1 /* host.c - DNS lookup utility 2 * 3 * Copyright 2014 Rich Felker <dalias (at) aerifal.cx> 4 * 5 * No standard, but there's a version in bind9 6 7 USE_HOST(NEWTOY(host, "<1>2avt:", TOYFLAG_USR|TOYFLAG_BIN)) 8 9 config 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 seprated address to reverse lookup. 17 SERVER (if present) is the DNS server to use. 18 19 -a no idea 20 -t not a clue 21 -v verbose 22 */ 23 24 #define FOR_host 25 #include "toys.h" 26 27 GLOBALS( 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 41 static 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 59 static const char rct[16][32] = { 60 "Success", 61 "Format error", 62 "Server failure", 63 "Non-existant domain", 64 "Not implemented", 65 "Refused", 66 }; 67 68 void 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 unsigned ttl, pri, v[5]; 73 unsigned char qbuf[280], abuf[512], *p; 74 char *name, *nsname, rrname[256], plname[640], ptrbuf[64]; 75 struct addrinfo *ai, iplit_hints = { .ai_flags = AI_NUMERICHOST }; 76 77 name = *toys.optargs; 78 nsname = toys.optargs[1]; 79 80 if (!TT.type_str && (toys.optflags & FLAG_a)) TT.type_str = "255"; 81 if (!getaddrinfo(name, 0, &iplit_hints, &ai)) { 82 unsigned char *a; 83 static const char xdigits[] = "0123456789abcdef"; 84 85 if (ai->ai_family == AF_INET) { 86 a = (void *)&((struct sockaddr_in *)ai->ai_addr)->sin_addr; 87 snprintf(ptrbuf, sizeof(ptrbuf), "%d.%d.%d.%d.in-addr.arpa", 88 a[3], a[2], a[1], a[0]); 89 } else if (ai->ai_family == AF_INET6) { 90 a = (void *)&((struct sockaddr_in6 *)ai->ai_addr)->sin6_addr; 91 for (j=0, i=15; i>=0; i--) { 92 ptrbuf[j++] = xdigits[a[i]&15]; 93 ptrbuf[j++] = '.'; 94 ptrbuf[j++] = xdigits[a[i]>>4]; 95 ptrbuf[j++] = '.'; 96 } 97 strcpy(ptrbuf+j, "ip6.arpa"); 98 } 99 name = ptrbuf; 100 if (!TT.type_str) TT.type_str="12"; 101 } else if (!TT.type_str) TT.type_str="1"; 102 103 if (TT.type_str[0]-'0' < 10u) type = atoi(TT.type_str); 104 else { 105 type = -1; 106 for (i=0; i < sizeof rrt / sizeof *rrt; i++) { 107 if (rrt[i].name && !strcasecmp(TT.type_str, rrt[i].name)) { 108 type = i; 109 break; 110 } 111 } 112 if (!strcasecmp(TT.type_str, "any")) type = 255; 113 if (type < 0) error_exit("Invalid query type: %s", TT.type_str); 114 } 115 116 qlen = res_mkquery(0, name, 1, type, 0, 0, 0, qbuf, sizeof qbuf); 117 if (qlen < 0) error_exit("Invalid query parameters: %s", name); 118 119 if (nsname) { 120 struct addrinfo ns_hints = { .ai_socktype = SOCK_DGRAM }; 121 122 if ((ret = getaddrinfo(nsname, "53", &ns_hints, &ai)) < 0) 123 error_exit("Error looking up server name: %s", gai_strerror(ret)); 124 int s = socket(ai->ai_family, ai->ai_socktype, ai->ai_protocol); 125 if (s < 0 || connect(s, ai->ai_addr, ai->ai_addrlen) < 0) 126 perror_exit("Socket error"); 127 setsockopt(s, SOL_SOCKET, SO_RCVTIMEO, &(struct