/*
* Copyright 2011 Kestrel Signal Processing, Inc.
* Copyright 2011 Range Networks, Inc.
*
* This software is distributed under the terms of the GNU Affero Public License.
* See the COPYING file in the main directory for details.
*
* This use of this software may be subject to additional restrictions.
* See the LEGAL file in the main directory for details.

	This program is free software: you can redistribute it and/or modify
	it under the terms of the GNU Affero General Public License as published by
	the Free Software Foundation, either version 3 of the License, 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 Affero General Public License for more details.

	You should have received a copy of the GNU Affero General Public License
	along with this program.  If not, see <http://www.gnu.org/licenses/>.

*/


#include <iostream>
#include <sstream>
#include <fstream>
#include <cstdlib>
#include <Configuration.h>
#include <string.h>

#include "servershare.h"
#include "sqlite3.h"
#include "Logger.h"
#include "SubscriberRegistry.h"

using namespace std;


extern ConfigurationTable gConfig;

// just using this for the database access
extern SubscriberRegistry gSubscriberRegistry;



ConfigurationKeyMap getConfigurationKeys()
{
	ConfigurationKeyMap map;
	ConfigurationKey *tmp;

	tmp = new ConfigurationKey("SIP.Proxy.Registration","127.0.0.1:5064",
		"",
		ConfigurationKey::CUSTOMERWARN,
		ConfigurationKey::IPANDPORT,
		"",
		false,
		"The IP host and port of the proxy to be used for registration and authentication.  "
			"This should normally be the subscriber registry SIP interface, not Asterisk."
	);
	map[tmp->getName()] = *tmp;
	delete tmp;

	tmp = new ConfigurationKey("SubscriberRegistry.A3A8","/OpenBTS/comp128",
		"",
		ConfigurationKey::CUSTOMERWARN,
		ConfigurationKey::FILEPATH,
		"",
		false,
		"Path to the program that implements the A3/A8 algorithm."
	);
	map[tmp->getName()] = *tmp;
	delete tmp;

	tmp = new ConfigurationKey("SubscriberRegistry.db","/var/lib/asterisk/sqlite3dir/sqlite3.db",
		"",
		ConfigurationKey::CUSTOMERWARN,
		ConfigurationKey::FILEPATH,
		"",
		false,
		"The location of the sqlite3 database holding the subscriber registry."
	);
	map[tmp->getName()] = *tmp;
	delete tmp;

	tmp = new ConfigurationKey("SubscriberRegistry.Manager.Title","Subscriber Registry",
		"",
		ConfigurationKey::CUSTOMER,
		ConfigurationKey::STRING,
		"^[[:print:]]+$",
		false,
		"Title text to be displayed on the subscriber registry manager."
	);
	map[tmp->getName()] = *tmp;
	delete tmp;

	tmp = new ConfigurationKey("SubscriberRegistry.Manager.VisibleColumns","name username type context host",
		"",
		ConfigurationKey::CUSTOMERTUNE,
		ConfigurationKey::STRING,
		"^(name){0,1} (username){0,1} (type){0,1} (context){0,1} (host){0,1}$",
		false,
		"A space separated list of columns to display in the subscriber registry manager."
	);
	map[tmp->getName()] = *tmp;
	delete tmp;

	tmp = new ConfigurationKey("SubscriberRegistry.Port","5064",
		"",
		ConfigurationKey::CUSTOMERWARN,
		ConfigurationKey::PORT,
		"",
		false,
		"Port used by the SIP Authentication Server. NOTE: In some older releases (pre-2.8.1) this is called SIP.myPort."
	);
	map[tmp->getName()] = *tmp;
	delete tmp;

	tmp = new ConfigurationKey("SubscriberRegistry.UpstreamServer","",
		"",
		ConfigurationKey::CUSTOMERWARN,
		ConfigurationKey::STRING_OPT,// audited
		"",
		false,
		"URL of the subscriber registry HTTP interface on the upstream server.  "
			"By default, this feature is disabled.  "
			"To enable, specify a server URL eg: http://localhost/cgi/subreg.cgi.  "
			"To disable again, execute \"unconfig SubscriberRegistry.UpstreamServer\"."
	);
	map[tmp->getName()] = *tmp;
	delete tmp;

