/***************************************************************************
 * getnameinfo.c -- A **PARTIAL** implementation of the getnameinfo(3)     *
 * host resolution call.  In particular, IPv6 is not supported and neither *
 * are some of the flags.  Service "names" are always returned as decimal  *
 * port numbers.                                                           *
 *                                                                         *
 ***********************IMPORTANT NMAP LICENSE TERMS************************
 *                                                                         *
 * The Nmap Security Scanner is (C) 1996-2020 Insecure.Com LLC ("The Nmap  *
 * Project"). Nmap is also a registered trademark of the Nmap Project.     *
 *                                                                         *
 * This program is distributed under the terms of the Nmap Public Source   *
 * License (NPSL). The exact license text applying to a particular Nmap    *
 * release or source code control revision is contained in the LICENSE     *
 * file distributed with that version of Nmap or source code control       *
 * revision. More Nmap copyright/legal information is available from       *
 * https://nmap.org/book/man-legal.html, and further information on the    *
 * NPSL license itself can be found at https://nmap.org/npsl. This header  *
 * summarizes some key points from the Nmap license, but is no substitute  *
 * for the actual license text.                                            *
 *                                                                         *
 * Nmap is generally free for end users to download and use themselves,    *
 * including commercial use. It is available from https://nmap.org.        *
 *                                                                         *
 * The Nmap license generally prohibits companies from using and           *
 * redistributing Nmap in commercial products, but we sell a special Nmap  *
 * OEM Edition with a more permissive license and special features for     *
 * this purpose. See https://nmap.org/oem                                  *
 *                                                                         *
 * If you have received a written Nmap license agreement or contract       *
 * stating terms other than these (such as an Nmap OEM license), you may   *
 * choose to use and redistribute Nmap under those terms instead.          *
 *                                                                         *
 * The official Nmap Windows builds include the Npcap software             *
 * (https://npcap.org) for packet capture and transmission. It is under    *
 * separate license terms which forbid redistribution without special      *
 * permission. So the official Nmap Windows builds may not be              *
 * redistributed without special permission (such as an Nmap OEM           *
 * license).                                                               *
 *                                                                         *
 * Source is provided to this software because we believe users have a     *
 * right to know exactly what a program is going to do before they run it. *
 * This also allows you to audit the software for security holes.          *
 *                                                                         *
 * Source code also allows you to port Nmap to new platforms, fix bugs,    *
 * and add new features.  You are highly encouraged to submit your         *
 * changes as a Github PR or by email to the dev@nmap.org mailing list     *
 * for possible incorporation into the main distribution. Unless you       *
 * specify otherwise, it is understood that you are offering us very       *
 * broad rights to use your submissions as described in the Nmap Public    *
 * Source License Contributor Agreement. This is important because we      *
 * fund the project by selling licenses with various terms, and also       *
 * because the inability to relicense code has caused devastating          *
 * problems for other Free Software projects (such as KDE and NASM).       *
 *                                                                         *
 * The free version of Nmap is distributed in the hope that it will be     *
 * useful, but WITHOUT ANY WARRANTY; without even the implied warranty of  *
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. Warranties,        *
 * indemnification and commercial support are all available through the    *
 * Npcap OEM program--see https://nmap.org/oem.                            *
 *                                                                         *
 ***************************************************************************/

/* $Id: getnameinfo.c 38085 2020-10-05 23:00:30Z dmiller $ */
#include "nbase.h"

#if HAVE_NETDB_H
#include <netdb.h>
#endif
#include <assert.h>
#include <stdio.h>
#if HAVE_SYS_SOCKET_H
#include <sys/socket.h>
#endif
#if HAVE_NETINET_IN_H
#include <netinet/in.h>
#endif
#if HAVE_ARPA_INET_H
#include <arpa/inet.h>
#endif

int getnameinfo(const struct sockaddr *sa, size_t salen,
                char *host, size_t hostlen,
                char *serv, size_t servlen, int flags) {

  struct sockaddr_in *sin = (struct sockaddr_in *)sa;
  struct hostent *he;

  if (sin->sin_family != AF_INET || salen != sizeof(struct sockaddr_in))
    return EAI_FAMILY;

  if (serv != NULL) {
    Snprintf(serv, servlen, "%d", ntohs(sin->sin_port));
    return 0;
  }

  if (host) {
    if (flags & NI_NUMERICHOST) {
      Strncpy(host, inet_ntoa(sin->sin_addr), hostlen);
      return 0;
    } else {
      he = gethostbyaddr((char *)&sin->sin_addr, sizeof(struct in_addr),
                         AF_INET);
      if (he == NULL) {
        if (flags & NI_NAMEREQD)
          return EAI_NONAME;

        Strncpy(host, inet_ntoa(sin->sin_addr), hostlen);
        return 0;
      }

      assert(he->h_name);
      Strncpy(host, he->h_name, hostlen);
      return 0;
    }
  }
  return 0;
}
