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 *
debug_ntoa(u32 address)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
main_callback(int result,char type,int count,int ttl,void * addrs,void * orig)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
gai_callback(int err,struct evutil_addrinfo * ai,void * arg)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
evdns_server_callback(struct evdns_server_request * req,void * data)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
logfn(int is_warn,const char * msg)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
main(int c,char ** v)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