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-rw-r--r--src/or/control.c2
-rw-r--r--src/or/dirauth/shared_random.c163
-rw-r--r--src/or/dirauth/shared_random.h8
-rw-r--r--src/or/dirauth/shared_random_state.c80
-rw-r--r--src/or/dirauth/shared_random_state.h5
-rw-r--r--src/or/hs_common.c2
-rw-r--r--src/or/hs_service.c2
-rw-r--r--src/or/include.am2
-rw-r--r--src/or/routerparse.c1
-rw-r--r--src/or/shared_random_common.c258
-rw-r--r--src/or/shared_random_common.h47
11 files changed, 313 insertions, 257 deletions
diff --git a/src/or/control.c b/src/or/control.c
index 3e643c2d76..aab854ecdd 100644
--- a/src/or/control.c
+++ b/src/or/control.c
@@ -76,7 +76,7 @@
#include "router.h"
#include "routerlist.h"
#include "routerparse.h"
-#include "dirauth/shared_random.h"
+#include "shared_random_common.h"
#ifndef _WIN32
#include <pwd.h>
diff --git a/src/or/dirauth/shared_random.c b/src/or/dirauth/shared_random.c
index e9644adf9e..5dee77dce9 100644
--- a/src/or/dirauth/shared_random.c
+++ b/src/or/dirauth/shared_random.c
@@ -96,6 +96,7 @@
#include "router.h"
#include "routerlist.h"
#include "shared_random_state.h"
+#include "shared_random_common.h"
#include "util.h"
#include "dirauth/dirvote.h"
@@ -499,20 +500,6 @@ get_vote_line_from_commit(const sr_commit_t *commit, sr_phase_t phase)
return vote_line;
}
-/* Convert a given srv object to a string for the control port. This doesn't
- * fail and the srv object MUST be valid. */
-static char *
-srv_to_control_string(const sr_srv_t *srv)
-{
- char *srv_str;
- char srv_hash_encoded[SR_SRV_VALUE_BASE64_LEN + 1];
- tor_assert(srv);
-
- sr_srv_encode(srv_hash_encoded, sizeof(srv_hash_encoded), srv);
- tor_asprintf(&srv_str, "%s", srv_hash_encoded);
- return srv_str;
-}
-
/* Return a heap allocated string that contains the given <b>srv</b> string
* representation formatted for a networkstatus document using the
* <b>key</b> as the start of the line. This doesn't return NULL. */
@@ -875,27 +862,6 @@ get_majority_srv_from_votes(const smartlist_t *votes, int current)
return the_srv;
}
-/* Encode the given shared random value and put it in dst. Destination
- * buffer must be at least SR_SRV_VALUE_BASE64_LEN plus the NULL byte. */
-void
-sr_srv_encode(char *dst, size_t dst_len, const sr_srv_t *srv)
-{
- int ret;
- /* Extra byte for the NULL terminated char. */
- char buf[SR_SRV_VALUE_BASE64_LEN + 1];
-
- tor_assert(dst);
- tor_assert(srv);
- tor_assert(dst_len >= sizeof(buf));
-
- ret = base64_encode(buf, sizeof(buf), (const char *) srv->value,
- sizeof(srv->value), 0);
- /* Always expect the full length without the NULL byte. */
- tor_assert(ret == (sizeof(buf) - 1));
- tor_assert(ret <= (int) dst_len);
- strlcpy(dst, buf, dst_len);
-}
-
/* Free a commit object. */
void
sr_commit_free_(sr_commit_t *commit)
@@ -1037,55 +1003,6 @@ sr_compute_srv(void)
tor_free(reveals);
}
-/* Parse a list of arguments from a SRV value either from a vote, consensus
- * or from our disk state and return a newly allocated srv object. NULL is
- * returned on error.
