1 #include <sys/socket.h>
2 #include <netinet/in.h>
15 #include "stdio_impl.h"
18 static int is_valid_hostname(const char *host
)
20 const unsigned char *s
;
21 if (strnlen(host
, 255)-1 >= 254 || mbstowcs(0, host
, 0) == -1) return 0;
22 for (s
=(void *)host
; *s
>=0x80 || *s
=='.' || *s
=='-' || isalnum(*s
); s
++);
26 static int name_from_null(struct address buf
[static 2], const char *name
, int family
, int flags
)
30 if (flags
& AI_PASSIVE
) {
31 if (family
!= AF_INET6
)
32 buf
[cnt
++] = (struct address
){ .family
= AF_INET
};
33 if (family
!= AF_INET
)
34 buf
[cnt
++] = (struct address
){ .family
= AF_INET6
};
36 if (family
!= AF_INET6
)
37 buf
[cnt
++] = (struct address
){ .family
= AF_INET
, .addr
= { 127,0,0,1 } };
38 if (family
!= AF_INET
)
39 buf
[cnt
++] = (struct address
){ .family
= AF_INET6
, .addr
= { [15] = 1 } };
44 static int name_from_numeric(struct address buf
[static 1], const char *name
, int family
)
46 return __lookup_ipliteral(buf
, name
, family
);
49 static int name_from_hosts(struct address buf
[static MAXADDRS
], char canon
[static 256], const char *name
, int family
)
52 size_t l
= strlen(name
);
53 int cnt
= 0, badfam
= 0;
54 unsigned char _buf
[1032];
55 FILE _f
, *f
= __fopen_rb_ca("/etc/hosts", &_f
, _buf
, sizeof _buf
);
56 if (!f
) switch (errno
) {
64 while (fgets(line
, sizeof line
, f
) && cnt
< MAXADDRS
) {
67 if ((p
=strchr(line
, '#'))) *p
++='\n', *p
=0;
68 for(p
=line
+1; (p
=strstr(p
, name
)) &&
69 (!isspace(p
[-1]) || !isspace(p
[l
])); p
++);
72 /* Isolate IP address to parse */
73 for (p
=line
; *p
&& !isspace(*p
); p
++);
75 switch (name_from_numeric(buf
+cnt
, line
, family
)) {
86 /* Extract first name as canonical name */
87 for (; *p
&& isspace(*p
); p
++);
88 for (z
=p
; *z
&& !isspace(*z
); z
++);
90 if (is_valid_hostname(p
)) memcpy(canon
, p
, z
-p
+1);
93 return cnt
? cnt
: badfam
;
97 struct address
*addrs
;
106 static int dns_parse_callback(void *c
, int rr
, const void *data
, int len
, const void *packet
)
109 struct dpc_ctx
*ctx
= c
;
110 if (ctx
->cnt
>= MAXADDRS
) return -1;
113 if (len
!= 4) return -1;
114 ctx
->addrs
[ctx
->cnt
].family
= AF_INET
;
115 ctx
->addrs
[ctx
->cnt
].scopeid
= 0;
116 memcpy(ctx
->addrs
[ctx
->cnt
++].addr
, data
, 4);
119 if (len
!= 16) return -1;
120 ctx
->addrs
[ctx
->cnt
].family
= AF_INET6
;
121 ctx
->addrs
[ctx
->cnt
].scopeid
= 0;
122 memcpy(ctx
->addrs
[ctx
->cnt
++].addr
, data
, 16);
125 if (__dn_expand(packet
, (const unsigned char *)packet
+ 512,
126 data
, tmp
, sizeof tmp
) > 0 && is_valid_hostname(tmp
))
127 strcpy(ctx
->canon
, tmp
);
133 static int name_from_dns(struct address buf
[static MAXADDRS
], char canon
[static 256], const char *name
, int family
, const struct resolvconf
*conf
)
135 unsigned char qbuf
[2][280], abuf
[2][512];
136 const unsigned char *qp
[2] = { qbuf
[0], qbuf
[1] };
137 unsigned char *ap
[2] = { abuf
[0], abuf
[1] };
138 int qlens
[2], alens
[2];
140 struct dpc_ctx ctx
= { .addrs
= buf
, .canon
= canon
};
141 static const struct { int af
; int rr
; } afrr
[2] = {
142 { .af
= AF_INET6
