diff --git a/include/ipc.h b/include/ipc.h
index aab9cf0c..25d2fc61 100644
--- a/include/ipc.h
+++ b/include/ipc.h
@@ -1,6 +1,17 @@
 #ifndef _SWAY_IPC_H
 #define _SWAY_IPC_H
 
+enum ipc_command_type {
+	IPC_COMMAND        = 0,
+	IPC_GET_WORKSPACES = 1,
+	IPC_SUBSCRIBE      = 2,
+	IPC_GET_OUTPUTS    = 3,
+	IPC_GET_TREE       = 4,
+	IPC_GET_MARKS      = 5,
+	IPC_GET_BAR_CONFIG = 6,
+	IPC_GET_VERSION    = 7,
+};
+
 void init_ipc(void);
 
 #endif
diff --git a/sway/ipc.c b/sway/ipc.c
index ac5246d2..1a074788 100644
--- a/sway/ipc.c
+++ b/sway/ipc.c
@@ -2,15 +2,23 @@
 #include <string.h>
 #include <sys/socket.h>
 #include <sys/un.h>
+#include <stdbool.h>
 #include <wlc/wlc.h>
 #include <unistd.h>
+#include <stdlib.h>
+#include "ipc.h"
 #include "log.h"
 #include "config.h"
 #include "commands.h"
 
 static int ipc_socket = -1;
 
+static const char ipc_magic[] = {'i', '3', '-', 'i', 'p', 'c'};
+
 int ipc_handle_connection(int fd, uint32_t mask, void *data);
+size_t ipc_handle_command(char **reply_data, char *data, ssize_t length);
+size_t ipc_format_reply(char **data, enum ipc_command_type command_type, const char *payload, uint32_t payload_length);
+
 
 void init_ipc() {
 	ipc_socket = socket(AF_UNIX, SOCK_STREAM | SOCK_NONBLOCK | SOCK_CLOEXEC, 0);
@@ -36,7 +44,8 @@ void init_ipc() {
 	wlc_event_loop_add_fd(ipc_socket, WLC_EVENT_READABLE, ipc_handle_connection, NULL);
 }
 
-int ipc_handle_connection(int /*fd*/, uint32_t /*mask*/, void */*data*/) {
+int ipc_handle_connection(int fd, uint32_t mask, void *data) {
+	sway_log(L_DEBUG, "Event on IPC listening socket");
 	int client_socket = accept(ipc_socket, NULL, NULL);
 	if (client_socket == -1) {
 		char error[256];
@@ -46,7 +55,9 @@ int ipc_handle_connection(int /*fd*/, uint32_t /*mask*/, void */*data*/) {
 	}
 
 	char buf[1024];
-	if (recv(client_socket, buf, sizeof(buf), 0) == -1) {
+	// Leave one byte of space at the end of the buffer for NULL terminator
+	ssize_t received = recv(client_socket, buf, sizeof(buf) - 1, 0);
+	if (received == -1) {
 		char error[256];
 		strerror_r(errno, error, sizeof(error));
 		sway_log(L_INFO, "Unable to receive from IPC client: %s", error);
@@ -54,17 +65,72 @@ int ipc_handle_connection(int /*fd*/, uint32_t /*mask*/, void */*data*/) {
 		return 0;
 	}
 
-	sway_log(L_INFO, "Executing IPC command: %s", buf);
+	char *reply_buf;
+	size_t reply_length = ipc_handle_command(&reply_buf, buf, received);
+	sway_log(L_DEBUG, "IPC reply: %s", reply_buf);
 
-	bool success = handle_command(config, buf);
-	snprintf(buf, sizeof(buf), "{\"success\":%s}\n", success ? "true" : "false");
-
-	if (send(client_socket, buf, strlen(buf), 0) == -1) {
+	if (send(client_socket, reply_buf, reply_length, 0) == -1) {
 		char error[256];
 		strerror_r(errno, error, sizeof(error));
 		sway_log(L_INFO, "Unable to send to IPC client: %s", error);
 	}
 
+	free(reply_buf);
 	close(client_socket);
 	return 0;
 }
+
+static const int ipc_header_size = sizeof(ipc_magic)+8;
+
+size_t ipc_handle_command(char **reply_data, char *data, ssize_t length) {
+	// See https://i3wm.org/docs/ipc.html for protocol details
+
+	if (length < ipc_header_size) {
+		sway_log(L_DEBUG, "IPC data too short");
+		return false;
+	}
+
+	if (memcmp(data, ipc_magic, sizeof(ipc_magic)) != 0) {
+		sway_log(L_DEBUG, "IPC header check failed");
+		return false;
+	}
+
+	uint32_t payload_length = *(uint32_t *)&data[sizeof(ipc_magic)];
+	uint32_t command_type = *(uint32_t *)&data[sizeof(ipc_magic)+4];
+
+	if (length != payload_length + ipc_header_size) {
+		// TODO: try to read enough data
+		sway_log(L_DEBUG, "IPC payload size mismatch");
+		return false;
+	}
+
+	switch (command_type) {
+		case IPC_COMMAND:
+		{
+			char *cmd = &data[ipc_header_size];
+			data[ipc_header_size + payload_length] = '\0';
+			bool success = handle_command(config, cmd);
+			char buf[64];
+			int length = snprintf(buf, sizeof(buf), "{\"success\":%s}", success ? "true" : "false");
+			return ipc_format_reply(reply_data, IPC_COMMAND, buf, (uint32_t) length);
+		}
+		default:
+			sway_log(L_INFO, "Unknown IPC command type %i", command_type);
+			return false;
+	}
+}
+
+size_t ipc_format_reply(char **data, enum ipc_command_type command_type, const char *payload, uint32_t payload_length) {
+	assert(data);
+	assert(payload);
+
+	size_t length = ipc_header_size + payload_length;
+	*data = malloc(length);
+
+	memcpy(*data, ipc_magic, sizeof(ipc_magic));
+	*(uint32_t *)&((*data)[sizeof(ipc_magic)]) = payload_length;
+	*(uint32_t *)&((*data)[sizeof(ipc_magic)+4]) = command_type;
+	memcpy(&(*data)[ipc_header_size], payload, payload_length);
+
+	return length;
+}