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[tor-commits] [tor/master] Refactor dirobj signature generation
commit cb75519bbf6d89ddaf6a6bb40a01a2dba09ad530
Author: Nick Mathewson <nickm@xxxxxxxxxxxxxx>
Date: Fri Feb 22 12:53:45 2013 -0500
Refactor dirobj signature generation
Now we can compute the hash and signature of a dirobj before
concatenating the smartlist, and we don't need to play silly games
with sigbuf and realloc any more.
---
src/common/crypto.c | 23 +++++++++++++++++
src/common/crypto.h | 4 +++
src/or/dirserv.c | 25 ++++++++----------
src/or/dirvote.c | 68 +++++++++++++++++--------------------------------
src/or/router.c | 25 ++++++++----------
src/or/routerparse.c | 59 +++++++++++++++++++++++++++++++++---------
src/or/routerparse.h | 3 ++
7 files changed, 122 insertions(+), 85 deletions(-)
diff --git a/src/common/crypto.c b/src/common/crypto.c
index 22d57c7..aeef1e3 100644
--- a/src/common/crypto.c
+++ b/src/common/crypto.c
@@ -1631,6 +1631,29 @@ crypto_digest_assign(crypto_digest_t *into,
memcpy(into,from,sizeof(crypto_digest_t));
}
+
+/** Given a list of strings in <b>lst</b>, set the <b>len_out</b>-byte digest
+ * at <b>digest_out</b> to the hash of the concatenation of those strings,
+ * plus the optional string <b>append</b>, computed with the algorithm
+ * <b>alg</b>. */
+void
+crypto_digest_smartlist(char *digest_out, size_t len_out,
+ const smartlist_t *lst, const char *append,
+ digest_algorithm_t alg)
+{
+ crypto_digest_t *d;
+ if (alg == DIGEST_SHA1)
+ d = crypto_digest_new();
+ else
+ d = crypto_digest256_new(alg);
+ SMARTLIST_FOREACH(lst, const char *, cp,
+ crypto_digest_add_bytes(d, cp, strlen(cp)));
+ if (append)
+ crypto_digest_add_bytes(d, append, strlen(append));
+ crypto_digest_get_digest(d, digest_out, len_out);
+ crypto_digest_free(d);
+}
+
/** Compute the HMAC-SHA-1 of the <b>msg_len</b> bytes in <b>msg</b>, using
* the <b>key</b> of length <b>key_len</b>. Store the DIGEST_LEN-byte result
* in <b>hmac_out</b>.
diff --git a/src/common/crypto.h b/src/common/crypto.h
index 12fcfae..e8f6eac 100644
--- a/src/common/crypto.h
+++ b/src/common/crypto.h
@@ -206,6 +206,10 @@ int crypto_digest(char *digest, const char *m, size_t len);
int crypto_digest256(char *digest, const char *m, size_t len,
digest_algorithm_t algorithm);
int crypto_digest_all(digests_t *ds_out, const char *m, size_t len);
+struct smartlist_t;
+void crypto_digest_smartlist(char *digest_out, size_t len_out,
+ const struct smartlist_t *lst, const char *append,
+ digest_algorithm_t alg);
const char *crypto_digest_algorithm_get_name(digest_algorithm_t alg);
int crypto_digest_algorithm_parse_name(const char *name);
crypto_digest_t *crypto_digest_new(void);
diff --git a/src/or/dirserv.c b/src/or/dirserv.c
index d5b90b9..2bbfc9a 100644
--- a/src/or/dirserv.c
+++ b/src/or/dirserv.c
@@ -2911,7 +2911,6 @@ generate_v2_networkstatus_opinion(void)
size_t identity_pkey_len;
char *status = NULL, *client_versions = NULL, *server_versions = NULL,
*identity_pkey = NULL, *hostname = NULL;
- size_t status_len;
const or_options_t *options = get_options();
char fingerprint[FINGERPRINT_LEN+1];
char published[ISO_TIME_LEN+1];
@@ -3032,23 +3031,21 @@ generate_v2_networkstatus_opinion(void)
smartlist_add_asprintf(chunks, "directory-signature %s\n",
options->Nickname);
- status = smartlist_join_strings(chunks, "", 0, NULL);
-#define MAX_V2_OPINION_SIGNATURE_LEN 4096
- status_len = strlen(status) + MAX_V2_OPINION_SIGNATURE_LEN + 1;
- status = tor_realloc(status, status_len);
-
- if (router_get_networkstatus_v2_hash(status, digest)<0) {
- log_warn(LD_BUG, "Unable to hash network status");
