1 /* 2 This example code shows how to use the high-level, low-level, and 3 server-level interfaces of evdns. 4 5 XXX It's pretty ugly and should probably be cleaned up. 6 */ 7 8 #include <event2/event-config.h> 9 10 /* Compatibility for possible missing IPv6 declarations */ 11 #include "../ipv6-internal.h" 12 13 #include <sys/types.h> 14 15 #ifdef EVENT__HAVE_UNISTD_H 16 #include <unistd.h> 17 #endif 18 19 #ifdef _WIN32 20 #include <winsock2.h> 21 #include <ws2tcpip.h> 22 #include <getopt.h> 23 #else 24 #include <sys/socket.h> 25 #include <netinet/in.h> 26 #include <arpa/inet.h> 27 #endif 28 29 #include <event2/event.h> 30 #include <event2/dns.h> 31 #include <event2/dns_struct.h> 32 #include <event2/util.h> 33 34 #ifdef EVENT__HAVE_NETINET_IN6_H 35 #include <netinet/in6.h> 36 #endif 37 38 #include <stdio.h> 39 #include <stdlib.h> 40 #include <string.h> 41 42 #define u32 ev_uint32_t 43 #define u8 ev_uint8_t 44 45 static const char * 46 debug_ntoa(u32 address) 47 { 48 static char buf[32]; 49 u32 a = ntohl(address); 50 evutil_snprintf(buf, sizeof(buf), "%d.%d.%d.%d", 51 (int)(u8)((a>>24)&0xff), 52 (int)(u8)((a>>16)&0xff), 53 (int)(u8)((a>>8 )&0xff), 54 (int)(u8)((a )&0xff)); 55 return buf; 56 } 57 58 static void 59 main_callback(int result, char type, int count, int ttl, 60 void *addrs, void *orig) { 61 char *n = (char*)orig; 62 int i; 63 for (i = 0; i < count; ++i) { 64 if (type == DNS_IPv4_A) { 65 printf("%s: %s\n", n, debug_ntoa(((u32*)addrs)[i])); 66 } else if (type == DNS_PTR) { 67 printf("%s: %s\n", n, ((char**)addrs)[i]); 68 } 69 } 70 if (!count) { 71 printf("%s: No answer (%d)\n", n, result); 72 } 73 fflush(stdout); 74 } 75 76 static void 77 gai_callback(int err, struct evutil_addrinfo *ai, void *arg) 78 { 79 const char *name = arg; 80 int i; 81 if (err) { 82 printf("%s: %s\n", name, evutil_gai_strerror(err)); 83 } 84 if (ai && ai->ai_canonname) 85 printf(" %s ==> %s\n", name, ai->ai_canonname); 86 for (i=0; ai; ai = ai->ai_next, ++i) { 87 char buf[128]; 88 if (ai->ai_family == PF_INET) { 89 struct sockaddr_in *sin = 90 (struct sockaddr_in*)ai->ai_addr; 91 evutil_inet_ntop(AF_INET, &sin->sin_addr, buf, 92 sizeof(buf)); 93 printf("[%d] %s: %s\n",i,name,buf); 94 } else { 95 struct sockaddr_in6 *sin6 = 96 (struct sockaddr_in6*)ai->ai_addr; 97 evutil_inet_ntop(AF_INET6, &sin6->sin6_addr, buf, 98 sizeof(buf)); 99 printf("[%d] %s: %s\n",i,name,buf); 100 } 101 } 102 } 103 104 static void 105 evdns_server_callback(struct evdns_server_request *req, void *data) 106 { 107 int i, r; 108 (void)data; 109 /* dummy; give 192.168.11.11 as an answer for all A questions, 110 * give foo.bar.example.com as an answer for all PTR questions. */ 111 for (i = 0; i < req->nquestions; ++i) { 112 u32 ans = htonl(0xc0a80b0bUL); 113 if (req->questions[i]->type == EVDNS_TYPE_A && 114 req->questions[i]->dns_question_class == EVDNS_CLASS_INET) { 115 printf(" -- replying for %s (A)\n", req->questions[i]->name); 116 r = evdns_server_request_add_a_reply(req, req->questions[i]->name, 117 1, &ans, 10); 118 if (r<0) 119 printf("eeep, didn't work.\n"); 120 } else if (req->questions[i]->type == EVDNS_TYPE_PTR && 121 req->questions[i]->dns_question_class == EVDNS_CLASS_INET) { 122 printf(" -- replying for %s (PTR)\n", req->questions[i]->name); 123 r = evdns_server_request_add_ptr_reply(req, NULL, req->questions[i]->name, 124 "foo.bar.example.com", 10); 125 if (r<0) 126 printf("ugh, no luck"); 127 } else { 128 printf(" -- skipping %s [%d %d]\n", req->questions[i]->name, 129 req->questions[i]->type, req->questions[i]->dns_question_class); 130 } 131 } 132 133 r = evdns_server_request_respond(req, 0); 134 if (r<0) 135 printf("eeek, couldn't send reply.