, .rr
= RR_A
},
143 { .af
= AF_INET
, .rr
= RR_AAAA
},
146 for (i
=0; i
<2; i
++) {
147 if (family
!= afrr
[i
].af
) {
148 qlens
[nq
] = __res_mkquery(0, name
, 1, afrr
[i
].rr
,
149 0, 0, 0, qbuf
[nq
], sizeof *qbuf
);
156 if (__res_msend_rc(nq
, qp
, qlens
, ap
, alens
, sizeof *abuf
, conf
) < 0)
160 __dns_parse(abuf
[i
], alens
[i
], dns_parse_callback
, &ctx
);
162 if (ctx
.cnt
) return ctx
.cnt
;
163 if (alens
[0] < 4 || (abuf
[0][3] & 15) == 2) return EAI_AGAIN
;
164 if ((abuf
[0][3] & 15) == 0) return EAI_NONAME
;
165 if ((abuf
[0][3] & 15) == 3) return 0;
169 static int name_from_dns_search(struct address buf
[static MAXADDRS
], char canon
[static 256], const char *name
, int family
)
172 struct resolvconf conf
;
176 if (__get_resolv_conf(&conf
, search
, sizeof search
) < 0) return -1;
178 /* Count dots, suppress search when >=ndots or name ends in
179 * a dot, which is an explicit request for global scope. */
180 for (dots
=l
=0; name
[l
]; l
++) if (name
[l
]=='.') dots
++;
181 if (dots
>= conf
.ndots
|| name
[l
-1]=='.') *search
= 0;
183 /* Strip final dot for canon, fail if multiple trailing dots. */
184 if (name
[l
-1]=='.') l
--;
185 if (!l
|| name
[l
-1]=='.') return EAI_NONAME
;
187 /* This can never happen; the caller already checked length. */
188 if (l
>= 256) return EAI_NONAME
;
190 /* Name with search domain appended is setup in canon[]. This both
191 * provides the desired default canonical name (if the requested
192 * name is not a CNAME record) and serves as a buffer for passing
193 * the full requested name to name_from_dns. */
194 memcpy(canon
, name
, l
);
197 for (p
=search
; *p
; p
=z
) {
198 for (; isspace(*p
); p
++);
199 for (z
=p
; *z
&& !isspace(*z
); z
++);
201 if (z
-p
< 256 - l
- 1) {
202 memcpy(canon
+l
+1, p
, z
-p
);
204 int cnt
= name_from_dns(buf
, canon
, canon
, family
, &conf
);
210 return name_from_dns(buf
, canon
, name
, family
, &conf
);
213 static const struct policy
{
214 unsigned char addr
[16];
215 unsigned char len
, mask
;
216 unsigned char prec
, label
;
218 { "\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\1", 15, 0xff, 50, 0 },
219 { "\0\0\0\0\0\0\0\0\0\0\xff\xff", 11, 0xff, 35, 4 },
220 { "\x20\2", 1, 0xff, 30, 2 },
221 { "\x20\1", 3, 0xff, 5, 5 },
222 { "\xfc", 0, 0xfe, 3, 13 },
224 /* These are deprecated and/or returned to the address
225 * pool, so despite the RFC, treating them as special
226 * is probably wrong. */
227 { "", 11, 0xff, 1, 3 },
228 { "\xfe\xc0", 1, 0xc0, 1, 11 },
229 { "\x3f\xfe", 1, 0xff, 1, 12 },
231 /* Last rule must match all addresses to stop loop. */
235 static const struct policy
*policyof(const struct in6_addr
*a
)
239 if (memcmp(a
->s6_addr
, defpolicy
[i
].addr
, defpolicy
[i
].len
))
241 if ((a
->s6_addr
[defpolicy
[i
].len
] & defpolicy
[i
].mask
)
242 != defpolicy
[i
].addr
[defpolicy
[i
].len
])
248 static int labelof(const struct in6_addr
*a
)
250 return policyof(a
)->label
;
253 static int scopeof(const struct in6_addr
*a
)
255 if (IN6_IS_ADDR_MULTICAST(a
)) return a
->s6_addr
[1] & 15;
256 if (IN6_IS_ADDR_LINKLOCAL(a
