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tor/src/or/shared_random_state.c

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/* Copyright (c) 2016, The Tor Project, Inc. */
/* See LICENSE for licensing information */
/**
* \file shared_random_state.c
*
* \brief Functions and data structures for the state of the random protocol
* as defined in proposal #250.
**/
#define SHARED_RANDOM_STATE_PRIVATE
#include "or.h"
#include "shared_random.h"
#include "config.h"
#include "confparse.h"
#include "dirvote.h"
#include "networkstatus.h"
#include "router.h"
#include "shared_random_state.h"
/* Default filename of the shared random state on disk. */
static const char default_fname[] = "sr-state";
/* String representation of a protocol phase. */
static const char *phase_str[] = { "unknown", "commit", "reveal" };
/* Our shared random protocol state. There is only one possible state per
* protocol run so this is the global state which is reset at every run once
* the shared random value has been computed. */
static sr_state_t *sr_state = NULL;
/* Representation of our persistent state on disk. The sr_state above
* contains the data parsed from this state. When we save to disk, we
* translate the sr_state to this sr_disk_state. */
static sr_disk_state_t *sr_disk_state = NULL;
/* Disk state file keys. */
static const char dstate_commit_key[] = "Commit";
static const char dstate_prev_srv_key[] = "SharedRandPreviousValue";
static const char dstate_cur_srv_key[] = "SharedRandCurrentValue";
/* These next two are duplicates or near-duplicates from config.c */
#define VAR(name, conftype, member, initvalue) \
{ name, CONFIG_TYPE_ ## conftype, STRUCT_OFFSET(sr_disk_state_t, member), \
initvalue }
/* As VAR, but the option name and member name are the same. */
#define V(member, conftype, initvalue) \
VAR(#member, conftype, member, initvalue)
/* Our persistent state magic number. */
#define SR_DISK_STATE_MAGIC 0x98AB1254
/* Each protocol phase has 12 rounds */
#define SHARED_RANDOM_N_ROUNDS 12
/* Number of phase we have in a protocol. */
#define SHARED_RANDOM_N_PHASES 2
static int
disk_state_validate_cb(void *old_state, void *state, void *default_state,
int from_setconf, char **msg);
/* Array of variables that are saved to disk as a persistent state. */
static config_var_t state_vars[] = {
V(Version, UINT, "0"),
V(TorVersion, STRING, NULL),
V(ValidAfter, ISOTIME, NULL),
V(ValidUntil, ISOTIME, NULL),
V(Commit, LINELIST, NULL),
V(SharedRandValues, LINELIST_V, NULL),
VAR("SharedRandPreviousValue",LINELIST_S, SharedRandValues, NULL),
VAR("SharedRandCurrentValue", LINELIST_S, SharedRandValues, NULL),
{ NULL, CONFIG_TYPE_OBSOLETE, 0, NULL }
};
/* "Extra" variable in the state that receives lines we can't parse. This
* lets us preserve options from versions of Tor newer than us. */
static config_var_t state_extra_var = {
"__extra", CONFIG_TYPE_LINELIST,
STRUCT_OFFSET(sr_disk_state_t, ExtraLines), NULL
};
/* Configuration format of sr_disk_state_t. */
static const config_format_t state_format = {
sizeof(sr_disk_state_t),
SR_DISK_STATE_MAGIC,
STRUCT_OFFSET(sr_disk_state_t, magic_),
NULL,
NULL,
state_vars,
disk_state_validate_cb,
&state_extra_var,
};
/* Return a string representation of a protocol phase. */
STATIC const char *
get_phase_str(sr_phase_t phase)
{
const char *the_string = NULL;
switch (phase) {
case SR_PHASE_COMMIT:
case SR_PHASE_REVEAL:
the_string = phase_str[phase];
break;
default:
/* Unknown phase shouldn't be possible. */
tor_assert(0);
}
return the_string;
}
/* Return the voting interval of the tor vote subsystem. */
static int
get_voting_interval(void)
{
int interval;
networkstatus_t *consensus = networkstatus_get_live_consensus(time(NULL));
if (consensus) {
interval = (int)(consensus->fresh_until - consensus->valid_after);
} else {
/* Same for both a testing and real network. We voluntarily ignore the
* InitialVotingInterval since it complexifies things and it doesn't
* affect the SR protocol. */
interval = get_options()->V3AuthVotingInterval;
}
tor_assert(interval > 0);
return interval;
}
/* Given the time <b>now</b>, return the start time of the current round of
* the SR protocol. For example, if it's 23:47:08, the current round thus
* started at 23:47:00 for a voting interval of 10 seconds. */
static time_t
get_start_time_of_current_round(time_t now)
{
const or_options_t *options = get_options();
int voting_interval = get_voting_interval();
voting_schedule_t *new_voting_schedule =
get_voting_schedule(options, now, LOG_INFO);
tor_assert(new_voting_schedule);
/* First, get the start time of the next round */
time_t next_start = new_voting_schedule->interval_starts;
/* Now roll back next_start by a voting interval to find the start time of
the current round. */
time_t curr_start = dirvote_get_start_of_next_interval(
next_start - voting_interval - 1,
voting_interval,
options->TestingV3AuthVotingStartOffset);
voting_schedule_free(new_voting_schedule);
return curr_start;
}
/* Return the time we should expire the state file created at <b>now</b>.
