/* 21-23 November 2025, by R. Harmsen:

   Determine the country from an IPv4 or IPv6 address, using publicly
   available internet resources. I successively try four of them
   (found using Grok), and stop as soon as one is successful. So
   hopefully if in future such a service goes out of business, some
   of the others will automatically take over. Same if one of them
   might get exhausted for free access, as a result of too many
   requests per day.

   This replaces an earlier mechanism that used a library and database
   by Maxmind.com. See below.

   See also https://rudhar.com/sfreview/IP2cntry.htm .
*/

#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <ctype.h>
#include <unistd.h>
#include "IP2cntr.h"

static char pattern1[] = /* ipapi.is   */
   "curl https://api.ipapi.is/?q='%s' 2> /dev/null | grep country_code | "
   "sed -E 's@^[^a-zA-Z]*country_code[^a-zA-Z]+([A-Z][A-Z])[^a-zA-Z]*$@\\1@'";
static char pattern2[] = /* ipinfo.io  */
   "curl https://ipinfo.io/'%s'/country 2> /dev/null";
static char pattern3[] = /* ip-api.com */
   "curl http://ip-api.com/json/'%s' 2> /dev/null | "
   "sed -E 's@^.*\"countryCode\" *: *\"([A-Z][A-Z])\".*$@\\1@'";
static char pattern4[] = /* db-ip.com  */
   "curl https://api.db-ip.com/v2/free/'%s' 2> /dev/null | grep countryCode | "
   "sed -E 's@^[^a-zA-Z]*countryCode[^a-zA-Z]+([A-Z][A-Z])[^a-zA-Z]*$@\\1@'";

char *patterns[] = {pattern1, pattern2, pattern3, pattern4};

/* To avoid any possibility of spoofing the IP address and thereby perhaps
   enabling code injection or similar nasty things. */
void sanitize_IP (char *IP)
{
   for (char *p = IP; *p; p++)
      if (*p != '.' && *p != ':' && !isxdigit(*p))
         *p = '-';
}

int IP2cntr (char *IPadress, char ISO_country[3], FILE *fperr)
{
   char command[sizeof pattern4 + /* Room for IP address, incl. IPv6 */ 8*4+7*1+1];
   FILE *pip;
   /* Size of the array ISO_country isn't known at runtime, so sizeof wouldn't work.
      I set the constant to the size minus 1, so not cointing the null byte. */
   const size_t netsize = 2;

   sanitize_IP(IPadress);

   for (int i = 0; i < sizeof patterns / sizeof patterns[0]; i++)
   {
      sprintf(command, patterns[i], IPadress);
      #ifdef DEBUG
      fprintf(fperr, "\nLine %3d in %s, index %d: the command for popen(3) is:\n%s\n",
         __LINE__, __FILE__, i + 1, command);
      #endif

      pip = popen(command, "r");
      if (!pip)
         return 1;
      memset(ISO_country, '\0', netsize + 1);
      if (fread(ISO_country, 1, netsize, pip) != netsize)
      {
         pclose(pip);
         return 2;
      }
      pclose(pip);

      #ifdef DEBUG
      fprintf(fperr, "\nLine %3d in %s, index %d: resulting country code is: %s\n",
         __LINE__, __FILE__, i + 1, ISO_country);
      #endif

      if (isascii(ISO_country[0]) && isupper(ISO_country[0]) &&
          isascii(ISO_country[1]) && isupper(ISO_country[1]))
         return 0;
   }
   return 3;
}

#if 0
/* =========================================================================
	21 November 2025: I no longer use Maxmind.com’s database and library,
	but online internet commands instead. For an explanation see
	http://rhar.info/sfreview/IP2cntry.htm
   ========================================================================*/

#include <stdio.h>
#include <string.h>
#include <maxminddb.h>
#include "IP2cntr.h"

static char *DatabasePath =
   "/var/db/maxmind/GeoLite2-Country/GeoLite2-Country.mmdb";

int IP2cntr (char *IPadress, char ISO_country[3], FILE *fperr)
{
   MMDB_s mmdb;
   int status, gai_error, mmdb_error, retval = 0;
   MMDB_lookup_result_s result;
   MMDB_entry_data_s entry_data;

   strcpy(ISO_country, "??");

   status = MMDB_open(DatabasePath, MMDB_MODE_MMAP, &mmdb);
   if (status != MMDB_SUCCESS)
   {
      if (fperr)
      {
         fprintf(fperr, "\nCould not open Country Database\n%s\n%s\n",
            DatabasePath, MMDB_strerror(status));
      }
      retval = 1;
      return retval;
   }
   result = MMDB_lookup_string(&mmdb, IPadress, &gai_error, &mmdb_error);
   if (gai_error != 0)
   {
      if (fperr)
      {
         fprintf(fperr, "\nGai-error looking up IP\n%s\n", MMDB_strerror(gai_error));
      }
      retval = 2;
      goto close_and_end;
   }
   if (mmdb_error != MMDB_SUCCESS)
   {
      if (fperr)
      {
         fprintf(fperr, "\nMmdb-error looking up IP address\n%s\n", MMDB_strerror(mmdb_error));
      }
      retval = 3;
      goto close_and_end;
   }
   if (!result.found_entry)
   {
      if (fperr)
      {
         fprintf(fperr, "\nIP adress not found\n%s\n", MMDB_strerror(mmdb_error));
      }
      retval = 4;
      goto close_and_end;
   }
   else
   {
      status = MMDB_get_value(&result.entry, &entry_data, "country", "iso_code", NULL);
      if (status != MMDB_SUCCESS)
      {
         if (fperr)
         {
            fprintf(fperr, "\nCould not get value\n%s\n", MMDB_strerror(status));
         }
         retval = 5;
         goto close_and_end;
      }
      if (entry_data.has_data && entry_data.type == MMDB_DATA_TYPE_UTF8_STRING)
      {
         sprintf(ISO_country, "%.*s",
            entry_data.data_size <= 2 ? entry_data.data_size : 2,
            entry_data.utf8_string);
      }
   }

   close_and_end: MMDB_close(&mmdb);

   return retval;
}
#endif