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kc3-lang/libevent/test/regress_dns.c

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  • Author : Nick Mathewson
    Date : 2009-10-21 02:14:16
    Hash : 50825466
    Message : Fix windows compilation warnings. svn:r1449

  • test/regress_dns.c
  • /*
     * Copyright (c) 2003-2007 Niels Provos <provos@citi.umich.edu>
     * Copyright (c) 2007-2009 Niels Provos and Nick Mathewson
     *
     * Redistribution and use in source and binary forms, with or without
     * modification, are permitted provided that the following conditions
     * are met:
     * 1. Redistributions of source code must retain the above copyright
     *    notice, this list of conditions and the following disclaimer.
     * 2. Redistributions in binary form must reproduce the above copyright
     *    notice, this list of conditions and the following disclaimer in the
     *    documentation and/or other materials provided with the distribution.
     * 3. The name of the author may not be used to endorse or promote products
     *    derived from this software without specific prior written permission.
     *
     * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
     * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
     * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
     * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
     * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
     * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
     * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
     * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
     * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
     * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
     */
    
    #ifdef WIN32
    #include <winsock2.h>
    #include <windows.h>
    #include <ws2tcpip.h>
    #endif
    
    #ifdef HAVE_CONFIG_H
    #include "event-config.h"
    #endif
    
    #include <sys/types.h>
    #include <sys/stat.h>
    #ifdef _EVENT_HAVE_SYS_TIME_H
    #include <sys/time.h>
    #endif
    #include <sys/queue.h>
    #ifndef WIN32
    #include <sys/socket.h>
    #include <signal.h>
    #include <netinet/in.h>
    #include <arpa/inet.h>
    #include <unistd.h>
    #endif
    #ifdef _EVENT_HAVE_NETINET_IN6_H
    #include <netinet/in6.h>
    #endif
    #ifdef HAVE_NETDB_H
    #include <netdb.h>
    #endif
    #include <fcntl.h>
    #include <stdlib.h>
    #include <stdio.h>
    #include <string.h>
    #include <errno.h>
    
    #include "event2/event.h"
    #include "event2/event_compat.h"
    #include <event2/util.h>
    #include "evdns.h"
    #include "log-internal.h"
    #include "regress.h"
    
    static int dns_ok = 0;
    static int dns_got_cancel = 0;
    static int dns_err = 0;
    
    static void
    dns_gethostbyname_cb(int result, char type, int count, int ttl,
        void *addresses, void *arg)
    {
    	dns_ok = dns_err = 0;
    
    	if (result == DNS_ERR_TIMEOUT) {
    		printf("[Timed out] ");
    		dns_err = result;
    		goto out;
    	}
    
    	if (result != DNS_ERR_NONE) {
    		printf("[Error code %d] ", result);
    		goto out;
    	}
    
            TT_BLATHER(("type: %d, count: %d, ttl: %d: ", type, count, ttl));
    
    	switch (type) {
    	case DNS_IPv6_AAAA: {
    #if defined(_EVENT_HAVE_STRUCT_IN6_ADDR) && defined(_EVENT_HAVE_INET_NTOP) && defined(INET6_ADDRSTRLEN)
    		struct in6_addr *in6_addrs = addresses;
    		char buf[INET6_ADDRSTRLEN+1];
    		int i;
    		/* a resolution that's not valid does not help */
    		if (ttl < 0)
    			goto out;
    		for (i = 0; i < count; ++i) {
    			const char *b = inet_ntop(AF_INET6, &in6_addrs[i], buf,sizeof(buf));
    			if (b)
    				TT_BLATHER(("%s ", b));
    			else
    				TT_BLATHER(("%s ", strerror(errno)));
    		}
    #endif
    		break;
    	}
    	case DNS_IPv4_A: {
    		struct in_addr *in_addrs = addresses;
    		int i;
    		/* a resolution that's not valid does not help */
    		if (ttl < 0)
    			goto out;
    		for (i = 0; i < count; ++i)
                            TT_BLATHER(("%s ", inet_ntoa(in_addrs[i])));
    		break;
    	}
    	case DNS_PTR:
    		/* may get at most one PTR */
    		if (count != 1)
    			goto out;
    
