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Prevent RNG overflow.

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Pass save under validation by pointer, so we could mess with underlying
values a little. Only thing I feel we can safely and sanely modify.
This commit is contained in:
NHOrus 2017-09-05 18:20:21 +03:00
parent 0dd40bba32
commit 96ead306b5
1 changed files with 30 additions and 25 deletions
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55
saveresume.c
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@ -105,7 +105,7 @@ int resume(void)
return restore(fp); return restore(fp);
} }
bool is_valid(struct game_t); bool is_valid(struct game_t*);
int restore(FILE* fp) int restore(FILE* fp)
{ {
@ -120,13 +120,13 @@ int restore(FILE* fp)
fclose(fp); fclose(fp);
if (save.version != VRSION) { if (save.version != VRSION) {
rspeak(VERSION_SKEW, save.version / 10, MOD(save.version, 10), VRSION / 10, MOD(VRSION, 10)); rspeak(VERSION_SKEW, save.version / 10, MOD(save.version, 10), VRSION / 10, MOD(VRSION, 10));
} else if (is_valid(save.game)) { } else if (is_valid(&save.game)) {
game = save.game; game = save.game;
} }
return GO_TOP; return GO_TOP;
} }
bool is_valid(struct game_t valgame) bool is_valid(struct game_t* valgame)
{ {
/* Save files can be roughly grouped into three groups: /* Save files can be roughly grouped into three groups:
* With valid, reaceable state, with valid, but unreachable * With valid, reaceable state, with valid, but unreachable
@ -135,48 +135,53 @@ bool is_valid(struct game_t valgame)
*/ */
/* Prevent division by zero */ /* Prevent division by zero */
if (valgame.abbnum == 0) { if (valgame->abbnum == 0) {
return false; return false;
} }
/* Prevent RNG substitution. Why we are saving PRNG parameters? */ /* Prevent RNG substitution. Why we are saving PRNG parameters? */
if (valgame.lcg_a != game.lcg_a || valgame.lcg_c != game.lcg_c || valgame.lcg_m != game.lcg_m) { if (valgame->lcg_a != game.lcg_a || valgame->lcg_c != game.lcg_c || valgame->lcg_m != game.lcg_m) {
return false; return false;
} }
/* Check for RNG overflow. Truncate */
if (valgame->lcg_x >= game.lcg_m) {
valgame->lcg_x %= game.lcg_m;
}
/* Bounds check for locations */ /* Bounds check for locations */
if ( valgame.chloc < -1 || valgame.chloc > NLOCATIONS || if ( valgame->chloc < -1 || valgame->chloc > NLOCATIONS ||
valgame.chloc2 < -1 || valgame.chloc2 > NLOCATIONS || valgame->chloc2 < -1 || valgame->chloc2 > NLOCATIONS ||
valgame.loc < -1 || valgame.loc > NLOCATIONS || valgame->loc < -1 || valgame->loc > NLOCATIONS ||
valgame.newloc < -1 || valgame.newloc > NLOCATIONS || valgame->newloc < -1 || valgame->newloc > NLOCATIONS ||
valgame.oldloc < -1 || valgame.oldloc > NLOCATIONS || valgame->oldloc < -1 || valgame->oldloc > NLOCATIONS ||
valgame.oldlc2 < -1 || valgame.oldlc2 > NLOCATIONS) { valgame->oldlc2 < -1 || valgame->oldlc2 > NLOCATIONS) {
return false; return false;
} }
/* Bounds check for location arrays */ /* Bounds check for location arrays */
for (int i = 0; i <= NDWARVES; i++) { for (int i = 0; i <= NDWARVES; i++) {
if (valgame.dloc[i] < -1 || valgame.dloc[i] > NLOCATIONS || if (valgame->dloc[i] < -1 || valgame->dloc[i] > NLOCATIONS ||
valgame.odloc[i] < -1 || valgame.odloc[i] > NLOCATIONS) { valgame->odloc[i] < -1 || valgame->odloc[i] > NLOCATIONS) {
