/* Copyright (C) 2011 NORDUnet A/S
 * See LICENSE for information about licensing.
 */

#include <stdio.h>		/* For sprintf().  */
#include <string.h>
#include <ctype.h>
#include <errno.h>
#include <nettle/sha.h>
#include <nettle/hmac.h>

#include <regex.h>
#include <pthread.h>
#include <sys/time.h>
#include "radsecproxy.h"
#include "debug.h"

#include "fticks.h"

static void
_format_hash(const uint8_t *hash, size_t out_len, uint8_t *out)
{
    int ir, iw;

    for (ir = 0, iw = 0; iw <= out_len - 3; ir++, iw += 2)
	sprintf((char *) out + iw, "%02x", hash[ir % SHA256_DIGEST_SIZE]);
}

static void
_hash(const uint8_t *in,
      const uint8_t *key,
      size_t out_len,
      uint8_t *out)
{
    if (key == NULL) {
	struct sha256_ctx ctx;
	uint8_t hash[SHA256_DIGEST_SIZE];

	sha256_init(&ctx);
	sha256_update(&ctx, strlen((char *) in), in);
	sha256_digest(&ctx, sizeof(hash), hash);
	_format_hash(hash, out_len, out);
    }
    else {
	struct hmac_sha256_ctx ctx;
	uint8_t hash[SHA256_DIGEST_SIZE];

	hmac_sha256_set_key(&ctx, strlen((char *) key), key);
	hmac_sha256_update(&ctx, strlen((char *) in), in);
	hmac_sha256_digest(&ctx, sizeof(hash), hash);
	_format_hash(hash, out_len, out);
    }
}

int
fticks_configure(struct options *options,
		 uint8_t **reportingp,
		 uint8_t **macp,
		 uint8_t **keyp)
{
    int r = 0;
    const char *reporting = (const char *) *reportingp;
    const char *mac = (const char *) *macp;

    if (reporting == NULL)
	goto out;

    if (strcasecmp(reporting, "None") == 0)
	options->fticks_reporting = RSP_FTICKS_REPORTING_NONE;
    else if (strcasecmp(reporting, "Basic") == 0)
	options->fticks_reporting = RSP_FTICKS_REPORTING_BASIC;
    else if (strcasecmp(reporting, "Full") == 0)
	options->fticks_reporting = RSP_FTICKS_REPORTING_FULL;
    else {
	debugx(1, DBG_ERR, "config error: invalid FTicksReporting value: %s",
	       reporting);
	r = 1;
	goto out;
    }

    if (strcasecmp(mac, "Static") == 0)
	options->fticks_mac = RSP_FTICKS_MAC_STATIC;
    else if (strcasecmp(mac, "Original") == 0)
	options->fticks_mac = RSP_FTICKS_MAC_ORIGINAL;
    else if (strcasecmp(mac, "VendorHashed") == 0)
	options->fticks_mac = RSP_FTICKS_MAC_VENDOR_HASHED;
    else if (strcasecmp(mac, "VendorKeyHashed") == 0)
	options->fticks_mac = RSP_FTICKS_MAC_VENDOR_KEY_HASHED;
    else if (strcasecmp(mac, "FullyHashed") == 0)
	options->fticks_mac = RSP_FTICKS_MAC_FULLY_HASHED;
    else if (strcasecmp(mac, "FullyKeyHashed") == 0)
	options->fticks_mac = RSP_FTICKS_MAC_FULLY_KEY_HASHED;
    else {
	debugx(1, DBG_ERR, "config error: invalid FTicksMAC value: %s", mac);
	r = 1;
	goto out;
    }

    if (*keyp == NULL
	&& (options->fticks_mac == RSP_FTICKS_MAC_VENDOR_KEY_HASHED
	    || options->fticks_mac == RSP_FTICKS_MAC_FULLY_KEY_HASHED)) {
	debugx(1, DBG_ERR,
	       "config error: FTicksMAC %s requires an FTicksKey", mac);
	options->fticks_mac = RSP_FTICKS_MAC_STATIC;
	r = 1;
	goto out;
    }

    if (*keyp != NULL)
	options->fticks_key = *keyp;

out:
    if (*reportingp != NULL) {
	free(*reportingp);
	*reportingp = NULL;
    }
    if (*macp != NULL) {
	free(*macp);
	*macp = NULL;
    }
    return r;
}

/** Hash the Ethernet MAC address in \a IN, keying a HMAC with \a KEY
    unless \a KEY is NULL.  If \a KEY is null \a IN is hashed with an
    ordinary cryptographic hash function such as SHA-2.

    \a IN and \a KEY are NULL terminated strings.

