258 lines
6.5 KiB
C
258 lines
6.5 KiB
C
/*
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This example code shows how to use the high-level, low-level, and
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server-level interfaces of evdns.
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XXX It's pretty ugly and should probably be cleaned up.
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*/
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#include <event2/event-config.h>
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/* Compatibility for possible missing IPv6 declarations */
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#include "../ipv6-internal.h"
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#include <sys/types.h>
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#ifdef EVENT__HAVE_UNISTD_H
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#include <unistd.h>
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#endif
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#ifdef _WIN32
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#include <winsock2.h>
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#include <ws2tcpip.h>
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#include <getopt.h>
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#else
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#include <sys/socket.h>
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#include <netinet/in.h>
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#include <arpa/inet.h>
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#endif
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#include <event2/event.h>
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#include <event2/dns.h>
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#include <event2/dns_struct.h>
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#include <event2/util.h>
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#ifdef EVENT__HAVE_NETINET_IN6_H
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#include <netinet/in6.h>
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#endif
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#include <stdio.h>
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#include <stdlib.h>
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#include <string.h>
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#define u32 ev_uint32_t
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#define u8 ev_uint8_t
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static const char *
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debug_ntoa(u32 address)
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{
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static char buf[32];
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u32 a = ntohl(address);
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evutil_snprintf(buf, sizeof(buf), "%d.%d.%d.%d",
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(int)(u8)((a>>24)&0xff),
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(int)(u8)((a>>16)&0xff),
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(int)(u8)((a>>8 )&0xff),
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(int)(u8)((a )&0xff));
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return buf;
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}
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static void
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main_callback(int result, char type, int count, int ttl,
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void *addrs, void *orig) {
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char *n = (char*)orig;
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int i;
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for (i = 0; i < count; ++i) {
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if (type == DNS_IPv4_A) {
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printf("%s: %s\n", n, debug_ntoa(((u32*)addrs)[i]));
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} else if (type == DNS_PTR) {
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printf("%s: %s\n", n, ((char**)addrs)[i]);
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}
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}
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if (!count) {
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printf("%s: No answer (%d)\n", n, result);
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}
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fflush(stdout);
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}
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static void
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gai_callback(int err, struct evutil_addrinfo *ai, void *arg)
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{
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const char *name = arg;
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int i;
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if (err) {
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printf("%s: %s\n", name, evutil_gai_strerror(err));
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}
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if (ai && ai->ai_canonname)
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printf(" %s ==> %s\n", name, ai->ai_canonname);
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for (i=0; ai; ai = ai->ai_next, ++i) {
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char buf[128];
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if (ai->ai_family == PF_INET) {
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struct sockaddr_in *sin =
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(struct sockaddr_in*)ai->ai_addr;
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evutil_inet_ntop(AF_INET, &sin->sin_addr, buf,
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sizeof(buf));
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printf("[%d] %s: %s\n",i,name,buf);
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} else {
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struct sockaddr_in6 *sin6 =
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(struct sockaddr_in6*)ai->ai_addr;
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evutil_inet_ntop(AF_INET6, &sin6->sin6_addr, buf,
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sizeof(buf));
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printf("[%d] %s: %s\n",i,name,buf);
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}
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}
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}
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static void
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evdns_server_callback(struct evdns_server_request *req, void *data)
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{
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int i, r;
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(void)data;
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/* dummy; give 192.168.11.11 as an answer for all A questions,
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* give foo.bar.example.com as an answer for all PTR questions. */
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for (i = 0; i < req->nquestions; ++i) {
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u32 ans = htonl(0xc0a80b0bUL);
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if (req->questions[i]->type == EVDNS_TYPE_A &&
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req->questions[i]->dns_question_class == EVDNS_CLASS_INET) {
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printf(" -- replying for %s (A)\n", req->questions[i]->name);
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r = evdns_server_request_add_a_reply(req, req->questions[i]->name,
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1, &ans, 10);
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if (r<0)
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printf("eeep, didn't work.\n");
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} else if (req->questions[i]->type == EVDNS_TYPE_PTR &&
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req->questions[i]->dns_question_class == EVDNS_CLASS_INET) {
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printf(" -- replying for %s (PTR)\n", req->questions[i]->name);
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r = evdns_server_request_add_ptr_reply(req, NULL, req->questions[i]->name,
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"foo.bar.example.com", 10);
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if (r<0)
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printf("ugh, no luck");
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} else {
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printf(" -- skipping %s [%d %d]\n", req->questions[i]->name,
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req->questions[i]->type, req->questions[i]->dns_question_class);
