diff -Nur ORIG.bind-9.16.0/bin/named/fuzz.c bind-9.16.0/bin/named/fuzz.c
--- ORIG.bind-9.16.0/bin/named/fuzz.c	2020-02-12 21:03:44.000000000 +0100
+++ bind-9.16.0/bin/named/fuzz.c	2020-02-23 01:30:24.786425215 +0100
@@ -724,7 +724,7 @@
 void
 named_fuzz_notify(void)
 {
-#ifdef ENABLE_AFL
+#if 0
 	if (getenv("AFL_CMIN")) {
 		named_server_flushonshutdown(named_g_server, false);
 		isc_app_shutdown();
@@ -745,7 +745,7 @@
 void
 named_fuzz_setup(void)
 {
-#ifdef ENABLE_AFL
+#if 0
 	if (getenv("__AFL_PERSISTENT") || getenv("AFL_CMIN")) {
 		pthread_t thread;
 		void *(fn) = NULL;
diff -Nur ORIG.bind-9.16.0/bin/named/main.c bind-9.16.0/bin/named/main.c
--- ORIG.bind-9.16.0/bin/named/main.c	2020-02-12 21:03:44.000000000 +0100
+++ bind-9.16.0/bin/named/main.c	2020-02-23 01:30:20.720359839 +0100
@@ -1431,9 +1431,258 @@
 