return false; return false;
} }
} }
for (int i = 0; i <= NOBJECTS; i++) { for (int i = 0; i <= NOBJECTS; i++) {
if (valgame.place[i] < -1 || valgame.place[i] > NLOCATIONS || if (valgame->place[i] < -1 || valgame->place[i] > NLOCATIONS ||
valgame.fixed[i] < -1 || valgame.fixed[i] > NLOCATIONS) { valgame->fixed[i] < -1 || valgame->fixed[i] > NLOCATIONS) {
return false; return false;
} }
} }
/* Bounds check for dwarves */ /* Bounds check for dwarves */
if (valgame.dtotal < 0 || valgame.dtotal > NDWARVES || if (valgame->dtotal < 0 || valgame->dtotal > NDWARVES ||
valgame.dkill < 0 || valgame.dkill > NDWARVES) { valgame->dkill < 0 || valgame->dkill > NDWARVES) {
return false; return false;
} }
/* Validate that we didn't die too many times in save */ /* Validate that we didn't die too many times in save */
if (valgame.numdie >= NDEATHS) { if (valgame->numdie >= NDEATHS) {
return false; return false;
} }
@ -184,18 +189,18 @@ bool is_valid(struct game_t valgame)
long temp_tally = 0; long temp_tally = 0;
for (int treasure = 1; treasure <= NOBJECTS; treasure++) { for (int treasure = 1; treasure <= NOBJECTS; treasure++) {
if (objects[treasure].is_treasure) { if (objects[treasure].is_treasure) {
if (valgame.prop[treasure] == STATE_NOTFOUND) { if (valgame->prop[treasure] == STATE_NOTFOUND) {
++temp_tally; ++temp_tally;
} }
} }
} }
if (temp_tally != valgame.tally) { if (temp_tally != valgame->tally) {
return false; return false;
} }
/* Check that properties of objects aren't beyond expected */ /* Check that properties of objects aren't beyond expected */
for (obj_t obj = 0; obj <= NOBJECTS; obj++) { for (obj_t obj = 0; obj <= NOBJECTS; obj++) {
if (valgame.prop[obj] < STATE_NOTFOUND || valgame.prop[obj] > 1) { if (valgame->prop[obj] < STATE_NOTFOUND || valgame->prop[obj] > 1) {
switch (obj) { switch (obj) {
case RUG: case RUG:
case DRAGON: case DRAGON:
@ -208,10 +213,10 @@ bool is_valid(struct game_t valgame)
case EGGS: case EGGS:
case VASE: case VASE:
case CHAIN: case CHAIN:
if (valgame.prop[obj] == 2) // There are multiple different states, but it's convenient to clump them together if (valgame->prop[obj] == 2) // There are multiple different states, but it's convenient to clump them together
continue; continue;
case BEAR: case BEAR:
if (valgame.prop[BEAR] == CONTENTED_BEAR || game.prop[BEAR] == BEAR_DEAD) if (valgame->prop[BEAR] == CONTENTED_BEAR || valgame->prop[BEAR] == BEAR_DEAD)
continue; continue;
default: default:
return false; return false;
@ -221,12 +226,12 @@ bool is_valid(struct game_t valgame)
/* Check that values in linked lists for objects in locations are inside bounds */ /* Check that values in linked lists for objects in locations are inside bounds */
for (loc_t loc = LOC_NOWHERE; loc <= NLOCATIONS; loc++) { for (loc_t loc = LOC_NOWHERE; loc <= NLOCATIONS; loc++) {
if (valgame.atloc[loc] < NO_OBJECT || valgame.atloc[loc] > NOBJECTS * 2) { if (valgame->atloc[loc] < NO_OBJECT || valgame->atloc[loc] > NOBJECTS * 2) {
return false; return false;
} }
} }
for (obj_t obj = 0; obj <= NOBJECTS * 2; obj++ ) { for (obj_t obj = 0; obj <= NOBJECTS * 2; obj++ ) {
if (valgame.link[obj] < NO_OBJECT || valgame.link[obj] > NOBJECTS * 2) { if (valgame->link[obj] < NO_OBJECT || valgame->link[obj] > NOBJECTS * 2) {
return false; return false;
} }
} }