- *
- * The arguments' order:
- * num_reveals, value
- */
-sr_srv_t *
-sr_parse_srv(const smartlist_t *args)
-{
- char *value;
- int ok, ret;
- uint64_t num_reveals;
- sr_srv_t *srv = NULL;
-
- tor_assert(args);
-
- if (smartlist_len(args) < 2) {
- goto end;
- }
-
- /* First argument is the number of reveal values */
- num_reveals = tor_parse_uint64(smartlist_get(args, 0),
- 10, 0, UINT64_MAX, &ok, NULL);
- if (!ok) {
- goto end;
- }
- /* Second and last argument is the shared random value it self. */
- value = smartlist_get(args, 1);
- if (strlen(value) != SR_SRV_VALUE_BASE64_LEN) {
- goto end;
- }
-
- srv = tor_malloc_zero(sizeof(*srv));
- srv->num_reveals = num_reveals;
- /* We subtract one byte from the srclen because the function ignores the
- * '=' character in the given buffer. This is broken but it's a documented
- * behavior of the implementation. */
- ret = base64_decode((char *) srv->value, sizeof(srv->value), value,
- SR_SRV_VALUE_BASE64_LEN - 1);
- if (ret != sizeof(srv->value)) {
- tor_free(srv);
- srv = NULL;
- goto end;
- }
- end:
- return srv;
-}
-
/* Parse a commit from a vote or from our disk state and return a newly
* allocated commit object. NULL is returned on error.
*
@@ -1353,84 +1270,6 @@ sr_save_and_cleanup(void)
sr_cleanup();
}
-/* Return the current SRV string representation for the control port. Return a
- * newly allocated string on success containing the value else "" if not found
- * or if we don't have a valid consensus yet. */
-char *
-sr_get_current_for_control(void)
-{
- char *srv_str;
- const networkstatus_t *c = networkstatus_get_latest_consensus();
- if (c && c->sr_info.current_srv) {
- srv_str = srv_to_control_string(c->sr_info.current_srv);
- } else {
- srv_str = tor_strdup("");
- }
- return srv_str;
-}
-
-/* Return the previous SRV string representation for the control port. Return
- * a newly allocated string on success containing the value else "" if not
- * found or if we don't have a valid consensus yet. */
-char *
-sr_get_previous_for_control(void)
-{
- char *srv_str;
- const networkstatus_t *c = networkstatus_get_latest_consensus();
- if (c && c->sr_info.previous_srv) {
- srv_str = srv_to_control_string(c->sr_info.previous_srv);
- } else {
- srv_str = tor_strdup("");
- }
- return srv_str;
-}
-
-/* Return current shared random value from the latest consensus. Caller can
- * NOT keep a reference to the returned pointer. Return NULL if none. */
-const sr_srv_t *
-sr_get_current(const networkstatus_t *ns)
-{
- const networkstatus_t *consensus;
-
- /* Use provided ns else get a live one */
- if (ns) {
- consensus = ns;
- } else {
- consensus = networkstatus_get_live_consensus(approx_time());
- }
- /* Ideally we would never be asked for an SRV without a live consensus. Make
- * sure this assumption is correct. */
- tor_assert_nonfatal(consensus);
-
- if (consensus) {
- return consensus->sr_info.current_srv;
- }
- return NULL;
-}
-
-/* Return previous shared random value from the latest consensus. Caller can
- * NOT keep a reference to the returned pointer. Return NULL if none. */
-const sr_srv_t *
-sr_get_previous(const networkstatus_t *ns)
-{
- const networkstatus_t *consensus;
-
- /* Use provided ns else get a live one */
- if (ns) {
- consensus = ns;
- } else {
- consensus = networkstatus_get_live_consensus(approx_time());
- }
