-strengthen payto validation logic

1 files changed, 398 insertions, 0 deletions

diff --git a/src/util/payto.c b/src/util/payto.c
index 54072d667..7819184e8 100644
--- a/src/util/payto.c
+++ b/src/util/payto.c
@@ -128,3 +128,401 @@ TALER_xtalerbank_account_from_payto (const char *payto)
   return GNUNET_strndup (beg,
                          end - beg);
 }
+
+
+/* Country table taken from GNU gettext */
+
+/**
+ * Entry in the country table.
+ */
+struct CountryTableEntry
+{
+  /**
+   * 2-Character international country code.
+   */
+  const char *code;
+
+  /**
+   * Long English name of the country.
+   */
+  const char *english;
+};
+
+
+/* Keep the following table in sync with gettext.
+   WARNING: the entries should stay sorted according to the code */
+/**
+ * List of country codes.
+ */
+static const struct CountryTableEntry country_table[] = {
+  { "AE", "U.A.E." },
+  { "AF", "Afghanistan" },
+  { "AL", "Albania" },
+  { "AM", "Armenia" },
+  { "AN", "Netherlands Antilles" },
+  { "AR", "Argentina" },
+  { "AT", "Austria" },
+  { "AU", "Australia" },
+  { "AZ", "Azerbaijan" },
+  { "BA", "Bosnia and Herzegovina" },
+  { "BD", "Bangladesh" },
+  { "BE", "Belgium" },
+  { "BG", "Bulgaria" },
+  { "BH", "Bahrain" },
+  { "BN", "Brunei Darussalam" },
+  { "BO", "Bolivia" },
+  { "BR", "Brazil" },
+  { "BT", "Bhutan" },
+  { "BY", "Belarus" },
+  { "BZ", "Belize" },
+  { "CA", "Canada" },
+  { "CG", "Congo" },
+  { "CH", "Switzerland" },
+  { "CI", "Cote d'Ivoire" },
+  { "CL", "Chile" },
+  { "CM", "Cameroon" },
+  { "CN", "People's Republic of China" },
+  { "CO", "Colombia" },
+  { "CR", "Costa Rica" },
+  { "CS", "Serbia and Montenegro" },
+  { "CZ", "Czech Republic" },
+  { "DE", "Germany" },
+  { "DK", "Denmark" },
+  { "DO", "Dominican Republic" },
+  { "DZ", "Algeria" },
+  { "EC", "Ecuador" },
+  { "EE", "Estonia" },
+  { "EG", "Egypt" },
+  { "ER", "Eritrea" },
+  { "ES", "Spain" },
+  { "ET", "Ethiopia" },
+  { "FI", "Finland" },
+  { "FO", "Faroe Islands" },
+  { "FR", "France" },
+  { "GB", "United Kingdom" },
+  { "GD", "Caribbean" },
+  { "GE", "Georgia" },
+  { "GL", "Greenland" },
+  { "GR", "Greece" },
+  { "GT", "Guatemala" },
+  { "HK", "Hong Kong" },
+  { "HK", "Hong Kong S.A.R." },
+  { "HN", "Honduras" },
+  { "HR", "Croatia" },
+  { "HT", "Haiti" },
+  { "HU", "Hungary" },
+  { "ID", "Indonesia" },
+  { "IE", "Ireland" },
+  { "IL", "Israel" },
+  { "IN", "India" },
+  { "IQ", "Iraq" },
+  { "IR", "Iran" },
+  { "IS", "Iceland" },
+  { "IT", "Italy" },
+  { "JM", "Jamaica" },
+  { "JO", "Jordan" },
+  { "JP", "Japan" },
+  { "KE", "Kenya" },
+  { "KG", "Kyrgyzstan" },
+  { "KH", "Cambodia" },
+  { "KR", "South Korea" },
+  { "KW", "Kuwait" },
+  { "KZ", "Kazakhstan" },
+  { "LA", "Laos" },
+  { "LB", "Lebanon" },
+  { "LI", "Liechtenstein" },
+  { "LK", "Sri Lanka" },
+  { "LT", "Lithuania" },
+  { "LU", "Luxembourg" },
+  { "LV", "Latvia" },
+  { "LY", "Libya" },
+  { "MA", "Morocco" },
+  { "MC", "Principality of Monaco" },
+  { "MD", "Moldava" },
+  { "MD", "Moldova" },
+  { "ME", "Montenegro" },
+  { "MK", "Former Yugoslav Republic of Macedonia" },
+  { "ML", "Mali" },
+  { "MM", "Myanmar" },
+  { "MN", "Mongolia" },
+  { "MO", "Macau S.A.R." },
+  { "MT", "Malta" },
+  { "MV", "Maldives" },
+  { "MX", "Mexico" },
+  { "MY", "Malaysia" },
+  { "NG", "Nigeria" },
+  { "NI", "Nicaragua" },
+  { "NL", "Netherlands" },
+  { "NO", "Norway" },
+  { "NP", "Nepal" },
+  { "NZ", "New Zealand" },
