external/bsd/libevent/dist/sample/dns-example.c

   1 /*      $NetBSD: dns-example.c,v 1.1.1.1 2013/04/11 16:43:31 christos Exp $     */
   2 /*
   3   This example code shows how to use the high-level, low-level, and
   4   server-level interfaces of evdns.
   5
   6   XXX It's pretty ugly and should probably be cleaned up.
   7  */
   8
   9 #include <event2/event-config.h>
  10
  11 /* Compatibility for possible missing IPv6 declarations */
  12 #include "../ipv6-internal.h"
  13
  14 #include <sys/types.h>
  15
  16 #ifdef WIN32
  17 #include <winsock2.h>
  18 #include <ws2tcpip.h>
  19 #else
  20 #include <sys/socket.h>
  21 #include <netinet/in.h>
  22 #include <arpa/inet.h>
  23 #endif
  24
  25 #include <event2/event.h>
  26 #include <event2/dns.h>
  27 #include <event2/dns_struct.h>
  28 #include <event2/util.h>
  29
  30 #ifdef _EVENT_HAVE_NETINET_IN6_H
  31 #include <netinet/in6.h>
  32 #endif
  33
  34 #include <stdio.h>
  35 #include <stdlib.h>
  36 #include <string.h>
  37
  38 #define u32 ev_uint32_t
  39 #define u8 ev_uint8_t
  40
  41 static const char *
  42 debug_ntoa(u32 address)
  43 {
  44         static char buf[32];
  45         u32 a = ntohl(address);
  46         evutil_snprintf(buf, sizeof(buf), "%d.%d.%d.%d",
  47                                         (int)(u8)((a>>24)&0xff),
  48                                         (int)(u8)((a>>16)&0xff),
  49                                         (int)(u8)((a>>8 )&0xff),
  50                                         (int)(u8)((a    )&0xff));
  51         return buf;
  52 }
  53
  54 static void
  55 main_callback(int result, char type, int count, int ttl,
  56                           void *addrs, void *orig) {
  57         char *n = (char*)orig;
  58         int i;
  59         for (i = 0; i < count; ++i) {
  60                 if (type == DNS_IPv4_A) {
  61                         printf("%s: %s\n", n, debug_ntoa(((u32*)addrs)[i]));
  62                 } else if (type == DNS_PTR) {
  63                         printf("%s: %s\n", n, ((char**)addrs)[i]);
  64                 }
  65         }
  66         if (!count) {
  67                 printf("%s: No answer (%d)\n", n, result);
  68         }
  69         fflush(stdout);
  70 }
  71
  72 static void
  73 gai_callback(int err, struct evutil_addrinfo *ai, void *arg)
  74 {
  75         const char *name = arg;
  76         int i;
  77         if (err) {
  78                 printf("%s: %s\n", name, evutil_gai_strerror(err));
  79         }
  80         if (ai && ai->ai_canonname)
  81                 printf("    %s ==> %s\n", name, ai->ai_canonname);
  82         for (i=0; ai; ai = ai->ai_next, ++i) {
  83                 char buf[128];
  84                 if (ai->ai_family == PF_INET) {
  85                         struct sockaddr_in *sin =
  86                             (struct sockaddr_in*)ai->ai_addr;
  87                         evutil_inet_ntop(AF_INET, &sin->sin_addr, buf,
  88                             sizeof(buf));
  89                         printf("[%d] %s: %s\n",i,name,buf);
  90                 } else {
  91                         struct sockaddr_in6 *sin6 =
  92                             (struct sockaddr_in6*)ai->ai_addr;
  93                         evutil_inet_ntop(AF_INET6, &sin6->sin6_addr, buf,
  94                             sizeof(buf));
  95                         printf("[%d] %s: %s\n",i,name,buf);
  96                 }
  97         }
  98 }
  99
 100 static void
 101 evdns_server_callback(struct evdns_server_request *req, void *data)
 102 {
 103         int i, r;
 104         (void)data;
 105         /* dummy; give 192.168.11.11 as an answer for all A questions,
 106          *      give foo.bar.example.com as an answer for all PTR questions. */
 107         for (i = 0; i < req->nquestions; ++i) {
 108                 u32 ans = htonl(0xc0a80b0bUL);
 109                 if (req->questions[i]->type == EVDNS_TYPE_A &&
 110                     req->questions[i]->dns_question_class == EVDNS_CLASS_INET) {
 111                         printf(" -- replying for %s (A)\n", req->questions[i]->name);
 112                         r = evdns_server_request_add_a_reply(req, req->questions[i]->name,
 113                                                                                   1, &ans, 10);
 114                         if (r<0)
 115                                 printf("eeep, didn't work.\n");
 116                 } else if (req->questions[i]->type == EVDNS_TYPE_PTR &&
 117                     req->questions[i]->dns_question_class == EVDNS_CLASS_INET) {
 118                         printf(" -- replying for %s (PTR)\n", req->questions[i]->name);
 119                         r = evdns_server_request_add_ptr_reply(req, NULL, req->questions[i]->name,
 120                                                                                         "foo.bar.example.com", 10);
 121                         if (r<0)
 122                                 printf("ugh, no luck");
 123                 } else {
 124                         printf(" -- skipping %s [%d %d]\n", req->questions[i]->name,
 125                                    req->questions[i]->type, req->questions[i]->dns_question_class);