- /* Ideally we would never be asked for an SRV without a live consensus. Make
- * sure this assumption is correct. */
- tor_assert_nonfatal(consensus);
-
- if (consensus) {
- return consensus->sr_info.previous_srv;
- }
- return NULL;
-}
-
#ifdef TOR_UNIT_TESTS
/* Set the global value of number of SRV agreements so the test can play
diff --git a/src/or/dirauth/shared_random.h b/src/or/dirauth/shared_random.h
index 675a8d8b06..d1b2ac2e25 100644
--- a/src/or/dirauth/shared_random.h
+++ b/src/or/dirauth/shared_random.h
@@ -109,13 +109,11 @@ void sr_act_post_consensus(const networkstatus_t *consensus);
void sr_handle_received_commits(smartlist_t *commits,
crypto_pk_t *voter_key);
sr_commit_t *sr_parse_commit(const smartlist_t *args);
-sr_srv_t *sr_parse_srv(const smartlist_t *args);
char *sr_get_string_for_vote(void);
char *sr_get_string_for_consensus(const smartlist_t *votes,
int32_t num_srv_agreements);
void sr_commit_free_(sr_commit_t *commit);
#define sr_commit_free(sr) FREE_AND_NULL(sr_commit_t, sr_commit_free_, (sr))
-void sr_srv_encode(char *dst, size_t dst_len, const sr_srv_t *srv);
/* Private methods (only used by shared_random_state.c): */
static inline
@@ -128,12 +126,6 @@ void sr_compute_srv(void);
sr_commit_t *sr_generate_our_commit(time_t timestamp,
const authority_cert_t *my_rsa_cert);
-char *sr_get_current_for_control(void);
-char *sr_get_previous_for_control(void);
-
-const sr_srv_t *sr_get_current(const networkstatus_t *ns);
-const sr_srv_t *sr_get_previous(const networkstatus_t *ns);
-
#ifdef SHARED_RANDOM_PRIVATE
/* Encode */
diff --git a/src/or/dirauth/shared_random_state.c b/src/or/dirauth/shared_random_state.c
index 11d7a06378..846c3c7aa2 100644
--- a/src/or/dirauth/shared_random_state.c
+++ b/src/or/dirauth/shared_random_state.c
@@ -17,6 +17,7 @@
#include "networkstatus.h"
#include "router.h"
#include "shared_random_state.h"
+#include "shared_random_common.h"
#include "dirauth/dirvote.h"
@@ -54,10 +55,6 @@ DUMMY_TYPECHECK_INSTANCE(sr_disk_state_t);
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,
@@ -116,81 +113,6 @@ get_phase_str(sr_phase_t phase)
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(void)
-{
- const or_options_t *options = get_options();
- int voting_interval = get_voting_interval();
- /* First, get the start time of the next round */
- time_t next_start = dirvote_get_next_valid_after_time();
- /* 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);
- return curr_start;
-}
-
-/** Return the start time of the current SR protocol run. For example, if the
- * time is 23/06/2017 23:47:08 and a full SR protocol run is 24 hours, this
- * function should return 23/06/2017 00:00:00. */
-time_t
-sr_state_get_start_time_of_current_protocol_run(time_t now)
-{
- int total_rounds = SHARED_RANDOM_N_ROUNDS * SHARED_RANDOM_N_PHASES;
- int voting_interval = get_voting_interval();
- /* Find the time the current round started. */
- time_t beginning_of_current_round = get_start_time_of_current_round();
-
- /* Get current SR protocol round */
- int current_round = (now / voting_interval) % total_rounds;
-
- /* Get start time by subtracting the time elapsed from the beginning of the
- protocol run */
- time_t time_elapsed_since_start_of_run = current_round * voting_interval;
- return beginning_of_current_round - time_elapsed_since_start_of_run;
-}
-
-/** Return the time (in seconds) it takes to complete a full SR protocol phase