+  { "OM", "Oman" },
+  { "PA", "Panama" },
+  { "PE", "Peru" },
+  { "PH", "Philippines" },
+  { "PK", "Islamic Republic of Pakistan" },
+  { "PL", "Poland" },
+  { "PR", "Puerto Rico" },
+  { "PT", "Portugal" },
+  { "PY", "Paraguay" },
+  { "QA", "Qatar" },
+  { "RE", "Reunion" },
+  { "RO", "Romania" },
+  { "RS", "Serbia" },
+  { "RU", "Russia" },
+  { "RW", "Rwanda" },
+  { "SA", "Saudi Arabia" },
+  { "SE", "Sweden" },
+  { "SG", "Singapore" },
+  { "SI", "Slovenia" },
+  { "SK", "Slovak" },
+  { "SN", "Senegal" },
+  { "SO", "Somalia" },
+  { "SR", "Suriname" },
+  { "SV", "El Salvador" },
+  { "SY", "Syria" },
+  { "TH", "Thailand" },
+  { "TJ", "Tajikistan" },
+  { "TM", "Turkmenistan" },
+  { "TN", "Tunisia" },
+  { "TR", "Turkey" },
+  { "TT", "Trinidad and Tobago" },
+  { "TW", "Taiwan" },
+  { "TZ", "Tanzania" },
+  { "UA", "Ukraine" },
+  { "US", "United States" },
+  { "UY", "Uruguay" },
+  { "VA", "Vatican" },
+  { "VE", "Venezuela" },
+  { "VN", "Viet Nam" },
+  { "YE", "Yemen" },
+  { "ZA", "South Africa" },
+  { "ZW", "Zimbabwe" }
+};
+
+
+/**
+ * Country code comparator function, for binary search with bsearch().
+ *
+ * @param ptr1 pointer to a `struct table_entry`
+ * @param ptr2 pointer to a `struct table_entry`
+ * @return result of memcmp()'ing the 2-digit country codes of the entries
+ */
+static int
+cmp_country_code (const void *ptr1,
+                  const void *ptr2)
+{
+  const struct CountryTableEntry *cc1 = ptr1;
+  const struct CountryTableEntry *cc2 = ptr2;
+
+  return memcmp (cc1->code,
+                 cc2->code,
+                 2);
+}
+
+
+/**
+ * Validates given IBAN according to the European Banking Standards.  See:
+ * http://www.europeanpaymentscouncil.eu/documents/ECBS%20IBAN%20standard%20EBS204_V3.2.pdf
+ *
+ * @param iban the IBAN number to validate
+ * @return NULL if correctly formatted; error message if not
+ */
+static char *
+validate_iban (const char *iban)
+{
+  char cc[2];
+  char ibancpy[35];
+  struct CountryTableEntry cc_entry;
+  unsigned int len;
+  char *nbuf;
+  unsigned long long dividend;
+  unsigned long long remainder;
+  unsigned int i;
+  unsigned int j;
+
+  len = strlen (iban);
+  if (len > 34)
+    return GNUNET_strdup ("IBAN number too long to be valid");
+  memcpy (cc, iban, 2);
+  memcpy (ibancpy, iban + 4, len - 4);
+  memcpy (ibancpy + len - 4, iban, 4);
+  ibancpy[len] = '\0';
+  cc_entry.code = cc;
+  cc_entry.english = NULL;
+  if (NULL ==
+      bsearch (&cc_entry,
+               country_table,
+               sizeof (country_table) / sizeof (struct CountryTableEntry),
+               sizeof (struct CountryTableEntry),
+               &cmp_country_code))
+  {
+    char *msg;
+
+    GNUNET_asprintf (&msg,
+                     "Country code `%c%c' not supported\n",
+                     cc[0],
+                     cc[1]);
+    return msg;
+  }
+  nbuf = GNUNET_malloc ((len * 2) + 1);
+  for (i = 0, j = 0; i < len; i++)
+  {
+    if (isalpha ((unsigned char) ibancpy[i]))
+    {
+      if (2 != snprintf (&nbuf[j],
+                         3,
+                         "%2u",
+                         (ibancpy[i] - 'A' + 10)))
+      {
+        GNUNET_break (0);
+        return GNUNET_strdup ("internal invariant violation");
+      }
+      j += 2;
+      continue;
+    }
+    nbuf[j] = ibancpy[i];
+    j++;
+  }
+  for (j = 0; '\0' != nbuf[j]; j++)
+  {
+    if (! isdigit ( (unsigned char) nbuf[j]))
+    {
+      char *msg;
+
