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-rw-r--r--libs/libevent/docs/sample/dns-example.c257
1 files changed, 257 insertions, 0 deletions
diff --git a/libs/libevent/docs/sample/dns-example.c b/libs/libevent/docs/sample/dns-example.c
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+++ b/libs/libevent/docs/sample/dns-example.c
@@ -0,0 +1,257 @@
+/*
+ This example code shows how to use the high-level, low-level, and
+ server-level interfaces of evdns.
+
+ XXX It's pretty ugly and should probably be cleaned up.
+ */
+
+#include <event2/event-config.h>
+
+/* Compatibility for possible missing IPv6 declarations */
+#include "../ipv6-internal.h"
+
+#include <sys/types.h>
+
+#ifdef EVENT__HAVE_UNISTD_H
+#include <unistd.h>
+#endif
+
+#ifdef _WIN32
+#include <winsock2.h>
+#include <ws2tcpip.h>
+#include <getopt.h>
+#else
+#include <sys/socket.h>
+#include <netinet/in.h>
+#include <arpa/inet.h>
+#endif
+
+#include <event2/event.h>
+#include <event2/dns.h>
+#include <event2/dns_struct.h>
+#include <event2/util.h>
+
+#ifdef EVENT__HAVE_NETINET_IN6_H
+#include <netinet/in6.h>
+#endif
+
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+
+#define u32 ev_uint32_t
+#define u8 ev_uint8_t
+
+static const char *
+debug_ntoa(u32 address)
+{
+ static char buf[32];
+ u32 a = ntohl(address);
+ evutil_snprintf(buf, sizeof(buf), "%d.%d.%d.%d",
+ (int)(u8)((a>>24)&0xff),
+ (int)(u8)((a>>16)&0xff),
+ (int)(u8)((a>>8 )&0xff),
+ (int)(u8)((a )&0xff));
+ return buf;
+}
+
+static void
+main_callback(int result, char type, int count, int ttl,
+ void *addrs, void *orig) {
+ char *n = (char*)orig;
+ int i;
+ for (i = 0; i < count; ++i) {
+ if (type == DNS_IPv4_A) {
+ printf("%s: %s\n", n, debug_ntoa(((u32*)addrs)[i]));
+ } else if (type == DNS_PTR) {
+ printf("%s: %s\n", n, ((char**)addrs)[i]);
+ }
+ }
+ if (!count) {
+ printf("%s: No answer (%d)\n", n, result);
+ }
+ fflush(stdout);
+}
+
+static void
+gai_callback(int err, struct evutil_addrinfo *ai, void *arg)
+{
+ const char *name = arg;
+ int i;
+ if (err) {
+ printf("%s: %s\n", name, evutil_gai_strerror(err));
+ }
+ if (ai && ai->ai_canonname)
+ printf(" %s ==> %s\n", name, ai->ai_canonname);
+ for (i=0; ai; ai = ai->ai_next, ++i) {
+ char buf[128];
+ if (ai->ai_family == PF_INET) {
+ struct sockaddr_in *sin =
+ (struct sockaddr_in*)ai->ai_addr;
+ evutil_inet_ntop(AF_INET, &sin->sin_addr, buf,
+ sizeof(buf));
+ printf("[%d] %s: %s\n",i,name,buf);
+ } else {
+ struct sockaddr_in6 *sin6 =
+ (struct sockaddr_in6*)ai->ai_addr;
+ evutil_inet_ntop(AF_INET6, &sin6->sin6_addr, buf,
+ sizeof(buf));
+ printf("[%d] %s: %s\n",i,name,buf);
+ }
+ }
+}
+
+static void
+evdns_server_callback(struct evdns_server_request *req, void *data)
+{
+ int i, r;
+ (void)data;
+ /* dummy; give 192.168.11.11 as an answer for all A questions,
+ * give foo.bar.example.com as an answer for all PTR questions. */
+ for (i = 0; i < req->nquestions; ++i) {
+ u32 ans = htonl(0xc0a80b0bUL);
+ if (req->questions[i]->type == EVDNS_TYPE_A &&
+ req->questions[i]->dns_question_class == EVDNS_CLASS_INET) {
+ printf(" -- replying for %s (A)\n", req->questions[i]->name);
+ r = evdns_server_request_add_a_reply(req, req->questions[i]->name,
+ 1, &ans, 10);
+ if (r<0)
+ printf("eeep, didn't work.\n");
+ } else if (req->questions[i]->type == EVDNS_TYPE_PTR &&
+ req->questions[i]->dns_question_class == EVDNS_CLASS_INET) {
+ printf(" -- replying for %s (PTR)\n", req->questions[i]->name);
+ r = evdns_server_request_add_ptr_reply(req, NULL, req->questions[i]->name,