)) return 2;
257 if (IN6_IS_ADDR_LOOPBACK(a
)) return 2;
258 if (IN6_IS_ADDR_SITELOCAL(a
)) return 5;
262 static int prefixmatch(const struct in6_addr
*s
, const struct in6_addr
*d
)
264 /* FIXME: The common prefix length should be limited to no greater
265 * than the nominal length of the prefix portion of the source
266 * address. However the definition of the source prefix length is
267 * not clear and thus this limiting is not yet implemented. */
269 for (i
=0; i
<128 && !((s
->s6_addr
[i
/8]^d
->s6_addr
[i
/8])&(128>>(i
%8))); i
++);
273 #define DAS_USABLE 0x40000000
274 #define DAS_MATCHINGSCOPE 0x20000000
275 #define DAS_MATCHINGLABEL 0x10000000
276 #define DAS_PREC_SHIFT 20
277 #define DAS_SCOPE_SHIFT 16
278 #define DAS_PREFIX_SHIFT 8
279 #define DAS_ORDER_SHIFT 0
281 static int addrcmp(const void *_a
, const void *_b
)
283 const struct address
*a
= _a
, *b
= _b
;
284 return b
->sortkey
- a
->sortkey
;
287 int __lookup_name(struct address buf
[static MAXADDRS
], char canon
[static 256], const char *name
, int family
, int flags
)
293 /* reject empty name and check len so it fits into temp bufs */
294 size_t l
= strnlen(name
, 255);
297 memcpy(canon
, name
, l
+1);
300 /* Procedurally, a request for v6 addresses with the v4-mapped
301 * flag set is like a request for unspecified family, followed
302 * by filtering of the results. */
303 if (flags
& AI_V4MAPPED
) {
304 if (family
== AF_INET6
) family
= AF_UNSPEC
;
305 else flags
-= AI_V4MAPPED
;
308 /* Try each backend until there's at least one result. */
309 cnt
= name_from_null(buf
, name
, family
, flags
);
310 if (!cnt
) cnt
= name_from_numeric(buf
, name
, family
);
311 if (!cnt
&& !(flags
& AI_NUMERICHOST
)) {
312 cnt
= name_from_hosts(buf
, canon
, name
, family
);
313 if (!cnt
) cnt
= name_from_dns_search(buf
, canon
, name
, family
);
315 if (cnt
<=0) return cnt
? cnt
: EAI_NONAME
;
317 /* Filter/transform results for v4-mapped lookup, if requested. */
318 if (flags
& AI_V4MAPPED
) {
319 if (!(flags
& AI_ALL
)) {
320 /* If any v6 results exist, remove v4 results. */
321 for (i
=0; i
<cnt
&& buf
[i
].family
!= AF_INET6
; i
++);
323 for (j
=0; i
<cnt
; i
++) {
324 if (buf
[i
].family
== AF_INET6
)
330 /* Translate any remaining v4 results to v6 */
331 for (i
=0; i
<cnt
; i
++) {
332 if (buf
[i
].family
!= AF_INET
) continue;
333 memcpy(buf
[i
].addr
+12, buf
[i
].addr
, 4);
334 memcpy(buf
[i
].addr
, "\0\0\0\0\0\0\0\0\0\0\xff\xff", 12);
335 buf
[i
].family
= AF_INET6
;
339 /* No further processing is needed if there are fewer than 2
340 * results or if there are only IPv4 results. */
341 if (cnt
<2 || family
==AF_INET
) return cnt
;
342 for (i
=0; i
<cnt
; i
++) if (buf
[i
].family
!= AF_INET
) break;
343 if (i
==cnt
) return cnt
;
346 pthread_setcancelstate(PTHREAD_CANCEL_DISABLE
, &cs
);
348 /* The following implements a subset of RFC 3484/6724 destination
349 * address selection by generating a single 31-bit sort key for
350 * each address. Rules 3, 4, and 7 are omitted for having
351 * excessive runtime and code size cost and dubious benefit.
