/* MIT License
 *
 * Copyright (c) 2005, 2013 Dominick Meglio
 *
 * Permission is hereby granted, free of charge, to any person obtaining a copy
 * of this software and associated documentation files (the "Software"), to deal
 * in the Software without restriction, including without limitation the rights
 * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
 * copies of the Software, and to permit persons to whom the Software is
 * furnished to do so, subject to the following conditions:
 *
 * The above copyright notice and this permission notice (including the next
 * paragraph) shall be included in all copies or substantial portions of the
 * Software.
 *
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
 * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
 * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
 * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
 * SOFTWARE.
 *
 * SPDX-License-Identifier: MIT
 */
#include "ares_setup.h"

#ifdef HAVE_GETSERVBYPORT_R
#  if !defined(GETSERVBYPORT_R_ARGS) || (GETSERVBYPORT_R_ARGS < 4) || \
    (GETSERVBYPORT_R_ARGS > 6)
#    error "you MUST specify a valid number of arguments for getservbyport_r"
#  endif
#endif

#ifdef HAVE_NETINET_IN_H
#  include <netinet/in.h>
#endif
#ifdef HAVE_NETDB_H
#  include <netdb.h>
#endif
#ifdef HAVE_ARPA_INET_H
#  include <arpa/inet.h>
#endif

#include "ares_nameser.h"

#ifdef HAVE_NET_IF_H
#  include <net/if.h>
#endif
#if defined(USE_WINSOCK) && defined(HAVE_IPHLPAPI_H)
#  include <iphlpapi.h>
#endif

#include "ares.h"
#include "ares_ipv6.h"
#include "ares_private.h"

struct nameinfo_query {
  ares_nameinfo_callback callback;
  void                  *arg;

  union {
    struct sockaddr_in  addr4;
    struct sockaddr_in6 addr6;
  } addr;

  int          family;
  unsigned int flags;
  size_t       timeouts;
};

#ifdef HAVE_STRUCT_SOCKADDR_IN6_SIN6_SCOPE_ID
#  define IPBUFSIZ \
    (sizeof("ffff:ffff:ffff:ffff:ffff:ffff:255.255.255.255") + IF_NAMESIZE)
#else
#  define IPBUFSIZ (sizeof("ffff:ffff:ffff:ffff:ffff:ffff:255.255.255.255"))
#endif

static void  nameinfo_callback(void *arg, int status, int timeouts,
                               struct hostent *host);
static char *lookup_service(unsigned short port, unsigned int flags, char *buf,
                            size_t buflen);
#ifdef HAVE_STRUCT_SOCKADDR_IN6_SIN6_SCOPE_ID
static void append_scopeid(const struct sockaddr_in6 *addr6,
                           unsigned int scopeid, char *buf, size_t buflen);
#endif
static char *ares_striendstr(const char *s1, const char *s2);

static void  ares_getnameinfo_int(ares_channel_t        *channel,
                                  const struct sockaddr *sa,
                                  ares_socklen_t salen, int flags_int,
                                  ares_nameinfo_callback callback, void *arg)
{
  const struct sockaddr_in  *addr  = NULL;
  const struct sockaddr_in6 *addr6 = NULL;
  struct nameinfo_query     *niquery;
  unsigned short             port  = 0;
  unsigned int               flags = (unsigned int)flags_int;

  /* Validate socket address family and length */
  if (sa && sa->sa_family == AF_INET &&
      salen >= (ares_socklen_t)sizeof(struct sockaddr_in)) {
    addr = CARES_INADDR_CAST(struct sockaddr_in *, sa);
    port = addr->sin_port;
  } else if (sa && sa->sa_family == AF_INET6 &&
             salen >= (ares_socklen_t)sizeof(struct sockaddr_in6)) {
    addr6 = CARES_INADDR_CAST(struct sockaddr_in6 *, sa);
    port  = addr6->sin6_port;
  } else {
    callback(arg, ARES_ENOTIMP, 0, NULL, NULL);
    return;
  }