 126                 }
 127         }
 128
 129         r = evdns_server_request_respond(req, 0);
 130         if (r<0)
 131                 printf("eeek, couldn't send reply.\n");
 132 }
 133
 134 static int verbose = 0;
 135
 136 static void
 137 logfn(int is_warn, const char *msg) {
 138         if (!is_warn && !verbose)
 139                 return;
 140         fprintf(stderr, "%s: %s\n", is_warn?"WARN":"INFO", msg);
 141 }
 142
 143 int
 144 main(int c, char **v) {
 145         int idx;
 146         int reverse = 0, servertest = 0, use_getaddrinfo = 0;
 147         struct event_base *event_base = NULL;
 148         struct evdns_base *evdns_base = NULL;
 149         const char *resolv_conf = NULL;
 150         if (c<2) {
 151                 fprintf(stderr, "syntax: %s [-x] [-v] [-c resolv.conf] hostname\n", v[0]);
 152                 fprintf(stderr, "syntax: %s [-servertest]\n", v[0]);
 153                 return 1;
 154         }
 155         idx = 1;
 156         while (idx < c && v[idx][0] == '-') {
 157                 if (!strcmp(v[idx], "-x"))
 158                         reverse = 1;
 159                 else if (!strcmp(v[idx], "-v"))
 160                         verbose = 1;
 161                 else if (!strcmp(v[idx], "-g"))
 162                         use_getaddrinfo = 1;
 163                 else if (!strcmp(v[idx], "-servertest"))
 164                         servertest = 1;
 165                 else if (!strcmp(v[idx], "-c")) {
 166                         if (idx + 1 < c)
 167                                 resolv_conf = v[++idx];
 168                         else
 169                                 fprintf(stderr, "-c needs an argument\n");
 170                 } else
 171                         fprintf(stderr, "Unknown option %s\n", v[idx]);
 172                 ++idx;
 173         }
 174
 175 #ifdef WIN32
 176         {
 177                 WSADATA WSAData;
 178                 WSAStartup(0x101, &WSAData);
 179         }
 180 #endif
 181
 182         event_base = event_base_new();
 183         evdns_base = evdns_base_new(event_base, 0);
 184         evdns_set_log_fn(logfn);
 185
 186         if (servertest) {
 187                 evutil_socket_t sock;
 188                 struct sockaddr_in my_addr;
 189                 sock = socket(PF_INET, SOCK_DGRAM, 0);
 190                 if (sock == -1) {
 191                         perror("socket");
 192                         exit(1);
 193                 }
 194                 evutil_make_socket_nonblocking(sock);
 195                 my_addr.sin_family = AF_INET;
 196                 my_addr.sin_port = htons(10053);
 197                 my_addr.sin_addr.s_addr = INADDR_ANY;
 198                 if (bind(sock, (struct sockaddr*)&my_addr, sizeof(my_addr))<0) {
 199                         perror("bind");
 200                         exit(1);
 201                 }
 202                 evdns_add_server_port_with_base(event_base, sock, 0, evdns_server_callback, NULL);
 203         }
 204         if (idx < c) {
 205                 int res;
 206 #ifdef WIN32
 207                 if (resolv_conf == NULL)
 208                         res = evdns_base_config_windows_nameservers(evdns_base);
 209                 else
 210 #endif
 211                         res = evdns_base_resolv_conf_parse(evdns_base,
 212                             DNS_OPTION_NAMESERVERS,
 213                             resolv_conf ? resolv_conf : "/etc/resolv.conf");
 214
 215                 if (res < 0) {
 216                         fprintf(stderr, "Couldn't configure nameservers");
 217                         return 1;
 218                 }
 219         }
 220
 221         printf("EVUTIL_AI_CANONNAME in example = %d\n", EVUTIL_AI_CANONNAME);
 222         for (; idx < c; ++idx) {
 223                 if (reverse) {
 224                         struct in_addr addr;
 225                         if (evutil_inet_pton(AF_INET, v[idx], &addr)!=1) {
 226                                 fprintf(stderr, "Skipping non-IP %s\n", v[idx]);
 227                                 continue;
 228                         }
 229                         fprintf(stderr, "resolving %s...\n",v[idx]);
 230                         evdns_base_resolve_reverse(evdns_base, &addr, 0, main_callback, v[idx]);
 231                 } else if (use_getaddrinfo) {
 232                         struct evutil_addrinfo hints;
 233                         memset(&hints, 0, sizeof(hints));
 234                         hints.ai_family = PF_UNSPEC;
 235                         hints.ai_protocol = IPPROTO_TCP;
 236                         hints.ai_flags = EVUTIL_AI_CANONNAME;
 237                         fprintf(stderr, "resolving (fwd) %s...\n",v[idx]);
 238                         evdns_getaddrinfo(evdns_base, v[idx], NULL, &hints,
 239                             gai_callback, v[idx]);
 240                 } else {
 241                         fprintf(stderr, "resolving (fwd) %s...\n",v[idx]);
 242                         evdns_base_resolve_ipv4(evdns_base, v[idx], 0, main_callback, v[idx]);
 243                 }
 244         }
 245         fflush(stdout);
 246         event_base_dispatch(event_base);
 247         return 0;
 248 }
 249