1 /*	$NetBSD: sethostent.c,v 1.20 2014/03/17 13:24:23 christos Exp $	*/
2 
3 /*
4  * Copyright (c) 1985, 1993
5  *	The Regents of the University of California.  All rights reserved.
6  *
7  * Redistribution and use in source and binary forms, with or without
8  * modification, are permitted provided that the following conditions
9  * are met:
10  * 1. Redistributions of source code must retain the above copyright
11  *    notice, this list of conditions and the following disclaimer.
12  * 2. Redistributions in binary form must reproduce the above copyright
13  *    notice, this list of conditions and the following disclaimer in the
14  *    documentation and/or other materials provided with the distribution.
15  * 3. Neither the name of the University nor the names of its contributors
16  *    may be used to endorse or promote products derived from this software
17  *    without specific prior written permission.
18  *
19  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
20  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
21  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
22  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
23  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
24  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
25  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
26  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
27  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
28  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
29  * SUCH DAMAGE.
30  */
31 
32 #include <arpa/inet.h>
33 #include <arpa/nameser.h>
34 #include <assert.h>
35 #include <errno.h>
36 #include <netdb.h>
37 #include <netinet/in.h>
38 #include <resolv.h>
39 #include <stdlib.h>
40 #include <string.h>
41 #include <sys/param.h>
42 
43 #include "hostent.h"
44 #include "resolv_private.h"
45 
46 constexpr int MAXALIASES = 35;
47 constexpr int MAXADDRS = 35;
48 
49 #define ALIGNBYTES (sizeof(uintptr_t) - 1)
50 #define ALIGN(p) (((uintptr_t)(p) + ALIGNBYTES) & ~ALIGNBYTES)
51 
52 static void sethostent_r(FILE** hf) {
53     if (!*hf)
54         *hf = fopen(_PATH_HOSTS, "re");
55     else
56         rewind(*hf);
57 }
58 
59 static void endhostent_r(FILE** hf) {
60     if (*hf) {
61         (void) fclose(*hf);
62         *hf = NULL;
63     }
64 }
65 
66 // TODO: Consider returning a boolean result as files_getaddrinfo() does because the error code
67 // does not currently return to netd.
68 int _hf_gethtbyname2(const char* name, int af, getnamaddr* info) {
69     struct hostent *hp, hent;
70     char *buf, *ptr;
71     size_t len, num, i;
72     char* aliases[MAXALIASES];
73     char* addr_ptrs[MAXADDRS];
74 
75     FILE* hf = NULL;
76     sethostent_r(&hf);
77     if (hf == NULL) {
78         // TODO: Consider converting to a private extended EAI_* error code.
79         // Currently, the EAI_* value has no corresponding error code for invalid argument socket
80         // length. In order to not rely on errno, convert the original error code pair, EAI_SYSTEM
81         // and EINVAL, to EAI_FAIL.
82         return EAI_FAIL;
83     }
84 
85     if ((ptr = buf = (char*) malloc(len = info->buflen)) == NULL) {
86         return EAI_MEMORY;
87     }
88 
89     hent.h_name = NULL;
90     hent.h_addrtype = 0;
91     hent.h_length = 0;
92 
93     size_t anum = 0;
94     for (num = 0; num < MAXADDRS; /**/) {
95         info->hp->h_addrtype = af;
96         info->hp->h_length = 0;
97 
98         int he;
99         hp = netbsd_gethostent_r(hf, info->hp, info->buf, info->buflen, &he);
100         if (hp == NULL) {
101             if (he == NETDB_INTERNAL && errno == ENOSPC) {
102                 goto nospc;  // glibc compatibility.
