add list-readers action to tool

also refactor ykpiv_list_readers() a bit

lib/ykpiv.c

@@ -228,9 +228,8 @@ ykpiv_rc ykpiv_connect(ykpiv_state *state, const char *wanted) {
   return YKPIV_GENERIC_ERROR;
 }
 
-ykpiv_rc ykpiv_list_readers(ykpiv_state *state, unsigned char **readers, unsigned long *len) {
+ykpiv_rc ykpiv_list_readers(ykpiv_state *state, char *readers, size_t *len) {
   unsigned long num_readers = 0;
-  char reader_buf[1024];
   long rc;
 
   if(SCardIsValidContext(state->context) != SCARD_S_SUCCESS) {
@@ -252,11 +251,11 @@ ykpiv_rc ykpiv_list_readers(ykpiv_state *state, unsigned char **readers, unsigne
     return YKPIV_PCSC_ERROR;
   }
 
-  if (num_readers > sizeof(reader_buf)) {
-    num_readers = sizeof(reader_buf);
+  if (num_readers > *len) {
+    num_readers = *len;
   }
 
-  rc = SCardListReaders(state->context, NULL, reader_buf, &num_readers);
+  rc = SCardListReaders(state->context, NULL, readers, &num_readers);
   if (rc != SCARD_S_SUCCESS)
   {
     if(state->verbose) {
@@ -266,16 +265,6 @@ ykpiv_rc ykpiv_list_readers(ykpiv_state *state, unsigned char **readers, unsigne
     return YKPIV_PCSC_ERROR;
   }
 
-  // Save available readers (aka PKCS11 slots)
-  *readers = malloc(sizeof(char) * num_readers);
-  if (*readers == NULL) {
-    if(state->verbose) {
-      fprintf (stderr, "error: malloc failed");
-    }
-    SCardReleaseContext(state->context);
-    return YKPIV_MEMORY_ERROR;
-  }
-  memcpy(*readers, reader_buf, num_readers);
   *len = num_readers;
 
   return YKPIV_OK;

lib/ykpiv.h

@@ -65,7 +65,7 @@ extern "C"
   ykpiv_rc ykpiv_init(ykpiv_state **state, int verbose);
   ykpiv_rc ykpiv_done(ykpiv_state *state);
   ykpiv_rc ykpiv_connect(ykpiv_state *state, const char *wanted);
-  ykpiv_rc ykpiv_list_readers(ykpiv_state *state, unsigned char **readers, unsigned long *len);
+  ykpiv_rc ykpiv_list_readers(ykpiv_state *state, char *readers, size_t *len);
   ykpiv_rc ykpiv_disconnect(ykpiv_state *state);
   ykpiv_rc ykpiv_transfer_data(ykpiv_state *state, const unsigned char *templ,
                                const unsigned char *in_data, long in_len,

tool/cmdline.ggo

@@ -32,7 +32,7 @@ option "action" a "Action to take" values="version","generate","set-mgm-key",
        "reset","pin-retries","import-key","import-certificate","set-chuid",
        "request-certificate","verify-pin","change-pin","change-puk","unblock-pin",
        "selfsign-certificate","delete-certificate","read-certificate","status",
-       "test-signature","test-decipher" enum multiple
+       "test-signature","test-decipher","list-readers" enum multiple
 text   "
        Multiple actions may be given at once and will be executed in order
        for example --action=verify-pin --action=request-certificate\n"

tool/yubico-piv-tool.c

@@ -1569,6 +1569,21 @@ decipher_out:
   return ret;
 }
 
+static bool list_readers(ykpiv_state *state) {
+  char readers[2048];
+  char *reader_ptr;
+  size_t len = sizeof(readers);
+  ykpiv_rc rc = ykpiv_list_readers(state, readers, &len);
+  if(rc != YKPIV_OK) {
+    fprintf(stderr, "Failed listing readers.\n");
+    return false;
+  }
+  for(reader_ptr = readers; *reader_ptr != '\0'; reader_ptr += strlen(reader_ptr) + 1) {
+    printf("%s\n", reader_ptr);
+  }
+  return true;
+}
+
 int main(int argc, char *argv[]) {
   struct gengetopt_args_info args_info;
   ykpiv_state *state;
@@ -1622,6 +1637,7 @@ int main(int argc, char *argv[]) {
       case action_arg_version:
       case action_arg_reset:
       case action_arg_status:
+      case action_arg_listMINUS_readers:
       case action__NULL:
       default:
         continue;
@@ -1666,6 +1682,7 @@ int main(int argc, char *argv[]) {
       case action_arg_status:
       case action_arg_testMINUS_signature:
       case action_arg_testMINUS_decipher:
+      case action_arg_listMINUS_readers:
       case action__NULL:
       default:
         if(verbosity) {
@@ -1850,6 +1867,11 @@ int main(int argc, char *argv[]) {
           ret = EXIT_FAILURE;
         }
         break;
+      case action_arg_listMINUS_readers:
+        if(list_readers(state) == false) {
+          ret = EXIT_FAILURE;
+        }
+        break;
       case action__NULL:
       default:
         fprintf(stderr, "Wrong action. %d.\n", action);

ykcs11/ykcs11.c

@@ -47,8 +47,8 @@ CK_DEFINE_FUNCTION(CK_RV, C_Initialize)(
 )
 {
   DIN;
-  CK_CHAR_PTR readers;
-  CK_ULONG len;
+  char readers[2048];
+  CK_ULONG len = sizeof(readers);
 
   // TODO: check for locks and mutexes
 
@@ -60,7 +60,7 @@ CK_DEFINE_FUNCTION(CK_RV, C_Initialize)(
     return CKR_FUNCTION_FAILED; // TODO: better error?
   }
 
-  if (ykpiv_list_readers(piv_state, &readers, &len) != YKPIV_OK) {
+  if (ykpiv_list_readers(piv_state, readers, &len) != YKPIV_OK) {
     DBG(("Unable to list readers"));
     return CKR_FUNCTION_FAILED;
   }