* We expire the state file in the beginning of the next protocol run. */
STATIC time_t
get_state_valid_until_time(time_t now)
{
int total_rounds = SHARED_RANDOM_N_ROUNDS * SHARED_RANDOM_N_PHASES;
int current_round, voting_interval, rounds_left;
time_t valid_until, beginning_of_current_round;
voting_interval = get_voting_interval();
/* Find the time the current round started. */
beginning_of_current_round = get_start_time_of_current_round(now);
/* Find how many rounds are left till the end of the protocol run */
current_round = (now / voting_interval) % total_rounds;
rounds_left = total_rounds - current_round;
/* To find the valid-until time now, take the start time of the current
* round and add to it the time it takes for the leftover rounds to
* complete. */
valid_until = beginning_of_current_round + (rounds_left * voting_interval);
{ /* Logging */
char tbuf[ISO_TIME_LEN + 1];
format_iso_time(tbuf, valid_until);
log_debug(LD_DIR, "SR: Valid until time for state set to %s.", tbuf);
}
return valid_until;
}
/* Given the consensus 'valid-after' time, return the protocol phase we should
* be in. */
STATIC sr_phase_t
get_sr_protocol_phase(time_t valid_after)
{
/* Shared random protocol has two phases, commit and reveal. */
int total_periods = SHARED_RANDOM_N_ROUNDS * SHARED_RANDOM_N_PHASES;
int current_slot;
/* Split time into slots of size 'voting_interval'. See which slot we are
* currently into, and find which phase it corresponds to. */
current_slot = (valid_after / get_voting_interval()) % total_periods;
if (current_slot < SHARED_RANDOM_N_ROUNDS) {
return SR_PHASE_COMMIT;
} else {
return SR_PHASE_REVEAL;
}
}
/* Add the given <b>commit</b> to <b>state</b>. It MUST be a valid commit
* and there shouldn't be a commit from the same authority in the state
* already else verification hasn't been done prior. This takes ownership of
* the commit once in our state. */
static void
commit_add_to_state(sr_commit_t *commit, sr_state_t *state)
{
sr_commit_t *saved_commit;
tor_assert(commit);
tor_assert(state);
saved_commit = digestmap_set(state->commits, commit->rsa_identity,
commit);
if (saved_commit != NULL) {
/* This means we already have that commit in our state so adding twice
* the same commit is either a code flow error, a corrupted disk state
* or some new unknown issue. */
log_warn(LD_DIR, "SR: Commit from %s exists in our state while "
"adding it: '%s'", sr_commit_get_rsa_fpr(commit),
commit->encoded_commit);
sr_commit_free(saved_commit);
}
}
/* Helper: deallocate a commit object. (Used with digestmap_free(), which
* requires a function pointer whose argument is void *). */
static void
commit_free_(void *p)
{
sr_commit_free(p);
}
/* Free a state that was allocated with state_new(). */
static void
state_free(sr_state_t *state)
{
if (state == NULL) {
return;
}
tor_free(state->fname);
digestmap_free(state->commits, commit_free_);
tor_free(state->current_srv);
tor_free(state->previous_srv);
tor_free(state);
}
/* Allocate an sr_state_t object and returns it. If no <b>fname</b>, the
* default file name is used. This function does NOT initialize the state
* timestamp, phase or shared random value. NULL is never returned. */
static sr_state_t *
state_new(const char *fname, time_t now)
{
sr_state_t *new_state = tor_malloc_zero(sizeof(*new_state));
/* If file name is not provided, use default. */
if (fname == NULL) {
fname = default_fname;
}
new_state->fname = tor_strdup(fname);
new_state->version = SR_PROTO_VERSION;
new_state->commits = digestmap_new();
new_state->phase = get_sr_protocol_phase(now);
new_state->valid_until = get_state_valid_until_time(now);
return new_state;
}
/* Set our global state pointer with the one given. */
static void
state_set(sr_state_t *state)
{
tor_assert(state);
if (sr_state != NULL) {
state_free(sr_state);
}
sr_state = state;
}
/* Free an allocated disk state. */
static void
disk_state_free(sr_disk_state_t *state)
{
if (state == NULL) {
return;
}
config_free(&state_format, state);
}
/* Allocate a new disk state, initialize it and return it. */
static sr_disk_state_t *
disk_state_new(time_t now)
{
sr_disk_state_t *new_state = tor_malloc_zero(sizeof(*new_state));
new_state->magic_ = SR_DISK_STATE_MAGIC;
new_state->Version = SR_PROTO_VERSION;
new_state->TorVersion = tor_strdup(get_version());
new_state->ValidUntil = get_state_valid_until_time(now);
new_state->ValidAfter = now;
/* Init config format. */
config_init(&state_format, new_state);
return new_state;
}
/* Set our global disk state with the given state. */
static void
disk_state_set(sr_disk_state_t *state)