    		TT_BLATHER(("%s ", *(char **)addresses));
    		break;
    	default:
    		goto out;
    	}
    
    	dns_ok = type;
    
    out:
    	if (arg == NULL)
    		event_loopexit(NULL);
    	else
    		event_base_loopexit((struct event_base *)arg, NULL);
    }
    
    static void
    dns_gethostbyname(void)
    {
    	dns_ok = 0;
    	evdns_resolve_ipv4("www.monkey.org", 0, dns_gethostbyname_cb, NULL);
    	event_dispatch();
    
            tt_int_op(dns_ok, ==, DNS_IPv4_A);
            test_ok = dns_ok;
    end:
            ;
    }
    
    static void
    dns_gethostbyname6(void)
    {
    	dns_ok = 0;
    	evdns_resolve_ipv6("www.ietf.org", 0, dns_gethostbyname_cb, NULL);
    	event_dispatch();
    
            if (!dns_ok && dns_err == DNS_ERR_TIMEOUT) {
                    tt_skip();
            }
    
            tt_int_op(dns_ok, ==, DNS_IPv6_AAAA);
            test_ok = 1;
    end:
            ;
    }
    
    static void
    dns_gethostbyaddr(void)
    {
    	struct in_addr in;
    	in.s_addr = htonl(0x7f000001ul); /* 127.0.0.1 */
    	dns_ok = 0;
    	evdns_resolve_reverse(&in, 0, dns_gethostbyname_cb, NULL);
    	event_dispatch();
    
            tt_int_op(dns_ok, ==, DNS_PTR);
            test_ok = dns_ok;
    end:
            ;
    }
    
    static void
    dns_resolve_reverse(void *ptr)
    {
    	struct in_addr in;
    	struct event_base *base = event_base_new();
    	struct evdns_base *dns = evdns_base_new(base, 1/* init name servers */);
    	struct evdns_request *req = NULL;
    
            tt_assert(base);
            tt_assert(dns);
    	in.s_addr = htonl(0x7f000001ul); /* 127.0.0.1 */
    	dns_ok = 0;
    
    	req = evdns_base_resolve_reverse(
    		dns, &in, 0, dns_gethostbyname_cb, base);
            tt_assert(req);
    
    	event_base_dispatch(base);
    
            tt_int_op(dns_ok, ==, DNS_PTR);
    
    end:
            if (dns)
                    evdns_base_free(dns, 0);
            if (base)
                    event_base_free(base);
    }
    
    static int n_server_responses = 0;
    
