diff --git a/common.c b/common.c
index e885945..ae92ecc 100644
--- a/common.c
+++ b/common.c
@@ -436,11 +436,16 @@ struct socks_connector
 		return false;                                                          \
 	BLOCK_END
 
-#define SOCKS_NEED_DATA(n)                                                     \
+#define SOCKS_READ_START(n)                                                    \
 	if (!socks_try_fill_read_buffer (self, (n)))                               \
 		return false;                                                          \
 	if (self->read_buffer.len < n)                                             \
-		return true
+		return true;                                                           \
+	struct msg_unpacker unpacker;                                              \
+	msg_unpacker_init (&unpacker, self->read_buffer.str, self->read_buffer.len)
+
+#define SOCKS_READ_END                                                         \
+	str_remove_slice (&self->read_buffer, 0, unpacker.offset)
 
 static bool
 socks_try_fill_read_buffer (struct socks_connector *self, size_t n)
@@ -496,15 +501,11 @@ socks_try_flush_write_buffer (struct socks_connector *self)
 static bool
 socks_4a_finish (struct socks_connector *self)
 {
-	SOCKS_NEED_DATA (8);
-
-	struct msg_unpacker unpacker;
-	msg_unpacker_init (&unpacker, self->read_buffer.str, self->read_buffer.len);
-
+	SOCKS_READ_START (8);
 	uint8_t null, status;
 	hard_assert (msg_unpacker_u8 (&unpacker, &null));
 	hard_assert (msg_unpacker_u8 (&unpacker, &status));
-	str_remove_slice (&self->read_buffer, 0, unpacker.offset);
+	SOCKS_READ_END;
 
 	if (null != 0)
 		SOCKS_FAIL ("protocol error");
@@ -578,12 +579,9 @@ socks_4a_start (struct socks_connector *self)
 static bool
 socks_5_request_port (struct socks_connector *self)
 {
-	SOCKS_NEED_DATA (2);
-
-	struct msg_unpacker unpacker;
-	msg_unpacker_init (&unpacker, self->read_buffer.str, self->read_buffer.len);
+	SOCKS_READ_START (2);
 	hard_assert (msg_unpacker_u16 (&unpacker, &self->bound_port));
-	str_remove_slice (&self->read_buffer, 0, unpacker.offset);
+	SOCKS_READ_END;
 
 	self->done = true;
 	return false;
@@ -593,7 +591,7 @@ static bool
 socks_5_request_ipv4 (struct socks_connector *self)
 {
 	size_t len = sizeof self->bound_address.data.ipv4;
-	SOCKS_NEED_DATA (len);
+	SOCKS_READ_START (len);
 	memcpy (self->bound_address.data.ipv4, self->read_buffer.str, len);
 	str_remove_slice (&self->read_buffer, 0, len);
 
@@ -605,7 +603,7 @@ static bool
 socks_5_request_ipv6 (struct socks_connector *self)
 {
 	size_t len = sizeof self->bound_address.data.ipv6;
-	SOCKS_NEED_DATA (len);
+	SOCKS_READ_START (len);
 	memcpy (self->bound_address.data.ipv6, self->read_buffer.str, len);
 	str_remove_slice (&self->read_buffer, 0, len);
 
@@ -617,7 +615,7 @@ static bool
 socks_5_request_domain_data (struct socks_connector *self)
 {
 	size_t len = self->bound_address_len;
-	SOCKS_NEED_DATA (len);
+	SOCKS_READ_START (len);
 	self->bound_address.data.domain = xstrndup (self->read_buffer.str, len);
 	str_remove_slice (&self->read_buffer, 0, len);
 
@@ -628,12 +626,9 @@ socks_5_request_domain_data (struct socks_connector *self)
 static bool
 socks_5_request_domain (struct socks_connector *self)
 {
-	SOCKS_NEED_DATA (1);
-
-	struct msg_unpacker unpacker;
-	msg_unpacker_init (&unpacker, self->read_buffer.str, self->read_buffer.len);
+	SOCKS_READ_START (1);
 	hard_assert (msg_unpacker_u8 (&unpacker, &self->bound_address_len));
-	str_remove_slice (&self->read_buffer, 0, unpacker.offset);
+	SOCKS_READ_END;
 
 	self->on_data = socks_5_request_domain_data;
 	return true;
@@ -642,17 +637,13 @@ socks_5_request_domain (struct socks_connector *self)
 static bool
 socks_5_request_finish (struct socks_connector *self)
 {
-	SOCKS_NEED_DATA (4);
-
-	struct msg_unpacker unpacker;
-	msg_unpacker_init (&unpacker, self->read_buffer.str, self->read_buffer.len);
-
+	SOCKS_READ_START (4);
 	uint8_t version, status, reserved, type;
 	hard_assert (msg_unpacker_u8 (&unpacker, &version));
 	hard_assert (msg_unpacker_u8 (&unpacker, &status));
 	hard_assert (msg_unpacker_u8 (&unpacker, &reserved));
 	hard_assert (msg_unpacker_u8 (&unpacker, &type));
-	str_remove_slice (&self->read_buffer, 0, unpacker.offset);
+	SOCKS_READ_END;
 
 	if (version != 0x05)
 		SOCKS_FAIL ("protocol error");
@@ -722,15 +713,11 @@ socks_5_request_start (struct socks_connector *self)
 static bool
 socks_5_userpass_finish (struct socks_connector *self)
 {
-	SOCKS_NEED_DATA (2);
-
-	struct msg_unpacker unpacker;
-	msg_unpacker_init (&unpacker, self->read_buffer.str, self->read_buffer.len);
-
+	SOCKS_READ_START (2);
 	uint8_t version, status;
 	hard_assert (msg_unpacker_u8 (&unpacker, &version));
 	hard_assert (msg_unpacker_u8 (&unpacker, &status));
-	str_remove_slice (&self->read_buffer, 0, unpacker.offset);
+	SOCKS_READ_END;
 
 	if (version != 0x01)
 		SOCKS_FAIL ("protocol error");
@@ -764,15 +751,11 @@ socks_5_userpass_start (struct socks_connector *self)
 static bool
 socks_5_auth_finish (struct socks_connector *self)
 {
-	SOCKS_NEED_DATA (2);
-
-	struct msg_unpacker unpacker;
-	msg_unpacker_init (&unpacker, self->read_buffer.str, self->read_buffer.len);
-
+	SOCKS_READ_START (2);
 	uint8_t version, method;
 	hard_assert (msg_unpacker_u8 (&unpacker, &version));
 	hard_assert (msg_unpacker_u8 (&unpacker, &method));
-	str_remove_slice (&self->read_buffer, 0, unpacker.offset);
+	SOCKS_READ_END;
 
 	if (version != 0x05)
 		SOCKS_FAIL ("protocol error");