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, have_canon = 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 break;
88 }
89
90 if (have_canon) continue;
91
92 /* Extract first name as canonical name */
93 for (; *p && isspace(*p); p++);
94 for (z=p; *z && !isspace(*z); z++);
95 *z = 0;
96 if (is_valid_hostname(p)) {
97 have_canon = 1;
98 memcpy(canon, p, z-p+1);
99 }
100 }
101 __fclose_ca(f);
102 return cnt ? cnt : badfam;
103 }
104
105 struct dpc_ctx {
106 struct address *addrs;
107 char *canon;
108 int cnt;
109 };
110
111 #define RR_A 1
112 #define RR_CNAME 5
113 #define RR_AAAA 28
114
dns_parse_callback(void * c,int rr,const void * data,int len,const void * packet)115 static int dns_parse_callback(void *c, int rr, const void *data, int len, const void *packet)
116 {
117 char tmp[256];
118 struct dpc_ctx *ctx = c;
119 if (ctx->cnt >= MAXADDRS) return -1;
120 switch (rr) {
121 case RR_A:
122 if (len != 4) return -1;
123 ctx->addrs[ctx->cnt].family = AF_INET;
124 ctx->addrs[ctx->cnt].scopeid = 0;
125 memcpy(ctx->addrs[ctx->cnt++].addr, data, 4);
126 break;
127 case RR_AAAA:
128 if (len != 16) return -1;
129 ctx->addrs[ctx->cnt].family = AF_INET6;
130 ctx->addrs[ctx->cnt].scopeid = 0;
131 memcpy(ctx->addrs[ctx->cnt++].addr, data, 16);
132 break;
133 case RR_CNAME:
134 if (__dn_expand(packet, (const unsigned char *)packet + 512,
135 data, tmp, sizeof tmp) > 0 && is_valid_hostname(tmp))
136 strcpy(ctx->canon, tmp);
137 break;
138 }
139 return 0;
140 }
141
name_from_dns(struct address buf[static MAXADDRS],char canon[static256],const char * name,int family,const struct resolvconf * conf)142 static int name_from_dns(struct address buf[static MAXADDRS], char canon[static 256], const char *name, int family, const struct resolvconf *conf)
143 {
144 unsigned char qbuf[2][280], abuf[2][512];
145 const unsigned char *qp[2] = { qbuf[0], qbuf[1] };
146 unsigned char *ap[2] = { abuf[0], abuf[1] };
147 int qlens[2], alens[2];
148 int i, nq = 0;
149 struct dpc_ctx ctx = { .addrs = buf, .canon = canon };
150 static const struct { int af; int rr; } afrr[2] = {
151 { .af = AF_INET6, .rr = RR_A },
152 { .af = AF_INET, .rr = RR_AAAA },
153 };
154
155 for (i=0; i<2; i++) {
156 if (family != afrr[i].af) {
157 qlens[nq] = __res_mkquery(0, name, 1, afrr[i].rr,
158 0, 0, 0, qbuf[nq], sizeof *qbuf);
159 if (qlens[nq] == -1)
160 return EAI_NONAME;
161 qbuf[nq][3] = 0; /* don't need AD flag */
162 nq++;
163 }
164 }
165
166 if (__res_msend_rc(nq, qp, qlens, ap, alens, sizeof *abuf, conf) < 0)
167 return EAI_SYSTEM;
168
169 for (i=0; i<nq; i++) {
170 if (alens[i] < 4 || (abuf[i][3] & 15) == 2) return EAI_AGAIN;
171 if ((abuf[i][3] & 15) == 3) return 0;
172 if ((abuf[i][3] & 15) != 0) return EAI_FAIL;
173 }
174
175 for (i=0; i<nq; i++)
176 __dns_parse(abuf[i], alens[i], dns_parse_callback, &ctx);
177
178 if (ctx.cnt) return ctx.cnt;
179 return EAI_NONAME;
180 }
181
name_from_dns_search(struct address buf[static MAXADDRS],char canon[static256],const char * name,int family)182 static int name_from_dns_search(struct address buf[static MAXADDRS], char canon[static 256], const char *name, int family)
183 {
184 #if OHOS_PERMISSION_INTERNET
185 if (is_allow_internet() == 0) {
186 errno = EPERM;
187 return -1;
188 }
189 #endif
190
191 char search[256];
192 struct resolvconf conf;
193 size_t l, dots;
194 char *p, *z;
195
196 if (__get_resolv_conf(&conf, search, sizeof search) < 0) return -1;
197
198 /* Count dots, suppress search when >=ndots or name ends in
199 * a dot, which is an explicit request for global scope. */
200 for (dots=l=0; name[l]; l++) if (name[l]=='.') dots++;
201 if (dots >= conf.ndots || name[l-1]=='.') *search = 0;
202
203 /* Strip final dot for canon, fail if multiple trailing dots. */
204 if (name[l-1]=='.') l--;
205 if (!l || name[l-1]=='.') return EAI_NONAME;
206