{
tor_assert(state);
if (sr_disk_state != NULL) {
disk_state_free(sr_disk_state);
}
sr_disk_state = state;
}
/* Return -1 if the disk state is invalid (something in there that we can't or
* shouldn't use). Return 0 if everything checks out. */
static int
disk_state_validate(const sr_disk_state_t *state)
{
time_t now;
tor_assert(state);
/* Do we support the protocol version in the state or is it 0 meaning
* Version wasn't found in the state file or bad anyway ? */
if (state->Version == 0 || state->Version > SR_PROTO_VERSION) {
goto invalid;
}
/* If the valid until time is before now, we shouldn't use that state. */
now = time(NULL);
if (state->ValidUntil < now) {
log_info(LD_DIR, "SR: Disk state has expired. Ignoring it.");
goto invalid;
}
/* Make sure we don't have a valid after time that is earlier than a valid
* until time which would make things not work well. */
if (state->ValidAfter >= state->ValidUntil) {
log_info(LD_DIR, "SR: Disk state valid after/until times are invalid.");
goto invalid;
}
return 0;
invalid:
return -1;
}
/* Validate the disk state (NOP for now). */
static int
disk_state_validate_cb(void *old_state, void *state, void *default_state,
int from_setconf, char **msg)
{
/* We don't use these; only options do. */
(void) from_setconf;
(void) default_state;
(void) old_state;
/* This is called by config_dump which is just before we are about to
* write it to disk. At that point, our global memory state has been
* copied to the disk state so it's fair to assume it's trustable. */
(void) state;
(void) msg;
return 0;
}
/* Parse the Commit line(s) in the disk state and translate them to the
* the memory state. Return 0 on success else -1 on error. */
static int
disk_state_parse_commits(sr_state_t *state,
const sr_disk_state_t *disk_state)
{
config_line_t *line;
smartlist_t *args = NULL;
tor_assert(state);
tor_assert(disk_state);
for (line = disk_state->Commit; line; line = line->next) {
sr_commit_t *commit = NULL;
/* Extra safety. */
if (strcasecmp(line->key, dstate_commit_key) ||
line->value == NULL) {
/* Ignore any lines that are not commits. */
tor_fragile_assert();
continue;
}
args = smartlist_new();
smartlist_split_string(args, line->value, " ",
SPLIT_SKIP_SPACE|SPLIT_IGNORE_BLANK, 0);
if (smartlist_len(args) < 3) {
log_warn(LD_BUG, "SR: Too few arguments in Commit Line: %s",
escaped(line->value));
goto error;
}
commit = sr_parse_commit(args);
if (commit == NULL) {
/* Ignore badly formed commit. It could also be a authority
* fingerprint that we don't know about so it shouldn't be used. */
continue;
}
/* We consider parseable commit from our disk state to be valid because
* they need to be in the first place to get in there. */
commit->valid = 1;
/* Add commit to our state pointer. */
commit_add_to_state(commit, state);
SMARTLIST_FOREACH(args, char *, cp, tor_free(cp));
smartlist_free(args);
}
return 0;
error:
SMARTLIST_FOREACH(args, char *, cp, tor_free(cp));
smartlist_free(args);
return -1;
}
/* Parse a share random value line from the disk state and save it to dst
* which is an allocated srv object. Return 0 on success else -1. */
static int
disk_state_parse_srv(const char *value, sr_srv_t *dst)
{
int ret = -1;
smartlist_t *args;
sr_srv_t *srv;
tor_assert(value);
tor_assert(dst);
args = smartlist_new();
smartlist_split_string(args, value, " ",
SPLIT_SKIP_SPACE|SPLIT_IGNORE_BLANK, 0);
if (smartlist_len(args) < 2) {
log_warn(LD_BUG, "SR: Too few arguments in shared random value. "
"Line: %s", escaped(value));
goto error;
}
srv = sr_parse_srv(args);
if (srv == NULL) {
goto error;
}
dst->num_reveals = srv->num_reveals;
memcpy(dst->value, srv->value, sizeof(dst->value));
tor_free(srv);
ret = 0;
error:
SMARTLIST_FOREACH(args, char *, s, tor_free(s));
smartlist_free(args);
return ret;
}
/* Parse both SharedRandCurrentValue and SharedRandPreviousValue line from
* the state. Return 0 on success else -1. */
static int
disk_state_parse_sr_values(sr_state_t *state,
const sr_disk_state_t *disk_state)
{
/* Only one value per type (current or previous) is allowed so we keep
* track of it with these flag. */
unsigned int seen_previous = 0, seen_current = 0;
config_line_t *line;
sr_srv_t *srv = NULL;
tor_assert(state);
tor_assert(disk_state);
for (line = disk_state->SharedRandValues; line; line = line->next) {
if (line->value == NULL) {
continue;
}
srv = tor_malloc_zero(sizeof(*srv));
if (disk_state_parse_srv(line->value, srv) < 0) {
log_warn(LD_BUG, "SR: Broken current SRV line in state %s",
escaped(line->value));
goto bad;
}
if (!strcasecmp(line->key, dstate_prev_srv_key)) {