  /* If neither, assume they want a host */
  if (!(flags & ARES_NI_LOOKUPSERVICE) && !(flags & ARES_NI_LOOKUPHOST)) {
    flags |= ARES_NI_LOOKUPHOST;
  }

  /* All they want is a service, no need for DNS */
  if ((flags & ARES_NI_LOOKUPSERVICE) && !(flags & ARES_NI_LOOKUPHOST)) {
    char  buf[33];
    char *service;

    service =
      lookup_service((unsigned short)(port & 0xffff), flags, buf, sizeof(buf));
    callback(arg, ARES_SUCCESS, 0, NULL, service);
    return;
  }

  /* They want a host lookup */
  if (flags & ARES_NI_LOOKUPHOST) {
    /* A numeric host can be handled without DNS */
    if (flags & ARES_NI_NUMERICHOST) {
      char  ipbuf[IPBUFSIZ];
      char  srvbuf[33];
      char *service = NULL;
      ipbuf[0]      = 0;

      /* Specifying not to lookup a host, but then saying a host
       * is required has to be illegal.
       */
      if (flags & ARES_NI_NAMEREQD) {
        callback(arg, ARES_EBADFLAGS, 0, NULL, NULL);
        return;
      }
      if (sa->sa_family == AF_INET6) {
        ares_inet_ntop(AF_INET6, &addr6->sin6_addr, ipbuf, IPBUFSIZ);
        /* If the system supports scope IDs, use it */
#ifdef HAVE_STRUCT_SOCKADDR_IN6_SIN6_SCOPE_ID
        append_scopeid(addr6, flags, ipbuf, sizeof(ipbuf));
#endif
      } else {
        ares_inet_ntop(AF_INET, &addr->sin_addr, ipbuf, IPBUFSIZ);
      }
      /* They also want a service */
      if (flags & ARES_NI_LOOKUPSERVICE) {
        service = lookup_service((unsigned short)(port & 0xffff), flags, srvbuf,
                                 sizeof(srvbuf));
      }
      callback(arg, ARES_SUCCESS, 0, ipbuf, service);
      return;
    } else {
      /* This is where a DNS lookup becomes necessary */
      niquery = ares_malloc(sizeof(struct nameinfo_query));
      if (!niquery) {
        callback(arg, ARES_ENOMEM, 0, NULL, NULL);
        return;
      }
      niquery->callback = callback;
      niquery->arg      = arg;
      niquery->flags    = flags;
      niquery->timeouts = 0;
      if (sa->sa_family == AF_INET) {
        niquery->family = AF_INET;
        memcpy(&niquery->addr.addr4, addr, sizeof(niquery->addr.addr4));
        ares_gethostbyaddr(channel, &addr->sin_addr, sizeof(struct in_addr),
                           AF_INET, nameinfo_callback, niquery);
      } else {
        niquery->family = AF_INET6;
        memcpy(&niquery->addr.addr6, addr6, sizeof(niquery->addr.addr6));
        ares_gethostbyaddr(channel, &addr6->sin6_addr,
                           sizeof(struct ares_in6_addr), AF_INET6,
                           nameinfo_callback, niquery);
      }
    }
  }
}

void ares_getnameinfo(ares_channel_t *channel, const struct sockaddr *sa,
                      ares_socklen_t salen, int flags_int,
                      ares_nameinfo_callback callback, void *arg)
{
  if (channel == NULL) {
    return;
  }

  ares__channel_lock(channel);
  ares_getnameinfo_int(channel, sa, salen, flags_int, callback, arg);
  ares__channel_unlock(channel);
}

static void nameinfo_callback(void *arg, int status, int timeouts,
                              struct hostent *host)
{
  struct nameinfo_query *niquery = (struct nameinfo_query *)arg;
  char                   srvbuf[33];
  char                  *service = NULL;

