_t *) (dispatcher_context->read_buffer.ptr + dispatcher_context->read_buffer.offset);
+        dispatcher_context->read_buffer.ptr + dispatcher_context->read_buffer.offset;
 
     cx_sha256_t hash_context;
 
@@ -100,8 +99,7 @@ int call_get_merkle_preimage(dispatcher_context_t *dispatcher_context,
             return -9;
         }
 
-        data_ptr = (uint8_t *) dispatcher_context->read_buffer.ptr +
-                   dispatcher_context->read_buffer.offset;
+        data_ptr = dispatcher_context->read_buffer.ptr + dispatcher_context->read_buffer.offset;
 
         // update hash
         crypto_hash_update(&hash_context.header, data_ptr, n_bytes);
diff --git a/src/handler/lib/get_merkleized_map.c b/src/handler/lib/get_merkleized_map.c
index f11ae5b..93e48c4 100644
--- a/src/handler/lib/get_merkleized_map.c
+++ b/src/handler/lib/get_merkleized_map.c
@@ -6,7 +6,6 @@
 #include "buffer.h"
 
 /* Local headers */
-#include "buffer_ext.h"
 #include "check_merkle_tree_sorted.h"
 #include "get_merkle_leaf_element.h"
 
diff --git a/src/handler/lib/get_preimage.c b/src/handler/lib/get_preimage.c
index aac7cf1..357b932 100644
--- a/src/handler/lib/get_preimage.c
+++ b/src/handler/lib/get_preimage.c
@@ -1,7 +1,6 @@
 #include <string.h>
 
 /* Local headers */
-#include "buffer_ext.h"
 #include "client_commands.h"
 #include "crypto.h"
 #include "stream_preimage.h"
@@ -47,7 +46,7 @@ int call_get_preimage(dispatcher_context_t *dispatcher_context,
     buffer_t buffer_out = buffer_create(out, out_len);
 
     uint8_t *data_ptr =
-        (uint8_t *) (dispatcher_context->read_buffer.ptr + dispatcher_context->read_buffer.offset);
+        dispatcher_context->read_buffer.ptr + dispatcher_context->read_buffer.offset;
 
     cx_sha256_t hash_context;
     cx_sha256_init(&hash_context);
@@ -87,8 +86,7 @@ int call_get_preimage(dispatcher_context_t *dispatcher_context,
             return -8;
         }
 
-        data_ptr = (uint8_t *) (dispatcher_context->read_buffer.ptr +
-                                dispatcher_context->read_buffer.offset);
+        data_ptr = dispatcher_context->read_buffer.ptr + dispatcher_context->read_buffer.offset;
 
         // update hash
         crypto_hash_update(&hash_context.header, data_ptr, n_bytes);
diff --git a/src/handler/lib/policy.c b/src/handler/lib/policy.c
index 5e3eaac..efae9ec 100644
--- a/src/handler/lib/policy.c
+++ b/src/handler/lib/policy.c
@@ -9,7 +9,6 @@
 
 /* Local headers */
 #include "bitvector.h"
-#include "buffer_ext.h"
 #include "crypto.h"
 #include "debug.h"
 #include "get_merkle_leaf_element.h"
diff --git a/src/handler/lib/psbt_parse_rawtx.c b/src/handler/lib/psbt_parse_rawtx.c
index 05808eb..7380e42 100644
--- a/src/handler/lib/psbt_parse_rawtx.c
+++ b/src/handler/lib/psbt_parse_rawtx.c
@@ -10,7 +10,6 @@
 #include "varint.h"
 
 /* Local headers */
-#include "buffer_ext.h"
 #include "crypto.h"
 #include "dispatcher.h"
 #include "get_merkleized_map_value_hash.h"
diff --git a/src/handler/lib/stream_preimage.c b/src/handler/lib/stream_preimage.c
index 09f8990..58996ec 100644
--- a/src/handler/lib/stream_preimage.c
+++ b/src/handler/lib/stream_preimage.c
@@ -3,7 +3,6 @@
 #include "stream_preimage.h"
 
 /* Local headers */
-#include "buffer_ext.h"
 #include "client_commands.h"
 #include "crypto.h"
 #include "sw.h"
@@ -51,7 +50,7 @@ int call_stream_preimage(dispatcher_context_t *dispatcher_context,
     }
 
     uint8_t *data_ptr =
-        (uint8_t *) (dispatcher_context->read_buffer.ptr + dispatcher_context->read_buffer.offset);
+        dispatcher_context->read_buffer.ptr + dispatcher_context->read_buffer.offset;
 
     cx_sha256_t hash_context;
     cx_sha256_init(&hash_context);
@@ -92,8 +91,7 @@ int call_stream_preimage(dispatcher_context_t *dispatcher_context,
             return -8;
         }
 
