/*-*- mode:c;indent-tabs-mode:nil;c-basic-offset:2;tab-width:8;coding:utf-8 -*-│
│vi: set net ft=c ts=2 sts=2 sw=2 fenc=utf-8                                :vi│
╞══════════════════════════════════════════════════════════════════════════════╡
│ Copyright 2020 Justine Alexandra Roberts Tunney                              │
│                                                                              │
│ Permission to use, copy, modify, and/or distribute this software for         │
│ any purpose with or without fee is hereby granted, provided that the         │
│ above copyright notice and this permission notice appear in all copies.      │
│                                                                              │
│ THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL                │
│ WARRANTIES WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED                │
│ WARRANTIES OF MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE             │
│ AUTHOR BE LIABLE FOR ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL         │
│ DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR        │
│ PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE OR OTHER               │
│ TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR             │
│ PERFORMANCE OF THIS SOFTWARE.                                                │
╚─────────────────────────────────────────────────────────────────────────────*/
#include "libc/calls/calls.h"
#include "libc/dns/dns.h"
#include "libc/dns/hoststxt.h"
#include "libc/dns/resolvconf.h"
#include "libc/dns/servicestxt.h"
#include "libc/fmt/conv.h"
#include "libc/macros.internal.h"
#include "libc/mem/gc.h"
#include "libc/mem/mem.h"
#include "libc/sock/sock.h"
#include "libc/str/str.h"
#include "libc/sysv/consts/af.h"
#include "libc/sysv/consts/inaddr.h"
#include "libc/sysv/consts/sock.h"
#include "libc/sysv/errfuns.h"

/**
 * Resolves address for internet name.
 *
 * @param name is either an ip string or a utf-8 hostname
 * @param service is the port number as a string
 * @param hints may be passed to specialize behavior (optional)
 * @param res receives a pointer that must be freed with freeaddrinfo(),
 *     and won't be modified if non-zero is returned
 * @return 0 on success or EAI_xxx value
 * @threadsafe
 */
int getaddrinfo(const char *name, const char *service,
                const struct addrinfo *hints, struct addrinfo **res) {
  int rc, port;
  const char *canon;
  struct addrinfo *ai;
  char proto[32];
  port = 0;
  if (!name && !service) {
    return EAI_NONAME;
  }
  if (!name && hints && (hints->ai_flags & AI_CANONNAME)) {
    return EAI_BADFLAGS;
  }
  if (service && (port = parseport(service)) == -1) {
    if (hints && hints->ai_socktype == SOCK_STREAM) {
      strcpy(proto, "tcp");
    } else if (hints && hints->ai_socktype == SOCK_DGRAM) {
      strcpy(proto, "udp");
    } else {  // ai_socktype == 0
      strcpy(proto, "");
    }
    if ((port = LookupServicesByName(service, proto, sizeof(proto), NULL, 0,
                                     NULL)) == -1) {
      return EAI_NONAME;
    }
  }
  if (!(ai = newaddrinfo(port))) {
    return EAI_MEMORY;
  }
  if (service) ai->ai_addr4->sin_port = htons(port);
  if (hints) {
    ai->ai_socktype = hints->ai_socktype;
    ai->ai_protocol = hints->ai_protocol;
  }
  if (!name) {
    ai->ai_addr4->sin_addr.s_addr =
        (hints && (hints->ai_flags & AI_PASSIVE) == AI_PASSIVE)
            ? htonl(INADDR_ANY)
            : htonl(INADDR_LOOPBACK);
    *res = ai;
    return 0;
  }
  if (inet_pton(AF_INET, name, &ai->ai_addr4->sin_addr.s_addr) == 1) {
    *res = ai;
    return 0;
  } else if (hints && (hints->ai_flags & AI_NUMERICHOST) == AI_NUMERICHOST) {
    freeaddrinfo(ai);
    return EAI_NONAME;
  } else if (ResolveHostsTxt(GetHostsTxt(), AF_INET, name, ai->ai_addr,
                             sizeof(ai->ai_addr4), &canon) > 0) {
    strlcpy(ai->ai_canonname, canon, DNS_NAME_MAX + 1);
    *res = ai;
    return 0;
  } else {
    rc = ResolveDns(GetResolvConf(), AF_INET, name, ai->ai_addr,
                    sizeof(ai->ai_addr4));
    if (rc > 0) {
      *res = ai;
      return 0;
    }
    freeaddrinfo(ai);
    if (rc == 0) {
      return EAI_NONAME;
    } else {
      return EAI_SYSTEM;
    }
  }
}