- * (e.g. the commit phase). */
-unsigned int
-sr_state_get_phase_duration(void)
-{
- return SHARED_RANDOM_N_ROUNDS * get_voting_interval();
-}
-
-/** Return the time (in seconds) it takes to complete a full SR protocol run */
-unsigned int
-sr_state_get_protocol_run_duration(void)
-{
- int total_protocol_rounds = SHARED_RANDOM_N_ROUNDS * SHARED_RANDOM_N_PHASES;
- return total_protocol_rounds * get_voting_interval();
-}
-
/* 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
diff --git a/src/or/dirauth/shared_random_state.h b/src/or/dirauth/shared_random_state.h
index fdbbf4919a..60a326f86c 100644
--- a/src/or/dirauth/shared_random_state.h
+++ b/src/or/dirauth/shared_random_state.h
@@ -121,16 +121,11 @@ int sr_state_is_initialized(void);
void sr_state_save(void);
void sr_state_free_all(void);
-time_t sr_state_get_start_time_of_current_protocol_run(time_t now);
-unsigned int sr_state_get_phase_duration(void);
-unsigned int sr_state_get_protocol_run_duration(void);
-
#ifdef SHARED_RANDOM_STATE_PRIVATE
STATIC int disk_state_load_from_disk_impl(const char *fname);
STATIC sr_phase_t get_sr_protocol_phase(time_t valid_after);
-STATIC time_t get_start_time_of_current_round(void);
STATIC time_t get_state_valid_until_time(time_t now);
STATIC const char *get_phase_str(sr_phase_t phase);
diff --git a/src/or/hs_common.c b/src/or/hs_common.c
index fc7bc5729b..8cc7d08911 100644
--- a/src/or/hs_common.c
+++ b/src/or/hs_common.c
@@ -28,7 +28,7 @@
#include "rendservice.h"
#include "routerset.h"
#include "router.h"
-#include "dirauth/shared_random.h"
+#include "shared_random_common.h"
#include "dirauth/shared_random_state.h"
/* Trunnel */
diff --git a/src/or/hs_service.c b/src/or/hs_service.c
index ebb58f7f68..4ac0df2add 100644
--- a/src/or/hs_service.c
+++ b/src/or/hs_service.c
@@ -24,7 +24,7 @@
#include "router.h"
#include "routerkeys.h"
#include "routerlist.h"
-#include "dirauth/shared_random_state.h"
+#include "shared_random_common.h"
#include "statefile.h"
#include "hs_circuit.h"
diff --git a/src/or/include.am b/src/or/include.am
index 9265ecf483..e90b1fb2ab 100644
--- a/src/or/include.am
+++ b/src/or/include.am
@@ -103,6 +103,7 @@ LIBTOR_A_SOURCES = \
src/or/scheduler.c \
src/or/scheduler_kist.c \
src/or/scheduler_vanilla.c \
+ src/or/shared_random_common.c \
src/or/statefile.c \
src/or/status.c \
src/or/torcert.c \
@@ -260,6 +261,7 @@ ORHEADERS = \
src/or/routerset.h \
src/or/routerparse.h \
src/or/scheduler.h \
+ src/or/shared_random_common.h \
src/or/statefile.h \
src/or/status.h \
src/or/torcert.h \
diff --git a/src/or/routerparse.c b/src/or/routerparse.c
index 84db239155..2d64a82b6f 100644
--- a/src/or/routerparse.c
+++ b/src/or/routerparse.c
@@ -74,6 +74,7 @@
#include "entrynodes.h"
#include "torcert.h"
#include "sandbox.h"
+#include "shared_random_common.h"
#include "dirauth/shared_random.h"
#undef log
diff --git a/src/or/shared_random_common.c b/src/or/shared_random_common.c
new file mode 100644
index 0000000000..c782e709ff
--- /dev/null
+++ b/src/or/shared_random_common.c
@@ -0,0 +1,258 @@
+/* Copyright (c) 2018, The Tor Project, Inc. */
+/* See LICENSE for licensing information */
+
+/**
+ * \file shared_random_common.c
+ * \brief This file contains functions that are from the shared random
+ * subsystem but used by many part of tor. The full feature is built
+ * as part of the dirauth module.