+      GNUNET_asprintf (&msg,
+                       "digit expected at `%s'",
+                       &nbuf[j]);
+      GNUNET_free (nbuf);
+      return msg;
+    }
+  }
+  GNUNET_assert (sizeof(dividend) >= 8);
+  remainder = 0;
+  for (unsigned int i = 0; i<j; i += 16)
+  {
+    int nread;
+
+    if (1 !=
+        sscanf (&nbuf[i],
+                "%16llu %n",
+                &dividend,
+                &nread))
+    {
+      char *msg;
+
+      GNUNET_asprintf (&msg,
+                       "wrong input for checksum calculation at `%s'",
+                       &nbuf[i]);
+      GNUNET_free (nbuf);
+      return msg;
+    }
+    if (0 != remainder)
+      dividend += remainder * (pow (10, nread));
+    remainder = dividend % 97;
+  }
+  GNUNET_free (nbuf);
+  if (1 != remainder)
+    return GNUNET_strdup ("IBAN checksum is wrong");
+  return NULL;
+}
+
+
+/**
+ * Validate payto://iban/ account URL (only account information,
+ * wire subject and amount are ignored).
+ *
+ * @param account_url URL to parse
+ * @return NULL on success, otherwise an error message
+ *      to be freed by the caller
+ */
+static char *
+validate_payto_iban (const char *account_url)
+{
+  const char *iban;
+  const char *q;
+  char *result;
+  char *err;
+
+#define IBAN_PREFIX "payto://iban/"
+  if (0 != strncasecmp (account_url,
+                        IBAN_PREFIX,
+                        strlen (IBAN_PREFIX)))
+    return NULL; /* not an IBAN */
+
+  iban = strrchr (account_url, '/') + 1;
+#undef IBAN_PREFIX
+  q = strchr (iban,
+              '?');
+  if (NULL != q)
+  {
+    result = GNUNET_strndup (iban,
+                             q - iban);
+  }
+  else
+  {
+    result = GNUNET_strdup (iban);
+  }
+  if (NULL !=
+      (err = validate_iban (result)))
+  {
+    GNUNET_free (result);
+    return err;
+  }
+  GNUNET_free (result);
+  return NULL;
+}
+
+
+/**
+ * Check that a payto:// URI is well-formed.
+ *
+ * @param payto_uri the URL to check
+ * @return NULL on success, otherwise an error
+ *         message to be freed by the caller!
+ */
+char *
+TALER_payto_validate (const char *payto_uri)
+{
+  char *ret;
+  const char *start;
+  const char *end;
+
+  if (0 != strncasecmp (payto_uri,
+                        PAYTO,
+                        strlen (PAYTO)))
+    return GNUNET_strdup ("invalid prefix");
+  for (unsigned int i = 0; '\0' != payto_uri[i]; i++)
+  {
+    /* This is more strict than RFC 8905, alas we do not need to support messages/instructions/etc.,
+       and it is generally better to start with a narrow whitelist; we can be more permissive later ...*/
+#define ALLOWED_CHARACTERS \
+  "abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ0123456789/:&?-.,="
+    if (NULL == strchr (ALLOWED_CHARACTERS,
+                        (int) payto_uri[i]))
+    {
+      char *ret;
+
+      GNUNET_asprintf (&ret,
+                       "Encountered invalid character `%c' at offset %u in payto URI `%s'",
+                       payto_uri[i],
+                       i,
+                       payto_uri);
+      return ret;
+    }
+#undef ALLOWED_CHARACTERS
+  }
+
+  start = &payto_uri[strlen (PAYTO)];
+  end = strchr (start,
+                (unsigned char) '/');
+  if (NULL == end)
+    return GNUNET_strdup ("missing '/' in payload");
+
+  if (NULL != (ret = validate_payto_iban (payto_uri)))
+    return ret; /* got a definitive answer */
+
+  /* Insert other bank account validation methods here later! */
+
+  return NULL;
+}