-        data_ptr = (uint8_t *) dispatcher_context->read_buffer.ptr +
-                   dispatcher_context->read_buffer.offset;
+        data_ptr = dispatcher_context->read_buffer.ptr + dispatcher_context->read_buffer.offset;
 
         // update hash
         crypto_hash_update(&hash_context.header, data_ptr, n_bytes);
diff --git a/src/handler/register_wallet.c b/src/handler/register_wallet.c
index 5a7b5d1..fe1d684 100644
--- a/src/handler/register_wallet.c
+++ b/src/handler/register_wallet.c
@@ -26,7 +26,6 @@
 #include "write.h"
 
 /* Local headers */
-#include "buffer_ext.h"
 #include "client_commands.h"
 #include "commands.h"
 #include "constants.h"
diff --git a/src/handler/sign_message.c b/src/handler/sign_message.c
index d4e4786..89e3341 100644
--- a/src/handler/sign_message.c
+++ b/src/handler/sign_message.c
@@ -21,7 +21,6 @@
 #include "bip32.h"
 
 /* Local headers */
-#include "buffer_ext.h"
 #include "commands.h"
 #include "constants.h"
 #include "crypto.h"
diff --git a/src/handler/sign_psbt.c b/src/handler/sign_psbt.c
index 3cad8be..a1401cc 100644
--- a/src/handler/sign_psbt.c
+++ b/src/handler/sign_psbt.c
@@ -29,7 +29,6 @@
 /* Local headers */
 #include "amount_from_psbt.h"
 #include "bitvector.h"
-#include "buffer_ext.h"
 #include "check_merkle_tree_sorted.h"
 #include "client_commands.h"
 #include "commands.h"
diff --git a/src/handler/sign_psbt/extract_bip32_derivation.c b/src/handler/sign_psbt/extract_bip32_derivation.c
index b17739a..7071747 100644
--- a/src/handler/sign_psbt/extract_bip32_derivation.c
+++ b/src/handler/sign_psbt/extract_bip32_derivation.c
@@ -8,7 +8,6 @@
 #include "varint.h"
 
 /* Local headers */
-#include "buffer_ext.h"
 #include "psbt.h"
 #include "stream_merkle_leaf_element.h"
 
diff --git a/src/handler/sign_psbt/txhashes.c b/src/handler/sign_psbt/txhashes.c
index a3f9e11..4849b00 100644
--- a/src/handler/sign_psbt/txhashes.c
+++ b/src/handler/sign_psbt/txhashes.c
@@ -28,7 +28,7 @@ static void cb_process_data(buffer_t *data, void *cb_state) {
     callback_state_t *state = (callback_state_t *) cb_state;
 
     size_t data_len = data->size - data->offset;
-    uint8_t *data_start_ptr = (uint8_t *) data->ptr + data->offset;
+    uint8_t *data_start_ptr = data->ptr + data->offset;
 
     if (state->hash_prefixed != NULL) {
         crypto_hash_update(state->hash_prefixed, data_start_ptr, data_len);
diff --git a/unit-tests/test_buffer.c b/unit-tests/test_buffer.c
index 554969e..c88ec88 100644
--- a/unit-tests/test_buffer.c
+++ b/unit-tests/test_buffer.c
@@ -427,29 +427,6 @@ static void test_buffer_is_cur_aligned(void **state) {
     assert_false(buffer_is_cur_aligned(&buf)); //9
 }
 
-// tests the buffer_snapshot/buffer_restore functions
-static void test_buffer_snapshot_restore(void **state) {
-    (void) state;
-
-    uint8_t data[32];
-
-    buffer_snapshot_t snap;
-    buffer_t buf;
-    buffer_t buf_correct;
-
-    buf = buffer_create(data, sizeof(data));
-    buf_correct = buf;
-
-    snap = buffer_snapshot(&buf);
-    buffer_alloc(&buf, 11, false);
-    buffer_restore(&buf, snap);
-
-    assert_int_equal(buf.offset, buf_correct.offset);
-    assert_ptr_equal(buf.ptr, buf_correct.ptr);
-    assert_int_equal(buf.size, buf_correct.size);
-}
-
-
 int main() {
     const struct CMUnitTest tests[] = {cmocka_unit_test(test_buffer_get_cur),
                                        cmocka_unit_test(test_buffer_read),
@@ -458,8 +435,7 @@ int main() {
                                        cmocka_unit_test(test_buffer_write),
                                        cmocka_unit_test(test_buffer_create),
                                        cmocka_unit_test(test_buffer_alloc),
-                                       cmocka_unit_test(test_buffer_is_cur_aligned),
-                                       cmocka_unit_test(test_buffer_snapshot_restore)};
+                                       cmocka_unit_test(test_buffer_is_cur_aligned)};
 
     return cmocka_run_group_tests(tests, NULL, NULL);
 }