/* ====================================================================
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 *
 * Portions of this software are based upon public domain software
 * originally written at the National Center for Supercomputing Applications,
 * University of Illinois, Urbana-Champaign.
 */

/*
 * mod_iptos: set IP type-of-service bits according to directory
 *
 * v1.0
 * 
 * author: dean gaudet <dean@arctic.org>
 *
 * 0.1: initial implementation
 * 0.2: added keyword "none"
 * 1.0: what the heck, it's official
 */

/*
	documentation:

	type-of-service bits in IP packets can be used for such things
	as quality-of-service guarantees.  this module allows you to
	set IP TOS bits on a per-directory basis (it'll also work for
	location and files containers of course).

	the four TOS bits are:

		lowdelay
		throughput
		reliability
		lowcost

	note that in ancient IP history you were permitted only to
	set none or one of those bits.  at some point someone gave
	meaning to the bitwise-OR of the bits... and i'm too lazy
	to go look up those meanings right now.  but since there are
	meanings to the bitwise-OR, this module accepts the '|'
	character as an OR operator to combine these bits.

	the magic keyword "none" will result in no IPTOS bits being set.
	(useful for a nested directory container to disable a TOS
	you've set on a parent directory.)

	there's only one command:  IPTOS bits

	as in:

	# default to lowdelay TOS
	IPTOS lowdelay

	# choose throughput TOS for the video directory
	<Directory /my/big/video/directory>
		IPTOS throughput
	</Directory>
*/

#include "httpd.h"
#include "http_config.h"
#include "http_log.h"
#include "http_request.h"

#include <netinet/ip.h>

typedef struct {
	unsigned tos;
} iptos_config;

module MODULE_VAR_EXPORT iptos_module;


static const char *iptos_parse_iptos(char *word, unsigned *ptos)
{
	unsigned tos;
	char *bar;

	tos = 0;
	if (!*word) {
usage:
		return "unrecognized TOS.  use none, lowdelay, throughput, reliability, or lowcost, possibly bitwise-or'd together by using '|'.";
	}
	for (;;) {
		bar = strchr(word, '|');
		if (!bar) {
			bar = word + strlen(word);
		}
		if (bar - word == 8 && strncasecmp(word, "lowdelay", 8) == 0) {
			tos |= IPTOS_LOWDELAY;
		}
		else if (bar - word == 10 && strncasecmp(word, "throughput", 10) == 0) {
			tos |= IPTOS_THROUGHPUT;
		}
		else if (bar - word == 11 && strncasecmp(word, "reliability", 11) == 0) {
			tos |= IPTOS_RELIABILITY;
		}
		else if (bar - word == 7 && strncasecmp(word, "lowcost", 7) == 0) {
			tos |= IPTOS_LOWCOST;
		}
		else if (bar - word == 4 && strncasecmp(word, "none", 4) == 0) {
			tos = 0;
		}
		else {
			goto usage;
		}
		if (*bar) {
			word = bar + 1;
		}
		else {
			break;
		}
	}
	*ptos = tos;
	return NULL;
}


static const char *iptos_cmd_iptos(cmd_parms *cmd, void *mconfig, char *word)
{
	iptos_config *config = mconfig;

	return iptos_parse_iptos(word, &config->tos);
}


static void *iptos_create_dir_config(pool *p, char *dirspec)
{
	iptos_config *config;

	config = ap_pcalloc(p, sizeof(iptos_config));
	config->tos = 0;
	return config;
}


static int iptos_fixup(request_rec *r)
{
	iptos_config *config = ap_get_module_config(r->per_dir_config, &iptos_module);
	unsigned tos;

	/* don't want to do this for subrequests */
	if (!ap_is_initial_req(r)) {
		return DECLINED;
	}
	tos = config->tos;	/* not sure if copy is necessary, but make one to be safe */
	if (setsockopt(r->connection->client->fd, IPPROTO_IP, IP_TOS, (char *)&tos, sizeof(tos))) {
		ap_log_rerror(APLOG_MARK, APLOG_INFO, r, "setsockopt(IP_TOS, %u)", tos);
	}
	return DECLINED;
}


static const command_rec iptos_cmds[] =
{
	{ "IPTOS", iptos_cmd_iptos, NULL, OR_OPTIONS, TAKE1,
	    "arg is none, lowdelay, throughput, reliability, or lowcost -- and can be bitwise-or'd together using '|'"
	},
	{NULL}
};


module MODULE_VAR_EXPORT iptos_module =
{
    STANDARD_MODULE_STUFF,
    NULL,			/* module initializer */
    iptos_create_dir_config,	/* per-directory config creator */
    NULL,			/* dir config merger */
    NULL,			/* server config creator */
    NULL,			/* server config merger */
    iptos_cmds,			/* command table */
    NULL,			/* [9] list of handlers */
    NULL,			/* [2] filename-to-URI translation */
    NULL,			/* [5] check/validate user_id */
    NULL,			/* [6] check user_id is valid *here* */
    NULL,			/* [4] check access by host address */
    NULL,			/* [7] MIME type checker/setter */
    iptos_fixup,		/* [8] fixups */
    NULL			/* [10] logger */
#if MODULE_MAGIC_NUMBER >= 19970103
    ,NULL			/* [3] header parser */
#endif
#if MODULE_MAGIC_NUMBER >= 19970719
    ,NULL			/* process initializer */
#endif
#if MODULE_MAGIC_NUMBER >= 19970728
    ,NULL			/* process exit/cleanup */
#endif
#if MODULE_MAGIC_NUMBER >= 19970902
    ,NULL			/* [1] post read_request handling */
#endif
};