1 #include <sys/socket.h>
2 #include <netinet/in.h>
3 #include <netdb.h>
4 #include <net/if.h>
5 #include <arpa/inet.h>
6 #include <ctype.h>
7 #include <stdlib.h>
8 #include <string.h>
9 #include <fcntl.h>
10 #include <unistd.h>
11 #include <pthread.h>
12 #include <errno.h>
13 #include <resolv.h>
14 #include "lookup.h"
15 #include "stdio_impl.h"
16 #include "syscall.h"
17
18 #if OHOS_PERMISSION_INTERNET
19 uint8_t is_allow_internet(void);
20 #endif
21
is_valid_hostname(const char * host)22 static int is_valid_hostname(const char *host)
23 {
24 const unsigned char *s;
25 if (strnlen(host, 255)-1 >= 254 || mbstowcs(0, host, 0) == -1) return 0;
26 for (s=(void *)host; *s>=0x80 || *s=='.' || *s=='-' || isalnum(*s); s++);
27 return !*s;
28 }
29
name_from_null(struct address buf[static2],const char * name,int family,int flags)30 static int name_from_null(struct address buf[static 2], const char *name, int family, int flags)
31 {
32 int cnt = 0;
33 if (name) return 0;
34 if (flags & AI_PASSIVE) {
35 if (family != AF_INET6)
36 buf[cnt++] = (struct address){ .family = AF_INET };
37 if (family != AF_INET)
38 buf[cnt++] = (struct address){ .family = AF_INET6 };
39 } else {
40 if (family != AF_INET6)
41 buf[cnt++] = (struct address){ .family = AF_INET, .addr = { 127,0,0,1 } };
42 if (family != AF_INET)
43 buf[cnt++] = (struct address){ .family = AF_INET6, .addr = { [15] = 1 } };
44 }
45 return cnt;
46 }
47
name_from_numeric(struct address buf[static1],const char * name,int family)48 static int name_from_numeric(struct address buf[static 1], const char *name, int family)
49 {
50 return __lookup_ipliteral(buf, name, family);
51 }
52
name_from_hosts(struct address buf[static MAXADDRS],char canon[static256],const char * name,int family)53 static int name_from_hosts(struct address buf[static MAXADDRS], char canon[static 256], const char *name, int family)
54 {
55 char line[512];
56 size_t l = strlen(name);
57 int cnt = 0, badfam = 0;
58 unsigned char _buf[1032];
59 FILE _f, *f = __fopen_rb_ca("/etc/hosts", &_f, _buf, sizeof _buf);
60 if (!f) switch (errno) {
61 case ENOENT:
62 case ENOTDIR:
63 case EACCES:
64 return 0;
65 default:
66 return EAI_SYSTEM;
67 }
68 while (fgets(line, sizeof line, f) && cnt < MAXADDRS) {
69 char *p, *z;
70
71 if ((p=strchr(line, '#'))) *p++='\n', *p=0;
72 for(p=line+1; (p=strstr(p, name)) &&
73 (!isspace(p[-1]) || !isspace(p[l])); p++);
74 if (!p) continue;
75
76 /* Isolate IP address to parse */
77 for (p=line; *p && !isspace(*p); p++);
78 *p++ = 0;
79 switch (name_from_numeric(buf+cnt, line, family)) {
80 case 1:
81 cnt++;
82 break;
83 case 0:
84 continue;
85 default:
86 badfam = EAI_NONAME;
87 continue;
88 }
89
90 /* Extract first name as canonical name */
91 for (; *p && isspace(*p); p++);
92 for (z=p; *z && !isspace(*z); z++);
93 *z = 0;
94 if (is_valid_hostname(p)) memcpy(canon, p, z-p+1);
95 }
96 __fclose_ca(f);
97 return cnt ? cnt : badfam;
98 }
99
100 struct dpc_ctx {
101 struct address *addrs;
102 char *canon;
103 int cnt;
104 };
105
106 #define RR_A 1
107 #define RR_CNAME 5
108 #define RR_AAAA 28
109
dns_parse_callback(void * c,int rr,const void * data,int len,const void * packet)110 static int dns_parse_callback(void *c, int rr, const void *data, int len, const void *packet)
111 {
112 char tmp[256];
113 struct dpc_ctx *ctx = c;
114 if (ctx->cnt >= MAXADDRS) return -1;
115 switch (rr) {
116 case RR_A:
117 if (len != 4) return -1;
118 ctx->addrs[ctx->cnt].family = AF_INET;
119 ctx->addrs[ctx->cnt].scopeid = 0;