207 /* This can never happen; the caller already checked length. */
208 if (l >= 256) return EAI_NONAME;
209
210 /* Name with search domain appended is setup in canon[]. This both
211 * provides the desired default canonical name (if the requested
212 * name is not a CNAME record) and serves as a buffer for passing
213 * the full requested name to name_from_dns. */
214 memcpy(canon, name, l);
215 canon[l] = '.';
216
217 for (p=search; *p; p=z) {
218 for (; isspace(*p); p++);
219 for (z=p; *z && !isspace(*z); z++);
220 if (z==p) break;
221 if (z-p < 256 - l - 1) {
222 memcpy(canon+l+1, p, z-p);
223 canon[z-p+1+l] = 0;
224 int cnt = name_from_dns(buf, canon, canon, family, &conf);
225 if (cnt) return cnt;
226 }
227 }
228
229 canon[l] = 0;
230 return name_from_dns(buf, canon, name, family, &conf);
231 }
232
233 static const struct policy {
234 unsigned char addr[16];
235 unsigned char len, mask;
236 unsigned char prec, label;
237 } defpolicy[] = {
238 { "\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\1", 15, 0xff, 50, 0 },
239 { "\0\0\0\0\0\0\0\0\0\0\xff\xff", 11, 0xff, 35, 4 },
240 { "\x20\2", 1, 0xff, 30, 2 },
241 { "\x20\1", 3, 0xff, 5, 5 },
242 { "\xfc", 0, 0xfe, 3, 13 },
243 #if 0
244 /* These are deprecated and/or returned to the address
245 * pool, so despite the RFC, treating them as special
246 * is probably wrong. */
247 { "", 11, 0xff, 1, 3 },
248 { "\xfe\xc0", 1, 0xc0, 1, 11 },
249 { "\x3f\xfe", 1, 0xff, 1, 12 },
250 #endif
251 /* Last rule must match all addresses to stop loop. */
252 { "", 0, 0, 40, 1 },
253 };
254
policyof(const struct in6_addr * a)255 static const struct policy *policyof(const struct in6_addr *a)
256 {
257 int i;
258 for (i=0; ; i++) {
259 if (memcmp(a->s6_addr, defpolicy[i].addr, defpolicy[i].len))
260 continue;
261 if ((a->s6_addr[defpolicy[i].len] & defpolicy[i].mask)
262 != defpolicy[i].addr[defpolicy[i].len])
263 continue;
264 return defpolicy+i;
265 }
266 }
267
labelof(const struct in6_addr * a)268 static int labelof(const struct in6_addr *a)
269 {
270 return policyof(a)->label;
271 }
272
scopeof(const struct in6_addr * a)273 static int scopeof(const struct in6_addr *a)
274 {
275 if (IN6_IS_ADDR_MULTICAST(a)) return a->s6_addr[1] & 15;
276 if (IN6_IS_ADDR_LINKLOCAL(a)) return 2;
277 if (IN6_IS_ADDR_LOOPBACK(a)) return 2;
278 if (IN6_IS_ADDR_SITELOCAL(a)) return 5;
279 return 14;
280 }
281
prefixmatch(const struct in6_addr * s,const struct in6_addr * d)282 static int prefixmatch(const struct in6_addr *s, const struct in6_addr *d)
283 {
284 /* FIXME: The common prefix length should be limited to no greater
285 * than the nominal length of the prefix portion of the source
286 * address. However the definition of the source prefix length is
287 * not clear and thus this limiting is not yet implemented. */
288 unsigned i;
289 for (i=0; i<128 && !((s->s6_addr[i/8]^d->s6_addr[i/8])&(128>>(i%8))); i++);
290 return i;
291 }
292
293 #define DAS_USABLE 0x40000000
294 #define DAS_MATCHINGSCOPE 0x20000000
295 #define DAS_MATCHINGLABEL 0x10000000
296 #define DAS_PREC_SHIFT 20
297 #define DAS_SCOPE_SHIFT 16
298 #define DAS_PREFIX_SHIFT 8
299 #define DAS_ORDER_SHIFT 0
300
addrcmp(const void * _a,const void * _b)301 static int addrcmp(const void *_a, const void *_b)
302 {
303 const struct address *a = _a, *b = _b;
304 return b->sortkey - a->sortkey;
305 }
306
__lookup_name(struct address buf[static MAXADDRS],char canon[static256],const char * name,int family,int flags)307 int __lookup_name(struct address buf[static MAXADDRS], char canon[static 256], const char *name, int family, int flags)
308 {
309 int cnt = 0, i, j;
310
311 *canon = 0;
312 if (name) {
313 /* reject empty name and check len so it fits into temp bufs */
314 size_t l = strnlen(name, 255);
315 if (l-1 >= 254)
316 return EAI_NONAME;
317 memcpy(canon, name, l+1);
318 }
319
320 /* Procedurally, a request for v6 addresses with the v4-mapped