    \a IN is supposed to be an Ethernet MAC address and is sanitised
    by lowercasing it, removing all but [0-9a-f] and truncating it at
    the first ';' found.  The truncation is done because RADIUS
    supposedly has a praxis of tacking on SSID to the MAC address in
    Calling-Station-Id.

    \return 0 on success, -ENOMEM on out of memory.
*/
int
fticks_hashmac(const uint8_t *in,
	       const uint8_t *key,
	       size_t out_len,
	       uint8_t *out)
{
    uint8_t *in_copy = NULL;
    uint8_t *p = NULL;
    int i;

    in_copy = calloc(1, strlen((const char *) in) + 1);
    if (in_copy == NULL)
	return -ENOMEM;

    /* Sanitise and lowercase 'in' into 'in_copy'.  */
    for (i = 0, p = in_copy; in[i] != '\0'; i++) {
	if (in[i] == ';') {
	    *p++ = '\0';
	    break;
	}
	if (in[i] >= '0' && in[i] <= '9') {
	    *p++ = in[i];
	}
	else if (tolower(in[i]) >= 'a' && tolower(in[i]) <= 'f') {
	    *p++ = tolower(in[i]);
	}
    }

    _hash(in_copy, key, out_len, out);
    free(in_copy);
    return 0;
}

void
fticks_log(const struct options *options,
	   const struct client *client,
	   const struct radmsg *msg,
	   const struct rqout *rqout)
{
    uint8_t *username = NULL;
    uint8_t *realm = NULL;
    uint8_t visinst[8+40+1+1]; /* Room for 40 octets of VISINST.  */
    uint8_t *macin = NULL;
    uint8_t macout[2*32+1]; /* Room for ASCII representation of SHA256.  */

    username = radattr2ascii(radmsg_gettype(rqout->rq->msg,
					    RAD_Attr_User_Name));
    if (username != NULL) {
	realm = (uint8_t *) strrchr((char *) username, '@');
	if (realm != NULL)
	    realm++;
    }
    if (realm == NULL)
	realm = (uint8_t *) "";

    memset(visinst, 0, sizeof(visinst));
    if (options->fticks_reporting == RSP_FTICKS_REPORTING_FULL) {
	snprintf((char *) visinst, sizeof(visinst), "VISINST=%s#",
		 client->conf->name);
    }

    memset(macout, 0, sizeof(macout));
    if (options->fticks_mac == RSP_FTICKS_MAC_STATIC) {
	strncpy((char *) macout, "undisclosed", sizeof(macout) - 1);
    }
    else {
	macin = radattr2ascii(radmsg_gettype(rqout->rq->msg,
					     RAD_Attr_Calling_Station_Id));
	if (macin) {
	    switch (options->fticks_mac)
	    {
	    case RSP_FTICKS_MAC_ORIGINAL:
		memcpy(macout, macin, sizeof(macout));
		break;
	    case RSP_FTICKS_MAC_VENDOR_HASHED:
		memcpy(macout, macin, 9);
		fticks_hashmac(macin, NULL, sizeof(macout) - 9, macout + 9);
		break;
	    case RSP_FTICKS_MAC_VENDOR_KEY_HASHED:
		memcpy(macout, macin, 9);
		/* We are hashing the first nine octets too for easier
		 * correlation between vendor-key-hashed and
		 * fully-key-hashed log records.  This opens up for a
		 * known plaintext attack on the key but the
		 * consequences of that is considered outweighed by
		 * the convenience gained.  */
		fticks_hashmac(macin, options->fticks_key,
			       sizeof(macout) - 9, macout + 9);
		break;
	    case RSP_FTICKS_MAC_FULLY_HASHED:
		fticks_hashmac(macin, NULL, sizeof(macout), macout);
		break;
	    case RSP_FTICKS_MAC_FULLY_KEY_HASHED:
		fticks_hashmac(macin, options->fticks_key, sizeof(macout),
			       macout);
		break;
	    default:
		debugx(2, DBG_ERR, "invalid fticks mac configuration: %d",
		       options->fticks_mac);
	    }
	}
    }
    debug(0xff,
	  "F-TICKS/eduroam/1.0#REALM=%s#VISCOUNTRY=%s#%sCSI=%s#RESULT=%s#",
	  realm,
	  client->conf->fticks_viscountry,
	  visinst,
	  macout,
	  msg->code == RAD_Access_Accept ? "OK" : "FAIL");
    if (macin != NULL)
	free(macin);
    if (username != NULL)
	free(username);
}

/* Local Variables: */
/* c-file-style: "stroustrup" */
/* End: */