Refactor consensus signature storage for multiple digests and flavors.

This patch introduces a new type called document_signature_t to represent the
signature of a consensus document.  Now, each consensus document can have up
to one document signature per voter per digest algorithm.  Also, each
detached-signatures document can have up to one signature per <voter,
algorithm, flavor>.

2 files changed, 51 insertions, 3 deletions

diff --git a/src/common/crypto.c b/src/common/crypto.c
index 21c8aed2d4..ac0e628c48 100644
--- a/src/common/crypto.c
+++ b/src/common/crypto.c
@@ -1448,6 +1448,39 @@ crypto_digest256(char *digest, const char *m, size_t len,
   return (SHA256((const unsigned char*)m,len,(unsigned char*)digest) == NULL);
 }
 
+/** Set the digests_t in <b>ds_out</b> to contain every digest on the
+ * <b>len</b> bytes in <b>m</b> that we know how to compute.  Return 0 on
+ * success, -1 on failure. */
+int
+crypto_digest_all(digests_t *ds_out, const char *m, size_t len)
+{
+  digest_algorithm_t i;
+  tor_assert(ds_out);
+  memset(ds_out, 0, sizeof(*ds_out));
+  if (crypto_digest(ds_out->d[DIGEST_SHA1], m, len) < 0)
+    return -1;
+  for (i = DIGEST_SHA256; i < N_DIGEST_ALGORITHMS; ++i) {
+    if (crypto_digest256(ds_out->d[i], m, len, i) < 0)
+      return -1;
+  }
+  return 0;
+}
+
+/** Return the name of an algorithm, as used in directory documents. */
+const char *
+crypto_digest_algorithm_get_name(digest_algorithm_t alg)
+{
+  switch (alg) {
+    case DIGEST_SHA1:
+      return "sha1";
+    case DIGEST_SHA256:
+      return "sha256";
+    default:
+      tor_fragile_assert();
+      return "??unknown_digest??";
+  }
+}
+
 /** Intermediate information about the digest of a stream of data. */
 struct crypto_digest_env_t {
   union {
diff --git a/src/common/crypto.h b/src/common/crypto.h
index 63ea96d056..ed8468046f 100644
--- a/src/common/crypto.h
+++ b/src/common/crypto.h
@@ -58,9 +58,22 @@
 #define HEX_DIGEST256_LEN 64
 
 typedef enum {
-  DIGEST_SHA1,
-  DIGEST_SHA256,
+  DIGEST_SHA1 = 0,
+  DIGEST_SHA256 = 1,
 } digest_algorithm_t;
+#define  N_DIGEST_ALGORITHMS (DIGEST_SHA256+1)
+
+/** A set of all the digests we know how to compute, taken on a single
+ * string.  Any digests that are shorter than 256 bits are right-padded
+ * with 0 bits.
+ *
+ * Note that this representation wastes 12 bytes for the SHA1 case, so
+ * don't use it for anything where we need to allocate a whole bunch at
+ * once.
+ **/
+typedef struct {
+  char d[N_DIGEST_ALGORITHMS][DIGEST256_LEN];
+} digests_t;
 
 typedef struct crypto_pk_env_t crypto_pk_env_t;
 typedef struct crypto_cipher_env_t crypto_cipher_env_t;
@@ -158,10 +171,12 @@ int crypto_cipher_decrypt_with_iv(crypto_cipher_env_t *env,
                                   char *to, size_t tolen,
                                   const char *from, size_t fromlen);
 
-/* SHA-1 */
+/* SHA-1 and other digests. */
 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);
+const char *crypto_digest_algorithm_get_name(digest_algorithm_t alg);
 crypto_digest_env_t *crypto_new_digest_env(void);
 crypto_digest_env_t *crypto_new_digest256_env(digest_algorithm_t algorithm);
 void crypto_free_digest_env(crypto_digest_env_t *digest);