Fix users of base32_decode to check for expected length in return.

Also, when we log about a failure from base32_decode(), we now
say that the length is wrong or that the characters were invalid:
previously we would just say that there were invalid characters.

Follow-up on 28913 work.

3 files changed, 8 insertions, 3 deletions

diff --git a/src/feature/hs/hs_client.c b/src/feature/hs/hs_client.c
index dfad216abb..a8a4aa776f 100644
--- a/src/feature/hs/hs_client.c
+++ b/src/feature/hs/hs_client.c
@@ -1517,7 +1517,10 @@ parse_auth_file_content(const char *client_key_str)
   auth = tor_malloc_zero(sizeof(hs_client_service_authorization_t));
   if (base32_decode((char *) auth->enc_seckey.secret_key,
                     sizeof(auth->enc_seckey.secret_key),
-                    seckey_b32, strlen(seckey_b32)) < 0) {
+                    seckey_b32, strlen(seckey_b32)) !=
+      sizeof(auth->enc_seckey.secret_key)) {
+    log_warn(LD_REND, "Client authorization encoded base32 private key "
+                      "can't be decoded: %s", seckey_b32);
     goto err;
   }
   strncpy(auth->onion_address, onion_address, HS_SERVICE_ADDR_LEN_BASE32);
diff --git a/src/feature/hs/hs_common.c b/src/feature/hs/hs_common.c
index 8dbd9485ea..97229ac11e 100644
--- a/src/feature/hs/hs_common.c
+++ b/src/feature/hs/hs_common.c
@@ -926,7 +926,8 @@ hs_parse_address(const char *address, ed25519_public_key_t *key_out,
   }
 
   /* Decode address so we can extract needed fields. */
-  if (base32_decode(decoded, sizeof(decoded), address, strlen(address)) < 0) {
+  if (base32_decode(decoded, sizeof(decoded), address, strlen(address))
+      != sizeof(decoded)) {
     log_warn(LD_REND, "Service address %s can't be decoded.",
              escaped_safe_str(address));
     goto invalid;
diff --git a/src/feature/hs/hs_service.c b/src/feature/hs/hs_service.c
index 623a239d50..6f6cf01053 100644
--- a/src/feature/hs/hs_service.c
+++ b/src/feature/hs/hs_service.c
@@ -1179,7 +1179,8 @@ parse_authorized_client(const char *client_key_str)
   client = tor_malloc_zero(sizeof(hs_service_authorized_client_t));
   if (base32_decode((char *) client->client_pk.public_key,
                     sizeof(client->client_pk.public_key),
-                    pubkey_b32, strlen(pubkey_b32)) < 0) {
+                    pubkey_b32, strlen(pubkey_b32)) !=
+      sizeof(client->client_pk.public_key)) {
     log_warn(LD_REND, "Client authorization public key cannot be decoded: %s",
              pubkey_b32);
     goto err;