103             }
104             break;
105         }
106 
107         if (strcasecmp(hp->h_name, name) != 0) {
108             char** cp;
109             for (cp = hp->h_aliases; *cp != NULL; cp++)
110                 if (strcasecmp(*cp, name) == 0) break;
111             // NOTE: does not increment num
112             if (*cp == NULL) continue;
113         }
114 
115         if (num == 0) {
116             hent.h_addrtype = hp->h_addrtype;
117             hent.h_length = hp->h_length;
118 
119             HENT_SCOPY(hent.h_name, hp->h_name, ptr, len);
120             for (anum = 0; hp->h_aliases[anum]; anum++) {
121                 if (anum >= MAXALIASES) goto nospc;
122                 HENT_SCOPY(aliases[anum], hp->h_aliases[anum], ptr, len);
123             }
124             ptr = (char*) ALIGN(ptr);
125             if ((size_t)(ptr - buf) >= info->buflen) goto nospc;
126         }
127 
128         if (num >= MAXADDRS) goto nospc;
129         HENT_COPY(addr_ptrs[num], hp->h_addr_list[0], hp->h_length, ptr, len);
130 
131         num++;
132     }
133     endhostent_r(&hf);
134 
135     if (num == 0) {
136         free(buf);
137         // TODO: Perhaps convert HOST_NOT_FOUND to EAI_NONAME instead.
138         // The original return error number is h_errno HOST_NOT_FOUND which was converted to
139         // EAI_NODATA.
140         return EAI_NODATA;
141     }
142 
143     hp = info->hp;
144     ptr = info->buf;
145     len = info->buflen;
146 
147     hp->h_addrtype = hent.h_addrtype;
148     hp->h_length = hent.h_length;
149 
150     HENT_ARRAY(hp->h_aliases, anum, ptr, len);
151     HENT_ARRAY(hp->h_addr_list, num, ptr, len);
152 
153     for (i = 0; i < num; i++) {
154         HENT_COPY(hp->h_addr_list[i], addr_ptrs[i], hp->h_length, ptr, len);
155 
156         // reserve space for mapping IPv4 address to IPv6 address in place
157         if (hp->h_addrtype == AF_INET) {
158             HENT_COPY(ptr, NAT64_PAD, sizeof(NAT64_PAD), ptr, len);
159         }
160     }
161     hp->h_addr_list[num] = NULL;
162 
163     HENT_SCOPY(hp->h_name, hent.h_name, ptr, len);
164 
165     for (i = 0; i < anum; i++) {
166         HENT_SCOPY(hp->h_aliases[i], aliases[i], ptr, len);
167     }
168     hp->h_aliases[anum] = NULL;
169 
170     free(buf);
171     return 0;
172 nospc:
173     free(buf);
174     return EAI_MEMORY;
175 }
176 
177 // TODO: Consider returning a boolean result as files_getaddrinfo() does because the error code
178 // does not currently return to netd.
179 int _hf_gethtbyaddr(const unsigned char* uaddr, int len, int af, getnamaddr* info) {
180     info->hp->h_length = len;
181     info->hp->h_addrtype = af;
182 
183     FILE* hf = NULL;
184     sethostent_r(&hf);
185     if (hf == NULL) {
186         // TODO: Consider converting to a private extended EAI_* error code.
187         // Currently, the EAI_* value has no corresponding error code for invalid argument socket
188         // length. In order to not rely on errno, convert the original error code pair, EAI_SYSTEM
189         // and EINVAL, to EAI_FAIL.
190         return EAI_FAIL;
191     }
192     struct hostent* hp;
193     int he;
194     while ((hp = netbsd_gethostent_r(hf, info->hp, info->buf, info->buflen, &he)) != NULL)
195         if (!memcmp(hp->h_addr_list[0], uaddr, (size_t) hp->h_length)) break;
196     endhostent_r(&hf);
197 
198     if (hp == NULL) {
199         if (errno == ENOSPC) return EAI_MEMORY;  // glibc compatibility.
200         // TODO: Perhaps convert HOST_NOT_FOUND to EAI_NONAME instead.
201         // The original return error number is h_errno HOST_NOT_FOUND which was converted to
202         // EAI_NODATA.
203         return EAI_NODATA;
204     }
205     return 0;
206 }
207