/* $Id: http_message.c,v 1.4 2004-02-13 21:27:42 rjkaes Exp $
 *
 * See 'http_message.h' for a detailed description.
 *
 * Copyright (C) 2003  Robert James Kaes (rjkaes@flarenet.com)
 *
 * This program is free software; you can redistribute it and/or modify it
 * under the terms of the GNU General Public License as published by the
 * Free Software Foundation; either version 2, or (at your option) any
 * later version.
 *
 * This program is distributed in the hope that it will be useful, but
 * WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
 * General Public License for more details.
 */

#include "common.h"
#include "heap.h"
#include "http_message.h"
#include "network.h"

/*
 * Package up an HTTP message into a nice little structure.  As you can
 * see this structure doesn't actually store any allocated strings;
 * therefore, the caller must free any memory referenced by this struct.
 * Also, the caller MUST NOT free the memory while the structure is
 * still in use---bad things would happen.
 */
struct http_message_s {
	/* Response string and code supplied on the HTTP status line */
	struct {
		const char* string;
		int code;
	} response;
       
	/*
	 * A group of headers to be sent with this message.  Right now
	 * the strings are referenced through pointers in an array.
	 * I might change this to a vector in the future.
	 */
	struct {
		char** strings;
		unsigned int total;
		unsigned int used;
	} headers;

	/* Body of the message (most likely an HTML message) */
	struct {
		const char* text;
		size_t length;
	} body;
};

/*
 * Check if the HTTP message is validly formed.  This is the one odd-ball
 * function.  It returns 0 if the message is invalid; otherwise, a positive
 * number is returned.  Useful for if() tests and assert() tests.
 */
static int
is_http_message_valid(http_message_t msg)
{
	if (msg == NULL) return 0;
	if (msg->headers.strings == NULL) return 0;
	if (msg->response.string == NULL) return 0;
	if (msg->response.code < 1 || msg->response.code > 999) return 0;

	return 1;
}

/* Initially allocate space for 128 headers */
#define NUMBER_OF_HEADERS 128

/*
 * Allocate a new http_message structure on the heap.
 * If memory could not be allocated, return a NULL.
 */
http_message_t
http_message_create(int response_code, const char* response_string)
{
	http_message_t msg;
	int ret;

	msg = safecalloc(1, sizeof(struct http_message_s));
	if (msg == NULL)
		return NULL;

	msg->headers.strings = safecalloc(NUMBER_OF_HEADERS, sizeof(char*));
	if (msg->headers.strings == NULL) {
		safefree(msg);
		return NULL;
	}

	msg->headers.total = NUMBER_OF_HEADERS;

	/* Store the HTTP response information in the structure */
	ret = http_message_set_response(msg, response_code, response_string);
	if (IS_HTTP_MSG_ERROR(ret)) {
		safefree(msg->headers.strings);
		safefree(msg);
		return NULL;
	}

	return msg;
}

/*
 * Free up the space associated with this HTTP message structure.
 * This DOES NOT free the pointers stored in this structure.  That memory
 * is the responsibility of the caller.
 */
int
http_message_destroy(http_message_t msg)
{
	assert(msg != NULL);
	assert(msg->headers.strings != NULL);

	/* Check for valid arguments */
	if (msg == NULL) return -EFAULT;

	if (msg->headers.strings != NULL)
		safefree(msg->headers.strings);
	safefree(msg);
	return 0;
}

/*
 * Set the HTTP response information for this structure.  The response_string
 * must be a NUL ('\0') terminated C string.
 */
int
http_message_set_response(http_message_t msg,
			  int response_code,
			  const char* response_string)
{
	/* Check for valid arguments */
	if (msg == NULL) return -EFAULT;
	if (response_code < 1 || response_code > 999) return -EINVAL;
	if (response_string == NULL) return -EINVAL;
	if (strlen(response_string) == 0) return -EINVAL;

	msg->response.code = response_code;
	msg->response.string = response_string;

	return 0;
}

/*
 * Set the HTTP message body.
 */
int
http_message_set_body(http_message_t msg, const char* body, size_t len)
{
	/* Check for valid arguments */
	if (msg == NULL) return -EFAULT;
	if (body == NULL) return -EINVAL;
	if (len == 0) return -EINVAL;

	msg->body.text = body;
	msg->body.length = len;

	return 0;
}

/*
 * Add headers to the structure.
 */
int
http_message_add_headers(http_message_t msg, char** headers,
			 int num_headers)
{
	char** new_headers;
	int i;

	/* Check for valid arguments */
	if (msg == NULL) return -EFAULT;
	if (headers == NULL) return -EINVAL;
	if (num_headers < 1) return -EINVAL;

	/*
	 * If the number of headers to add is greater than the space
	 * available, reallocate the memory.
	 */
	if (msg->headers.used + num_headers > msg->headers.total) {
		new_headers = safecalloc(msg->headers.total * 2,
					 sizeof(char*));
		if (new_headers == NULL)
			return -ENOMEM;

		/* Copy the array */
		for (i = 0; i != msg->headers.used; ++i)
			new_headers[i] = msg->headers.strings[i];

		/* Remove the old array and replace it with the new array */
		safefree(msg->headers.strings);
		msg->headers.strings = new_headers;
		msg->headers.total *= 2;
	}

	/*
	 * Add the new headers to the structure
	 */
	for (i = 0; i != num_headers; ++i)
		msg->headers.strings[i + msg->headers.used] = headers[i];
	msg->headers.used += num_headers;

	return 0;
}

/*
 * Send the completed HTTP message via the supplied file descriptor.
 */
int
http_message_send(http_message_t msg, int fd)
{
	char timebuf[30];
	time_t global_time;
	unsigned int i;

	assert(is_http_message_valid(msg));

	/* Check for valid arguments */
	if (msg == NULL) return -EFAULT;
	if (fd < 1) return -EBADF;
	if (!is_http_message_valid(msg)) return -EINVAL;

	/* Write the response line */
	write_message(fd, "HTTP/1.0 %d %s\r\n",
		      msg->response.code, msg->response.string);

	/* Go through all the headers */
	for (i = 0; i != msg->headers.used; ++i)
		write_message(fd, "%s\r\n", msg->headers.strings[i]);

	/* Output the date */
	global_time = time(NULL);
	strftime(timebuf, sizeof(timebuf), "%a, %d %b %Y %H:%M:%S GMT",
		 gmtime(&global_time));
	write_message(fd, "Date: %s\r\n", timebuf);

	/* Output the content-length */
	write_message(fd, "Content-length: %u\r\n", msg->body.length);

	/* Write the separator between the headers and body */
	safe_write(fd, "\r\n", 2);

	/* If there's a body, send it! */
	if (msg->body.length > 0)
		safe_write(fd, msg->body.text, msg->body.length);

	return 0;
}