321 * flag set is like a request for unspecified family, followed
322 * by filtering of the results. */
323 if (flags & AI_V4MAPPED) {
324 if (family == AF_INET6) family = AF_UNSPEC;
325 else flags -= AI_V4MAPPED;
326 }
327
328 /* Try each backend until there's at least one result. */
329 cnt = name_from_null(buf, name, family, flags);
330 if (!cnt) cnt = name_from_numeric(buf, name, family);
331 if (!cnt && !(flags & AI_NUMERICHOST)) {
332 cnt = name_from_hosts(buf, canon, name, family);
333 if (!cnt) cnt = name_from_dns_search(buf, canon, name, family);
334 }
335 if (cnt<=0) return cnt ? cnt : EAI_NONAME;
336
337 /* Filter/transform results for v4-mapped lookup, if requested. */
338 if (flags & AI_V4MAPPED) {
339 if (!(flags & AI_ALL)) {
340 /* If any v6 results exist, remove v4 results. */
341 for (i=0; i<cnt && buf[i].family != AF_INET6; i++);
342 if (i<cnt) {
343 for (j=0; i<cnt; i++) {
344 if (buf[i].family == AF_INET6)
345 buf[j++] = buf[i];
346 }
347 cnt = i = j;
348 }
349 }
350 /* Translate any remaining v4 results to v6 */
351 for (i=0; i<cnt; i++) {
352 if (buf[i].family != AF_INET) continue;
353 memcpy(buf[i].addr+12, buf[i].addr, 4);
354 memcpy(buf[i].addr, "\0\0\0\0\0\0\0\0\0\0\xff\xff", 12);
355 buf[i].family = AF_INET6;
356 }
357 }
358
359 /* No further processing is needed if there are fewer than 2
360 * results or if there are only IPv4 results. */
361 if (cnt<2 || family==AF_INET) return cnt;
362 for (i=0; i<cnt; i++) if (buf[i].family != AF_INET) break;
363 if (i==cnt) return cnt;
364
365 int cs;
366 pthread_setcancelstate(PTHREAD_CANCEL_DISABLE, &cs);
367
368 /* The following implements a subset of RFC 3484/6724 destination
369 * address selection by generating a single 31-bit sort key for
370 * each address. Rules 3, 4, and 7 are omitted for having
371 * excessive runtime and code size cost and dubious benefit.
372 * So far the label/precedence table cannot be customized. */
373 for (i=0; i<cnt; i++) {
374 int family = buf[i].family;
375 int key = 0;
376 struct sockaddr_in6 sa6 = { 0 }, da6 = {
377 .sin6_family = AF_INET6,
378 .sin6_scope_id = buf[i].scopeid,
379 .sin6_port = 65535
380 };
381 struct sockaddr_in sa4 = { 0 }, da4 = {
382 .sin_family = AF_INET,
383 .sin_port = 65535
384 };
385 void *sa, *da;
386 socklen_t salen, dalen;
387 if (family == AF_INET6) {
388 memcpy(da6.sin6_addr.s6_addr, buf[i].addr, 16);
389 da = &da6; dalen = sizeof da6;
390 sa = &sa6; salen = sizeof sa6;
391 } else {
392 memcpy(sa6.sin6_addr.s6_addr,
393 "\0\0\0\0\0\0\0\0\0\0\xff\xff", 12);
394 memcpy(da6.sin6_addr.s6_addr+12, buf[i].addr, 4);
395 memcpy(da6.sin6_addr.s6_addr,
396 "\0\0\0\0\0\0\0\0\0\0\xff\xff", 12);
397 memcpy(da6.sin6_addr.s6_addr+12, buf[i].addr, 4);
398 memcpy(&da4.sin_addr, buf[i].addr, 4);
399 da = &da4; dalen = sizeof da4;
400 sa = &sa4; salen = sizeof sa4;
401 }
402 const struct policy *dpolicy = policyof(&da6.sin6_addr);
403 int dscope = scopeof(&da6.sin6_addr);
404 int dlabel = dpolicy->label;
405 int dprec = dpolicy->prec;
406 int prefixlen = 0;
407 int fd = socket(family, SOCK_DGRAM|SOCK_CLOEXEC, IPPROTO_UDP);
408 if (fd >= 0) {
409 if (!connect(fd, da, dalen)) {
410 key |= DAS_USABLE;
411 if (!getsockname(fd, sa, &salen)) {
412 if (family == AF_INET) memcpy(
413 sa6.sin6_addr.s6_addr+12,
414 &sa4.sin_addr, 4);
415 if (dscope == scopeof(&sa6.sin6_addr))
416 key |= DAS_MATCHINGSCOPE;
417 if (dlabel == labelof(&sa6.sin6_addr))
418 key |= DAS_MATCHINGLABEL;
419 prefixlen = prefixmatch(&sa6.sin6_addr,
420 &da6.sin6_addr);
421 }
422 }
423 close(fd);
424 }
425 key |= dprec << DAS_PREC_SHIFT;
426 key |= (15-dscope) << DAS_SCOPE_SHIFT;
427 key |= prefixlen << DAS_PREFIX_SHIFT;
428 key |= (MAXADDRS-i) << DAS_ORDER_SHIFT;
429 buf[i].sortkey = key;
430 }
431 qsort(buf, cnt, sizeof *buf, addrcmp);
432
433 pthread_setcancelstate(cs, 0);
434
435 return cnt;
436 }
437