	return map;
}

string imsiGet(string imsi, string key)
{
	string name = imsi.substr(0,4) == "IMSI" ? imsi : "IMSI" + imsi;
	char *value;
	if (!sqlite3_single_lookup(gSubscriberRegistry.db(), "sip_buddies", "username", name.c_str(), key.c_str(), value)) {
		return "";
	}
	if (!value) { return ""; }
	string retValue = value;
	free(value);
	return retValue;
}

void imsiSet(string imsi, string key, string value)
{
	string name = imsi.substr(0,4) == "IMSI" ? imsi : "IMSI" + imsi;
	ostringstream os2;
	os2 << "update sip_buddies set " << key << " = \"" << value << "\" where username = \"" << name << "\"";
	if (!sqlite3_command(gSubscriberRegistry.db(), os2.str().c_str())) {
		LOG(ERR) << "sqlite3_command problem";
		return;
	}
}

void imsiSet(string imsi, string key1, string value1, string key2, string value2)
{
	string name = imsi.substr(0,4) == "IMSI" ? imsi : "IMSI" + imsi;
	ostringstream os2;
	os2 << "update sip_buddies set " << key1 << " = \"" << value1 << "\"," << key2 << " = \"" << value2 << "\" where username = \"" << name << "\"";
	if (!sqlite3_command(gSubscriberRegistry.db(), os2.str().c_str())) {
		LOG(ERR) << "sqlite3_command problem";
		return;
	}
}

string soGenerateIt()
{
	ostringstream os;
	for (int i = 0; i < 32; i++) {
		// if rand() is too slow you can call it fewer times
		os << hex << (rand() & 0xf);
	}
	return os.str();
}



// generate a 128' random number
string generateRand(string imsi)
{
	string ki = imsiGet(imsi, "ki");
	string ret;
	if (ki.length() != 0) {
		LOG(INFO) << "ki is known";
		// generate and return rand (clear any cached rand or sres)
		imsiSet(imsi, "rand", "", "sres", "");
		ret = soGenerateIt();
	} else {
		string wRand = imsiGet(imsi, "rand");
		if (wRand.length() != 0) {
			LOG(INFO) << "ki is unknown, rand is cached";
			// return cached rand
			ret = wRand;
		} else {
			LOG(INFO) << "ki is unknown, rand is not cached";
			// generate rand, cache rand, clear sres, and return rand
			wRand = soGenerateIt();
			imsiSet(imsi, "rand", wRand, "sres", "");
			ret = wRand;
		}
	}
	return ret;
}

bool strEqual(string a, string b)
{
	return 0 == strcasecmp(a.c_str(), b.c_str());
}

bool sresEqual(string a, string b)
{
	stringstream ss1;
	stringstream ss2;
	uint32_t sres1 = 0xffffffff;
	uint32_t sres2 = 0xffffffff;

	if (a.empty() || b.empty())
		return false;

	ss1 << hex << a;
	ss2 << hex << b;

	ss1 >> sres1;
	ss2 >> sres2;

	LOG(DEBUG) << "sres1 = " << sres1;
	LOG(DEBUG) << "sres2 = " << sres2;

	return (sres1 == sres2);
}

bool randEqual(string a, string b)
{
	uint64_t rand1h = 0;
	uint64_t rand1l = 0;
	uint64_t rand2h = 0;
	uint64_t rand2l = 0;

	if (a.empty() || b.empty())
		return false;

	gSubscriberRegistry.stringToUint(a, &rand1h, &rand1l);
	gSubscriberRegistry.stringToUint(b, &rand2h, &rand2l);

	LOG(DEBUG) << "rand1h = " << rand1h << ", rand1l = " << rand1l;
	LOG(DEBUG) << "rand2h = " << rand2h << ", rand2l = " << rand2l;