\n"); 136 } 137 138 static int verbose = 0; 139 140 static void 141 logfn(int is_warn, const char *msg) { 142 if (!is_warn && !verbose) 143 return; 144 fprintf(stderr, "%s: %s\n", is_warn?"WARN":"INFO", msg); 145 } 146 147 int 148 main(int c, char **v) { 149 struct options { 150 int reverse; 151 int use_getaddrinfo; 152 int servertest; 153 const char *resolv_conf; 154 const char *ns; 155 }; 156 struct options o; 157 char opt; 158 struct event_base *event_base = NULL; 159 struct evdns_base *evdns_base = NULL; 160 161 memset(&o, 0, sizeof(o)); 162 163 if (c < 2) { 164 fprintf(stderr, "syntax: %s [-x] [-v] [-c resolv.conf] [-s ns] hostname\n", v[0]); 165 fprintf(stderr, "syntax: %s [-T]\n", v[0]); 166 return 1; 167 } 168 169 while ((opt = getopt(c, v, "xvc:Ts:")) != -1) { 170 switch (opt) { 171 case 'x': o.reverse = 1; break; 172 case 'v': ++verbose; break; 173 case 'g': o.use_getaddrinfo = 1; break; 174 case 'T': o.servertest = 1; break; 175 case 'c': o.resolv_conf = optarg; break; 176 case 's': o.ns = optarg; break; 177 default : fprintf(stderr, "Unknown option %c\n", opt); break; 178 } 179 } 180 181 #ifdef _WIN32 182 { 183 WSADATA WSAData; 184 WSAStartup(0x101, &WSAData); 185 } 186 #endif 187 188 event_base = event_base_new(); 189 evdns_base = evdns_base_new(event_base, EVDNS_BASE_DISABLE_WHEN_INACTIVE); 190 evdns_set_log_fn(logfn); 191 192 if (o.servertest) { 193 evutil_socket_t sock; 194 struct sockaddr_in my_addr; 195 sock = socket(PF_INET, SOCK_DGRAM, 0); 196 if (sock == -1) { 197 perror("socket"); 198 exit(1); 199 } 200 evutil_make_socket_nonblocking(sock); 201 my_addr.sin_family = AF_INET; 202 my_addr.sin_port = htons(10053); 203 my_addr.sin_addr.s_addr = INADDR_ANY; 204 if (bind(sock, (struct sockaddr*)&my_addr, sizeof(my_addr))<0) { 205 perror("bind"); 206 exit(1); 207 } 208 evdns_add_server_port_with_base(event_base, sock, 0, evdns_server_callback, NULL); 209 } 210 if (optind < c) { 211 int res; 212 #ifdef _WIN32 213 if (o.resolv_conf == NULL && !o.ns) 214 res = evdns_base_config_windows_nameservers(evdns_base); 215 else 216 #endif 217 if (o.ns) 218 res = evdns_base_nameserver_ip_add(evdns_base, o.ns); 219 else 220 res = evdns_base_resolv_conf_parse(evdns_base, 221 DNS_OPTION_NAMESERVERS, o.resolv_conf); 222 223 if (res < 0) { 224 fprintf(stderr, "Couldn't configure nameservers"); 225 return 1; 226 } 227 } 228 229 printf("EVUTIL_AI_CANONNAME in example = %d\n", EVUTIL_AI_CANONNAME); 230 for (; optind < c; ++optind) { 231 if (o.reverse) { 232 struct in_addr addr; 233 if (evutil_inet_pton(AF_INET, v[optind], &addr)!=1) { 234 fprintf(stderr, "Skipping non-IP %s\n", v[optind]); 235 continue; 236 } 237 fprintf(stderr, "resolving %s...\n",v[optind]); 238 evdns_base_resolve_reverse(evdns_base, &addr, 0, main_callback, v[optind]); 239 } else if (o.use_getaddrinfo) { 240 struct evutil_addrinfo hints; 241 memset(&hints, 0, sizeof(hints)); 242 hints.ai_family = PF_UNSPEC; 243 hints.ai_protocol = IPPROTO_TCP; 244 hints.ai_flags = EVUTIL_AI_CANONNAME; 245 fprintf(stderr, "resolving (fwd) %s...\n",v[optind]); 246 evdns_getaddrinfo(evdns_base, v[optind], NULL, &hints, 247 gai_callback, v[optind]); 248 } else { 249 fprintf(stderr, "resolving (fwd) %s...\n",v[optind]); 250 evdns_base_resolve_ipv4(evdns_base, v[optind], 0, main_callback, v[optind]); 251 } 252 } 253 fflush(stdout); 254 event_base_dispatch(event_base); 255 return 0; 256 } 257 258
