path: root/e-util/e-host-utils.c

/* -*- Mode: C; indent-tabs-mode: t; c-basic-offset: 8; tab-width: 8 -*- */
/* e-host-utils.c
 *
 * Copyright (C) 2001  Ximian, Inc.
 *
 * This program is free software; you can redistribute it and/or
 * modify it under the terms of version 2 of the GNU General Public
 * License as published by the Free Software Foundation.
 *
 * This program 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.  See the GNU
 * General Public License for more details.
 *
 * You should have received a copy of the GNU General Public
 * License along with this program; if not, write to the
 * Free Software Foundation, Inc., 59 Temple Place - Suite 330,
 * Boston, MA 02111-1307, USA.
 *
 * Author: Chris Toshok, Jeffrey Stedfast
 */


#ifdef HAVE_CONFIG_H
#include <config.h>
#endif

#include <glib.h>

#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <sys/types.h>
#include <sys/socket.h>
#include <netinet/in.h>
#include <arpa/inet.h>
#include <errno.h>

#include "e-host-utils.h"


#if !defined (HAVE_GETHOSTBYNAME_R) || !defined (HAVE_GETHOSTBYADDR_R)
G_LOCK_DEFINE_STATIC (gethost_mutex);
#endif


#define ALIGN(x) (((x) + (sizeof (char *) - 1)) & ~(sizeof (char *) - 1))

#define GETHOST_PROCESS(h, host, buf, buflen, herr) G_STMT_START {     \
    int num_aliases = 0, num_addrs = 0;                            \
    int req_length;                                                \
    char *p;                                                       \
    int i;                                                         \
                                                                   \
    /* check to make sure we have enough room in our buffer */     \
    req_length = 0;                                                \
    if (h->h_aliases) {                                            \
        for (i = 0; h->h_aliases[i]; i++)                      \
            req_length += strlen (h->h_aliases[i]) + 1;    \
        num_aliases = i;                                       \
    }                                                              \
                                                                   \
    if (h->h_addr_list) {                                          \
        for (i = 0; h->h_addr_list[i]; i++)                    \
            req_length += h->h_length;                     \
        num_addrs = i;                                         \
    }                                                              \
                                                                   \
    req_length += sizeof (char *) * (num_aliases + 1);             \
    req_length += sizeof (char *) * (num_addrs + 1);               \
    req_length += strlen (h->h_name) + 1;                          \
                                                                   \
    if (buflen < req_length) {                                     \
        *herr = ERANGE;                                        \
        G_UNLOCK (gethost_mutex);                              \
        return ERANGE;                                         \
    }                                                              \
                                                                   \
    /* we store the alias/addr pointers in the buffer */           \
        /* their addresses here. */                                    \
    p = buf;                                                       \
    if (num_aliases) {                                             \
        host->h_aliases = (char **) p;                         \
        p += sizeof (char *) * (num_aliases + 1);              \
    } else                                                         \
        host->h_aliases = NULL;                                \
                                                                       \
    if (num_addrs) {                                               \
        host->h_addr_list = (char **) p;                       \
        p += sizeof (char *) * (num_addrs + 1);                \
    } else                                                         \
        host->h_addr_list = NULL;                              \
                                                                   \
    /* copy the host name into the buffer */                       \
    host->h_name = p;                                              \
    strcpy (p, h->h_name);                                         \
    p += strlen (h->h_name) + 1;                                   \
    host->h_addrtype = h->h_addrtype;                              \
    host->h_length = h->h_length;                                  \
                                                                   \
    /* copy the aliases/addresses into the buffer */               \
        /* and assign pointers into the hostent */                     \
    *p = 0;                                                        \
    if (num_aliases) {                                             \
        for (i = 0; i < num_aliases; i++) {                    \
            strcpy (p, h->h_aliases[i]);                   \
            host->h_aliases[i] = p;                        \
            p += strlen (h->h_aliases[i]);                 \
        }                                                      \
        host->h_aliases[num_aliases] = NULL;                   \
    }                                                              \
                                                                   \
    if (num_addrs) {                                               \
        for (i = 0; i < num_addrs; i++) {                      \
            memcpy (p, h->h_addr_list[i], h->h_length);    \
            host->h_addr_list[i] = p;                      \
            p += h->h_length;                              \
        }                                                      \
        host->h_addr_list[num_addrs] = NULL;                   \
    }                                                              \
} G_STMT_END