timeval){ .tv_sec = 5 }, 128 sizeof(struct timeval)); 129 printf("Using domain server %s:\n", nsname); 130 send(s, qbuf, qlen, 0); 131 alen = recv(s, abuf, sizeof abuf, 0); 132 } else alen = res_send(qbuf, qlen, abuf, sizeof abuf); 133 134 if (alen < 12) error_exit("Host not found."); 135 136 rcode = abuf[3] & 15; 137 138 if (verbose) { 139 printf("rcode = %d (%s), ancount = %d\n", 140 rcode, rct[rcode], 256*abuf[6] + abuf[7]); 141 if (!(abuf[2] & 4)) printf("The following answer is not authoritative:\n"); 142 } 143 144 if (rcode) error_exit("Host not found."); 145 146 p = abuf + 12; 147 for (sec=0; sec<4; sec++) { 148 count = 256*abuf[4+2*sec] + abuf[5+2*sec]; 149 if (verbose && count>0 && sec>1) 150 puts(sec==2 ? "For authoritative answers, see:" 151 : "Additional information:"); 152 153 for (; count--; p += pllen) { 154 p += dn_expand(abuf, abuf+alen, p, rrname, sizeof(rrname)); 155 type = (p[0]<<8) + p[1]; 156 p += 4; 157 if (!sec) continue; 158 ttl = (p[0]<<24)+(p[1]<<16)+(p[2]<<8)+p[3]; 159 p += 4; 160 pllen = (p[0]<<8) + p[1]; 161 p += 2; 162 163 switch (type<sizeof(rrt)/sizeof(*rrt) ? rrt[type].pl : 0) { 164 case PL_IP: 165 inet_ntop(rrt[type].af, p, plname, sizeof plname); 166 break; 167 case PL_NAME: 168 dn_expand(abuf, abuf+alen, p, plname, sizeof plname); 169 break; 170 case PL_TEXT: 171 snprintf(plname, sizeof plname, "\"%.*s\"", pllen, p); 172 break; 173 case PL_SOA: 174 i = dn_expand(abuf, abuf+alen, p, plname, sizeof plname - 1); 175 strcat(plname, " "); 176 i += dn_expand(abuf, abuf+alen, p+i, plname+strlen(plname), 177 sizeof(plname)-strlen(plname)); 178 for (j=0; j<5; j++) 179 v[j] = (p[i+4*j]<<24)+(p[1+i+4*j]<<16)+(p[2+i+4*j]<<8)+p[3+i+4*j]; 180 snprintf(plname+strlen(plname), sizeof(plname)-strlen(plname), 181 "(\n\t\t%u\t;serial (version)\n" 182 "\t\t%u\t;refresh period\n" 183 "\t\t%u\t;retry interval\n" 184 "\t\t%u\t;expire time\n" 185 "\t\t%u\t;default ttl\n" 186 "\t\t)", v[0], v[1], v[2], v[3], v[4]); 187 break; 188 case PL_MX: 189 pri = (p[0]<<8)+p[1]; 190 snprintf(plname, sizeof(plname), verbose ? "%d " : "(pri=%d) by ", pri); 191 dn_expand(abuf, abuf+alen, p+2, plname+strlen(plname), 192 sizeof plname - strlen(plname)); 193 break; 194 case PL_SRV: 195 for (j=0; j<3; j++) v[j] = (p[2*j]<<8) + p[1+2*j]; 196 snprintf(plname, sizeof(plname), "%u %u %u ", v[0], v[1], v[2]); 197 dn_expand(abuf, abuf+alen, p+6, plname+strlen(plname), 198 sizeof plname - strlen(plname)); 199 break; 200 default: 201 printf("%s unsupported RR type %u\n", rrname, type); 202 continue; 203 } 204 205 if (verbose) 206 printf("%s\t%u\tIN %s\t%s\n", rrname, ttl, rrt[type].name, plname); 207 else if (rrt[type].msg) 208 printf("%s %s %s\n", rrname, rrt[type].msg, plname); 209 } 210 if (!verbose && sec==1) break; 211 } 212 213 toys.exitval = rcode; 214 } 215