    static void
    dns_server_request_cb(struct evdns_server_request *req, void *data)
    {
    	int i, r;
    	const char TEST_ARPA[] = "11.11.168.192.in-addr.arpa";
    	for (i = 0; i < req->nquestions; ++i) {
    		struct in_addr ans;
    		ans.s_addr = htonl(0xc0a80b0bUL); /* 192.168.11.11 */
    		if (req->questions[i]->type == EVDNS_TYPE_A &&
    			req->questions[i]->dns_question_class == EVDNS_CLASS_INET &&
    			!evutil_ascii_strcasecmp(req->questions[i]->name, "zz.example.com")) {
    			r = evdns_server_request_add_a_reply(req,
    												 req->questions[i]->name,
    												 1, &ans.s_addr, 12345);
    			if (r<0)
    				dns_ok = 0;
    		} else if (req->questions[i]->type == EVDNS_TYPE_AAAA &&
    				   req->questions[i]->dns_question_class == EVDNS_CLASS_INET &&
    				   !evutil_ascii_strcasecmp(req->questions[i]->name, "zz.example.com")) {
    			char addr6[17] = "abcdefghijklmnop";
    			r = evdns_server_request_add_aaaa_reply(req,
    													req->questions[i]->name,
    												 1, addr6, 123);
    			if (r<0)
    				dns_ok = 0;
    		} else if (req->questions[i]->type == EVDNS_TYPE_PTR &&
    				   req->questions[i]->dns_question_class == EVDNS_CLASS_INET &&
    				   !evutil_ascii_strcasecmp(req->questions[i]->name, TEST_ARPA)) {
    			r = evdns_server_request_add_ptr_reply(req, NULL,
    												   req->questions[i]->name,
    												   "ZZ.EXAMPLE.COM", 54321);
    			if (r<0)
    				dns_ok = 0;
                    } else if (req->questions[i]->type == EVDNS_TYPE_A &&
    		    req->questions[i]->dns_question_class == EVDNS_CLASS_INET &&
    		    !evutil_ascii_strcasecmp(req->questions[i]->name, "drop.example.com")) {
    			if (evdns_server_request_drop(req)<0)
    				dns_ok = 0;
    			return;
    		} else {
    			printf("Unexpected question %d %d \"%s\" ",
    					req->questions[i]->type,
    					req->questions[i]->dns_question_class,
    					req->questions[i]->name);
    			dns_ok = 0;
    		}
    	}
    	r = evdns_server_request_respond(req, 0);
    	if (r<0) {
    		printf("Couldn't send reply. ");
    		dns_ok = 0;
    	}
    }
    
    static void
    dns_server_gethostbyname_cb(int result, char type, int count, int ttl,
        void *addresses, void *arg)
    {
    	if (result == DNS_ERR_CANCEL) {
    		if (arg != (void*)(char*)90909) {
    			printf("Unexpected cancelation");
    			dns_ok = 0;
    		}
    		dns_got_cancel = 1;
    		goto out;
    	}
    	if (result != DNS_ERR_NONE) {
    		printf("Unexpected result %d. ", result);
    		dns_ok = 0;
    		goto out;
    	}
    	if (count != 1) {
    		printf("Unexpected answer count %d. ", count);
    		dns_ok = 0;
    		goto out;
    	}
    	switch (type) {
    	case DNS_IPv4_A: {
    		struct in_addr *in_addrs = addresses;
    		if (in_addrs[0].s_addr != htonl(0xc0a80b0bUL) || ttl != 12345) {
    			printf("Bad IPv4 response \"%s\" %d. ",
    					inet_ntoa(in_addrs[0]), ttl);
    			dns_ok = 0;
    			goto out;
    		}
    		break;
    	}
    	case DNS_IPv6_AAAA: {
    #if defined (_EVENT_HAVE_STRUCT_IN6_ADDR) && defined(_EVENT_HAVE_INET_NTOP) && defined(INET6_ADDRSTRLEN)
    		struct in6_addr *in6_addrs = addresses;
    		char buf[INET6_ADDRSTRLEN+1];
    		if (memcmp(&in6_addrs[0].s6_addr, "abcdefghijklmnop", 16)
    			|| ttl != 123) {
    			const char *b = inet_ntop(AF_INET6, &in6_addrs[0],buf,sizeof(buf));
    			printf("Bad IPv6 response \"%s\" %d. ", b, ttl);
    			dns_ok = 0;
    			goto out;
    		}
    #endif
    		break;
    	}
    	case DNS_PTR: {
    		char **addrs = addresses;
    		if (strcmp(addrs[0], "ZZ.EXAMPLE.COM") || ttl != 54321) {
    			printf("Bad PTR response \"%s\" %d. ",
    					addrs[0], ttl);
    			dns_ok = 0;
    			goto out;
    		}
    		break;
    	}
    	default:
    		printf("Bad response type %d. ", type);
    		dns_ok = 0;
    	}
    
     out:
    	if (++n_server_responses == 3) {
    		event_loopexit(NULL);
    	}
    }
    
    static void
    dns_server(void)
    {
            evutil_socket_t sock=-1;
    	struct sockaddr_in my_addr;
    	struct evdns_server_port *port=NULL;
    	struct in_addr resolve_addr;
    	struct evdns_base *base=NULL;
    	struct evdns_request *req=NULL;
    
    	dns_ok = 1;
    
    	base = evdns_base_new(NULL, 0);
    
