7 #include <sys/socket.h>
9 #include <netinet/in.h>
16 #include "stdio_impl.h"
20 #define PACKET_MAX 512
21 #define PTR_MAX (64 + sizeof ".in-addr.arpa")
23 static void cleanup(void *p)
28 int __dns_doqueries(unsigned char *dest, const char *name, int *rr, int rrcnt)
33 unsigned char _buf[256];
34 char line[64], *s, *z;
36 struct sockaddr_in sin;
37 struct sockaddr_in6 sin6;
38 } sa = {0}, ns[3] = {{0}};
39 socklen_t sl = sizeof sa.sin;
42 unsigned char q[280] = "", *r = dest;
45 int got = 0, failed = 0;
46 int errcode = EAI_AGAIN;
53 pthread_setcancelstate(PTHREAD_CANCEL_DISABLE, &cs);
55 /* Construct query template - RR and ID will be filled later */
56 if (strlen(name)-1 >= 254U) return EAI_NONAME;
58 strcpy((char *)q+13, name);
59 for (i=13; q[i]; i=j+1) {
60 for (j=i; q[j] && q[j] != '.'; j++);
61 if (j-i-1u > 62u) return EAI_NONAME;
67 /* Make a reasonably unpredictable id */
68 clock_gettime(CLOCK_REALTIME, &ts);
69 id = ts.tv_nsec + ts.tv_nsec/65536UL & 0xffff;
71 /* Get nameservers from resolv.conf, fallback to localhost */
72 f = __fopen_rb_ca("/etc/resolv.conf", &_f, _buf, sizeof _buf);
73 if (f) for (nns=0; nns<3 && fgets(line, sizeof line, f); ) {
74 if (strncmp(line, "nameserver", 10) || !isspace(line[10]))
76 for (s=line+11; isspace(*s); s++);
77 for (z=s; *z && !isspace(*z); z++);
79 if (__ipparse(ns+nns, AF_UNSPEC, s) < 0) continue;
80 ns[nns].sin.sin_port = htons(53);
81 if (ns[nns++].sin.sin_family == AF_INET6) {
86 if (f) __fclose_ca(f);
88 ns[0].sin.sin_family = family = AF_INET;
89 ns[0].sin.sin_port = htons(53);
90 ns[0].sin.sin_addr.s_addr = htonl(0x7f000001);
95 /* Get local address and open/bind a socket */
96 sa.sin.sin_family = family;
97 fd = socket(family, SOCK_DGRAM|SOCK_CLOEXEC|SOCK_NONBLOCK, 0);
99 /* Handle case where system lacks IPv6 support */
100 if (fd < 0 && errno == EAFNOSUPPORT) {
101 if (family != AF_INET6) return EAI_SYSTEM;
102 fd = socket(AF_INET, SOCK_DGRAM|SOCK_CLOEXEC|SOCK_NONBLOCK, 0);
105 if (fd < 0) return EAI_SYSTEM;
107 /* Convert any IPv4 addresses in a mixed environment to v4-mapped */
108 if (family == AF_INET6) {
109 setsockopt(fd, IPPROTO_IPV6, IPV6_V6ONLY, &(int){0}, sizeof 0);
110 for (i=0; i<nns; i++) {
111 if (ns[i].sin.sin_family != AF_INET) continue;
112 memcpy(ns[i].sin6.sin6_addr.s6_addr+12,
113 &ns[i].sin.sin_addr, 4);
114 memcpy(ns[i].sin6.sin6_addr.s6_addr,
115 "\0\0\0\0\0\0\0\0\0\0\xff\xff", 12);
116 ns[i].sin6.sin6_family = AF_INET6;
117 ns[i].sin6.sin6_flowinfo = 0;
118 ns[i].sin6.sin6_scope_id = 0;
122 pthread_cleanup_push(cleanup, (void *)(intptr_t)fd);
123 pthread_setcancelstate(cs, 0);
125 if (bind(fd, (void *)&sa, sl) < 0) {
126 errcode = EAI_SYSTEM;
133 /* Loop until we timeout; break early on success */
134 for (; time(0)-t0 < TIMEOUT; ) {