  niquery->timeouts += (size_t)timeouts;
  if (status == ARES_SUCCESS) {
    /* They want a service too */
    if (niquery->flags & ARES_NI_LOOKUPSERVICE) {
      if (niquery->family == AF_INET) {
        service = lookup_service(niquery->addr.addr4.sin_port, niquery->flags,
                                 srvbuf, sizeof(srvbuf));
      } else {
        service = lookup_service(niquery->addr.addr6.sin6_port, niquery->flags,
                                 srvbuf, sizeof(srvbuf));
      }
    }
    /* NOFQDN means we have to strip off the domain name portion.  We do
       this by determining our own domain name, then searching the string
       for this domain name and removing it.
     */
#ifdef HAVE_GETHOSTNAME
    if (niquery->flags & ARES_NI_NOFQDN) {
      char        buf[255];
      const char *domain;
      gethostname(buf, 255);
      if ((domain = strchr(buf, '.')) != NULL) {
        char *end = ares_striendstr(host->h_name, domain);
        if (end) {
          *end = 0;
        }
      }
    }
#endif
    niquery->callback(niquery->arg, ARES_SUCCESS, (int)niquery->timeouts,
                      host->h_name, service);
    ares_free(niquery);
    return;
  }
  /* We couldn't find the host, but it's OK, we can use the IP */
  else if (status == ARES_ENOTFOUND && !(niquery->flags & ARES_NI_NAMEREQD)) {
    char ipbuf[IPBUFSIZ];
    if (niquery->family == AF_INET) {
      ares_inet_ntop(AF_INET, &niquery->addr.addr4.sin_addr, ipbuf, IPBUFSIZ);
    } else {
      ares_inet_ntop(AF_INET6, &niquery->addr.addr6.sin6_addr, ipbuf, IPBUFSIZ);
#ifdef HAVE_STRUCT_SOCKADDR_IN6_SIN6_SCOPE_ID
      append_scopeid(&niquery->addr.addr6, niquery->flags, ipbuf,
                     sizeof(ipbuf));
#endif
    }
    /* They want a service too */
    if (niquery->flags & ARES_NI_LOOKUPSERVICE) {
      if (niquery->family == AF_INET) {
        service = lookup_service(niquery->addr.addr4.sin_port, niquery->flags,
                                 srvbuf, sizeof(srvbuf));
      } else {
        service = lookup_service(niquery->addr.addr6.sin6_port, niquery->flags,
                                 srvbuf, sizeof(srvbuf));
      }
    }
    niquery->callback(niquery->arg, ARES_SUCCESS, (int)niquery->timeouts, ipbuf,
                      service);
    ares_free(niquery);
    return;
  }
  niquery->callback(niquery->arg, status, (int)niquery->timeouts, NULL, NULL);
  ares_free(niquery);
}

static char *lookup_service(unsigned short port, unsigned int flags, char *buf,
                            size_t buflen)
{
  const char     *proto;
  struct servent *sep;
#ifdef HAVE_GETSERVBYPORT_R
  struct servent se;
#endif
  char        tmpbuf[4096];
  const char *name;
  size_t      name_len;

  if (port) {
    if (flags & ARES_NI_NUMERICSERV) {
      sep = NULL;
    } else {
      if (flags & ARES_NI_UDP) {
        proto = "udp";
      } else if (flags & ARES_NI_SCTP) {
        proto = "sctp";
      } else if (flags & ARES_NI_DCCP) {
        proto = "dccp";
      } else {
        proto = "tcp";
      }
#ifdef HAVE_GETSERVBYPORT_R
      memset(&se, 0, sizeof(se));
      sep = &se;
      memset(tmpbuf, 0, sizeof(tmpbuf));
#  if GETSERVBYPORT_R_ARGS == 6
      if (getservbyport_r(port, proto, &se, (void *)tmpbuf, sizeof(tmpbuf),
                          &sep) != 0) {
        sep = NULL; /* LCOV_EXCL_LINE: buffer large so this never fails */
      }
#  elif GETSERVBYPORT_R_ARGS == 5
      sep = getservbyport_r(port, proto, &se, (void *)tmpbuf, sizeof(tmpbuf));
#  elif GETSERVBYPORT_R_ARGS == 4
      if (getservbyport_r(port, proto, &se, (void *)tmpbuf) != 0) {
        sep = NULL;
      }
#  else
      /* Lets just hope the OS uses TLS! */
      sep = getservbyport(port, proto);
#  endif
#else
      /* Lets just hope the OS uses TLS! */
#  if (defined(NETWARE) && !defined(__NOVELL_LIBC__))
      sep = getservbyport(port, (char *)proto);
#  else
      sep = getservbyport(port, proto);
#  endif
#endif
    }
    if (sep && sep->s_name) {
      /* get service name */
      name = sep->s_name;
    } else {
      /* get port as a string */
      snprintf(tmpbuf, sizeof(tmpbuf), "%u", (unsigned int)ntohs(port));
      name = tmpbuf;
    }
    name_len = ares_strlen(name);
    if (name_len < buflen) {
      /* return it if buffer big enough */
      memcpy(buf, name, name_len + 1);
    } else {
      /* avoid reusing previous one */
      buf[0] = '\0'; /* LCOV_EXCL_LINE: no real service names are too big */
    }
    return buf;
  }
  buf[0] = '\0';
  return NULL;
}

