From d41fa3a7b62216e35cc5a7be665f80481b6f9c78 Mon Sep 17 00:00:00 2001
From: Aki <please@ignore.pl>
Date: Sun, 16 Aug 2020 16:50:48 +0200
Subject: Single handedly implemented Lua based response send without testing

---
 plop.c     |  14 ++-------
 response.c | 104 +++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
 response.h |   3 ++
 3 files changed, 109 insertions(+), 12 deletions(-)

diff --git a/plop.c b/plop.c
index 0f045f8..da51251 100644
--- a/plop.c
+++ b/plop.c
@@ -137,17 +137,7 @@ int handle_client(lua_State * L, struct epoll_event * event)
 	lua_insert((*request)->lua, 1);
 	lua_call((*request)->lua, 5, 1);
 
-	size_t length;
-	const char * body = lua_tolstring((*request)->lua, -1, &length);
-
-	if (NULL != body)
-	{
-		respond_with_body((*request)->fd, STATUS_OK, body, (int) length);
-	}
-	else
-	{
-		respond_only_status((*request)->fd, STATUS_INTERNAL_SERVER_ERROR);
-	}
+	int result = response_send((*request)->lua, (*request)->fd);
 
 	close((*request)->fd);
 
@@ -157,7 +147,7 @@ int handle_client(lua_State * L, struct epoll_event * event)
 		*request = NULL;
 	}
 
-	return 0;
+	return result;
 }
 
 /// Accepts awaiting connections if any.
diff --git a/response.c b/response.c
index df465d0..b2a72d7 100644
--- a/response.c
+++ b/response.c
@@ -1,10 +1,114 @@
 #include "response.h"
 
 #include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
 #include <unistd.h>
 
+#include <lua.h>
+
 #include "http.h"
 
+/// Sends a response based on the current top value on the stack.
+/// \param L Lua state to send response for
+/// \param fd File descriptor of a socket to write to
+/// \return Bytes written or -1 on error
+/// \see write(2)
+// TODO: Consider splitting response_send into smaller functions.
+int response_send(lua_State * L, const int fd)
+{
+	static const char * error_response =
+		"HTTP/1.1 500\r\n"
+		"Connection: close\r\n"
+		"\r\n";
+
+	if (0 == lua_istable(L, -1) || 0 == lua_checkstack(L, 5))
+	{
+		lua_pop(L, 1);
+		return write(fd, error_response, strlen(error_response));
+	}
+
+	int bytes_total = 2048 * sizeof(char);
+	int bytes_used = 0;
+	char * buffer = malloc(bytes_total);
+
+	lua_pushstring(L, "status");
+	lua_gettable(L, -2);
+	const lua_Integer status = lua_tointeger(L, -1);
+	lua_pop(L, 1);
+
+	if (0 == status || NULL == buffer)
+	{
+		lua_pop(L, 1);
+		return write(fd, error_response, strlen(error_response));
+	}
+
+	bytes_used = snprintf(buffer, bytes_total, "HTTP/1.1 %d\r\n\r\n", (int) status) - 2;
+
+	lua_pushstring(L, "headers");
+	lua_gettable(L, -2);
+
+	if (0 == lua_istable(L, -1))
+	{
+		lua_pop(L, 2);
+		return write(fd, buffer, bytes_used + 2);
+	}
+
+	static const char * header_pattern = "%s: %s\r\n";
+
+	lua_pushnil(L);
+	while (0 != lua_next(L, -2) && 0 != lua_isstring(L, -2))
+	{
+		const char * key = lua_tostring(L, -2);
+		const char * value = lua_tostring(L, -1); // TODO: Check the type of the header's value?
+		const int bytes_left = bytes_total - bytes_used;
+		int new_bytes = snprintf(buffer + bytes_used, bytes_left, header_pattern, key, value);
+		while (bytes_left <= new_bytes)
+		{
+			bytes_total += 2048;
+			if (65536 < bytes_total)
+			{
+				free(buffer);
+				lua_pop(L, 4);
+				return write(fd, error_response, strlen(error_response));
+			}
+			buffer = realloc(buffer, bytes_total);
+			if (NULL == buffer)
+			{
+				lua_pop(L, 4);
+				return write(fd, error_response, strlen(error_response));
+			}
+			new_bytes = snprintf(buffer + bytes_used, bytes_left, header_pattern, key, value);
+		}
+		bytes_used += new_bytes;
+		lua_pop(L, 1);
+	}
+
+	if (bytes_total < bytes_used + 2)
+	{
+		bytes_total += 2;
+		buffer = realloc(buffer, bytes_total);
+		if (NULL == buffer)
+		{
+			lua_pop(L, 2);
+			return write(fd, error_response, strlen(error_response));
+		}
+	}
+
+	lua_pop(L, 1);
+	buffer[bytes_used] = '\r';
+	buffer[bytes_used + 1] = '\n';
+	bytes_used += 2;
+
+	// TODO: Add data write
+
+	int result = write(fd, buffer, bytes_used );
+	free(buffer);
+	lua_pop(L, 1);
+
+	return result;
+}
+
 /// Sends a simple response only with a status to the client.
 /// \param fd File descriptor of the client socket
 /// \param status HTTP response status code
diff --git a/response.h b/response.h
index ec90bc5..c9b9c06 100644
--- a/response.h
+++ b/response.h
@@ -1,6 +1,9 @@
 #pragma once
 
+#include <lua.h>
+
 #include "http.h"
 
+int response_send(lua_State *, const int);
 int respond_only_status(int, enum status);
 int respond_with_body(int, enum status, const char *, int);
-- 
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