120 memcpy(ctx->addrs[ctx->cnt++].addr, data, 4);
121 break;
122 case RR_AAAA:
123 if (len != 16) return -1;
124 ctx->addrs[ctx->cnt].family = AF_INET6;
125 ctx->addrs[ctx->cnt].scopeid = 0;
126 memcpy(ctx->addrs[ctx->cnt++].addr, data, 16);
127 break;
128 case RR_CNAME:
129 if (__dn_expand(packet, (const unsigned char *)packet + 512,
130 data, tmp, sizeof tmp) > 0 && is_valid_hostname(tmp))
131 strcpy(ctx->canon, tmp);
132 break;
133 }
134 return 0;
135 }
136
name_from_dns(struct address buf[static MAXADDRS],char canon[static256],const char * name,int family,const struct resolvconf * conf)137 static int name_from_dns(struct address buf[static MAXADDRS], char canon[static 256], const char *name, int family, const struct resolvconf *conf)
138 {
139 unsigned char qbuf[2][280], abuf[2][512];
140 const unsigned char *qp[2] = { qbuf[0], qbuf[1] };
141 unsigned char *ap[2] = { abuf[0], abuf[1] };
142 int qlens[2], alens[2];
143 int i, nq = 0;
144 struct dpc_ctx ctx = { .addrs = buf, .canon = canon };
145 static const struct { int af; int rr; } afrr[2] = {
146 { .af = AF_INET6, .rr = RR_A },
147 { .af = AF_INET, .rr = RR_AAAA },
148 };
149
150 for (i=0; i<2; i++) {
151 if (family != afrr[i].af) {
152 qlens[nq] = __res_mkquery(0, name, 1, afrr[i].rr,
153 0, 0, 0, qbuf[nq], sizeof *qbuf);
154 if (qlens[nq] == -1)
155 return EAI_NONAME;
156 nq++;
157 }
158 }
159
160 if (__res_msend_rc(nq, qp, qlens, ap, alens, sizeof *abuf, conf) < 0)
161 return EAI_SYSTEM;
162
163 for (i=0; i<nq; i++)
164 __dns_parse(abuf[i], alens[i], dns_parse_callback, &ctx);
165
166 if (ctx.cnt) return ctx.cnt;
167 if (alens[0] < 4 || (abuf[0][3] & 15) == 2) return EAI_AGAIN;
168 if ((abuf[0][3] & 15) == 0) return EAI_NONAME;
169 if ((abuf[0][3] & 15) == 3) return 0;
170 return EAI_FAIL;
171 }
172
name_from_dns_search(struct address buf[static MAXADDRS],char canon[static256],const char * name,int family)173 static int name_from_dns_search(struct address buf[static MAXADDRS], char canon[static 256], const char *name, int family)
174 {
175 #if OHOS_PERMISSION_INTERNET
176 if (is_allow_internet() == 0) {
177 errno = EPERM;
178 return -1;
179 }
180 #endif
181
182 char search[256];
183 struct resolvconf conf;
184 size_t l, dots;
185 char *p, *z;
186
187 if (__get_resolv_conf(&conf, search, sizeof search) < 0) return -1;
188
189 /* Count dots, suppress search when >=ndots or name ends in
190 * a dot, which is an explicit request for global scope. */
191 for (dots=l=0; name[l]; l++) if (name[l]=='.') dots++;
192 if (dots >= conf.ndots || name[l-1]=='.') *search = 0;
193
194 /* Strip final dot for canon, fail if multiple trailing dots. */
195 if (name[l-1]=='.') l--;
196 if (!l || name[l-1]=='.') return EAI_NONAME;
197
198 /* This can never happen; the caller already checked length. */
199 if (l >= 256) return EAI_NONAME;
200
201 /* Name with search domain appended is setup in canon[]. This both
202 * provides the desired default canonical name (if the requested
203 * name is not a CNAME record) and serves as a buffer for passing
204 * the full requested name to name_from_dns. */
205 memcpy(canon, name, l);
206 canon[l] = '.';
207
208 for (p=search; *p; p=z) {
209 for (; isspace(*p); p++);
210 for (z=p; *z && !isspace(*z); z++);
211 if (z==p) break;
212 if (z-p < 256 - l - 1) {
213 memcpy(canon+l+1, p, z-p);
214 canon[z-p+1+l] = 0;
215 int cnt = name_from_dns(buf, canon, canon, family, &conf);
216 if (cnt) return cnt;
217 }
218 }
219
220 canon[l] = 0;