    	/* Add ourself as the only nameserver, and make sure we really are
    	 * the only nameserver. */
    	evdns_base_nameserver_ip_add(base, "127.0.0.1:35353");
    
    	tt_int_op(evdns_base_count_nameservers(base), ==, 1);
    	/* Now configure a nameserver port. */
    	sock = socket(AF_INET, SOCK_DGRAM, 0);
            if (sock<=0) {
                    tt_abort_perror("socket");
            }
    
            evutil_make_socket_nonblocking(sock);
    
    	memset(&my_addr, 0, sizeof(my_addr));
    	my_addr.sin_family = AF_INET;
    	my_addr.sin_port = htons(35353);
    	my_addr.sin_addr.s_addr = htonl(0x7f000001UL);
    	if (bind(sock, (struct sockaddr*)&my_addr, sizeof(my_addr)) < 0) {
    		tt_abort_perror("bind");
    	}
    	port = evdns_add_server_port(sock, 0, dns_server_request_cb, NULL);
    
    	/* Send some queries. */
    	evdns_base_resolve_ipv4(base, "zz.example.com", DNS_QUERY_NO_SEARCH,
    					   dns_server_gethostbyname_cb, NULL);
    	evdns_base_resolve_ipv6(base, "zz.example.com", DNS_QUERY_NO_SEARCH,
    					   dns_server_gethostbyname_cb, NULL);
    	resolve_addr.s_addr = htonl(0xc0a80b0bUL); /* 192.168.11.11 */
    	evdns_base_resolve_reverse(base, &resolve_addr, 0,
                dns_server_gethostbyname_cb, NULL);
    	req = evdns_base_resolve_ipv4(base,
    	    "drop.example.com", DNS_QUERY_NO_SEARCH,
    	    dns_server_gethostbyname_cb, (void*)(char*)90909);
    
    	evdns_cancel_request(base, req);
    
    	event_dispatch();
    
    	tt_assert(dns_got_cancel);
            test_ok = dns_ok;
    
    end:
            if (port)
                    evdns_close_server_port(port);
            if (sock >= 0)
                    EVUTIL_CLOSESOCKET(sock);
    	if (base)
    		evdns_base_free(base, 0);
    }
    
    struct generic_dns_server_table {
    	const char *q;
    	const char *anstype;
    	const char *ans;
    	int seen;
    };
    
    static void
    generic_dns_server_cb(struct evdns_server_request *req, void *data)
    {
    	struct generic_dns_server_table *tab = data;
    	const char *question;
    
    	if (req->nquestions != 1)
    		TT_DIE(("Only handling one question at a time; got %d",
    			req->nquestions));
    
    	question = req->questions[0]->name;
    
    	while (tab->q && evutil_ascii_strcasecmp(question, tab->q) &&
    	    strcmp("*", tab->q))
    		++tab;
    	if (tab->q == NULL)
    		TT_DIE(("Unexpected question: '%s'", question));
    
    	++tab->seen;
    
    	if (!strcmp(tab->anstype, "err")) {
    		int err = atoi(tab->ans);
    		tt_assert(! evdns_server_request_respond(req, err));
    		return;
    	} else if (!strcmp(tab->anstype, "A")) {
    		struct in_addr in;
    		evutil_inet_pton(AF_INET, tab->ans, &in);
    		evdns_server_request_add_a_reply(req, question, 1, &in.s_addr,
    		    100);
    	} else if (!strcmp(tab->anstype, "AAAA")) {
    		struct in6_addr in6;
    		evutil_inet_pton(AF_INET6, tab->ans, &in6);
    		evdns_server_request_add_aaaa_reply(req,
    		    question, 1, &in6.s6_addr, 100);
    	} else {
    		TT_DIE(("Weird table entry with type '%s'", tab->anstype));
    	}
    	tt_assert(! evdns_server_request_respond(req, 0))
    	return;
    end:
    	tt_want(! evdns_server_request_drop(req));
    }
    
