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
45static const char *
46debug_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
58static void
59main_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
76static void
77gai_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
104static void
105evdns_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
138static int verbose = 0;
139
140static void
141logfn(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
147int
148main(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