#ifdef ENABLE_IPv6
/* some helpful utils for IPv6 lookups */
#define IPv6_BUFLEN_MIN  (sizeof (char *) * 3)

static int
ai_to_herr (int error)
{
    switch (error) {
    case EAI_NONAME:
    case EAI_FAIL:
        return HOST_NOT_FOUND;
        break;
    case EAI_SERVICE:
        return NO_DATA;
        break;
    case EAI_ADDRFAMILY:
        return NO_ADDRESS;
        break;
    case EAI_NODATA:
        return NO_DATA;
        break;
    case EAI_MEMORY:
        return ENOMEM;
        break;
    case EAI_AGAIN:
        return TRY_AGAIN;
        break;
    case EAI_SYSTEM:
        return errno;
        break;
    default:
        return NO_RECOVERY;
        break;
    }
}

#endif /* ENABLE_IPv6 */

/**
 * e_gethostbyname_r:
 * @name: the host to resolve
 * @host: a buffer pointing to a struct hostent to use for storage
 * @buf: a buffer to use for hostname storage
 * @buflen: the size of @buf
 * @herr: a pointer to a variable to store an error code in
 *
 * Resolves the hostname @name, in a hopefully-reentrant fashion.
 *
 * Return value: 0 on success, ERANGE if @buflen is too small,
 * "something else" otherwise (in which case *@herr will be set to
 * one of the gethostbyname() error codes).
 **/
int
e_gethostbyname_r (const char *name, struct hostent *host,
           char *buf, size_t buflen, int *herr)
{
#ifdef ENABLE_IPv6
    struct addrinfo hints, *res;
    int retval, len;
    char *addr;
    
    memset (&hints, 0, sizeof (struct addrinfo));
    hints.ai_flags = AI_CANONNAME;
    hints.ai_family = PF_UNSPEC;
    hints.ai_socktype = 0;
    hints.ai_protocol = 0;
    
    if ((retval = getaddrinfo (name, NULL, &hints, &res)) != 0) {
        *herr = ai_to_herr (retval);
        return -1;
    }
    
    len = ALIGN (strlen (res->ai_canonname) + 1);
    if (buflen < IPv6_BUFLEN_MIN + len + res->ai_addrlen + sizeof (char *))
        return ERANGE;
    
    /* h_name */
    strcpy (buf, res->ai_canonname);
    host->h_name = buf;
    buf += len;
    
    /* h_aliases */
    ((char **) buf)[0] = NULL;
    host->h_aliases = (char **) buf;
    buf += sizeof (char *);
    
    /* h_addrtype and h_length */
    host->h_length = res->ai_addrlen;
    if (res->ai_family == PF_INET6) {
        host->h_addrtype = AF_INET6;
        
        addr = (char *) &((struct sockaddr_in6 *) res->ai_addr)->sin6_addr;
    } else {
        host->h_addrtype = AF_INET;
        
        addr = (char *) &((struct sockaddr_in *) res->ai_addr)->sin_addr;
    }
    
    memcpy (buf, addr, host->h_length);
    addr = buf;
    buf += ALIGN (host->h_length);
    
    /* h_addr_list */
    ((char **) buf)[0] = addr;
    ((char **) buf)[1] = NULL;
    host->h_addr_list = (char **) buf;
    
    freeaddrinfo (res);
    
    return 0;
#else /* No support for IPv6 addresses */
#ifdef HAVE_GETHOSTBYNAME_R
#ifdef GETHOSTBYNAME_R_FIVE_ARGS
    if (gethostbyname_r (name, host, buf, buflen, herr))
        return 0;
    else
        return errno;
#else
    struct hostent *hp;
    int retval;
    
    retval = gethostbyname_r (name, host, buf, buflen, &hp, herr);
    if (hp != NULL)
        *herr = 0;
    return retval;
#endif
#else /* No support for gethostbyname_r */
    struct hostent *h;
    
    G_LOCK (gethost_mutex);
    
    h = gethostbyname (name);
    
    if (!h) {
        *herr = h_errno;
        G_UNLOCK (gethost_mutex);
        return -1;
    }
    
    GETHOST_PROCESS (h, host, buf, buflen, herr);
    