    static struct evdns_server_port *
    get_generic_server(struct event_base *base,
        ev_uint64_t portnum,
        evdns_request_callback_fn_type cb,
        void *arg)
    {
    	struct evdns_server_port *port = NULL;
    	evutil_socket_t sock;
    	struct sockaddr_in my_addr;
    
    	sock = socket(AF_INET, SOCK_DGRAM, 0);
            if (sock<=0) {
                    tt_abort_perror("socket");
            }
    
            evutil_make_socket_nonblocking(sock);
    
    	memset(&my_addr, 0, sizeof(my_addr));
    	my_addr.sin_family = AF_INET;
    	my_addr.sin_port = htons(portnum);
    	my_addr.sin_addr.s_addr = htonl(0x7f000001UL);
    	if (bind(sock, (struct sockaddr*)&my_addr, sizeof(my_addr)) < 0) {
    		tt_abort_perror("bind");
    	}
    	port = evdns_add_server_port_with_base(base, sock, 0, cb, arg);
    
    	return port;
    end:
    	return NULL;
    }
    
    static int n_replies_left;
    static struct event_base *exit_base;
    
    struct generic_dns_callback_result {
    	int result;
    	char type;
    	int count;
    	int ttl;
    	void *addrs;
    };
    
    static void
    generic_dns_callback(int result, char type, int count, int ttl, void *addresses,
        void *arg)
    {
    	size_t len;
    	struct generic_dns_callback_result *res = arg;
    	res->result = result;
    	res->type = type;
    	res->count = count;
    	res->ttl = ttl;
    
    	if (type == DNS_IPv4_A)
    		len = count * 4;
    	else if (type == DNS_IPv6_AAAA)
    		len = count * 16;
    	else if (type == DNS_PTR)
    		len = strlen(addresses)+1;
    	else {
    		len = 0;
    		res->addrs = NULL;
    	}
    	if (len) {
    		res->addrs = malloc(len);
    		memcpy(res->addrs, addresses, len);
    	}
    
    	if (--n_replies_left == 0)
    		event_base_loopexit(exit_base, NULL);
    }
    
    static struct generic_dns_server_table search_table[] = {
    	{ "host.a.example.com", "err", "3", 0 },
    	{ "host.b.example.com", "err", "3", 0 },
    	{ "host.c.example.com", "A", "11.22.33.44", 0 },
    	{ "host2.a.example.com", "err", "3", 0 },
    	{ "host2.b.example.com", "A", "200.100.0.100", 0 },
    	{ "host2.c.example.com", "err", "3", 0 },
    
    	{ "host", "err", "3", 0 },
    	{ "host2", "err", "3", 0 },
    	{ "*", "err", "3", 0 },
    	{ NULL, NULL, NULL, 0 }
    };
    
    static void
    dns_search_test(void *arg)
    {
    	struct basic_test_data *data = arg;
    	struct event_base *base = data->base;
    	struct evdns_server_port *port = NULL;
    	struct evdns_base *dns = NULL;
    
    	struct generic_dns_callback_result r1, r2, r3, r4, r5;
    
    	port = get_generic_server(base, 53900, generic_dns_server_cb,
    	    search_table);
    	tt_assert(port);
    
    	dns = evdns_base_new(base, 0);
    	tt_assert(!evdns_base_nameserver_ip_add(dns, "127.0.0.1:53900"));
    
    	evdns_base_search_add(dns, "a.example.com");
    	evdns_base_search_add(dns, "b.example.com");
    	evdns_base_search_add(dns, "c.example.com");
    