- goto done;
- }
+ crypto_digest_smartlist(digest, DIGEST_LEN, chunks, "", DIGEST_SHA1);
note_crypto_pk_op(SIGN_DIR);
- if (router_append_dirobj_signature(status, status_len,digest,DIGEST_LEN,
- private_key)<0) {
- log_warn(LD_BUG, "Unable to sign router status.");
- goto done;
+ {
+ char *sig;
+ if (!(sig = router_get_dirobj_signature(digest,DIGEST_LEN,
+ private_key))) {
+ log_warn(LD_BUG, "Unable to sign router status.");
+ goto done;
+ }
+ smartlist_add(chunks, sig);
}
+ status = smartlist_join_strings(chunks, "", 0, NULL);
+
{
networkstatus_v2_t *ns;
if (!(ns = networkstatus_v2_parse_from_string(status))) {
diff --git a/src/or/dirvote.c b/src/or/dirvote.c
index a787670..6ae4944 100644
--- a/src/or/dirvote.c
+++ b/src/or/dirvote.c
@@ -75,7 +75,6 @@ format_networkstatus_vote(crypto_pk_t *private_signing_key,
char *client_versions_line = NULL, *server_versions_line = NULL;
networkstatus_voter_info_t *voter;
char *status = NULL;
- size_t status_len;
tor_assert(private_signing_key);
tor_assert(v3_ns->type == NS_TYPE_VOTE || v3_ns->type == NS_TYPE_OPINION);
@@ -185,6 +184,11 @@ format_networkstatus_vote(crypto_pk_t *private_signing_key,
smartlist_add(chunks, tor_strdup("directory-footer\n"));
+ /* The digest includes everything up through the space after
+ * directory-signature. (Yuck.) */
+ crypto_digest_smartlist(digest, DIGEST_LEN, chunks,
+ "directory-signature ", DIGEST_SHA1);
+
{
char signing_key_fingerprint[FINGERPRINT_LEN+1];
if (crypto_pk_get_fingerprint(private_signing_key,
@@ -197,22 +201,19 @@ format_networkstatus_vote(crypto_pk_t *private_signing_key,
signing_key_fingerprint);
}
- status = smartlist_join_strings(chunks, "", 0, NULL);
-#define MAX_VOTE_SIGNATURE_LEN 4096
- status_len = strlen(status) + MAX_VOTE_SIGNATURE_LEN + 1;
- status = tor_realloc(status, status_len);
-
- if (router_get_networkstatus_v3_hash(status, digest, DIGEST_SHA1)<0)
- goto err;
note_crypto_pk_op(SIGN_DIR);
- if (router_append_dirobj_signature(status+strlen(status),
- status_len,
- digest, DIGEST_LEN,
- private_signing_key)<0) {
- log_warn(LD_BUG, "Unable to sign networkstatus vote.");
- goto err;
+ {
+ char *sig = router_get_dirobj_signature(digest, DIGEST_LEN,
+ private_signing_key);
+ if (!sig) {
+ log_warn(LD_BUG, "Unable to sign networkstatus vote.");
+ goto err;
+ }
+ smartlist_add(chunks, sig);
}
+ status = smartlist_join_strings(chunks, "", 0, NULL);
+
{
networkstatus_t *v;
if (!(v = networkstatus_parse_vote_from_string(status, NULL,
@@ -479,24 +480,6 @@ compute_routerstatus_consensus(smartlist_t *votes, int consensus_method,
return most;
}
-/** Given a list of strings in <b>lst</b>, set the <b>len_out</b>-byte digest
- * at <b>digest_out</b> to the hash of the concatenation of those strings,
- * computed with the algorithm <b>alg</b>. */
-static void
-hash_list_members(char *digest_out, size_t len_out,
- smartlist_t *lst, digest_algorithm_t alg)
-{
- crypto_digest_t *d;
- if (alg == DIGEST_SHA1)
- d = crypto_digest_new();
- else
- d = crypto_digest256_new(alg);
- SMARTLIST_FOREACH(lst, const char *, cp,
- crypto_digest_add_bytes(d, cp, strlen(cp)));
- crypto_digest_get_digest(d, digest_out, len_out);
- crypto_digest_free(d);
-}
-
/** Sorting helper: compare two strings based on their values as base-ten
* positive integers. (Non-integers are treated as prior to all integers, and
* compared lexically.) */
@@ -2095,12 +2078,12 @@ networkstatus_compute_consensus(smartlist_t *votes,
size_t digest_len =
flavor == FLAV_NS ? DIGEST_LEN : DIGEST256_LEN;
const char *algname = crypto_digest_algorithm_get_name(digest_alg);
- char sigbuf[4096];
+ char *signature;
