/*
 * Copyright (C) 2000-2003 Damien Miller.  All rights reserved.
 * Copyright (C) 1999 WIDE Project.  All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 * 3. Neither the name of the project nor the names of its contributors
 *    may be used to endorse or promote products derived from this software
 *    without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE PROJECT AND CONTRIBUTORS ``AS IS'' AND
 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 * ARE DISCLAIMED.  IN NO EVENT SHALL THE PROJECT OR CONTRIBUTORS BE LIABLE
 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
 * SUCH DAMAGE.
 */

/*
 * Pseudo-implementation of RFC2553 name / address resolution functions
 *
 * But these functions are not implemented correctly. The minimum subset
 * is implemented for ssh use only. For example, this routine assumes
 * that ai_family is AF_INET. Don't use it for another purpose.
 */
#include "tclInt.h"

TCL_DECLARE_MUTEX(netdbMutex)

#ifndef HAVE_GETNAMEINFO
#ifndef HAVE_STRLCPY
static size_t
strlcpy(char *dst, const char *src, size_t siz)
{
        char *d = dst;
        const char *s = src;
        size_t n = siz;

        /* Copy as many bytes as will fit */
        if (n != 0 && --n != 0) {
                do {
                        if ((*d++ = *s++) == 0)
                                break;
                } while (--n != 0);
        }

        /* Not enough room in dst, add NUL and traverse rest of src */
        if (n == 0) {
                if (siz != 0)
                        *d = '\0';              /* NUL-terminate dst */
                while (*s++)
                        ;
        }

        return(s - src - 1);    /* count does not include NUL */
}
#endif

int fake_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 *hp;
	char tmpserv[16];

	if (sa->sa_family != AF_UNSPEC && sa->sa_family != AF_INET)
		return (EAI_FAMILY);
	if (serv != NULL) {
		snprintf(tmpserv, sizeof(tmpserv), "%d", ntohs(sin->sin_port));
		if (strlcpy(serv, tmpserv, servlen) >= servlen)
			return (EAI_MEMORY);
	}

	if (host != NULL) {
		if (flags & NI_NUMERICHOST) {
			size_t len;
			Tcl_MutexLock(&netdbMutex);
			len = strlcpy(host, inet_ntoa(sin->sin_addr), hostlen);
			Tcl_MutexUnlock(&netdbMutex);
			if (len >= hostlen) {
				return (EAI_MEMORY);
			} else {
				return (0);
			}
		} else {
			int ret;
			Tcl_MutexLock(&netdbMutex);
			hp = gethostbyaddr((char *)&sin->sin_addr,
			    sizeof(struct in_addr), AF_INET);
			if (hp == NULL) {
				ret = EAI_NODATA;
			} else if (strlcpy(host, hp->h_name, hostlen)
				   >= hostlen) {
				ret = EAI_MEMORY;
			} else {
				ret = 0;
			}
			Tcl_MutexUnlock(&netdbMutex);
			return ret;
		}
	}
	return (0);
}
#endif /* !HAVE_GETNAMEINFO */

#ifndef HAVE_GAI_STRERROR
const char *
fake_gai_strerror(int err)
{
	switch (err) {
	case EAI_NODATA:
		return ("no address associated with name");
	case EAI_MEMORY:
		return ("memory allocation failure.");
	case EAI_NONAME:
		return ("nodename nor servname provided, or not known");
	case EAI_FAMILY:
		return ("ai_family not supported");
	default:
		return ("unknown/invalid error.");
	}
}
#endif /* !HAVE_GAI_STRERROR */

#ifndef HAVE_FREEADDRINFO
void
fake_freeaddrinfo(struct addrinfo *ai)
{
	struct addrinfo *next;

	for(; ai != NULL;) {
		next = ai->ai_next;
		free(ai);
		ai = next;
	}
}
#endif /* !HAVE_FREEADDRINFO */

#ifndef HAVE_GETADDRINFO
static struct
addrinfo *malloc_ai(int port, u_long addr, const struct addrinfo *hints)
{
	struct addrinfo *ai;

	ai = malloc(sizeof(*ai) + sizeof(struct sockaddr_in));
	if (ai == NULL)
		return (NULL);

	memset(ai, '\0', sizeof(*ai) + sizeof(struct sockaddr_in));

	ai->ai_addr = (struct sockaddr *)(ai + 1);
	/* XXX -- ssh doesn't use sa_len */
	ai->ai_addrlen = sizeof(struct sockaddr_in);
	ai->ai_addr->sa_family = ai->ai_family = AF_INET;

	((struct sockaddr_in *)(ai)->ai_addr)->sin_port = port;
	((struct sockaddr_in *)(ai)->ai_addr)->sin_addr.s_addr = addr;

	/* XXX: the following is not generally correct, but does what we want */
	if (hints->ai_socktype)
		ai->ai_socktype = hints->ai_socktype;
	else
		ai->ai_socktype = SOCK_STREAM;

	if (hints->ai_protocol)
		ai->ai_protocol = hints->ai_protocol;

	return (ai);
}

int
fake_getaddrinfo(const char *hostname, const char *servname,
    const struct addrinfo *hints, struct addrinfo **res)
{
	struct hostent *hp;
	struct servent *sp;
	struct in_addr in;
	int i;
	long int port;
	u_long addr;

	port = 0;
	if (hints && hints->ai_family != AF_UNSPEC &&
	    hints->ai_family != AF_INET)
		return (EAI_FAMILY);
	if (servname != NULL) {
		char *cp;

		port = strtol(servname, &cp, 10);
		if (port > 0 && port <= 65535 && *cp == '\0')
			port = htons((unsigned short)port);
		else if ((sp = getservbyname(servname, NULL)) != NULL)
			port = sp->s_port;
		else
			port = 0;
	}

	if (hints && hints->ai_flags & AI_PASSIVE) {
		addr = htonl(0x00000000);
		if (hostname && inet_aton(hostname, &in) != 0)
			addr = in.s_addr;
		*res = malloc_ai(port, addr, hints);
		if (*res == NULL)
			return (EAI_MEMORY);
		return (0);
	}

	if (!hostname) {
		*res = malloc_ai(port, htonl(0x7F000001), hints);
		if (*res == NULL)
			return (EAI_MEMORY);
		return (0);
	}

	if (inet_aton(hostname, &in)) {
		*res = malloc_ai(port, in.s_addr, hints);
		if (*res == NULL)
			return (EAI_MEMORY);
		return (0);
	}

	/* Don't try DNS if AI_NUMERICHOST is set */
	if (hints && hints->ai_flags & AI_NUMERICHOST)
		return (EAI_NONAME);

	Tcl_MutexLock(&netdbMutex);
	hp = gethostbyname(hostname);
	if (hp && hp->h_name && hp->h_name[0] && hp->h_addr_list[0]) {
		struct addrinfo *cur, *prev;

		cur = prev = *res = NULL;
		for (i = 0; hp->h_addr_list[i]; i++) {
			struct in_addr *in = (struct in_addr *)hp->h_addr_list[i];

			cur = malloc_ai(port, in->s_addr, hints);
			if (cur == NULL) {
				if (*res != NULL)
					freeaddrinfo(*res);
				Tcl_MutexUnlock(&netdbMutex);
				return (EAI_MEMORY);
			}
			if (prev)
				prev->ai_next = cur;
			else
				*res = cur;

			prev = cur;
		}
		Tcl_MutexUnlock(&netdbMutex);
		return (0);
	}
	Tcl_MutexUnlock(&netdbMutex);
	return (EAI_NODATA);
}
#endif /* !HAVE_GETADDRINFO */