    	n_replies_left = 5;
    	exit_base = base;
    
    	evdns_base_resolve_ipv4(dns, "host", 0, generic_dns_callback, &r1);
    	evdns_base_resolve_ipv4(dns, "host2", 0, generic_dns_callback, &r2);
    	evdns_base_resolve_ipv4(dns, "host", DNS_NO_SEARCH, generic_dns_callback, &r3);
    	evdns_base_resolve_ipv4(dns, "host2", DNS_NO_SEARCH, generic_dns_callback, &r4);
    	evdns_base_resolve_ipv4(dns, "host3", 0, generic_dns_callback, &r5);
    
    	event_base_dispatch(base);
    
    	tt_int_op(r1.type, ==, DNS_IPv4_A);
    	tt_int_op(r1.count, ==, 1);
    	tt_int_op(((ev_uint32_t*)r1.addrs)[0], ==, htonl(0x0b16212c));
    	tt_int_op(r2.type, ==, DNS_IPv4_A);
    	tt_int_op(r2.count, ==, 1);
    	tt_int_op(((ev_uint32_t*)r2.addrs)[0], ==, htonl(0xc8640064));
    	tt_int_op(r3.result, ==, DNS_ERR_NOTEXIST);
    	tt_int_op(r4.result, ==, DNS_ERR_NOTEXIST);
    	tt_int_op(r5.result, ==, DNS_ERR_NOTEXIST);
    
    end:
    	if (dns)
    		evdns_base_free(dns, 0);
    	if (port)
    		evdns_close_server_port(port);
    }
    
    static void
    fail_server_cb(struct evdns_server_request *req, void *data)
    {
    	const char *question;
    	int *count = data;
    	struct in_addr in;
    
    	/* Drop the first N requests that we get. */
    	if (*count > 0) {
    		--*count;
    		tt_want(! evdns_server_request_drop(req));
    		return;
    	}
    
    	if (req->nquestions != 1)
    		TT_DIE(("Only handling one question at a time; got %d",
    			req->nquestions));
    
    	question = req->questions[0]->name;
    
    	if (!evutil_ascii_strcasecmp(question, "google.com")) {
    		/* Detect a probe, and get out of the loop. */
    		event_base_loopexit(exit_base, NULL);
    	}
    
    	evutil_inet_pton(AF_INET, "16.32.64.128", &in);
    	evdns_server_request_add_a_reply(req, question, 1, &in.s_addr,
    	    100);
    	tt_assert(! evdns_server_request_respond(req, 0))
    	return;
    end:
    	tt_want(! evdns_server_request_drop(req));
    }
    
    static void
    dns_retry_test(void *arg)
    {
    	struct basic_test_data *data = arg;
    	struct event_base *base = data->base;
    	struct evdns_server_port *port = NULL;
    	struct evdns_base *dns = NULL;
    	int drop_count = 2;
    
    	struct generic_dns_callback_result r1;
    
    	port = get_generic_server(base, 53900, fail_server_cb,
    	    &drop_count);
    	tt_assert(port);
    
    	dns = evdns_base_new(base, 0);
    	tt_assert(!evdns_base_nameserver_ip_add(dns, "127.0.0.1:53900"));
    	tt_assert(! evdns_base_set_option(dns, "timeout:", "0.3", DNS_OPTIONS_ALL));
    	tt_assert(! evdns_base_set_option(dns, "max-timeouts:", "10", DNS_OPTIONS_ALL));
    
    	evdns_base_resolve_ipv4(dns, "host.example.com", 0,
    	    generic_dns_callback, &r1);
    
    	n_replies_left = 1;
    	exit_base = base;
    
    	event_base_dispatch(base);
    
    	tt_int_op(drop_count, ==, 0);
    
    	tt_int_op(r1.type, ==, DNS_IPv4_A);
    	tt_int_op(r1.count, ==, 1);
    	tt_int_op(((ev_uint32_t*)r1.addrs)[0], ==, htonl(0x10204080));
    