221 return name_from_dns(buf, canon, name, family, &conf);
222 }
223
224 static const struct policy {
225 unsigned char addr[16];
226 unsigned char len, mask;
227 unsigned char prec, label;
228 } defpolicy[] = {
229 { "\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\1", 15, 0xff, 50, 0 },
230 { "\0\0\0\0\0\0\0\0\0\0\xff\xff", 11, 0xff, 35, 4 },
231 { "\x20\2", 1, 0xff, 30, 2 },
232 { "\x20\1", 3, 0xff, 5, 5 },
233 { "\xfc", 0, 0xfe, 3, 13 },
234 #if 0
235 /* These are deprecated and/or returned to the address
236 * pool, so despite the RFC, treating them as special
237 * is probably wrong. */
238 { "", 11, 0xff, 1, 3 },
239 { "\xfe\xc0", 1, 0xc0, 1, 11 },
240 { "\x3f\xfe", 1, 0xff, 1, 12 },
241 #endif
242 /* Last rule must match all addresses to stop loop. */
243 { "", 0, 0, 40, 1 },
244 };
245
policyof(const struct in6_addr * a)246 static const struct policy *policyof(const struct in6_addr *a)
247 {
248 int i;
249 for (i=0; ; i++) {
250 if (memcmp(a->s6_addr, defpolicy[i].addr, defpolicy[i].len))
251 continue;
252 if ((a->s6_addr[defpolicy[i].len] & defpolicy[i].mask)
253 != defpolicy[i].addr[defpolicy[i].len])
254 continue;
255 return defpolicy+i;
256 }
257 }
258
labelof(const struct in6_addr * a)259 static int labelof(const struct in6_addr *a)
260 {
261 return policyof(a)->label;
262 }
263
scopeof(const struct in6_addr * a)264 static int scopeof(const struct in6_addr *a)
265 {
266 if (IN6_IS_ADDR_MULTICAST(a)) return a->s6_addr[1] & 15;
267 if (IN6_IS_ADDR_LINKLOCAL(a)) return 2;
268 if (IN6_IS_ADDR_LOOPBACK(a)) return 2;
269 if (IN6_IS_ADDR_SITELOCAL(a)) return 5;
270 return 14;
271 }
272
prefixmatch(const struct in6_addr * s,const struct in6_addr * d)273 static int prefixmatch(const struct in6_addr *s, const struct in6_addr *d)
274 {
275 /* FIXME: The common prefix length should be limited to no greater
276 * than the nominal length of the prefix portion of the source
277 * address. However the definition of the source prefix length is
278 * not clear and thus this limiting is not yet implemented. */
279 unsigned i;
280 for (i=0; i<128 && !((s->s6_addr[i/8]^d->s6_addr[i/8])&(128>>(i%8))); i++);
281 return i;
282 }
283
284 #define DAS_USABLE 0x40000000
285 #define DAS_MATCHINGSCOPE 0x20000000
286 #define DAS_MATCHINGLABEL 0x10000000
287 #define DAS_PREC_SHIFT 20
288 #define DAS_SCOPE_SHIFT 16
289 #define DAS_PREFIX_SHIFT 8
290 #define DAS_ORDER_SHIFT 0
291
addrcmp(const void * _a,const void * _b)292 static int addrcmp(const void *_a, const void *_b)
293 {
294 const struct address *a = _a, *b = _b;
295 return b->sortkey - a->sortkey;
296 }
297
__lookup_name(struct address buf[static MAXADDRS],char canon[static256],const char * name,int family,int flags)298 int __lookup_name(struct address buf[static MAXADDRS], char canon[static 256], const char *name, int family, int flags)
299 {
300 int cnt = 0, i, j;
301
302 *canon = 0;
303 if (name) {
304 /* reject empty name and check len so it fits into temp bufs */
305 size_t l = strnlen(name, 255);
306 if (l-1 >= 254)
307 return EAI_NONAME;
308 memcpy(canon, name, l+1);
309 }
310
311 /* Procedurally, a request for v6 addresses with the v4-mapped
312 * flag set is like a request for unspecified family, followed
313 * by filtering of the results. */
314 if (flags & AI_V4MAPPED) {
315 if (family == AF_INET6) family = AF_UNSPEC;
316 else flags -= AI_V4MAPPED;
317 }
318
319 /* Try each backend until there's at least one result. */
320 cnt = name_from_null(buf, name, family, flags);