smartlist_add(chunks, tor_strdup("directory-signature "));
/* Compute the hash of the chunks. */
- hash_list_members(digest, digest_len, chunks, digest_alg);
+ crypto_digest_smartlist(digest, digest_len, chunks, "", digest_alg);
/* Get the fingerprints */
crypto_pk_get_fingerprint(identity_key, fingerprint, 0);
@@ -2116,14 +2099,12 @@ networkstatus_compute_consensus(smartlist_t *votes,
signing_key_fingerprint);
}
/* And the signature. */
- sigbuf[0] = '\0';
- if (router_append_dirobj_signature(sigbuf, sizeof(sigbuf),
- digest, digest_len,
- signing_key)) {
+ if (!(signature = router_get_dirobj_signature(digest, digest_len,
+ signing_key))) {
log_warn(LD_BUG, "Couldn't sign consensus networkstatus.");
goto done;
}
- smartlist_add(chunks, tor_strdup(sigbuf));
+ smartlist_add(chunks, signature);
if (legacy_id_key_digest && legacy_signing_key && consensus_method >= 3) {
smartlist_add(chunks, tor_strdup("directory-signature "));
@@ -2139,14 +2120,13 @@ networkstatus_compute_consensus(smartlist_t *votes,
algname, fingerprint,
signing_key_fingerprint);
}
- sigbuf[0] = '\0';
- if (router_append_dirobj_signature(sigbuf, sizeof(sigbuf),
- digest, digest_len,
- legacy_signing_key)) {
+
+ if (!(signature = router_get_dirobj_signature(digest, digest_len,
+ legacy_signing_key))) {
log_warn(LD_BUG, "Couldn't sign consensus networkstatus.");
goto done;
}
- smartlist_add(chunks, tor_strdup(sigbuf));
+ smartlist_add(chunks, signature);
}
}
diff --git a/src/or/router.c b/src/or/router.c
index 1b5909e..a391cdd 100644
--- a/src/or/router.c
+++ b/src/or/router.c
@@ -2248,7 +2248,6 @@ router_dump_router_to_string(routerinfo_t *router,
const or_options_t *options = get_options();
smartlist_t *chunks = NULL;
char *output = NULL;
- size_t output_len;
/* Make sure the identity key matches the one in the routerinfo. */
if (!crypto_pk_eq_keys(ident_key, router->identity_pkey)) {
@@ -2395,24 +2394,22 @@ router_dump_router_to_string(routerinfo_t *router,
/* Sign the descriptor */
smartlist_add(chunks, tor_strdup("router-signature\n"));
- output = smartlist_join_strings(chunks, "", 0, NULL);
-#define MAX_DESC_SIGNATURE_LEN 4096
- output_len = strlen(output) + MAX_DESC_SIGNATURE_LEN + 1;
- output = tor_realloc(output, output_len);
-
- if (router_get_router_hash(output, strlen(output), digest) < 0) {
- goto err;
- }
+ crypto_digest_smartlist(digest, DIGEST_LEN, chunks, "", DIGEST_SHA1);
note_crypto_pk_op(SIGN_RTR);
- if (router_append_dirobj_signature(output, output_len,
- digest,DIGEST_LEN,ident_key)<0) {
- log_warn(LD_BUG, "Couldn't sign router descriptor");
- goto err;
+ {
+ char *sig;
+ if (!(sig = router_get_dirobj_signature(digest, DIGEST_LEN, ident_key))) {
+ log_warn(LD_BUG, "Couldn't sign router descriptor");
+ goto err;
+ }
+ smartlist_add(chunks, sig);
}
/* include a last '\n' */
- strlcat(output, "\n", output_len);
+ smartlist_add(chunks, tor_strdup("\n"));
+
+ output = smartlist_join_strings(chunks, "", 0, NULL);
#ifdef DEBUG_ROUTER_DUMP_ROUTER_TO_STRING
{
diff --git a/src/or/routerparse.c b/src/or/routerparse.c
index ce2cd5c..63f8fab 100644
--- a/src/or/routerparse.c
+++ b/src/or/routerparse.c
@@ -683,20 +683,19 @@ router_get_extrainfo_hash(const char *s, size_t s_len, char *digest)
"\nrouter-signature",'\n', DIGEST_SHA1);
}
-/** Helper: used to generate signatures for routers, directories and
- * network-status objects. Given a digest in <b>digest</b> and a secret
- * <b>private_key</b>, generate an PKCS1-padded signature, BASE64-encode it,
- * surround it with -----BEGIN/END----- pairs, and write it to the
- * <b>buf_len</b>-byte buffer at <b>buf</b>. Return 0 on success, -1 on
- * failure.