    
    	/* Now try again, but this time have the server get treated as
    	 * failed, so we can send it a test probe. */
    	drop_count = 4;
    	tt_assert(! evdns_base_set_option(dns, "max-timeouts:", "3", DNS_OPTIONS_ALL));
    	tt_assert(! evdns_base_set_option(dns, "attempts:", "4", DNS_OPTIONS_ALL));
    	memset(&r1, 0, sizeof(r1));
    
    	evdns_base_resolve_ipv4(dns, "host.example.com", 0,
    	    generic_dns_callback, &r1);
    
    	n_replies_left = 2;
    
    	/* This will run until it answers the "google.com" probe request. */
    	/* XXXX It takes 10 seconds to retry the probe, which makes the test
    	 * slow. */
    	event_base_dispatch(base);
    
    	/* We'll treat the server as failed here. */
    	tt_int_op(r1.result, ==, DNS_ERR_TIMEOUT);
    
    	/* It should work this time. */
    	tt_int_op(drop_count, ==, 0);
    	evdns_base_resolve_ipv4(dns, "host.example.com", 0,
    	    generic_dns_callback, &r1);
    
    	event_base_dispatch(base);
    	tt_int_op(r1.result, ==, DNS_ERR_NONE);
    	tt_int_op(r1.type, ==, DNS_IPv4_A);
    	tt_int_op(r1.count, ==, 1);
    	tt_int_op(((ev_uint32_t*)r1.addrs)[0], ==, htonl(0x10204080));
    
    end:
    	if (dns)
    		evdns_base_free(dns, 0);
    	if (port)
    		evdns_close_server_port(port);
    }
    
    static struct generic_dns_server_table internal_error_table[] = {
    	/* Error 4 (NOTIMPL) makes us reissue the request to another server
    	   if we can.
    
    	   XXXX we should reissue under a much wider set of circumstances!
    	 */
    	{ "foof.example.com", "err", "4", 0 },
    	{ NULL, NULL, NULL, 0 }
    };
    
    static struct generic_dns_server_table reissue_table[] = {
    	{ "foof.example.com", "A", "240.15.240.15", 0 },
    	{ NULL, NULL, NULL, 0 }
    };
    
    static void
    dns_reissue_test(void *arg)
    {
    	struct basic_test_data *data = arg;
    	struct event_base *base = data->base;
    	struct evdns_server_port *port1 = NULL, *port2 = NULL;
    	struct evdns_base *dns = NULL;
    	struct generic_dns_callback_result r1;
    
    	port1 = get_generic_server(base, 53900, generic_dns_server_cb,
    	    internal_error_table);
    	tt_assert(port1);
    	port2 = get_generic_server(base, 53901, generic_dns_server_cb,
    	    reissue_table);
    	tt_assert(port2);
    
    	dns = evdns_base_new(base, 0);
    	tt_assert(!evdns_base_nameserver_ip_add(dns, "127.0.0.1:53900"));
    	tt_assert(! evdns_base_set_option(dns, "timeout:", "0.3", DNS_OPTIONS_ALL));
    	tt_assert(! evdns_base_set_option(dns, "max-timeouts:", "2", DNS_OPTIONS_ALL));
    	tt_assert(! evdns_base_set_option(dns, "attempts:", "5", DNS_OPTIONS_ALL));
    
    	memset(&r1, 0, sizeof(r1));
    	evdns_base_resolve_ipv4(dns, "foof.example.com", 0,
    	    generic_dns_callback, &r1);
    
    	/* Add this after, so that we are sure to get a reissue. */
    	tt_assert(!evdns_base_nameserver_ip_add(dns, "127.0.0.1:53901"));
    
    	n_replies_left = 1;
    	exit_base = base;
    
    	event_base_dispatch(base);
    	tt_int_op(r1.result, ==, DNS_ERR_NONE);
    	tt_int_op(r1.type, ==, DNS_IPv4_A);
    	tt_int_op(r1.count, ==, 1);
    	tt_int_op(((ev_uint32_t*)r1.addrs)[0], ==, htonl(0xf00ff00f));
    
