Adds source files for fuzzing DTLS

fuzz/build.info

@@ -33,6 +33,10 @@ IF[{- !$disabled{"fuzz-afl"} || !$disabled{"fuzz-libfuzzer"} -}]
     PROGRAMS{noinst}=quic-client quic-srtm quic-lcidm quic-rcidm
   ENDIF
 
+  IF[{- !$disabled{"dtls"} -}]
+    PROGRAMS{noinst}=dtlsclient dtlsserver
+  ENDIF
+
   SOURCE[asn1]=asn1.c driver.c fuzz_rand.c
   INCLUDE[asn1]=../include {- $ex_inc -}
   DEPEND[asn1]=../libcrypto ../libssl {- $ex_lib -}
@@ -73,6 +77,14 @@ IF[{- !$disabled{"fuzz-afl"} || !$disabled{"fuzz-libfuzzer"} -}]
   INCLUDE[ct]=../include {- $ex_inc -}
   DEPEND[ct]=../libcrypto {- $ex_lib -}
 
+  SOURCE[dtlsclient]=dtlsclient.c driver.c fuzz_rand.c
+  INCLUDE[dtlsclient]=../include {- $ex_inc -}
+  DEPEND[dtlsclient]=../libcrypto ../libssl {- $ex_lib -}
+
+  SOURCE[dtlsserver]=dtlsserver.c driver.c fuzz_rand.c
+  INCLUDE[dtlsserver]=../include {- $ex_inc -}
+  DEPEND[dtlsserver]=../libcrypto ../libssl {- $ex_lib -}
+
   SOURCE[pem]=pem.c driver.c
   INCLUDE[pem]=../include {- $ex_inc -}
   DEPEND[pem]=../libcrypto.a {- $ex_lib -}

fuzz/dtlsclient.c

@@ -0,0 +1,108 @@
+/*
+ * Copyright 2016-2022 The OpenSSL Project Authors. All Rights Reserved.
+ *
+ * Licensed under the Apache License 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ * https://www.openssl.org/source/license.html
+ * or in the file LICENSE in the source distribution.
+ */
+
+#include <time.h>
+#include <openssl/rand.h>
+#include <openssl/ssl.h>
+#include <openssl/rsa.h>
+#include <openssl/dsa.h>
+#include <openssl/ec.h>
+#include <openssl/dh.h>
+#include <openssl/err.h>
+#include "fuzzer.h"
+
+/* unused, to avoid warning. */
+static int idx;
+
+#define FUZZTIME 1485898104
+
+#define TIME_IMPL(t) { if (t != NULL) *t = FUZZTIME; return FUZZTIME; }
+
+/*
+ * This might not work in all cases (and definitely not on Windows
+ * because of the way linkers are) and callees can still get the
+ * current time instead of the fixed time. This will just result
+ * in things not being fully reproducible and have a slightly
+ * different coverage.
+ */
+#if !defined(_WIN32)
+time_t time(time_t *t) TIME_IMPL(t)
+#endif
+
+int FuzzerInitialize(int *argc, char ***argv)
+{
+    STACK_OF(SSL_COMP) *comp_methods;
+
+    FuzzerSetRand();
+    OPENSSL_init_crypto(OPENSSL_INIT_LOAD_CRYPTO_STRINGS | OPENSSL_INIT_ASYNC, NULL);
+    OPENSSL_init_ssl(OPENSSL_INIT_LOAD_SSL_STRINGS, NULL);
+    ERR_clear_error();
+    CRYPTO_free_ex_index(0, -1);
+    idx = SSL_get_ex_data_X509_STORE_CTX_idx();
+    comp_methods = SSL_COMP_get_compression_methods();
+    if (comp_methods != NULL)
+        sk_SSL_COMP_sort(comp_methods);
+
+    return 1;
+}
+
+int FuzzerTestOneInput(const uint8_t *buf, size_t len)
+{
+    SSL *client = NULL;
+    BIO *in;
+    BIO *out;
+    SSL_CTX *ctx;
+
+    if (len == 0)
+        return 0;
+
+    /* This only fuzzes the initial flow from the client so far. */
+    ctx = SSL_CTX_new(DTLS_client_method());
+    if (ctx == NULL)
+        goto end;
+
+    client = SSL_new(ctx);
+    if (client == NULL)
+        goto end;
+    OPENSSL_assert(SSL_set_min_proto_version(client, 0) == 1);
+    OPENSSL_assert(SSL_set_cipher_list(client, "ALL:eNULL:@SECLEVEL=0") == 1);
+    SSL_set_tlsext_host_name(client, "localhost");
+    in = BIO_new(BIO_s_mem());
+    if (in == NULL)
+        goto end;
+    out = BIO_new(BIO_s_mem());
+    if (out == NULL) {
+        BIO_free(in);
+        goto end;
+    }
+    SSL_set_bio(client, in, out);
+    SSL_set_connect_state(client);
+    OPENSSL_assert((size_t)BIO_write(in, buf, len) == len);
+    if (SSL_do_handshake(client) == 1) {
+        /* Keep reading application data until error or EOF. */
+        uint8_t tmp[1024];
+        for (;;) {
+            if (SSL_read(client, tmp, sizeof(tmp)) <= 0) {
+                break;
+            }
+        }
+    }
+ end:
+    SSL_free(client);
+    ERR_clear_error();
+    SSL_CTX_free(ctx);
+
+    return 0;
+}
+
+void FuzzerCleanup(void)
+{
+    FuzzerClearRand();
+}