    G_UNLOCK (gethost_mutex);
    
    return 0;
#endif /* HAVE_GETHOSTBYNAME_R */
#endif /* ENABLE_IPv6 */
}


/**
 * e_gethostbyaddr_r:
 * @addr: the addr to resolve
 * @addrlen: address length
 * @type: AF type
 * @host: a buffer pointing to a struct hostent to use for storage
 * @buf: a buffer to use for hostname storage
 * @buflen: the size of @buf
 * @herr: a pointer to a variable to store an error code in
 *
 * Resolves the address @addr, in a hopefully-reentrant fashion.
 *
 * Return value: 0 on success, ERANGE if @buflen is too small,
 * "something else" otherwise (in which case *@herr will be set to
 * one of the gethostbyaddr() error codes).
 **/
int
e_gethostbyaddr_r (const char *addr, int addrlen, int type, struct hostent *host,
           char *buf, size_t buflen, int *herr)
{
#ifdef ENABLE_IPv6
    struct addrinfo hints, *res;
    const char *name;
    int retval, len;
    
    if ((name = inet_ntop (type, addr, buf, buflen)) == NULL) {
        if (errno == ENOSPC)
            return ERANGE;
        
        return -1;
    }
    
    memset (&hints, 0, sizeof (struct addrinfo));
    hints.ai_flags = AI_CANONNAME;
    hints.ai_family = type == AF_INET6 ? PF_INET6 : PF_INET;
    hints.ai_socktype = 0;
    hints.ai_protocol = 0;
    
    if ((retval = getaddrinfo (name, NULL, &hints, &res)) != 0) {
        *herr = ai_to_herr (retval);
        return -1;
    }
    
    /* If nodename is not null, and if requested by the AI_CANONNAME flag, the ai_canonname
     * field of the first returned addrinfo structure shall point to a null-terminated
     * string containing the canonical name corresponding to the input nodename; if the
     * canonical name is not available, then ai_canonname shall refer to the nodename
     * argument or a string with the same contents.
     *
     * Note: NetBSD seems to set res->ai_canonname to NULL in this case instead.
     */
    if (!res->ai_canonname || !strcmp (res->ai_canonname, name)) {
        *herr = HOST_NOT_FOUND;
        return -1;
    }
    
    len = ALIGN (strlen (res->ai_canonname) + 1);
    if (buflen < IPv6_BUFLEN_MIN + len + res->ai_addrlen + sizeof (char *))
        return ERANGE;
    
    /* h_name */
    strcpy (buf, res->ai_canonname);
    host->h_name = buf;
    buf += len;
    
    /* h_aliases */
    ((char **) buf)[0] = NULL;
    host->h_aliases = (char **) buf;
    buf += sizeof (char *);
    
    /* h_addrtype and h_length */
    host->h_length = res->ai_addrlen;
    if (res->ai_family == PF_INET6) {
        host->h_addrtype = AF_INET6;
        
        addr = (char *) &((struct sockaddr_in6 *) res->ai_addr)->sin6_addr;
    } else {
        host->h_addrtype = AF_INET;
        
        addr = (char *) &((struct sockaddr_in *) res->ai_addr)->sin_addr;
    }
    
    memcpy (buf, addr, host->h_length);
    addr = buf;
    buf += ALIGN (host->h_length);
    
    /* h_addr_list */
    ((char **) buf)[0] = addr;
    ((char **) buf)[1] = NULL;
    host->h_addr_list = (char **) buf;
    
    freeaddrinfo (res);
    
    return 0;
#else /* No support for IPv6 addresses */
#ifdef HAVE_GETHOSTBYADDR_R
#ifdef GETHOSTBYADDR_R_SEVEN_ARGS
    if (gethostbyaddr_r (addr, addrlen, type, host, buf, buflen, herr))
        return 0;
    else
        return errno;
#else
    struct hostent *hp;
    int retval;
    
    retval = gethostbyaddr_r (addr, addrlen, type, host, buf, buflen, &hp, herr);
    if (hp != NULL) {
        *herr = 0;
        retval = 0;
    } else if (retval == 0) {
        /* glibc 2.3.2 workaround - it seems that
         * gethostbyaddr_r will sometimes return 0 on fail and
         * fill @host with garbage strings from /etc/hosts
         * (failure to parse the file? who knows). Luckily, it
         * seems that we can rely on @hp being NULL on
         * fail.
         */
        retval = -1;
    }
    
    return retval;
#endif
#else /* No support for gethostbyaddr_r */
    struct hostent *h;
    
    G_LOCK (gethost_mutex);
    
    h = gethostbyaddr (addr, addrlen, type);
    
    if (!h) {
        *herr = h_errno;
        G_UNLOCK (gethost_mutex);
        return -1;
    }
    
    GETHOST_PROCESS (h, host, buf, buflen, herr);
    
    G_UNLOCK (gethost_mutex);
    
    return 0;
#endif /* HAVE_GETHOSTBYADDR_R */
#endif /* ENABLE_IPv6 */
}