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 #include <sys/types.h> 11 12 #ifdef WIN32 13 #include <winsock2.h> 14 #include <ws2tcpip.h> 15 #else 16 #include <sys/socket.h> 17 #include <netinet/in.h> 18 #include <arpa/inet.h> 19 #endif 20 21 #include <event2/event.h> 22 #include <event2/dns.h> 23 #include <event2/dns_struct.h> 24 #include <event2/util.h> 25 26 #ifdef _EVENT_HAVE_NETINET_IN6_H 27 #include <netinet/in6.h> 28 #endif 29 30 #include <stdio.h> 31 #include <stdlib.h> 32 #include <string.h> 33 34 #define u32 ev_uint32_t 35 #define u8 ev_uint8_t 36 37 static const char * 38 debug_ntoa(u32 address) 39 { 40 static char buf[32]; 41 u32 a = ntohl(address); 42 evutil_snprintf(buf, sizeof(buf), "%d.%d.%d.%d", 43 (int)(u8)((a>>24)&0xff), 44 (int)(u8)((a>>16)&0xff), 45 (int)(u8)((a>>8 )&0xff), 46 (int)(u8)((a )&0xff)); 47 return buf; 48 } 49 50 static void 51 main_callback(int result, char type, int count, int ttl, 52 void *addrs, void *orig) { 53 char *n = (char*)orig; 54 int i; 55 for (i = 0; i < count; ++i) { 56 if (type == DNS_IPv4_A) { 57 printf("%s: %s\n", n, debug_ntoa(((u32*)addrs)[i])); 58 } else if (type == DNS_PTR) { 59 printf("%s: %s\n", n, ((char**)addrs)[i]); 60 } 61 } 62 if (!count) { 63 printf("%s: No answer (%d)\n", n, result); 64 } 65 fflush(stdout); 66 } 67 68 static void 69 gai_callback(int err, struct evutil_addrinfo *ai, void *arg) 70 { 71 const char *name = arg; 72 struct evutil_addrinfo *ai_first = NULL; 73 int i; 74 if (err) { 75 printf("%s: %s\n", name, evutil_gai_strerror(err)); 76 } 77 if (ai && ai->ai_canonname) 78 printf(" %s ==> %s\n", name, ai->ai_canonname); 79 for (i=0; ai; ai = ai->ai_next, ++i) { 80 char buf[128]; 81 if (ai->ai_family == PF_INET) { 82 struct sockaddr_in *sin = 83 (struct sockaddr_in*)ai->ai_addr; 84 evutil_inet_ntop(AF_INET, &sin->sin_addr, buf, 85 sizeof(buf)); 86 printf("[%d] %s: %s\n",i,name,buf); 87 } else { 88 struct sockaddr_in6 *sin6 = 89 (struct sockaddr_in6*)ai->ai_addr; 90 evutil_inet_ntop(AF_INET6, &sin6->sin6_addr, buf, 91 sizeof(buf)); 92 printf("[%d] %s: %s\n",i,name,buf); 93 } 94 } 95 if (ai_first) 96 evutil_freeaddrinfo(ai_first); 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 } else { 121 printf(" -- skipping %s [%d %d]\n", req->questions[i]->name, 122 req->questions[i]->type, req->questions[i]->dns_question_class); 123 } 124 } 125 126 r = evdns_server_request_respond(req, 0); 127 if (r<0) 128 printf("eeek, couldn't send reply.\n"); 129 } 130 131 static int verbose = 0; 132 133 static void 134 logfn(int is_warn, const char *msg) { 135 if (!is_warn && !verbose) 136 return; 137 fprintf(stderr, "%s: %s\n", is_warn?"WARN":"INFO", msg); 138 } 139 140 int 141 main(int c, char **v) { 142 int idx; 143 int reverse = 0, servertest = 0, use_getaddrinfo = 0; 144 struct event_base *event_base = NULL; 145 struct evdns_base *evdns_base = NULL; 146 if (c<2) { 147 fprintf(stderr, "syntax: %s [-x] [-v] hostname\n", v[0]); 148 fprintf(stderr, "syntax: %s [-servertest]\n", v[0]); 149 return 1; 150 } 151 idx = 1; 152 while (idx < c && v[idx][0] == '-') { 153 if (!strcmp(v[idx], "-x")) 154 reverse = 1; 155 else if (!strcmp(v[idx], "-v")) 156 verbose = 1; 157 else if (!strcmp(v[idx], "-g")) 158 use_getaddrinfo = 1; 159 else if (!strcmp(v[idx], "-servertest")) 160 servertest = 1; 161 else 162 fprintf(stderr, "Unknown option %s\n", v[idx]); 163 ++idx; 164 } 165 166 event_base = event_base_new(); 167 evdns_base = evdns_base_new(event_base, 0); 168 evdns_set_log_fn(logfn); 169 170 if (servertest) { 171 evutil_socket_t sock; 172 struct sockaddr_in my_addr; 173 sock = socket(PF_INET, SOCK_DGRAM, 0); 174 evutil_make_socket_nonblocking(sock); 175 my_addr.sin_family = AF_INET; 176 my_addr.sin_port = htons(10053); 177 my_addr.sin_addr.s_addr = INADDR_ANY; 178 if (bind(sock, (struct sockaddr*)&my_addr, sizeof(my_addr))<0) { 179 perror("bind"); 180 exit(1); 181 } 182 evdns_add_server_port_with_base(event_base, sock, 0, evdns_server_callback, NULL); 183 } 184 if (idx < c) { 185 #ifdef WIN32 186 evdns_base_config_windows_nameservers(evdns_base); 187 #else 188 evdns_base_resolv_conf_parse(evdns_base, DNS_OPTION_NAMESERVERS, 189 "/etc/resolv.conf"); 190 #endif 191 } 192 193 printf("EVUTIL_AI_CANONNAME in example = %d\n", EVUTIL_AI_CANONNAME); 194 for (; idx < c; ++idx) { 195 if (reverse) { 196 struct in_addr addr; 197 if (evutil_inet_pton(AF_INET, v[idx], &addr)!=1) { 198 fprintf(stderr, "Skipping non-IP %s\n", v[idx]); 199 continue; 200 } 201 fprintf(stderr, "resolving %s...\n",v[idx]); 202 evdns_base_resolve_reverse(evdns_base, &addr, 0, main_callback, v[idx]); 203 } else if (use_getaddrinfo) { 204 struct evutil_addrinfo hints; 205 memset(&hints, 0, sizeof(hints)); 206 hints.ai_family = PF_UNSPEC; 207 hints.ai_protocol = IPPROTO_TCP; 208 hints.ai_flags = EVUTIL_AI_CANONNAME; 209 fprintf(stderr, "resolving (fwd) %s...\n",v[idx]); 210 evdns_getaddrinfo(evdns_base, v[idx], NULL, &hints, 211 gai_callback, v[idx]); 212 } else { 213 fprintf(stderr, "resolving (fwd) %s...\n",v[idx]); 214 evdns_base_resolve_ipv4(evdns_base, v[idx], 0, main_callback, v[idx]); 215 } 216 } 217 fflush(stdout); 218 event_base_dispatch(event_base); 219 return 0; 220 } 221 222