352 * So far the label/precedence table cannot be customized. */
353 for (i
=0; i
<cnt
; i
++) {
354 int family
= buf
[i
].family
;
356 struct sockaddr_in6 sa6
= { 0 }, da6
= {
357 .sin6_family
= AF_INET6
,
358 .sin6_scope_id
= buf
[i
].scopeid
,
361 struct sockaddr_in sa4
= { 0 }, da4
= {
362 .sin_family
= AF_INET
,
366 socklen_t salen
, dalen
;
367 if (family
== AF_INET6
) {
368 memcpy(da6
.sin6_addr
.s6_addr
, buf
[i
].addr
, 16);
369 da
= &da6
; dalen
= sizeof da6
;
370 sa
= &sa6
; salen
= sizeof sa6
;
372 memcpy(sa6
.sin6_addr
.s6_addr
,
373 "\0\0\0\0\0\0\0\0\0\0\xff\xff", 12);
374 memcpy(da6
.sin6_addr
.s6_addr
+12, buf
[i
].addr
, 4);
375 memcpy(da6
.sin6_addr
.s6_addr
,
376 "\0\0\0\0\0\0\0\0\0\0\xff\xff", 12);
377 memcpy(da6
.sin6_addr
.s6_addr
+12, buf
[i
].addr
, 4);
378 memcpy(&da4
.sin_addr
, buf
[i
].addr
, 4);
379 da
= &da4
; dalen
= sizeof da4
;
380 sa
= &sa4
; salen
= sizeof sa4
;
382 const struct policy
*dpolicy
= policyof(&da6
.sin6_addr
);
383 int dscope
= scopeof(&da6
.sin6_addr
);
384 int dlabel
= dpolicy
->label
;
385 int dprec
= dpolicy
->prec
;
387 int fd
= socket(family
, SOCK_DGRAM
|SOCK_CLOEXEC
, IPPROTO_UDP
);
389 if (!connect(fd
, da
, dalen
)) {
391 if (!getsockname(fd
, sa
, &salen
)) {
392 if (family
== AF_INET
) memcpy(
393 sa6
.sin6_addr
.s6_addr
+12,
395 if (dscope
== scopeof(&sa6
.sin6_addr
))
396 key
|= DAS_MATCHINGSCOPE
;
397 if (dlabel
== labelof(&sa6
.sin6_addr
))
398 key
|= DAS_MATCHINGLABEL
;
399 prefixlen
= prefixmatch(&sa6
.sin6_addr
,
405 key
|= dprec
<< DAS_PREC_SHIFT
;
406 key
|= (15-dscope
) << DAS_SCOPE_SHIFT
;
407 key
|= prefixlen
<< DAS_PREFIX_SHIFT
;
408 key
|= (MAXADDRS
-i
) << DAS_ORDER_SHIFT
;
409 buf
[i
].sortkey
= key
;
411 qsort(buf
, cnt
, sizeof *buf
, addrcmp
);
413 pthread_setcancelstate(cs
, 0);