if (seen_previous) {
log_warn(LD_DIR, "SR: Second previous SRV value seen. Bad state");
goto bad;
}
state->previous_srv = srv;
seen_previous = 1;
} else if (!strcasecmp(line->key, dstate_cur_srv_key)) {
if (seen_current) {
log_warn(LD_DIR, "SR: Second current SRV value seen. Bad state");
goto bad;
}
state->current_srv = srv;
seen_current = 1;
} else {
/* Unknown key. Ignoring. */
tor_free(srv);
}
}
return 0;
bad:
tor_free(srv);
return -1;
}
/* Parse the given disk state and set a newly allocated state. On success,
* return that state else NULL. */
static sr_state_t *
disk_state_parse(const sr_disk_state_t *new_disk_state)
{
sr_state_t *new_state = state_new(default_fname, time(NULL));
tor_assert(new_disk_state);
new_state->version = new_disk_state->Version;
new_state->valid_until = new_disk_state->ValidUntil;
new_state->valid_after = new_disk_state->ValidAfter;
/* Set our current phase according to the valid-after time in our disk
* state. The disk state we are parsing contains everything for the phase
* starting at valid_after so make sure our phase reflects that. */
new_state->phase = get_sr_protocol_phase(new_state->valid_after);
/* Parse the shared random values. */
if (disk_state_parse_sr_values(new_state, new_disk_state) < 0) {
goto error;
}
/* Parse the commits. */
if (disk_state_parse_commits(new_state, new_disk_state) < 0) {
goto error;
}
/* Great! This new state contains everything we had on disk. */
return new_state;
error:
state_free(new_state);
return NULL;
}
/* From a valid commit object and an allocated config line, set the line's
* value to the state string representation of a commit. */
static void
disk_state_put_commit_line(const sr_commit_t *commit, config_line_t *line)
{
char *reveal_str = NULL;
tor_assert(commit);
tor_assert(line);
if (!tor_mem_is_zero(commit->encoded_reveal,
sizeof(commit->encoded_reveal))) {
/* Add extra whitespace so we can format the line correctly. */
tor_asprintf(&reveal_str, " %s", commit->encoded_reveal);
}
tor_asprintf(&line->value, "%u %s %s %s%s",
SR_PROTO_VERSION,
crypto_digest_algorithm_get_name(commit->alg),
sr_commit_get_rsa_fpr(commit),
commit->encoded_commit,
reveal_str != NULL ? reveal_str : "");
if (reveal_str != NULL) {
memwipe(reveal_str, 0, strlen(reveal_str));
tor_free(reveal_str);
}
}
/* From a valid srv object and an allocated config line, set the line's
* value to the state string representation of a shared random value. */
static void
disk_state_put_srv_line(const sr_srv_t *srv, config_line_t *line)
{
char encoded[SR_SRV_VALUE_BASE64_LEN + 1];
tor_assert(line);
/* No SRV value thus don't add the line. This is possible since we might
* not have a current or previous SRV value in our state. */
if (srv == NULL) {
return;
}
sr_srv_encode(encoded, sizeof(encoded), srv);
tor_asprintf(&line->value, "%" PRIu64 " %s", srv->num_reveals, encoded);
}
/* Reset disk state that is free allocated memory and zeroed the object. */
static void
disk_state_reset(void)
{
/* Free allocated memory */
config_free_lines(sr_disk_state->Commit);
config_free_lines(sr_disk_state->SharedRandValues);
config_free_lines(sr_disk_state->ExtraLines);
tor_free(sr_disk_state->TorVersion);
/* Clean up the struct */
memset(sr_disk_state, 0, sizeof(*sr_disk_state));
/* Reset it with useful data */
sr_disk_state->magic_ = SR_DISK_STATE_MAGIC;
sr_disk_state->TorVersion = tor_strdup(get_version());
}
/* Update our disk state based on our global SR state. */
static void
disk_state_update(void)
{
config_line_t **next, *line;
tor_assert(sr_disk_state);
tor_assert(sr_state);
/* Reset current disk state. */
disk_state_reset();
/* First, update elements that we don't need to do a construction. */
sr_disk_state->Version = sr_state->version;
sr_disk_state->ValidUntil = sr_state->valid_until;
sr_disk_state->ValidAfter = sr_state->valid_after;
/* Shared random values. */
next = &sr_disk_state->SharedRandValues;
if (sr_state->previous_srv != NULL) {
*next = line = tor_malloc_zero(sizeof(config_line_t));
line->key = tor_strdup(dstate_prev_srv_key);
disk_state_put_srv_line(sr_state->previous_srv, line);
/* Go to the next shared random value. */
next = &(line->next);
}
if (sr_state->current_srv != NULL) {
*next = line = tor_malloc_zero(sizeof(*line));
line->key = tor_strdup(dstate_cur_srv_key);
disk_state_put_srv_line(sr_state->current_srv, line);
}
/* Parse the commits and construct config line(s). */
next = &sr_disk_state->Commit;
DIGESTMAP_FOREACH(sr_state->commits, key, sr_commit_t *, commit) {
*next = line = tor_malloc_zero(sizeof(*line));