	return (rand1h == rand2h) && (rand1l == rand2l);
}

// verify sres given rand and imsi's ki
// may set kc
// may cache sres and rand
bool authenticate(string imsi, string randx, string sres, string *kc)
{
	string ki = imsiGet(imsi, "ki");
	bool ret;
	if (ki.length() == 0) {
		// Ki is unknown
		string upstream_server = gConfig.getStr("SubscriberRegistry.UpstreamServer");
		if (upstream_server.length()) {
			LOG(INFO) << "ki unknown, upstream server";
			// there's an upstream server for authentication.
			// TODO - call the upstream server
			ret = false;
		} else {
			// there's no upstream server for authentication.  fake it.
			string sres2 = imsiGet(imsi, "sres");
			if (sres2.length() == 0) {
				LOG(INFO) << "ki unknown, no upstream server, sres not cached";
				// first time - cache sres and rand so next time
				// correct cell phone will calc same sres from same rand
				imsiSet(imsi, "sres", sres, "rand", randx);
				ret = true;
			} else {
				LOG(INFO) << "ki unknown, no upstream server, sres cached";
				// check against cached values of rand and sres
				string rand2 = imsiGet(imsi, "rand");
				// TODO - on success, compute and return kc
				LOG(DEBUG) << "comparing " << sres << " to " << sres2 << " and " << randx << " to " << rand2;
				ret = sresEqual(sres, sres2) && randEqual(randx, rand2);
			}
		}
	} else {
		LOG(INFO) << "ki known";
		// Ki is known, so do normal authentication
		ostringstream os;
		// per user value from subscriber registry
		string a3a8 = imsiGet(imsi, "a3_a8");
		if (a3a8.length() == 0) {
			// config value is default
			a3a8 = gConfig.getStr("SubscriberRegistry.A3A8");
		}
		os << a3a8 << " 0x" << ki << " 0x" << randx;
		// must not put ki into the log
		// LOG(INFO) << "running " << os.str();
		FILE *f = popen(os.str().c_str(), "r");
		if (f == NULL) {
			LOG(CRIT) << "error: popen failed";
			return false;
		}
		char sres2[26];
		char *str = fgets(sres2, 26, f);
		if (str != NULL && strlen(str) == 25) str[24] = 0;
		if (str == NULL || strlen(str) != 24) {
			LOG(CRIT) << "error: popen result failed";
			return false;
		}
		int st = pclose(f);
		if (st == -1) {
			LOG(CRIT) << "error: pclose failed";
			return false;
		}
		// first 8 chars are SRES;  rest are Kc
		*kc = sres2+8;
		sres2[8] = 0;
		LOG(INFO) << "result = " << sres2;
		ret = sresEqual(sres, sres2);
	}
	LOG(INFO) << "returning = " << ret;
	return ret;
}

void decodeQuery(map<string,string> &args)
{
	string query;
	// this works for GET or POST.
	// get the request method
	char *g = getenv("REQUEST_METHOD");
	string method = g ? g : "";
	LOG(INFO) << "REQUEST_METHOD = " << g;
	// if POST, then read from stdin the number of bytes specified in CONTENT_LENGTH, and that's the query
	if (method == "POST") {
		int lth = atoi(getenv("CONTENT_LENGTH"));
		LOG(INFO) << "CONTENT_LENGTH = " << lth;
		char *buf = new char[lth+1];
		cin.get(buf, lth+1);
		int nread = cin.gcount();
		if (nread != lth) {
			LOG(ERR) << "content length changed to " << nread;
			lth = nread;
		}
		query = string(buf, lth);
		LOG(INFO) << "QUERY = " << query;
		delete[] buf;
	// if GET, then the query is in the environment variable QUERY_STRING
	} else if (method == "GET") {
		char *q = getenv("QUERY_STRING");
		query = q ? q : "";
		LOG(INFO) << "QUERY_STRING = " << q;
	}
	if (query.length() != 0) {
		// fields of http request are separated with "&"
		vector<string> fields;
		split('&', query, &fields);
		vector<string>::iterator it;
		for (it = fields.begin(); it != fields.end(); it++) {
			string field = *it;
			size_t p = field.find('=');
			string key = field.substr(0, p);
			string value = field.substr(p+1);
			p = 0;
			while (1) {
				size_t q = value.find('%', p);
				if (q == string::npos) break;
				string hex = value.substr(q+1, 2);
				char s[2];
				strcpy(s, "x");
				int i;
				sscanf(hex.c_str(), "%x", &i);
				s[0] = i;
				string hexx = s;
				value.replace(q, 3, hexx);
			}
			args[key] = value;
		}
	}
}

string join(string separator, vector<string> &strings)
{
	string result("");
	vector<string>::iterator it;
	for (it = strings.begin(); it != strings.end(); it++) {
		if (it != strings.begin()) result.append(separator);
		result.append(*it);
	}
	return result;
}

void split(char separator, string tosplit, vector<string> *fields)
{
	int p = 0;
	while (1) {
		size_t q = tosplit.find(separator, p);
		if (q == string::npos) {
			fields->push_back(tosplit.substr(p));
			break;
		}
		fields->push_back(tosplit.substr(p, q-p));
		p = q+1;
	}
}