 /* main entry point, possibly hooked */
 
-int
-main(int argc, char *argv[])
-{
+#include <arpa/inet.h>
+#include <errno.h>
+#include <fcntl.h>
+#include <libhfcommon/util.h>
+#include <libhfuzz/libhfuzz.h>
+#include <named/globals.h>
+#include <net/if.h>
+#include <net/route.h>
+#include <netinet/ip6.h>
+#include <netinet/tcp.h>
+#include <pthread.h>
+#include <sched.h>
+#include <sys/ioctl.h>
+#include <sys/resource.h>
+#include <sys/socket.h>
+#include <sys/stat.h>
+#include <sys/time.h>
+#include <sys/types.h>
+#include <sys/uio.h>
+#include <sys/wait.h>
+#include <unistd.h>
+
+static void enter_namespaces(void) {
+	if (linuxEnterNs(CLONE_NEWUSER | CLONE_NEWNET | CLONE_NEWNS | CLONE_NEWIPC) == false) {
+		exit(1);
+	}
+	if (linuxIfaceUp("lo") == false) {
+		exit(1);
+	}
+	if (linuxMountTmpfs("/tmp", "size=10000000") == false) {
+		exit(1);
+	}
+}
+
+static size_t rlen = 0;
+static const uint8_t *rbuf = NULL;
+
+__attribute__((no_sanitize("memory"))) __attribute__((no_sanitize("address"))) static void *
+bind_thr(void *unused __attribute__((unused))) {
+	while (!named_g_run_done) {
+		usleep(300000);
+	}
+
+	if (named_g_fuzz_type != isc_fuzz_resolver) {
+		for (;;) {
+			pause();
+		}
+	}
+
+	int myfd = socket(AF_INET, SOCK_STREAM, IPPROTO_IP);
+	if (myfd == -1) {
+		perror("socket");
+		exit(1);
+	}
+	int val = 1;
+	if (setsockopt(myfd, SOL_SOCKET, SO_REUSEADDR, &val, sizeof(val)) == -1) {
+		perror("setsockopt(SO_REUSEADDR)");
+	}
+
+	const struct sockaddr_in saddr = {
+	    .sin_family = AF_INET,
+	    .sin_port = htons(5353),
+	    .sin_addr.s_addr = inet_addr("127.0.0.2"),
+	};
+	if (bind(myfd, &saddr, sizeof(saddr)) == -1) {
+		perror("bind");
+		exit(1);
+	}
+
+	if (listen(myfd, SOMAXCONN) == -1) {
+		perror("listen");
+		exit(1);
+	}
+
+	for (;;) {
+		struct sockaddr_in cli;
+		socklen_t cli_len = sizeof(cli);
+
+		int nfd = TEMP_FAILURE_RETRY(accept(myfd, &cli, &cli_len));
+		if (nfd == -1) {
+			perror("accept");
+			exit(1);
+		}
+
+		static char b[1024 * 1024];
+		ssize_t sz = TEMP_FAILURE_RETRY(recv(nfd, b, sizeof(b), 0));
+		if (sz == -1) {
+			perror("recv");
+			_exit(1);
+		}
+		if (sz < 4) {
+			close(nfd);
+			continue;
+		}
+
+		HF_ITER(&rbuf, &rlen);
+
+		uint16_t t_l = htons(rlen + 2);
+		const struct iovec iov[] = {
+		    {
+			.iov_base = &t_l,
+			.iov_len = sizeof(t_l),
+		    },
+		    {
+			.iov_base = &b[2],
+			.iov_len = 2,
+		    },
+		    {
+			.iov_base = rbuf,
+			.iov_len = rlen,
+		    },
+		};
+
+		if (TEMP_FAILURE_RETRY(writev(nfd, iov, 3)) == -1) {
+			perror("writev() failed 1");
+		}
+
+		close(nfd);
+	}
+
+	return NULL;
+}
+
+static void rndloop(int sock) {
+	const struct sockaddr_in bsaddr = {
+	    .sin_family = AF_INET,
+	    .sin_port = htons(0),
+	    .sin_addr.s_addr = htonl((((uint32_t)util_rnd64()) & 0x00FFFFFF) | 0x7F000000),
+	};
+	if (TEMP_FAILURE_RETRY(bind(sock, (const struct sockaddr *)&bsaddr, sizeof(bsaddr))) ==
+	    -1) {
+		perror("bind");
+	}
+}
+
+__attribute__((no_sanitize("memory"))) __attribute__((no_sanitize("address"))) static void *
+connect_thr(void *unused __attribute__((unused))) {
+	while (!named_g_run_done) {
+		usleep(300000);
+	}
+
+	for (;;) {
+		int myfd = socket(AF_INET, SOCK_STREAM, IPPROTO_IP);
+		if (myfd == -1) {
+			perror("socket");
+			exit(1);
+		}
+		int val = 1;
+		if (setsockopt(myfd, SOL_SOCKET, SO_REUSEADDR, &val, sizeof(val)) == -1) {
+			perror("setsockopt(SO_REUSEADDR)");
+		}
+
+		rndloop(myfd);
+
+		const struct sockaddr_in saddr = {
+		    .sin_family = AF_INET,
+		    .sin_port = htons(53),
+		    .sin_addr.s_addr = htonl(INADDR_LOOPBACK),
+		};
+		if (TEMP_FAILURE_RETRY(connect(myfd, &saddr, sizeof(saddr))) == -1) {
+			close(myfd);
+			continue;
+		}
+
+		const uint8_t *buf;
+		size_t len;
+
+		if (named_g_fuzz_type == isc_fuzz_client) {
+			HF_ITER(&buf, &len);
+		} else {
+			static uint8_t qbuf[] = {0x88, 0x0c, 0x01, 0x20, 0x00, 0x01, 0x00, 0x00,
+			    0x00, 0x00, 0x00, 0x01, 0x0a, 0x61, 0x61, 0x61, 0x61, 0x61, 0x61, 0x61,
+			    0x61, 0x61, 0x61, 0x07, 0x65, 0x78, 0x61, 0x6d, 0x70, 0x6c, 0x65, 0x00,
+			    0x00, 0x01, 0x00, 0x01, 0x00, 0x00, 0x29, 0x10, 0x00, 0x00, 0x00, 0x80,
+			    0x00, 0x00, 0x00};
+
+			/* Randomize the query */
+			uint64_t rnd;
+			getrandom(&rnd, sizeof(rnd), 0);
+			char tstr[32];
+			snprintf(tstr, sizeof(tstr), "%09llx", rnd);
+			memcpy(&qbuf[14], tstr, 9);
+
+			buf = qbuf;
+			len = sizeof(qbuf);
+		}
+
+		uint16_t t_l = htons(len);
+		const struct iovec iov[] = {
+		    {
+			.iov_base = &t_l,
+			.iov_len = sizeof(t_l),
+		    },
+		    {
+			.iov_base = (void *)buf,
+			.iov_len = len,
+		    },
+		};
+
+		if (TEMP_FAILURE_RETRY(writev(myfd, iov, 2)) == -1) {
+			perror("write");
+			close(myfd);
+			continue;
+		}
+
+		if (shutdown(myfd, SHUT_WR) == -1) {
+			if (errno == ENOTCONN) {
+				close(myfd);
+				continue;
+			}
+			perror("shutdown");
+			_exit(1);
+		}
+
+		uint8_t b[1024 * 512];
+		while (TEMP_FAILURE_RETRY(recv(myfd, b, sizeof(b), 0)) > 0)
+			;
+		close(myfd);
+	}
+}
+
+static void launch_thr(void) {
+	pthread_attr_t attr;
+	pthread_attr_init(&attr);
+	pthread_attr_setstacksize(&attr, 1024 * 1024 * 4);
+	pthread_attr_setdetachstate(&attr, PTHREAD_CREATE_DETACHED);
+
+	pthread_t t;
+	if (pthread_create(&t, &attr, bind_thr, NULL) < 0) {
+		perror("pthread_create(bind_thr)");
+		exit(1);
+	}
+
+	pthread_attr_init(&attr);
+	pthread_attr_setstacksize(&attr, 1024 * 1024 * 4);
+	pthread_attr_setdetachstate(&attr, PTHREAD_CREATE_DETACHED);
+	if (pthread_create(&t, &attr, connect_thr, NULL) < 0) {
+		perror("pthread_create(connect_thr)");
+		exit(1);
+	}
+}
+
+/* main entry point, possibly hooked */
+
+int main(int argc, char *argv[]) {
+	if (!getenv("NO_FUZZ")) {
+		named_g_fuzz_addr = "127.0.0.1:53";
+		named_g_fuzz_type = isc_fuzz_client;
+		enter_namespaces();
+		launch_thr();
+	}
+
 	isc_result_t result;
 #ifdef HAVE_LIBSCF
 	char *instance = NULL;
diff -Nur ORIG.bind-9.16.0/compile.sh bind-9.16.0/compile.sh
--- ORIG.bind-9.16.0/compile.sh	1970-01-01 01:00:00.000000000 +0100
+++ bind-9.16.0/compile.sh	2020-02-23 01:30:08.528163810 +0100
@@ -0,0 +1,19 @@
+#!/bin/sh
+
+set -ex
+
+export CC="$HOME"/src/honggfuzz/hfuzz_cc/hfuzz-clang
+export CXX="$HOME"/src/honggfuzz/hfuzz_cc/hfuzz-clang++
+export CFLAGS="-fsanitize=address -Wno-shift-negative-value -Wno-logical-not-parentheses -g -ggdb -O3 -D__AFL_COMPILER"
+./configure \
+		--prefix="$HOME"/fuzz/bind/dist/ \
+		--without-gssapi \
+		--disable-chroot \
+		--disable-linux-caps \
+		--without-libtool \
+		--enable-fuzzing=afl \
+		--disable-backtrace \
+		--with-openssl=yes
+
+make clean
+make -j$(nproc)
diff -Nur ORIG.bind-9.16.0/lib/dns/request.c bind-9.16.0/lib/dns/request.c
--- ORIG.bind-9.16.0/lib/dns/request.c	2020-02-12 21:03:44.000000000 +0100
+++ bind-9.16.0/lib/dns/request.c	2020-02-23 01:30:47.162785069 +0100
@@ -751,7 +751,7 @@
 		goto cleanup;
 	}
 
