xref: /third_party/toybox/toys/pending/host.c (revision 0f66f451) 
1/* host.c - DNS lookup utility
2 *
3 * Copyright 2014 Rich Felker <dalias@aerifal.cx>
4 *
5 * No standard, but there's a version in bind9
6
7USE_HOST(NEWTOY(host, "<1>2avt:", TOYFLAG_USR|TOYFLAG_BIN))
8
9config HOST
10  bool "host"
11  default n
12  help
13    usage: host [-av] [-t TYPE] NAME [SERVER]
14
15    Perform DNS lookup on NAME, which can be a domain name to lookup,
16    or an IPv4 dotted or IPv6 colon-separated address to reverse lookup.
17    SERVER (if present) is the DNS server to use.
18
19    -a	-v -t ANY
20    -t TYPE	query records of type TYPE
21    -v	verbose
22*/
23
24#define FOR_host
25#include "toys.h"
26
27GLOBALS(
28  char *type_str;
29)
30
31#include <resolv.h>
32
33#define PL_IP 1
34#define PL_NAME 2
35#define PL_DATA 3
36#define PL_TEXT 4
37#define PL_SOA 5
38#define PL_MX 6
39#define PL_SRV 7
40
41static const struct rrt {
42  const char *name;
43  const char *msg;
44  int pl;
45  int af;
46} rrt[] = {
47  [1] = { "A", "has address", PL_IP, AF_INET },
48  [28] = { "AAAA", "has address", PL_IP, AF_INET6 },
49  [2] = { "NS", "name server", PL_NAME },
50  [5] = { "CNAME", "is a nickname for", PL_NAME },
51  [16] = { "TXT", "descriptive text", PL_TEXT },
52  [6] = { "SOA", "start of authority", PL_SOA },
53  [12] = { "PTR", "domain name pointer", PL_NAME },
54  [15] = { "MX", "mail is handled", PL_MX },
55  [33] = { "SRV", "mail is handled", PL_SRV },
56  [255] = { "*", 0, 0 },
57};
58
59static const char rct[16][32] = {
60  "Success",
61  "Format error",
62  "Server failure",
63  "Non-existant domain",
64  "Not implemented",
65  "Refused",
66};
67
68void host_main(void)
69{
70  int verbose=(toys.optflags & (FLAG_a|FLAG_v)), type,
71      i, j, ret, sec, count, rcode, qlen, alen, pllen = 0,
72      abuf_len = 65536; // Largest TCP response.
73  unsigned ttl, pri, v[5];
74  unsigned char *abuf = xmalloc(abuf_len);
75  char *rrname = xmalloc(MAXDNAME);
76  unsigned char qbuf[280], *p;
77  char *name, *nsname, plname[640], ptrbuf[128];
78  struct addrinfo *ai, iplit_hints = { .ai_flags = AI_NUMERICHOST };
79
80  name = *toys.optargs;
81  nsname = toys.optargs[1];
82
83  if (!TT.type_str && (toys.optflags & FLAG_a)) TT.type_str = "255";
84  if (!getaddrinfo(name, 0, &iplit_hints, &ai)) {
85    unsigned char *a;
86    static const char xdigits[] = "0123456789abcdef";
87
88    if (ai->ai_family == AF_INET) {
89      a = (void *)&((struct sockaddr_in *)ai->ai_addr)->sin_addr;
90      snprintf(ptrbuf, sizeof(ptrbuf), "%d.%d.%d.%d.in-addr.arpa",
91        a[3], a[2], a[1], a[0]);
92    } else if (ai->ai_family == AF_INET6) {
93      a = (void *)&((struct sockaddr_in6 *)ai->ai_addr)->sin6_addr;
94      for (j=0, i=15; i>=0; i--) {
95        ptrbuf[j++] = xdigits[a[i]&15];
96        ptrbuf[j++] = '.';
97        ptrbuf[j++] = xdigits[a[i]>>4];
98        ptrbuf[j++] = '.';
99      }
100      strcpy(ptrbuf+j, "ip6.arpa");
101    }
102    name = ptrbuf;
103    if (!TT.type_str) TT.type_str="12";
104  } else if (!TT.type_str) TT.type_str="1";
105
106  if (TT.type_str[0]-'0' < 10u) type = atoi(TT.type_str);
107  else {
108    type = -1;
109    for (i=0; i<ARRAY_LEN(rrt); i++) {
110      if (rrt[i].name && !strcasecmp(TT.type_str, rrt[i].name)) {
111        type = i;
112        break;
113      }
114    }
115    if (!strcasecmp(TT.type_str, "any")) type = 255;
116    if (type < 0) error_exit("Invalid query type: %s", TT.type_str);
117  }
118
119  qlen = res_mkquery(0, name, 1, type, 0, 0, 0, qbuf, sizeof(qbuf));
120  if (qlen < 0) error_exit("Invalid query parameters: %s", name);
121
122  if (nsname) {