line->key = tor_strdup(dstate_commit_key);
disk_state_put_commit_line(commit, line);
next = &(line->next);
} DIGESTMAP_FOREACH_END;
}
/* Load state from disk and put it into our disk state. If the state passes
* validation, our global state will be updated with it. Return 0 on
* success. On error, -EINVAL is returned if the state on disk did contained
* something malformed or is unreadable. -ENOENT is returned indicating that
* the state file is either empty of non existing. */
static int
disk_state_load_from_disk(void)
{
int ret;
char *fname;
fname = get_datadir_fname(default_fname);
ret = disk_state_load_from_disk_impl(fname);
tor_free(fname);
return ret;
}
/* Helper for disk_state_load_from_disk(). */
STATIC int
disk_state_load_from_disk_impl(const char *fname)
{
int ret;
char *content = NULL;
sr_state_t *parsed_state = NULL;
sr_disk_state_t *disk_state = NULL;
/* Read content of file so we can parse it. */
if ((content = read_file_to_str(fname, 0, NULL)) == NULL) {
log_warn(LD_FS, "SR: Unable to read SR state file %s",
escaped(fname));
ret = -errno;
goto error;
}
{
config_line_t *lines = NULL;
char *errmsg = NULL;
/* Every error in this code path will return EINVAL. */
ret = -EINVAL;
if (config_get_lines(content, &lines, 0) < 0) {
config_free_lines(lines);
goto error;
}
disk_state = disk_state_new(time(NULL));
config_assign(&state_format, disk_state, lines, 0, &errmsg);
config_free_lines(lines);
if (errmsg) {
log_warn(LD_DIR, "SR: Reading state error: %s", errmsg);
tor_free(errmsg);
goto error;
}
}
/* So far so good, we've loaded our state file into our disk state. Let's
* validate it and then parse it. */
if (disk_state_validate(disk_state) < 0) {
ret = -EINVAL;
goto error;
}
parsed_state = disk_state_parse(disk_state);
if (parsed_state == NULL) {
ret = -EINVAL;
goto error;
}
state_set(parsed_state);
disk_state_set(disk_state);
tor_free(content);
log_info(LD_DIR, "SR: State loaded successfully from file %s", fname);
return 0;
error:
disk_state_free(disk_state);
tor_free(content);
return ret;
}
/* Save the disk state to disk but before that update it from the current
* state so we always have the latest. Return 0 on success else -1. */
static int
disk_state_save_to_disk(void)
{
int ret;
char *state, *content = NULL, *fname = NULL;
char tbuf[ISO_TIME_LEN + 1];
time_t now = time(NULL);
/* If we didn't have the opportunity to setup an internal disk state,
* don't bother saving something to disk. */
if (sr_disk_state == NULL) {
ret = 0;
goto done;
}
/* Make sure that our disk state is up to date with our memory state
* before saving it to disk. */
disk_state_update();
state = config_dump(&state_format, NULL, sr_disk_state, 0, 0);
format_local_iso_time(tbuf, now);
tor_asprintf(&content,
"# Tor shared random state file last generated on %s "
"local time\n"
"# Other times below are in UTC\n"
"# Please *do not* edit this file.\n\n%s",
tbuf, state);
tor_free(state);
fname = get_datadir_fname(default_fname);
if (write_str_to_file(fname, content, 0) < 0) {
log_warn(LD_FS, "SR: Unable to write SR state to file %s", fname);
ret = -1;
goto done;
}
ret = 0;
log_debug(LD_DIR, "SR: Saved state to file %s", fname);
done:
tor_free(fname);
tor_free(content);
return ret;
}
/* Reset our state to prepare for a new protocol run. Once this returns, all
* commits in the state will be removed and freed. */
STATIC void
reset_state_for_new_protocol_run(time_t valid_after)
{
tor_assert(sr_state);
/* Keep counters in track */
sr_state->n_reveal_rounds = 0;
sr_state->n_commit_rounds = 0;
sr_state->n_protocol_runs++;
/* Reset valid-until */
sr_state->valid_until = get_state_valid_until_time(valid_after);
sr_state->valid_after = valid_after;
/* We are in a new protocol run so cleanup commits. */
sr_state_delete_commits();
}
/* This is the first round of the new protocol run starting at
* <b>valid_after</b>. Do the necessary housekeeping. */
STATIC void
new_protocol_run(time_t valid_after)
{
sr_commit_t *our_commitment = NULL;
/* Only compute the srv at the end of the reveal phase. */
if (sr_state->phase == SR_PHASE_REVEAL) {
/* We are about to compute a new shared random value that will be set in
* our state as the current value so rotate values. */
state_rotate_srv();
/* Compute the shared randomness value of the day. */
sr_compute_srv();
}
/* Prepare for the new protocol run by reseting the state */
reset_state_for_new_protocol_run(valid_after);
/* Do some logging */
log_info(LD_DIR, "SR: Protocol run #%" PRIu64 " starting!",
sr_state->n_protocol_runs);
/* Generate fresh commitments for this protocol run */
