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