helpers: allow 19-digit reported ICCIDs

The mm_3gpp_parse_iccid() method does validation of the ICCID string
and was originally implemented to handle +CRSM reported values. The
implementation was looking for 20-digit strings, even for 19-digit
ICCIDs (those finished with a trailing 'F').

We now extend the logic to also validate ICCID strings reported as
19-digit values directly, and when that happens we won't allow
swapping of the digits (a +CRSM specific requirement) or trailing 'F'
characters (as that is only required when reporting 19-digit ICCIDs
with 20-digit strings).

This change allows us to e.g. use the u-blox specific AT+CCID command
and validate the returned ICCID with the same helper method, which
currently fails:

  (ttyACM2): --> 'AT+CCID<CR>'
  (ttyACM2): <-- '<CR><LF>+CCID: 8934077700015848638<CR><LF><CR><LF>OK<CR><LF>'
  couldn't load SIM identifier: 'Invalid ICCID response size (was 19, expected 20)'

src/mm-modem-helpers.c

@@ -3537,10 +3537,10 @@ mm_3gpp_parse_iccid (const char *raw_iccid, GError **error)
         goto error;
     }
 
-    /* BCD encoded ICCIDs are 20 digits long */
-    if (len != 20) {
+    /* ICCIDs are 19 or 20 digits long */
+    if (len < 19 || len > 20) {
         g_set_error (error, MM_CORE_ERROR, MM_CORE_ERROR_FAILED,
-                     "Invalid ICCID response size (was %zd, expected 20)",
+                     "Invalid ICCID response size (was %zd, expected 19 or 20)",
                      len);
         goto error;
     }
@@ -3549,9 +3549,16 @@ mm_3gpp_parse_iccid (const char *raw_iccid, GError **error)
      * should be '89' for telecommunication purposes according to ISO/IEC 7812.
      */
     if (buf[0] == '8' && buf[1] == '9') {
-      swap = FALSE;
+        swap = FALSE;
     } else if (buf[0] == '9' && buf[1] == '8') {
-      swap = TRUE;
+        /* swapped digits are only expected in raw +CRSM responses, which must all
+         * be 20-bytes long */
+        if (len != 20) {
+            g_set_error (error, MM_CORE_ERROR, MM_CORE_ERROR_FAILED,
+                         "Invalid ICCID response size while swap needed (expected 20)");
+            goto error;
+        }
+        swap = TRUE;
     } else {
       /* FIXME: Instead of erroring out, revisit this solution if we find any SIM
        * that doesn't use '89' as the major industry identifier of the ICCID.
@@ -3562,9 +3569,10 @@ mm_3gpp_parse_iccid (const char *raw_iccid, GError **error)
     }
 
     /* Ensure if there's an 'F' that it's second-to-last if swap = TRUE,
-     * otherwise last if swap = FALSE */
+     * otherwise last if swap = FALSE. Also fail if an F is found within a
+     * 19-digit reported ICCID. */
     if (f_pos >= 0) {
-        if ((swap && (f_pos != len - 2)) || (!swap && (f_pos != len - 1))) {
+        if ((len != 20) || (swap && (f_pos != len - 2)) || (!swap && (f_pos != len - 1))) {
             g_set_error_literal (error, MM_CORE_ERROR, MM_CORE_ERROR_FAILED,
                                  "Invalid ICCID length (unexpected F position)");
             goto error;
@@ -3577,7 +3585,8 @@ mm_3gpp_parse_iccid (const char *raw_iccid, GError **error)
          *
          *    21436587 -> 12345678
          */
-        swapped = g_malloc0 (25);
+        g_assert (len == 20);
+        swapped = g_malloc0 (21);
         for (i = 0; i < 10; i++) {
             swapped[i * 2] = buf[(i * 2) + 1];
             swapped[(i * 2) + 1] = buf[i * 2];

src/tests/test-modem-helpers.c

@@ -2090,6 +2090,20 @@ test_iccid_parse_unquoted_unswapped_19_digit (void *f, gpointer d)
     g_free (parsed);
 }
 
+static void
+test_iccid_parse_unquoted_unswapped_19_digit_no_f (void *f, gpointer d)
+{
+    const char *raw_iccid = "8944200053671052499";
+    const char *expected = "8944200053671052499";
+    char *parsed;
+    GError *error = NULL;
+
+    parsed = mm_3gpp_parse_iccid (raw_iccid, &error);
+    g_assert_no_error (error);
+    g_assert_cmpstr (parsed, ==, expected);
+    g_free (parsed);
+}
+
 static void
 test_iccid_parse_quoted_unswapped_20_digit (void *f, gpointer d)
 {
@@ -3924,6 +3938,7 @@ int main (int argc, char **argv)
     g_test_suite_add (suite, TESTCASE (test_iccid_parse_quoted_swap_19_digit, NULL));
     g_test_suite_add (suite, TESTCASE (test_iccid_parse_unquoted_swap_20_digit, NULL));
     g_test_suite_add (suite, TESTCASE (test_iccid_parse_unquoted_unswapped_19_digit, NULL));
+    g_test_suite_add (suite, TESTCASE (test_iccid_parse_unquoted_unswapped_19_digit_no_f, NULL));
     g_test_suite_add (suite, TESTCASE (test_iccid_parse_quoted_unswapped_20_digit, NULL));
     g_test_suite_add (suite, TESTCASE (test_iccid_parse_short, NULL));
     g_test_suite_add (suite, TESTCASE (test_iccid_parse_invalid_chars, NULL));