136 /* Query all configured namservers in parallel */
137 for (i=0; i<rrcnt; i++) if (rr[i]) for (j=0; j<nns; j++) {
141 sendto(fd, q, ql, MSG_NOSIGNAL, (void *)&ns[j], sl);
144 /* Wait for a response, or until time to retry */
145 if (poll(&pfd, 1, RETRY) <= 0) continue;
147 /* Process any and all replies */
148 while (got+failed < rrcnt && (rlen = recvfrom(fd, r, 512, 0,
149 (void *)&sa, (socklen_t[1]){sl})) >= 2)
151 /* Ignore replies from addresses we didn't send to */
152 for (i=0; i<nns; i++) if (!memcmp(ns+i, &sa, sl)) break;
153 if (i==nns) continue;
155 /* Compute index of the query from id */
156 i = r[0]*256+r[1] - id & 0xffff;
157 if ((unsigned)i >= rrcnt || !rr[i]) continue;
159 /* Interpret the result code */
165 if (1) errcode = EAI_NONAME; else
171 /* Mark this record as answered */
176 /* Check to see if we have answers to all queries */
177 if (got+failed == rrcnt) break;
180 pthread_cleanup_pop(1);
182 /* Return the number of results, or an error code if none */
187 static void mkptr4(char *s, const unsigned char *ip)
189 sprintf(s, "%d.%d.%d.%d.in-addr.arpa",
190 ip[3], ip[2], ip[1], ip[0]);
193 static void mkptr6(char *s, const unsigned char *ip)
195 static const char xdigits[] = "0123456789abcdef";
197 for (i=15; i>=0; i--) {
198 *s++ = xdigits[ip[i]&15]; *s++ = '.';
199 *s++ = xdigits[ip[i]>>4]; *s++ = '.';
201 strcpy(s, "ip6.arpa");
204 int __dns_query(unsigned char *r, const void *a, int family, int ptr)
207 int rr[2], rrcnt = 1;
210 if (family == AF_INET6) mkptr6(buf, a);
214 } else if (family == AF_INET6) {
218 if (family != AF_INET) rr[rrcnt++] = RR_AAAA;
221 return __dns_doqueries(r, a, rr, rrcnt);
224 int __dn_expand(const unsigned char *, const unsigned char *, const unsigned char *, char *, int);
226 int __dns_get_rr(void *dest, size_t stride, size_t maxlen, size_t limit, const unsigned char *r, int rr, int dec)
228 int qdcount, ancount;
229 const unsigned char *p;
234 if ((r[3]&15)) return 0;
236 qdcount = r[4]*256 + r[5];
237 ancount = r[6]*256 + r[7];
238 if (qdcount+ancount > 64) return -1;
240 while (p-r < 512 && *p-1U < 127) p++;
241 if (*p>193 || (*p==193 && p[1]>254) || p>r+506)
246 while (p-r < 512 && *p-1U < 127) p++;
247 if (*p>193 || (*p==193 && p[1]>254) || p>r+506)
250 len = p[8]*256 + p[9];
251 if (p+len > r+512) return -1;
252 if (p[1]==rr && len <= maxlen) {
253 if (dec && __dn_expand(r, r+512, p+10, tmp, sizeof tmp)<0)
256 if (dec) strcpy(dest, tmp);
257 else memcpy(dest, p+10, len);
258 dest = (char *)dest + stride;
268 int __dns_count_addrs(const unsigned char *r, int cnt)
271 static const int p[2][2] = { { 4, RR_A }, { 16, RR_AAAA } };
274 for (i=0; i<2; i++) {
275 res = __dns_get_rr(0, 0, p[i][0], -1, r, p[i][1], 0);
276 if (res < 0) return res;