- */
-int
-router_append_dirobj_signature(char *buf, size_t buf_len, const char *digest,
- size_t digest_len, crypto_pk_t *private_key)
+/** DOCDOC */
+char *
+router_get_dirobj_signature(const char *digest,
+ size_t digest_len,
+ crypto_pk_t *private_key)
{
char *signature;
size_t i, keysize;
int siglen;
+ char *buf = NULL;
+ size_t buf_len;
+ /* overestimate of BEGIN/END lines total len. */
+#define BEGIN_END_OVERHEAD_LEN 64
keysize = crypto_pk_keysize(private_key);
signature = tor_malloc(keysize);
@@ -706,7 +705,12 @@ router_append_dirobj_signature(char *buf, size_t buf_len, const char *digest,
log_warn(LD_BUG,"Couldn't sign digest.");
goto err;
}
- if (strlcat(buf, "-----BEGIN SIGNATURE-----\n", buf_len) >= buf_len)
+
+ /* The *2 here is a ridiculous overestimate of base-64 overhead. */
+ buf_len = (siglen * 2) + BEGIN_END_OVERHEAD_LEN;
+ buf = tor_malloc(buf_len);
+
+ if (strlcpy(buf, "-----BEGIN SIGNATURE-----\n", buf_len) >= buf_len)
goto truncated;
i = strlen(buf);
@@ -719,13 +723,42 @@ router_append_dirobj_signature(char *buf, size_t buf_len, const char *digest,
goto truncated;
tor_free(signature);
- return 0;
+ return buf;
truncated:
log_warn(LD_BUG,"tried to exceed string length.");
err:
tor_free(signature);
- return -1;
+ tor_free(buf);
+ return NULL;
+}
+
+/** Helper: used to generate signatures for routers, directories and
+ * network-status objects. Given a digest in <b>digest</b> and a secret
+ * <b>private_key</b>, generate an PKCS1-padded signature, BASE64-encode it,
+ * surround it with -----BEGIN/END----- pairs, and write it to the
+ * <b>buf_len</b>-byte buffer at <b>buf</b>. Return 0 on success, -1 on
+ * failure.
+ */
+int
+router_append_dirobj_signature(char *buf, size_t buf_len, const char *digest,
+ size_t digest_len, crypto_pk_t *private_key)
+{
+ size_t sig_len, s_len;
+ char *sig = router_get_dirobj_signature(digest, digest_len, private_key);
+ if (!sig) {
+ log_warn(LD_BUG, "No signature generated");
+ return -1;
+ }
+ sig_len = strlen(sig);
+ s_len = strlen(buf);
+ if (sig_len + s_len + 1 > buf_len) {
+ log_warn(LD_BUG, "Not enough room for signature");
+ tor_free(sig);
+ return -1;
+ }
+ memcpy(buf+s_len, sig, sig_len+1);
+ return 0;
}
/** Return VS_RECOMMENDED if <b>myversion</b> is contained in
diff --git a/src/or/routerparse.h b/src/or/routerparse.h
index 859a691..8eac3a2 100644
--- a/src/or/routerparse.h
+++ b/src/or/routerparse.h
@@ -21,6 +21,9 @@ int router_get_networkstatus_v3_hash(const char *s, char *digest,
int router_get_networkstatus_v3_hashes(const char *s, digests_t *digests);
int router_get_extrainfo_hash(const char *s, size_t s_len, char *digest);
#define DIROBJ_MAX_SIG_LEN 256
+char *router_get_dirobj_signature(const char *digest,
+ size_t digest_len,
+ crypto_pk_t *private_key);
int router_append_dirobj_signature(char *buf, size_t buf_len,
const char *digest,
size_t digest_len,
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