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}
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}
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r = evdns_server_request_respond(req, 0);
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if (r<0)
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printf("eeek, couldn't send reply.\n");
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}
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static int verbose = 0;
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static void
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logfn(int is_warn, const char *msg) {
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if (!is_warn && !verbose)
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return;
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fprintf(stderr, "%s: %s\n", is_warn?"WARN":"INFO", msg);
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}
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int
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main(int c, char **v) {
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struct options {
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int reverse;
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int use_getaddrinfo;
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int servertest;
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const char *resolv_conf;
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const char *ns;
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};
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struct options o;
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char opt;
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struct event_base *event_base = NULL;
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struct evdns_base *evdns_base = NULL;
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memset(&o, 0, sizeof(o));
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if (c < 2) {
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fprintf(stderr, "syntax: %s [-x] [-v] [-c resolv.conf] [-s ns] hostname\n", v[0]);
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fprintf(stderr, "syntax: %s [-T]\n", v[0]);
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return 1;
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}
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while ((opt = getopt(c, v, "xvc:Ts:")) != -1) {
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switch (opt) {
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case 'x': o.reverse = 1; break;
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case 'v': ++verbose; break;
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case 'g': o.use_getaddrinfo = 1; break;
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case 'T': o.servertest = 1; break;
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case 'c': o.resolv_conf = optarg; break;
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case 's': o.ns = optarg; break;
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default : fprintf(stderr, "Unknown option %c\n", opt); break;
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}
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}
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#ifdef _WIN32
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{
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WSADATA WSAData;
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WSAStartup(0x101, &WSAData);
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}
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#endif
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event_base = event_base_new();
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evdns_base = evdns_base_new(event_base, EVDNS_BASE_DISABLE_WHEN_INACTIVE);
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evdns_set_log_fn(logfn);
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if (o.servertest) {
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evutil_socket_t sock;
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struct sockaddr_in my_addr;
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sock = socket(PF_INET, SOCK_DGRAM, 0);
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if (sock == -1) {
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perror("socket");
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exit(1);
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}
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evutil_make_socket_nonblocking(sock);
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my_addr.sin_family = AF_INET;
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my_addr.sin_port = htons(10053);
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my_addr.sin_addr.s_addr = INADDR_ANY;
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if (bind(sock, (struct sockaddr*)&my_addr, sizeof(my_addr))<0) {
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perror("bind");
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exit(1);
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}
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evdns_add_server_port_with_base(event_base, sock, 0, evdns_server_callback, NULL);
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}
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if (optind < c) {
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int res;
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#ifdef _WIN32
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if (o.resolv_conf == NULL && !o.ns)
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res = evdns_base_config_windows_nameservers(evdns_base);
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else
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#endif
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if (o.ns)
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res = evdns_base_nameserver_ip_add(evdns_base, o.ns);
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else
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res = evdns_base_resolv_conf_parse(evdns_base,
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DNS_OPTION_NAMESERVERS, o.resolv_conf);
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if (res < 0) {
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fprintf(stderr, "Couldn't configure nameservers");
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return 1;
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}
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}
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printf("EVUTIL_AI_CANONNAME in example = %d\n", EVUTIL_AI_CANONNAME);
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for (; optind < c; ++optind) {
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if (o.reverse) {
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struct in_addr addr;
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if (evutil_inet_pton(AF_INET, v[optind], &addr)!=1) {
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fprintf(stderr, "Skipping non-IP %s\n", v[optind]);
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continue;
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}
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fprintf(stderr, "resolving %s...\n",v[optind]);
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evdns_base_resolve_reverse(evdns_base, &addr, 0, main_callback, v[optind]);
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} else if (o.use_getaddrinfo) {
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struct evutil_addrinfo hints;
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memset(&hints, 0, sizeof(hints));
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hints.ai_family = PF_UNSPEC;
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hints.ai_protocol = IPPROTO_TCP;
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hints.ai_flags = EVUTIL_AI_CANONNAME;
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fprintf(stderr, "resolving (fwd) %s...\n",v[optind]);
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evdns_getaddrinfo(evdns_base, v[optind], NULL, &hints,
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gai_callback, v[optind]);
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} else {
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fprintf(stderr, "resolving (fwd) %s...\n",v[optind]);
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evdns_base_resolve_ipv4(evdns_base, v[optind], 0, main_callback, v[optind]);
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}
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}
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fflush(stdout);
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event_base_dispatch(event_base);
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return 0;
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}
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