1 files changed, 299 insertions, 0 deletions
diff --git a/lib/isc/win32/entropy.c b/lib/isc/win32/entropy.c
new file mode 100644
index 0000000..2480c02
--- /dev/null
+++ b/lib/isc/win32/entropy.c
@@ -0,0 +1,299 @@
+/*
+ * Copyright (C) Internet Systems Consortium, Inc. ("ISC")
+ *
+ * This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/.
+ *
+ * See the COPYRIGHT file distributed with this work for additional
+ * information regarding copyright ownership.
+ */
+
+
+/*
+ * This is the system dependent part of the ISC entropy API.
+ */
+
+#include <config.h>
+
+#include <stdbool.h>
+
+#include <windows.h>
+#include <wincrypt.h>
+
+#include <process.h>
+#include <io.h>
+#include <share.h>
+
+/*
+ * There is only one variable in the entropy data structures that is not
+ * system independent, but pulling the structure that uses it into this file
+ * ultimately means pulling several other independent structures here also to
+ * resolve their interdependencies.  Thus only the problem variable's type
+ * is defined here.
+ */
+#define FILESOURCE_HANDLE_TYPE	HCRYPTPROV
+
+typedef struct {
+	int dummy;
+} isc_entropyusocketsource_t;
+
+#include "../entropy.c"
+
+static unsigned int
+get_from_filesource(isc_entropysource_t *source, uint32_t desired) {
+	isc_entropy_t *ent = source->ent;
+	unsigned char buf[128];
+	HCRYPTPROV hcryptprov = source->sources.file.handle;
+	ssize_t ndesired;
+	unsigned int added;
+
+	if (source->bad)
+		return (0);
+
+	desired = desired / 8 + (((desired & 0x07) > 0) ? 1 : 0);
+
+	added = 0;
+	while (desired > 0) {
+		ndesired = ISC_MIN(desired, sizeof(buf));
+		if (!CryptGenRandom(hcryptprov, (DWORD)ndesired, buf)) {
+			CryptReleaseContext(hcryptprov, 0);
+			source->bad = true;
+			goto out;
+		}
+
+		entropypool_adddata(ent, buf,
+				    (unsigned int)ndesired,
+				    (unsigned int)ndesired * 8);
+		added += (unsigned int)ndesired * 8;
+		desired -= (uint32_t)ndesired;
+	}
+
+ out:
+	return (added);
+}
+
+/*
+ * Poll each source, trying to get data from it to stuff into the entropy
+ * pool.
+ */
+static void
+fillpool(isc_entropy_t *ent, unsigned int desired, bool blocking) {
+	unsigned int added;
+	unsigned int remaining;
+	unsigned int needed;
+	unsigned int nsource;
+	isc_entropysource_t *source;
+	isc_entropysource_t *firstsource;
+
+	REQUIRE(VALID_ENTROPY(ent));
+
+	needed = desired;
+
+	/*
+	 * This logic is a little strange, so an explanation is in order.
+	 *
+	 * If needed is 0, it means we are being asked to "fill to whatever
+	 * we think is best."  This means that if we have at least a
+	 * partially full pool (say, > 1/4th of the pool) we probably don't
+	 * need to add anything.
+	 *
+	 * Also, we will check to see if the "pseudo" count is too high.
+	 * If it is, try to mix in better data.  Too high is currently
+	 * defined as 1/4th of the pool.
+	 *
+	 * Next, if we are asked to add a specific bit of entropy, make
+	 * certain that we will do so.  Clamp how much we try to add to
+	 * (DIGEST_SIZE * 8 < needed < POOLBITS - entropy).
+	 *
+	 * Note that if we are in a blocking mode, we will only try to
+	 * get as much data as we need, not as much as we might want
+	 * to build up.
+	 */
+	if (needed == 0) {
+		REQUIRE(!blocking);
+
+		if ((ent->pool.entropy >= RND_POOLBITS / 4)
+		    && (ent->pool.pseudo <= RND_POOLBITS / 4))
+			return;
+
+		needed = THRESHOLD_BITS * 4;
+	} else {
+		needed = ISC_MAX(needed, THRESHOLD_BITS);
+		needed = ISC_MIN(needed, RND_POOLBITS);
+	}
+
+	/*
+	 * In any case, clamp how much we need to how much we can add.
+	 */
+	needed = ISC_MIN(needed, RND_POOLBITS - ent->pool.entropy);
+
+	/*
+	 * But wait!  If we're not yet initialized, we need at least
+	 *	THRESHOLD_BITS
+	 * of randomness.
