diff --git a/src/CMakeLists.txt b/src/CMakeLists.txt
index 980ac9f..8fac055 100644
--- a/src/CMakeLists.txt
+++ b/src/CMakeLists.txt
@@ -1,6 +1,7 @@
 add_executable(${PROJECT_NAME}
   main.c
-  network.c
+  connection.c
+  buffer.c
 )
 target_link_libraries(${PROJECT_NAME}
   libev::ev
diff --git a/src/buffer.c b/src/buffer.c
new file mode 100644
index 0000000..38198a4
--- /dev/null
+++ b/src/buffer.c
@@ -0,0 +1,34 @@
+#include <buffer.h>
+#include <string.h>
+
+#if INTERFACE
+
+#include <stdlib.h>
+
+struct Buffer {
+  size_t size;
+  char data[4096];
+};
+
+#define buffer_size(buffer) ((buffer)->size)
+#define buffer_capacity(buffer) (sizeof(buffer)->data)
+#define buffer_data(buffer) ((buffer)->data)
+
+#endif
+
+void buffer_consume(Buffer *buffer, size_t n) {
+  buffer->size -= n;
+  memmove(buffer->data, &buffer->data[n], buffer->size);
+}
+
+void buffer_provide(Buffer *buffer, size_t n) {
+  buffer->size += n;
+}
+
+size_t buffer_size_remaining(Buffer *buffer) {
+  return buffer_capacity(buffer) - buffer_size(buffer);
+}
+
+char *buffer_data_remaining(Buffer *buffer) {
+  return &buffer->data[buffer_size(buffer)];
+}
diff --git a/src/network.c b/src/connection.c
similarity index 83%
rename from src/network.c
rename to src/connection.c
index 2787ef5..c0b2ac6 100644
--- a/src/network.c
+++ b/src/connection.c
@@ -1,5 +1,5 @@
 #include <assert.h>
-#include <network.h>
+#include <connection.h>
 #include <unistd.h>
 
 #if INTERFACE
@@ -18,20 +18,6 @@ struct Connection {
   Buffer write_buf;
 };
 
-struct Buffer {
-  size_t size;
-  char data[4096];
-};
-
-#endif
-
-void connection_init(EV_P_ Connection *connection, struct tls_config *config) {
-  (void)(EV_A_ 0);
-  ev_io_init(&connection->watcher, NULL, STDIN_FILENO, 0);
-  connection->ctx = tls_client();
-  tls_configure(connection->ctx, config);
-}
-
 #define connection_set_failure_cb(connection, callback) \
   do {                                                  \
     (connection)->failure_cb = callback;                \
@@ -45,6 +31,15 @@ void connection_init(EV_P_ Connection *connection, struct tls_config *config) {
 #define connection_read_buf(connection) &((connection)->read_buf)
 #define connection_write_buf(connection) &((connection)->write_buf)
 
+#endif
+
+void connection_init(EV_P_ Connection *connection, struct tls_config *config) {
+  (void)(EV_A_ 0);
+  ev_io_init(&connection->watcher, NULL, STDIN_FILENO, 0);
+  connection->ctx = tls_client();
+  tls_configure(connection->ctx, config);
+}
+
 void connection_read_some(EV_P_ Connection *connection) {
   assert(connection->success_cb && connection->failure_cb);
   ev_set_cb(&connection->watcher, connection_read_some_cb);
@@ -57,9 +52,8 @@ static void connection_read_some_cb(EV_P_ ev_io *watcher, int revents) {
 
   (void)revents;
   ev_io_stop(EV_A_ watcher);
-  n = tls_read(connection->ctx,
-               &connection->read_buf.data[connection->read_buf.size],
-               sizeof(connection->read_buf.data) - connection->read_buf.size);
+  n = tls_read(connection->ctx, buffer_data_remaining(&connection->read_buf),
+               buffer_size_remaining(&connection->read_buf));
   if (n == TLS_WANT_POLLIN) {
     ev_io_modify(watcher, EV_READ);
     ev_io_start(EV_A_ watcher);
@@ -69,7 +63,7 @@ static void connection_read_some_cb(EV_P_ ev_io *watcher, int revents) {
   } else if (n == -1) {
     connection->failure_cb(EV_A_ connection);
   } else {
-    connection->read_buf.size += n;
+    buffer_provide(&connection->read_buf, n);
     connection->success_cb(EV_A_ connection);
   }
 }
@@ -86,8 +80,8 @@ static void connection_write_some_cb(EV_P_ ev_io *watcher, int revents) {
 
   (void)revents;
   ev_io_stop(EV_A_ watcher);
-  n = tls_write(connection->ctx, connection->write_buf.data,
-                connection->write_buf.size);
+  n = tls_write(connection->ctx, buffer_data(&connection->write_buf),
+                buffer_size(&connection->write_buf));
   if (n == TLS_WANT_POLLIN) {
     ev_io_modify(watcher, EV_READ);
     ev_io_start(EV_A_ watcher);
@@ -97,9 +91,7 @@ static void connection_write_some_cb(EV_P_ ev_io *watcher, int revents) {
   } else if (n == -1) {
     connection->failure_cb(EV_A_ connection);
   } else {
-    connection->write_buf.size -= n;
-    memmove(connection->write_buf.data, &connection->write_buf.data[n],
-            connection->write_buf.size);
+    buffer_consume(&connection->write_buf, n);
     connection->success_cb(EV_A_ connection);
   }
 }
diff --git a/src/main.c b/src/main.c
index 94a5803..19fd759 100644
--- a/src/main.c
+++ b/src/main.c
@@ -6,7 +6,7 @@ int main(int argc, char **argv) {
   struct tls_config *config;
   Connection connection;
 
-  (void) argc, (void) argv;
+  (void)argc, (void)argv;
   tls_init();
   config = tls_config_new();
   connection_init(EV_DEFAULT_ & connection, config);