+ **/
+
+#define SHARED_RANDOM_COMMON_PRIVATE
+#include "shared_random_common.h"
+
+#include "config.h"
+#include "networkstatus.h"
+#include "util.h"
+#include "util_format.h"
+
+/* Convert a given srv object to a string for the control port. This doesn't
+ * fail and the srv object MUST be valid. */
+static char *
+srv_to_control_string(const sr_srv_t *srv)
+{
+ char *srv_str;
+ char srv_hash_encoded[SR_SRV_VALUE_BASE64_LEN + 1];
+ tor_assert(srv);
+
+ sr_srv_encode(srv_hash_encoded, sizeof(srv_hash_encoded), srv);
+ tor_asprintf(&srv_str, "%s", srv_hash_encoded);
+ return srv_str;
+}
+
+/* Return the voting interval of the tor vote subsystem. */
+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. */
+time_t
+get_start_time_of_current_round(void)
+{
+ const or_options_t *options = get_options();
+ int voting_interval = get_voting_interval();
+ /* First, get the start time of the next round */
+ time_t next_start = dirvote_get_next_valid_after_time();
+ /* 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);
+ return curr_start;
+}
+
+/*
+ * Public API
+ */
+
+/* Encode the given shared random value and put it in dst. Destination
+ * buffer must be at least SR_SRV_VALUE_BASE64_LEN plus the NULL byte. */
+void
+sr_srv_encode(char *dst, size_t dst_len, const sr_srv_t *srv)
+{
+ int ret;
+ /* Extra byte for the NULL terminated char. */
+ char buf[SR_SRV_VALUE_BASE64_LEN + 1];
+
+ tor_assert(dst);
+ tor_assert(srv);
+ tor_assert(dst_len >= sizeof(buf));
+
+ ret = base64_encode(buf, sizeof(buf), (const char *) srv->value,
+ sizeof(srv->value), 0);
+ /* Always expect the full length without the NULL byte. */
+ tor_assert(ret == (sizeof(buf) - 1));
+ tor_assert(ret <= (int) dst_len);
+ strlcpy(dst, buf, dst_len);
+}
+
+/* Return the current SRV string representation for the control port. Return a
+ * newly allocated string on success containing the value else "" if not found
+ * or if we don't have a valid consensus yet. */
+char *
+sr_get_current_for_control(void)
+{
+ char *srv_str;
+ const networkstatus_t *c = networkstatus_get_latest_consensus();
+ if (c && c->sr_info.current_srv) {
+ srv_str = srv_to_control_string(c->sr_info.current_srv);
+ } else {
+ srv_str = tor_strdup("");
+ }
+ return srv_str;
+}
+
+/* Return the previous SRV string representation for the control port. Return
+ * a newly allocated string on success containing the value else "" if not
+ * found or if we don't have a valid consensus yet. */
+char *
+sr_get_previous_for_control(void)
+{
+ char *srv_str;
+ const networkstatus_t *c = networkstatus_get_latest_consensus();
+ if (c && c->sr_info.previous_srv) {
+ srv_str = srv_to_control_string(c->sr_info.previous_srv);
+ } else {
+ srv_str = tor_strdup("");
+ }
+ return srv_str;
+}
+
+/* Return current shared random value from the latest consensus. Caller can
+ * NOT keep a reference to the returned pointer. Return NULL if none. */
+const sr_srv_t *
+sr_get_current(const networkstatus_t *ns)
+{
+ const networkstatus_t *consensus;
+
+ /* Use provided ns else get a live one */
+ if (ns) {
+ consensus = ns;
+ } else {
+ consensus = networkstatus_get_live_consensus(approx_time());
+ }
+ /* Ideally we would never be asked for an SRV without a live consensus. Make
+ * sure this assumption is correct. */
+ tor_assert_nonfatal(consensus);
+
+ if (consensus) {
+ return consensus->sr_info.current_srv;
+ }
+ return NULL;
+}
+
+/* Return previous shared random value from the latest consensus. Caller can
+ * NOT keep a reference to the returned pointer. Return NULL if none. */
+const sr_srv_t *
+sr_get_previous(const networkstatus_t *ns)
+{
+ const networkstatus_t *consensus;
+
+ /* Use provided ns else get a live one */
+ if (ns) {
+ consensus = ns;
+ } else {
+ consensus = networkstatus_get_live_consensus(approx_time());
+ }
+ /* Ideally we would never be asked for an SRV without a live consensus. Make
+ * sure this assumption is correct. */
+ tor_assert_nonfatal(consensus);
+
+ if (consensus) {
+ return consensus->sr_info.previous_srv;
+ }
+ return NULL;
+}
+
+/* Parse a list of arguments from a SRV value either from a vote, consensus
+ * or from our disk state and return a newly allocated srv object. NULL is
+ * returned on error.