our_commitment = sr_generate_our_commit(valid_after,
get_my_v3_authority_cert());
if (our_commitment) {
/* Add our commitment to our state. In case we are unable to create one
* (highly unlikely), we won't vote for this protocol run since our
* commitment won't be in our state. */
sr_state_add_commit(our_commitment);
}
}
/* Return 1 iff the <b>next_phase</b> is a phase transition from the current
* phase that is it's different. */
STATIC int
is_phase_transition(sr_phase_t next_phase)
{
return sr_state->phase != next_phase;
}
/* Helper function: return a commit using the RSA fingerprint of the
* authority or NULL if no such commit is known. */
static sr_commit_t *
state_query_get_commit(const char *rsa_fpr)
{
tor_assert(rsa_fpr);
return digestmap_get(sr_state->commits, rsa_fpr);
}
/* Helper function: This handles the GET state action using an
* <b>obj_type</b> and <b>data</b> needed for the action. */
static void *
state_query_get_(sr_state_object_t obj_type, const void *data)
{
void *obj = NULL;
switch (obj_type) {
case SR_STATE_OBJ_COMMIT:
{
obj = state_query_get_commit(data);
break;
}
case SR_STATE_OBJ_COMMITS:
obj = sr_state->commits;
break;
case SR_STATE_OBJ_CURSRV:
obj = sr_state->current_srv;
break;
case SR_STATE_OBJ_PREVSRV:
obj = sr_state->previous_srv;
break;
case SR_STATE_OBJ_PHASE:
obj = &sr_state->phase;
break;
case SR_STATE_OBJ_VALID_AFTER:
default:
tor_assert(0);
}
return obj;
}
/* Helper function: This handles the PUT state action using an
* <b>obj_type</b> and <b>data</b> needed for the action. */
static void
state_query_put_(sr_state_object_t obj_type, void *data)
{
switch (obj_type) {
case SR_STATE_OBJ_COMMIT:
{
sr_commit_t *commit = data;
tor_assert(commit);
commit_add_to_state(commit, sr_state);
break;
}
case SR_STATE_OBJ_CURSRV:
sr_state->current_srv = (sr_srv_t *) data;
break;
case SR_STATE_OBJ_PREVSRV:
sr_state->previous_srv = (sr_srv_t *) data;
break;
case SR_STATE_OBJ_VALID_AFTER:
sr_state->valid_after = *((time_t *) data);
break;
/* It's not allowed to change the phase nor the full commitments map from
* the state. The phase is decided during a strict process post voting and
* the commits should be put individually. */
case SR_STATE_OBJ_PHASE:
case SR_STATE_OBJ_COMMITS:
default:
tor_assert(0);
}
}
/* Helper function: This handles the DEL_ALL state action using an
* <b>obj_type</b> and <b>data</b> needed for the action. */
static void
state_query_del_all_(sr_state_object_t obj_type)
{
switch (obj_type) {
case SR_STATE_OBJ_COMMIT:
{
/* We are in a new protocol run so cleanup commitments. */
DIGESTMAP_FOREACH_MODIFY(sr_state->commits, key, sr_commit_t *, c) {
sr_commit_free(c);
MAP_DEL_CURRENT(key);
} DIGESTMAP_FOREACH_END;
break;
}
/* The following object are _NOT_ suppose to be removed. */
case SR_STATE_OBJ_CURSRV:
case SR_STATE_OBJ_PREVSRV:
case SR_STATE_OBJ_PHASE:
case SR_STATE_OBJ_COMMITS:
case SR_STATE_OBJ_VALID_AFTER:
default:
tor_assert(0);
}
}
/* Helper function: This handles the DEL state action using an
* <b>obj_type</b> and <b>data</b> needed for the action. */
static void
state_query_del_(sr_state_object_t obj_type, void *data)
{
(void) data;
switch (obj_type) {
case SR_STATE_OBJ_PREVSRV:
tor_free(sr_state->previous_srv);
break;
case SR_STATE_OBJ_CURSRV:
tor_free(sr_state->current_srv);
break;
case SR_STATE_OBJ_COMMIT:
case SR_STATE_OBJ_COMMITS:
case SR_STATE_OBJ_PHASE:
case SR_STATE_OBJ_VALID_AFTER:
default:
tor_assert(0);
}
}
/* Query state using an <b>action</b> for an object type <b>obj_type</b>.
* The <b>data</b> pointer needs to point to an object that the action needs
* to use and if anything is required to be returned, it is stored in
* <b>out</b>.
*
* This mechanism exists so we have one single point where we synchronized
* our memory state with our disk state for every actions that changes it.
* We then trigger a write on disk immediately.
*
* This should be the only entry point to our memory state. It's used by all
* our state accessors and should be in the future. */
static void
state_query(sr_state_action_t action, sr_state_object_t obj_type,
void *data, void **out)
{
switch (action) {
case SR_STATE_ACTION_GET:
*out = state_query_get_(obj_type, data);
break;
case SR_STATE_ACTION_PUT:
state_query_put_(obj_type, data);
break;
case SR_STATE_ACTION_DEL:
state_query_del_(obj_type, data);
break;
case SR_STATE_ACTION_DEL_ALL:
state_query_del_all_(obj_type);
break;
case SR_STATE_ACTION_SAVE:
/* Only trigger a disk state save. */
break;
default:
tor_assert(0);
}
/* If the action actually changes the state, immediately save it to disk.