    	/* Make sure we dropped at least once. */
    	tt_int_op(internal_error_table[0].seen, >, 0);
    
    end:
    	if (dns)
    		evdns_base_free(dns, 0);
    	if (port1)
    		evdns_close_server_port(port1);
    	if (port2)
    		evdns_close_server_port(port2);
    }
    
    static void
    dumb_bytes_fn(char *p, size_t n)
    {
    	unsigned i;
    	/* This gets us 6 bits of entropy per transaction ID, which means we
    	 * will have probably have collisions and need to pick again. */
    	for(i=0;i<n;++i)
    		p[i] = (char)(rand() & 7);
    }
    
    static void
    dns_inflight_test(void *arg)
    {
    	struct basic_test_data *data = arg;
    	struct event_base *base = data->base;
    	struct evdns_server_port *port = NULL;
    	struct evdns_base *dns = NULL;
    
    	struct generic_dns_callback_result r[20];
    	int i;
    
    	port = get_generic_server(base, 53900, generic_dns_server_cb,
    	    reissue_table);
    	tt_assert(port);
    
    	/* Make sure that having another (very bad!) RNG doesn't mess us
    	 * up. */
    	evdns_set_random_bytes_fn(dumb_bytes_fn);
    
    	dns = evdns_base_new(base, 0);
    	tt_assert(!evdns_base_nameserver_ip_add(dns, "127.0.0.1:53900"));
    	tt_assert(! evdns_base_set_option(dns, "max-inflight:", "3", DNS_OPTIONS_ALL));
    	tt_assert(! evdns_base_set_option(dns, "randomize-case:", "0", DNS_OPTIONS_ALL));
    
    	for(i=0;i<20;++i)
    		evdns_base_resolve_ipv4(dns, "foof.example.com", 0, generic_dns_callback, &r[i]);
    
    	n_replies_left = 20;
    	exit_base = base;
    
    	event_base_dispatch(base);
    
    	for (i=0;i<20;++i) {
    		tt_int_op(r[i].type, ==, DNS_IPv4_A);
    		tt_int_op(r[i].count, ==, 1);
    		tt_int_op(((ev_uint32_t*)r[i].addrs)[0], ==, htonl(0xf00ff00f));
    	}
    
    end:
    	if (dns)
    		evdns_base_free(dns, 0);
    	if (port)
    		evdns_close_server_port(port);
    }
    
    #define DNS_LEGACY(name, flags)                                        \
    	{ #name, run_legacy_test_fn, flags|TT_LEGACY, &legacy_setup,   \
                        dns_##name }
    
    struct testcase_t dns_testcases[] = {
            DNS_LEGACY(server, TT_FORK|TT_NEED_BASE),
            DNS_LEGACY(gethostbyname, TT_FORK|TT_NEED_BASE|TT_NEED_DNS),
            DNS_LEGACY(gethostbyname6, TT_FORK|TT_NEED_BASE|TT_NEED_DNS),
            DNS_LEGACY(gethostbyaddr, TT_FORK|TT_NEED_BASE|TT_NEED_DNS),
            { "resolve_reverse", dns_resolve_reverse, TT_FORK, NULL, NULL },
    	{ "search", dns_search_test, TT_FORK|TT_NEED_BASE, &basic_setup, NULL },
    	{ "retry", dns_retry_test, TT_FORK|TT_NEED_BASE, &basic_setup, NULL },
    	{ "reissue", dns_reissue_test, TT_FORK|TT_NEED_BASE, &basic_setup, NULL },
    	{ "inflight", dns_inflight_test, TT_FORK|TT_NEED_BASE, &basic_setup, NULL },
    
            END_OF_TESTCASES
    };