-	if ((options & DNS_REQUESTOPT_TCP) != 0 || r.length > 512)
+	if ((options & DNS_REQUESTOPT_TCP) != 0 || r.length >= 0)
 		tcp = true;
 	share = (options & DNS_REQUESTOPT_SHARE);
 
@@ -1025,6 +1025,8 @@
 	dns_compress_t cctx;
 	bool	       cleanup_cctx = false;
 
+	options |= DNS_REQUESTOPT_TCP;
+
 	REQUIRE(bufferp != NULL && *bufferp == NULL);
 
 	req_log(ISC_LOG_DEBUG(3), "request_render");
diff -Nur ORIG.bind-9.16.0/lib/dns/resolver.c bind-9.16.0/lib/dns/resolver.c
--- ORIG.bind-9.16.0/lib/dns/resolver.c	2020-02-12 21:03:44.000000000 +0100
+++ bind-9.16.0/lib/dns/resolver.c	2020-02-23 01:30:54.164897676 +0100
@@ -1979,7 +1979,7 @@
 
 	query = isc_mem_get(fctx->mctx, sizeof(*query));
 	query->mctx = fctx->mctx;
-	query->options = options;
+	query->options = options | DNS_FETCHOPT_TCP;
 	query->attributes = 0;
 	query->sends = 0;
 	query->connects = 0;