#ifdef HAVE_STRUCT_SOCKADDR_IN6_SIN6_SCOPE_ID
static void append_scopeid(const struct sockaddr_in6 *addr6, unsigned int flags,
                           char *buf, size_t buflen)
{
#  ifdef HAVE_IF_INDEXTONAME
  int is_ll;
  int is_mcll;
#  endif
  char   tmpbuf[IF_NAMESIZE + 2];
  size_t bufl;

  tmpbuf[0] = '%';

#  ifdef HAVE_IF_INDEXTONAME
  is_ll   = IN6_IS_ADDR_LINKLOCAL(&addr6->sin6_addr);
  is_mcll = IN6_IS_ADDR_MC_LINKLOCAL(&addr6->sin6_addr);
  if ((flags & ARES_NI_NUMERICSCOPE) || (!is_ll && !is_mcll)) {
    snprintf(&tmpbuf[1], sizeof(tmpbuf) - 1, "%lu",
             (unsigned long)addr6->sin6_scope_id);
  } else {
    if (if_indextoname(addr6->sin6_scope_id, &tmpbuf[1]) == NULL) {
      snprintf(&tmpbuf[1], sizeof(tmpbuf) - 1, "%lu",
               (unsigned long)addr6->sin6_scope_id);
    }
  }
#  else
  snprintf(&tmpbuf[1], sizeof(tmpbuf) - 1, "%lu",
           (unsigned long)addr6->sin6_scope_id);
  (void)flags;
#  endif
  tmpbuf[IF_NAMESIZE + 1] = '\0';
  bufl                    = ares_strlen(buf);

  if (bufl + ares_strlen(tmpbuf) < buflen) {
    /* only append the scopeid string if it fits in the target buffer */
    ares_strcpy(&buf[bufl], tmpbuf, buflen - bufl);
  }
}
#endif

/* Determines if s1 ends with the string in s2 (case-insensitive) */
static char *ares_striendstr(const char *s1, const char *s2)
{
  const char *c1;
  const char *c2;
  const char *c1_begin;
  int         lo1;
  int         lo2;
  size_t      s1_len = ares_strlen(s1);
  size_t      s2_len = ares_strlen(s2);

  if (s1 == NULL || s2 == NULL) {
    return NULL;
  }

  /* If the substr is longer than the full str, it can't match */
  if (s2_len > s1_len) {
    return NULL;
  }

  /* Jump to the end of s1 minus the length of s2 */
  c1_begin = s1 + s1_len - s2_len;
  c1       = c1_begin;
  c2       = s2;
  while (c2 < s2 + s2_len) {
    lo1 = TOLOWER(*c1);
    lo2 = TOLOWER(*c2);
    if (lo1 != lo2) {
      return NULL;
    } else {
      c1++;
      c2++;
    }
  }
  /* Cast off const */
  return (char *)((size_t)c1_begin);
}

ares_bool_t ares__is_onion_domain(const char *name)
{
  if (ares_striendstr(name, ".onion")) {
    return ARES_TRUE;
  }

  if (ares_striendstr(name, ".onion.")) {
    return ARES_TRUE;
  }

  return ARES_FALSE;
}