* The following will sync the state -> disk state and then save it. */
if (action != SR_STATE_ACTION_GET) {
disk_state_save_to_disk();
}
}
/* Delete the current SRV value from the state freeing it and the value is set
* to NULL meaning empty. */
static void
state_del_current_srv(void)
{
state_query(SR_STATE_ACTION_DEL, SR_STATE_OBJ_CURSRV, NULL, NULL);
}
/* Delete the previous SRV value from the state freeing it and the value is
* set to NULL meaning empty. */
static void
state_del_previous_srv(void)
{
state_query(SR_STATE_ACTION_DEL, SR_STATE_OBJ_PREVSRV, NULL, NULL);
}
/* Rotate SRV value by freeing the previous value, assigning the current
* value to the previous one and nullifying the current one. */
STATIC void
state_rotate_srv(void)
{
/* First delete previous SRV from the state. Object will be freed. */
state_del_previous_srv();
/* Set previous SRV with the current one. */
sr_state_set_previous_srv(sr_state_get_current_srv());
/* Nullify the current srv. */
sr_state_set_current_srv(NULL);
}
/* Set valid after time in the our state. */
void
sr_state_set_valid_after(time_t valid_after)
{
state_query(SR_STATE_ACTION_PUT, SR_STATE_OBJ_VALID_AFTER,
(void *) &valid_after, NULL);
}
/* Return the phase we are currently in according to our state. */
sr_phase_t
sr_state_get_phase(void)
{
void *ptr;
state_query(SR_STATE_ACTION_GET, SR_STATE_OBJ_PHASE, NULL, &ptr);
return *(sr_phase_t *) ptr;
}
/* Return the previous SRV value from our state. Value CAN be NULL. */
const sr_srv_t *
sr_state_get_previous_srv(void)
{
const sr_srv_t *srv;
state_query(SR_STATE_ACTION_GET, SR_STATE_OBJ_PREVSRV, NULL,
(void *) &srv);
return srv;
}
/* Set the current SRV value from our state. Value CAN be NULL. The srv
* object ownership is transfered to the state object. */
void
sr_state_set_previous_srv(const sr_srv_t *srv)
{
state_query(SR_STATE_ACTION_PUT, SR_STATE_OBJ_PREVSRV, (void *) srv,
NULL);
}
/* Return the current SRV value from our state. Value CAN be NULL. */
const sr_srv_t *
sr_state_get_current_srv(void)
{
const sr_srv_t *srv;
state_query(SR_STATE_ACTION_GET, SR_STATE_OBJ_CURSRV, NULL,
(void *) &srv);
return srv;
}
/* Set the current SRV value from our state. Value CAN be NULL. The srv
* object ownership is transfered to the state object. */
void
sr_state_set_current_srv(const sr_srv_t *srv)
{
state_query(SR_STATE_ACTION_PUT, SR_STATE_OBJ_CURSRV, (void *) srv,
NULL);
}
/* Clean all the SRVs in our state. */
void
sr_state_clean_srvs(void)
{
/* Remove SRVs from state. They will be set to NULL as "empty". */
state_del_previous_srv();
state_del_current_srv();
}
/* Return a pointer to the commits map from our state. CANNOT be NULL. */
digestmap_t *
sr_state_get_commits(void)
{
digestmap_t *commits;
state_query(SR_STATE_ACTION_GET, SR_STATE_OBJ_COMMITS,
NULL, (void *) &commits);
tor_assert(commits);
return commits;
}
/* Update the current SR state as needed for the upcoming voting round at
* <b>valid_after</b>. */
void
sr_state_update(time_t valid_after)
{
sr_phase_t next_phase;
tor_assert(sr_state);
/* Don't call this function twice in the same voting period. */
if (valid_after <= sr_state->valid_after) {
log_info(LD_DIR, "SR: Asked to update state twice. Ignoring.");
return;
}
/* Get phase of upcoming round. */
next_phase = get_sr_protocol_phase(valid_after);
/* If we are transitioning to a new protocol phase, prepare the stage. */
if (is_phase_transition(next_phase)) {
if (next_phase == SR_PHASE_COMMIT) {
/* Going into commit phase means we are starting a new protocol run. */
new_protocol_run(valid_after);
}
/* Set the new phase for this round */
sr_state->phase = next_phase;
} else if (sr_state->phase == SR_PHASE_COMMIT &&
digestmap_size(sr_state->commits) == 0) {
/* We are _NOT_ in a transition phase so if we are in the commit phase
* and have no commit, generate one. Chances are that we are booting up
* so let's have a commit in our state for the next voting period. */
sr_commit_t *our_commit =
sr_generate_our_commit(valid_after, get_my_v3_authority_cert());
if (our_commit) {
/* Add our commitment to our state. In case we are unable to create one
* (highly unlikely), we won't vote for this protocol run since our
* commitment won't be in our state. */
sr_state_add_commit(our_commit);
}
}
sr_state_set_valid_after(valid_after);
/* Count the current round */
if (sr_state->phase == SR_PHASE_COMMIT) {
/* invariant check: we've not entered reveal phase yet */
tor_assert(sr_state->n_reveal_rounds == 0);
sr_state->n_commit_rounds++;
} else {
sr_state->n_reveal_rounds++;
}
{ /* Debugging. */
char tbuf[ISO_TIME_LEN + 1];
format_iso_time(tbuf, valid_after);
log_info(LD_DIR, "SR: State prepared for upcoming voting period (%s). "
"Upcoming phase is %s (counters: %d commit & %d reveal rounds).",
tbuf, get_phase_str(sr_state->phase),
sr_state->n_commit_rounds, sr_state->n_reveal_rounds);
}
}
/* Return commit object from the given authority digest <b>rsa_identity</b>.