+ "foo.bar.example.com", 10);
+ if (r<0)
+ printf("ugh, no luck");
+ } else {
+ printf(" -- skipping %s [%d %d]\n", req->questions[i]->name,
+ req->questions[i]->type, req->questions[i]->dns_question_class);
+ }
+ }
+
+ r = evdns_server_request_respond(req, 0);
+ if (r<0)
+ printf("eeek, couldn't send reply.\n");
+}
+
+static int verbose = 0;
+
+static void
+logfn(int is_warn, const char *msg) {
+ if (!is_warn && !verbose)
+ return;
+ fprintf(stderr, "%s: %s\n", is_warn?"WARN":"INFO", msg);
+}
+
+int
+main(int c, char **v) {
+ struct options {
+ int reverse;
+ int use_getaddrinfo;
+ int servertest;
+ const char *resolv_conf;
+ const char *ns;
+ };
+ struct options o;
+ char opt;
+ struct event_base *event_base = NULL;
+ struct evdns_base *evdns_base = NULL;
+
+ memset(&o, 0, sizeof(o));
+
+ if (c < 2) {
+ fprintf(stderr, "syntax: %s [-x] [-v] [-c resolv.conf] [-s ns] hostname\n", v[0]);
+ fprintf(stderr, "syntax: %s [-T]\n", v[0]);
+ return 1;
+ }
+
+ while ((opt = getopt(c, v, "xvc:Ts:")) != -1) {
+ switch (opt) {
+ case 'x': o.reverse = 1; break;
+ case 'v': ++verbose; break;
+ case 'g': o.use_getaddrinfo = 1; break;
+ case 'T': o.servertest = 1; break;
+ case 'c': o.resolv_conf = optarg; break;
+ case 's': o.ns = optarg; break;
+ default : fprintf(stderr, "Unknown option %c\n", opt); break;
+ }
+ }
+
+#ifdef _WIN32
+ {
+ WSADATA WSAData;
+ WSAStartup(0x101, &WSAData);
+ }
+#endif
+
+ event_base = event_base_new();
+ evdns_base = evdns_base_new(event_base, EVDNS_BASE_DISABLE_WHEN_INACTIVE);
+ evdns_set_log_fn(logfn);
+
+ if (o.servertest) {
+ evutil_socket_t sock;
+ struct sockaddr_in my_addr;
+ sock = socket(PF_INET, SOCK_DGRAM, 0);
+ if (sock == -1) {
+ perror("socket");
+ exit(1);
+ }
+ evutil_make_socket_nonblocking(sock);
+ my_addr.sin_family = AF_INET;
+ my_addr.sin_port = htons(10053);
+ my_addr.sin_addr.s_addr = INADDR_ANY;
+ if (bind(sock, (struct sockaddr*)&my_addr, sizeof(my_addr))<0) {
+ perror("bind");
+ exit(1);
+ }
+ evdns_add_server_port_with_base(event_base, sock, 0, evdns_server_callback, NULL);
+ }
+ if (optind < c) {
+ int res;
+#ifdef _WIN32
+ if (o.resolv_conf == NULL && !o.ns)
+ res = evdns_base_config_windows_nameservers(evdns_base);
+ else
+#endif
+ if (o.ns)
+ res = evdns_base_nameserver_ip_add(evdns_base, o.ns);
+ else
+ res = evdns_base_resolv_conf_parse(evdns_base,
+ DNS_OPTION_NAMESERVERS, o.resolv_conf);
+
+ if (res < 0) {
+ fprintf(stderr, "Couldn't configure nameservers");
+ return 1;
+ }
+ }
+
+ printf("EVUTIL_AI_CANONNAME in example = %d\n", EVUTIL_AI_CANONNAME);
+ for (; optind < c; ++optind) {
+ if (o.reverse) {
+ struct in_addr addr;
+ if (evutil_inet_pton(AF_INET, v[optind], &addr)!=1) {
+ fprintf(stderr, "Skipping non-IP %s\n", v[optind]);
+ continue;
+ }
+ fprintf(stderr, "resolving %s...\n",v[optind]);
+ evdns_base_resolve_reverse(evdns_base, &addr, 0, main_callback, v[optind]);
+ } else if (o.use_getaddrinfo) {
+ struct evutil_addrinfo hints;
+ memset(&hints, 0, sizeof(hints));
+ hints.ai_family = PF_UNSPEC;
+ hints.ai_protocol = IPPROTO_TCP;
+ hints.ai_flags = EVUTIL_AI_CANONNAME;
+ fprintf(stderr, "resolving (fwd) %s...\n",v[optind]);
+ evdns_getaddrinfo(evdns_base, v[optind], NULL, &hints,
+ gai_callback, v[optind]);
+ } else {
+ fprintf(stderr, "resolving (fwd) %s...\n",v[optind]);
+ evdns_base_resolve_ipv4(evdns_base, v[optind], 0, main_callback, v[optind]);
+ }
+ }
+ fflush(stdout);
+ event_base_dispatch(event_base);
+ return 0;
+}
+
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