+ *
+ * The arguments' order:
+ * num_reveals, value
+ */
+sr_srv_t *
+sr_parse_srv(const smartlist_t *args)
+{
+ char *value;
+ int ok, ret;
+ uint64_t num_reveals;
+ sr_srv_t *srv = NULL;
+
+ tor_assert(args);
+
+ if (smartlist_len(args) < 2) {
+ goto end;
+ }
+
+ /* First argument is the number of reveal values */
+ num_reveals = tor_parse_uint64(smartlist_get(args, 0),
+ 10, 0, UINT64_MAX, &ok, NULL);
+ if (!ok) {
+ goto end;
+ }
+ /* Second and last argument is the shared random value it self. */
+ value = smartlist_get(args, 1);
+ if (strlen(value) != SR_SRV_VALUE_BASE64_LEN) {
+ goto end;
+ }
+
+ srv = tor_malloc_zero(sizeof(*srv));
+ srv->num_reveals = num_reveals;
+ /* We subtract one byte from the srclen because the function ignores the
+ * '=' character in the given buffer. This is broken but it's a documented
+ * behavior of the implementation. */
+ ret = base64_decode((char *) srv->value, sizeof(srv->value), value,
+ SR_SRV_VALUE_BASE64_LEN - 1);
+ if (ret != sizeof(srv->value)) {
+ tor_free(srv);
+ srv = NULL;
+ goto end;
+ }
+ end:
+ return srv;
+}
+
+/** Return the start time of the current SR protocol run. For example, if the
+ * time is 23/06/2017 23:47:08 and a full SR protocol run is 24 hours, this
+ * function should return 23/06/2017 00:00:00. */
+time_t
+sr_state_get_start_time_of_current_protocol_run(time_t now)
+{
+ int total_rounds = SHARED_RANDOM_N_ROUNDS * SHARED_RANDOM_N_PHASES;
+ int voting_interval = get_voting_interval();
+ /* Find the time the current round started. */
+ time_t beginning_of_current_round = get_start_time_of_current_round();
+
+ /* Get current SR protocol round */
+ int current_round = (now / voting_interval) % total_rounds;
+
+ /* Get start time by subtracting the time elapsed from the beginning of the
+ protocol run */
+ time_t time_elapsed_since_start_of_run = current_round * voting_interval;
+ return beginning_of_current_round - time_elapsed_since_start_of_run;
+}
+
+/** Return the time (in seconds) it takes to complete a full SR protocol phase
+ * (e.g. the commit phase). */
+unsigned int
+sr_state_get_phase_duration(void)
+{
+ return SHARED_RANDOM_N_ROUNDS * get_voting_interval();
+}
+
+/** Return the time (in seconds) it takes to complete a full SR protocol run */
+unsigned int
+sr_state_get_protocol_run_duration(void)
+{
+ int total_protocol_rounds = SHARED_RANDOM_N_ROUNDS * SHARED_RANDOM_N_PHASES;
+ return total_protocol_rounds * get_voting_interval();
+}
+
diff --git a/src/or/shared_random_common.h b/src/or/shared_random_common.h
new file mode 100644
index 0000000000..35e08ddf32
--- /dev/null
+++ b/src/or/shared_random_common.h
@@ -0,0 +1,47 @@
+/* Copyright (c) 2018, The Tor Project, Inc. */
+/* See LICENSE for licensing information */
+
+/**
+ * \file shared_random_common.h
+ * \brief Header file for shared_random_common.c.
+ **/
+
+#ifndef TOR_SHARED_RANDOM_COMMON_H
+#define TOR_SHARED_RANDOM_COMMON_H
+
+/* Dirauth module. */
+#include "dirauth/shared_random.h"
+
+/* Helper functions. */
+void sr_srv_encode(char *dst, size_t dst_len, const sr_srv_t *srv);
+int get_voting_interval(void);
+
+/* Control port functions. */
+char *sr_get_current_for_control(void);
+char *sr_get_previous_for_control(void);
+
+/* SRV functions. */
+const sr_srv_t *sr_get_current(const networkstatus_t *ns);
+const sr_srv_t *sr_get_previous(const networkstatus_t *ns);
+sr_srv_t *sr_parse_srv(const smartlist_t *args);
+
+/*
+ * Shared Random State API
+ */
+
+/* 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
+
+time_t sr_state_get_start_time_of_current_protocol_run(time_t now);
+unsigned int sr_state_get_phase_duration(void);
+unsigned int sr_state_get_protocol_run_duration(void);
+time_t get_start_time_of_current_round(void);
+
+#ifdef TOR_UNIT_TESTS
+
+#endif /* TOR_UNIT_TESTS */
+
+#endif /* TOR_SHARED_RANDOM_COMMON_H */
+