* Return NULL if not found. */
sr_commit_t *
sr_state_get_commit(const char *rsa_identity)
{
sr_commit_t *commit;
tor_assert(rsa_identity);
state_query(SR_STATE_ACTION_GET, SR_STATE_OBJ_COMMIT,
(void *) rsa_identity, (void *) &commit);
return commit;
}
/* Add <b>commit</b> to the permanent state. The commit object ownership is
* transfered to the state so the caller MUST not free it. */
void
sr_state_add_commit(sr_commit_t *commit)
{
tor_assert(commit);
/* Put the commit to the global state. */
state_query(SR_STATE_ACTION_PUT, SR_STATE_OBJ_COMMIT,
(void *) commit, NULL);
log_debug(LD_DIR, "SR: Commit from %s has been added to our state.",
sr_commit_get_rsa_fpr(commit));
}
/* Remove all commits from our state. */
void
sr_state_delete_commits(void)
{
state_query(SR_STATE_ACTION_DEL_ALL, SR_STATE_OBJ_COMMIT, NULL, NULL);
}
/* Copy the reveal information from <b>commit</b> into <b>saved_commit</b>.
* This <b>saved_commit</b> MUST come from our current SR state. Once modified,
* the disk state is updated. */
void
sr_state_copy_reveal_info(sr_commit_t *saved_commit, const sr_commit_t *commit)
{
tor_assert(saved_commit);
tor_assert(commit);
saved_commit->reveal_ts = commit->reveal_ts;
memcpy(saved_commit->random_number, commit->random_number,
sizeof(saved_commit->random_number));
strlcpy(saved_commit->encoded_reveal, commit->encoded_reveal,
sizeof(saved_commit->encoded_reveal));
state_query(SR_STATE_ACTION_SAVE, 0, NULL, NULL);
log_debug(LD_DIR, "SR: Reveal value learned %s (for commit %s) from %s",
saved_commit->encoded_reveal, saved_commit->encoded_commit,
sr_commit_get_rsa_fpr(saved_commit));
}
/* Set the fresh SRV flag from our state. This doesn't need to trigger a
* disk state synchronization so we directly change the state. */
void
sr_state_set_fresh_srv(void)
{
sr_state->is_srv_fresh = 1;
}
/* Unset the fresh SRV flag from our state. This doesn't need to trigger a
* disk state synchronization so we directly change the state. */
void
sr_state_unset_fresh_srv(void)
{
sr_state->is_srv_fresh = 0;
}
/* Return the value of the fresh SRV flag. */
unsigned int
sr_state_srv_is_fresh(void)
{
return sr_state->is_srv_fresh;
}
/* Cleanup and free our disk and memory state. */
void
sr_state_free(void)
{
state_free(sr_state);
disk_state_free(sr_disk_state);
/* Nullify our global state. */
sr_state = NULL;
sr_disk_state = NULL;
}
/* Save our current state in memory to disk. */
void
sr_state_save(void)
{
/* Query a SAVE action on our current state so it's synced and saved. */
state_query(SR_STATE_ACTION_SAVE, 0, NULL, NULL);
}
/* Return 1 iff the state has been initialized that is it exists in memory.
* Return 0 otherwise. */
int
sr_state_is_initialized(void)
{
return sr_state == NULL ? 0 : 1;
}
/* Initialize the disk and memory state.
*
* If save_to_disk is set to 1, the state is immediately saved to disk after
* creation else it's not thus only kept in memory.
* If read_from_disk is set to 1, we try to load the state from the disk and
* if not found, a new state is created.
*
* Return 0 on success else a negative value on error. */
int
sr_state_init(int save_to_disk, int read_from_disk)
{
int ret = -ENOENT;
time_t now = time(NULL);
/* We shouldn't have those assigned. */
tor_assert(sr_disk_state == NULL);
tor_assert(sr_state == NULL);
/* First, try to load the state from disk. */
if (read_from_disk) {
ret = disk_state_load_from_disk();
}
if (ret < 0) {
switch (-ret) {
case EINVAL:
/* We have a state on disk but it contains something we couldn't parse
* or an invalid entry in the state file. Let's remove it since it's
* obviously unusable and replace it by an new fresh state below. */
case ENOENT:
{
/* No state on disk so allocate our states for the first time. */
sr_state_t *new_state = state_new(default_fname, now);
sr_disk_state_t *new_disk_state = disk_state_new(now);
state_set(new_state);
/* It's important to set our disk state pointer since the save call
* below uses it to synchronized it with our memory state. */
disk_state_set(new_disk_state);
/* No entry, let's save our new state to disk. */
if (save_to_disk && disk_state_save_to_disk() < 0) {
goto error;
}
break;
}
default:
/* Big problem. Not possible. */
tor_assert(0);
}
}
/* We have a state in memory, let's make sure it's updated for the current
* and next voting round. */
{
time_t valid_after = get_next_valid_after_time(now);
sr_state_update(valid_after);
}
return 0;
error:
return -1;
}
#ifdef TOR_UNIT_TESTS
/* Set the current phase of the protocol. Used only by unit tests. */
void
set_sr_phase(sr_phase_t phase)
{
tor_assert(sr_state);
sr_state->phase = phase;
}
/* Get the SR state. Used only by unit tests */
sr_state_t *
get_sr_state(void)
{
return sr_state;
}
#endif /* TOR_UNIT_TESTS */
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