123    struct addrinfo ns_hints = { .ai_socktype = SOCK_DGRAM };
124
125    if ((ret = getaddrinfo(nsname, "53", &ns_hints, &ai)) < 0)
126      error_exit("Error looking up server name: %s", gai_strerror(ret));
127    int s = xsocket(ai->ai_family, ai->ai_socktype, ai->ai_protocol);
128    xconnect(s, ai->ai_addr, ai->ai_addrlen);
129    setsockopt(s, SOL_SOCKET, SO_RCVTIMEO, &(struct timeval){ .tv_sec = 5 },
130      sizeof(struct timeval));
131    printf("Using domain server %s:\n", nsname);
132    send(s, qbuf, qlen, 0);
133    alen = recv(s, abuf, abuf_len, 0);
134  } else alen = res_send(qbuf, qlen, abuf, abuf_len);
135
136  if (alen < 12) error_exit("Host not found.");
137
138  rcode = abuf[3] & 15;
139
140  if (verbose) {
141    printf("rcode = %d (%s), ancount = %d\n",
142      rcode, rct[rcode], 256*abuf[6] + abuf[7]);
143    if (!(abuf[2] & 4)) printf("The following answer is not authoritative:\n");
144  }
145
146  if (rcode) error_exit("Host not found.");
147
148  p = abuf + 12;
149  for (sec=0; sec<4; sec++) {
150    count = 256*abuf[4+2*sec] + abuf[5+2*sec];
151    if (verbose && count>0 && sec>1)
152      puts(sec==2 ? "For authoritative answers, see:"
153        : "Additional information:");
154
155    for (; count--; p += pllen) {
156      p += dn_expand(abuf, abuf+alen, p, rrname, MAXDNAME);
157      type = (p[0]<<8) + p[1];
158      p += 4;
159      if (!sec) continue;
160      ttl = (p[0]<<24)+(p[1]<<16)+(p[2]<<8)+p[3];
161      p += 4;
162      pllen = (p[0]<<8) + p[1];
163      p += 2;
164
165      switch (type<ARRAY_LEN(rrt) ? rrt[type].pl : 0) {
166      case PL_IP:
167        inet_ntop(rrt[type].af, p, plname, sizeof(plname));
168        break;
169      case PL_NAME:
170        dn_expand(abuf, abuf+alen, p, plname, sizeof(plname));
171        break;
172      case PL_TEXT:
173        snprintf(plname, sizeof(plname), "\"%.*s\"", pllen, p);
174        break;
175      case PL_SOA:
176        i = dn_expand(abuf, abuf+alen, p, plname, sizeof(plname) - 1);
177        strcat(plname, " ");
178        i += dn_expand(abuf, abuf+alen, p+i, plname+strlen(plname),
179          sizeof(plname)-strlen(plname));
180        for (j=0; j<5; j++)
181          v[j] = (p[i+4*j]<<24)+(p[1+i+4*j]<<16)+(p[2+i+4*j]<<8)+p[3+i+4*j];
182        snprintf(plname+strlen(plname), sizeof(plname)-strlen(plname),
183          "(\n\t\t%u\t;serial (version)\n"
184          "\t\t%u\t;refresh period\n"
185          "\t\t%u\t;retry interval\n"
186          "\t\t%u\t;expire time\n"
187          "\t\t%u\t;default ttl\n"
188          "\t\t)", v[0], v[1], v[2], v[3], v[4]);
189        break;
190      case PL_MX:
191        pri = (p[0]<<8)+p[1];
192        snprintf(plname, sizeof(plname), verbose ? "%d " : "(pri=%d) by ", pri);
193        dn_expand(abuf, abuf+alen, p+2, plname+strlen(plname),
194          sizeof(plname) - strlen(plname));
195        break;
196      case PL_SRV:
197        for (j=0; j<3; j++) v[j] = (p[2*j]<<8) + p[1+2*j];
198        snprintf(plname, sizeof(plname), "%u %u %u ", v[0], v[1], v[2]);
199        dn_expand(abuf, abuf+alen, p+6, plname+strlen(plname),
200          sizeof(plname) - strlen(plname));
201        break;
202      default:
203        printf("%s unsupported RR type %u\n", rrname, type);
204        continue;
205      }
206
207      if (verbose)
208        printf("%s\t%u\tIN %s\t%s\n", rrname, ttl, rrt[type].name, plname);
209      else if (rrt[type].msg)
210        printf("%s %s %s\n", rrname, rrt[type].msg, plname);
211    }
212    if (!verbose && sec==1) break;
213  }
214
215  if (CFG_TOYBOX_FREE) {
216    free(abuf);
217    free(rrname);
218  }
219  toys.exitval = rcode;
220}
221