321 if (!cnt) cnt = name_from_numeric(buf, name, family);
322 if (!cnt && !(flags & AI_NUMERICHOST)) {
323 cnt = name_from_hosts(buf, canon, name, family);
324 if (!cnt) cnt = name_from_dns_search(buf, canon, name, family);
325 }
326 if (cnt<=0) return cnt ? cnt : EAI_NONAME;
327
328 /* Filter/transform results for v4-mapped lookup, if requested. */
329 if (flags & AI_V4MAPPED) {
330 if (!(flags & AI_ALL)) {
331 /* If any v6 results exist, remove v4 results. */
332 for (i=0; i<cnt && buf[i].family != AF_INET6; i++);
333 if (i<cnt) {
334 for (j=0; i<cnt; i++) {
335 if (buf[i].family == AF_INET6)
336 buf[j++] = buf[i];
337 }
338 cnt = i = j;
339 }
340 }
341 /* Translate any remaining v4 results to v6 */
342 for (i=0; i<cnt; i++) {
343 if (buf[i].family != AF_INET) continue;
344 memcpy(buf[i].addr+12, buf[i].addr, 4);
345 memcpy(buf[i].addr, "\0\0\0\0\0\0\0\0\0\0\xff\xff", 12);
346 buf[i].family = AF_INET6;
347 }
348 }
349
350 /* No further processing is needed if there are fewer than 2
351 * results or if there are only IPv4 results. */
352 if (cnt<2 || family==AF_INET) return cnt;
353 for (i=0; i<cnt; i++) if (buf[i].family != AF_INET) break;
354 if (i==cnt) return cnt;
355
356 int cs;
357 pthread_setcancelstate(PTHREAD_CANCEL_DISABLE, &cs);
358
359 /* The following implements a subset of RFC 3484/6724 destination
360 * address selection by generating a single 31-bit sort key for
361 * each address. Rules 3, 4, and 7 are omitted for having
362 * excessive runtime and code size cost and dubious benefit.
363 * So far the label/precedence table cannot be customized. */
364 for (i=0; i<cnt; i++) {
365 int family = buf[i].family;
366 int key = 0;
367 struct sockaddr_in6 sa6 = { 0 }, da6 = {
368 .sin6_family = AF_INET6,
369 .sin6_scope_id = buf[i].scopeid,
370 .sin6_port = 65535
371 };
372 struct sockaddr_in sa4 = { 0 }, da4 = {
373 .sin_family = AF_INET,
374 .sin_port = 65535
375 };
376 void *sa, *da;
377 socklen_t salen, dalen;
378 if (family == AF_INET6) {
379 memcpy(da6.sin6_addr.s6_addr, buf[i].addr, 16);
380 da = &da6; dalen = sizeof da6;
381 sa = &sa6; salen = sizeof sa6;
382 } else {
383 memcpy(sa6.sin6_addr.s6_addr,
384 "\0\0\0\0\0\0\0\0\0\0\xff\xff", 12);
385 memcpy(da6.sin6_addr.s6_addr+12, buf[i].addr, 4);
386 memcpy(da6.sin6_addr.s6_addr,
387 "\0\0\0\0\0\0\0\0\0\0\xff\xff", 12);
388 memcpy(da6.sin6_addr.s6_addr+12, buf[i].addr, 4);
389 memcpy(&da4.sin_addr, buf[i].addr, 4);
390 da = &da4; dalen = sizeof da4;
391 sa = &sa4; salen = sizeof sa4;
392 }
393 const struct policy *dpolicy = policyof(&da6.sin6_addr);
394 int dscope = scopeof(&da6.sin6_addr);
395 int dlabel = dpolicy->label;
396 int dprec = dpolicy->prec;
397 int prefixlen = 0;
398 int fd = socket(family, SOCK_DGRAM|SOCK_CLOEXEC, IPPROTO_UDP);
399 if (fd >= 0) {
400 if (!connect(fd, da, dalen)) {
401 key |= DAS_USABLE;
402 if (!getsockname(fd, sa, &salen)) {
403 if (family == AF_INET) memcpy(
404 sa6.sin6_addr.s6_addr+12,
405 &sa4.sin_addr, 4);
406 if (dscope == scopeof(&sa6.sin6_addr))
407 key |= DAS_MATCHINGSCOPE;
408 if (dlabel == labelof(&sa6.sin6_addr))
409 key |= DAS_MATCHINGLABEL;
410 prefixlen = prefixmatch(&sa6.sin6_addr,
411 &da6.sin6_addr);
412 }
413 }
414 close(fd);
415 }
416 key |= dprec << DAS_PREC_SHIFT;
417 key |= (15-dscope) << DAS_SCOPE_SHIFT;
418 key |= prefixlen << DAS_PREFIX_SHIFT;
419 key |= (MAXADDRS-i) << DAS_ORDER_SHIFT;
420 buf[i].sortkey = key;
421 }
422 qsort(buf, cnt, sizeof *buf, addrcmp);
423
424 pthread_setcancelstate(cs, 0);
425
426 return cnt;
427 }
428