+	 */
+	if (ent->initialized < THRESHOLD_BITS)
+		needed = ISC_MAX(needed, THRESHOLD_BITS - ent->initialized);
+
+	/*
+	 * Poll each file source to see if we can read anything useful from
+	 * it.  XXXMLG When where are multiple sources, we should keep a
+	 * record of which one we last used so we can start from it (or the
+	 * next one) to avoid letting some sources build up entropy while
+	 * others are always drained.
+	 */
+
+	added = 0;
+	remaining = needed;
+	if (ent->nextsource == NULL) {
+		ent->nextsource = ISC_LIST_HEAD(ent->sources);
+		if (ent->nextsource == NULL)
+			return;
+	}
+	source = ent->nextsource;
+	/*
+	 * Remember the first source so we can break if we have looped back to
+	 * the beginning and still have nothing
+	 */
+	firstsource = source;
+ again_file:
+	for (nsource = 0; nsource < ent->nsources; nsource++) {
+		unsigned int got;
+
+		if (remaining == 0)
+			break;
+
+		got = 0;
+
+		if (source->type == ENTROPY_SOURCETYPE_FILE)
+			got = get_from_filesource(source, remaining);
+
+		added += got;
+
+		remaining -= ISC_MIN(remaining, got);
+
+		source = ISC_LIST_NEXT(source, link);
+		if (source == NULL)
+			source = ISC_LIST_HEAD(ent->sources);
+	}
+	ent->nextsource = source;
+
+	/*
+	 * Go again only if there's been progress and we've not
+	 * gone back to the beginning
+	 */
+	if (!(ent->nextsource == firstsource && added == 0)) {
+		if (blocking && remaining != 0) {
+				goto again_file;
+		}
+	}
+
+	/*
+	 * Here, if there are bits remaining to be had and we can block,
+	 * check to see if we have a callback source.  If so, call them.
+	 */
+	source = ISC_LIST_HEAD(ent->sources);
+	while ((remaining != 0) && (source != NULL)) {
+		unsigned int got;
+
+		got = 0;
+
+		if (source->type == ENTROPY_SOURCETYPE_CALLBACK)
+			got = get_from_callback(source, remaining, blocking);
+
+		added += got;
+		remaining -= ISC_MIN(remaining, got);
+
+		if (added >= needed)
+			break;
+
+		source = ISC_LIST_NEXT(source, link);
+	}
+
+	/*
+	 * Mark as initialized if we've added enough data.
+	 */
+	if (ent->initialized < THRESHOLD_BITS)
+		ent->initialized += added;
+}
+
+
+
+/*
+ * Requires "ent" be locked.
+ */
+static void
+destroyfilesource(isc_entropyfilesource_t *source) {
+	CryptReleaseContext(source->handle, 0);
+}
+
+static void
+destroyusocketsource(isc_entropyusocketsource_t *source) {
+	UNUSED(source);
+}
+
+
+isc_result_t
+isc_entropy_createfilesource(isc_entropy_t *ent, const char *fname) {
+	isc_result_t ret;
+	isc_entropysource_t *source;
+	HCRYPTPROV hcryptprov;
+	BOOL err;
+
+	REQUIRE(VALID_ENTROPY(ent));
+	REQUIRE(fname != NULL);
+
+	LOCK(&ent->lock);
+
+	source = NULL;
+
+	/*
+	 * The first time we just try to acquire the context
+	 */
+	err = CryptAcquireContext(&hcryptprov, NULL, NULL, PROV_RSA_FULL,
+				  CRYPT_VERIFYCONTEXT);
+	if (!err){
+		(void)GetLastError();
+		ret = ISC_R_IOERROR;
+		goto errout;
+	}
+
+	source = isc_mem_get(ent->mctx, sizeof(isc_entropysource_t));
+	if (source == NULL) {
+		ret = ISC_R_NOMEMORY;
+		goto closecontext;
+	}
+
+	/*
+	 * From here down, no failures can occur.
+	 */
+	source->magic = SOURCE_MAGIC;
+	source->type = ENTROPY_SOURCETYPE_FILE;
+	source->ent = ent;
+	source->total = 0;
+	source->bad = false;
+	memset(source->name, 0, sizeof(source->name));
+	ISC_LINK_INIT(source, link);
+	source->sources.file.handle = hcryptprov;
+
+	/*
+	 * Hook it into the entropy system.
+	 */
+	ISC_LIST_APPEND(ent->sources, source, link);
+	ent->nsources++;
+
+	UNLOCK(&ent->lock);
+	return (ISC_R_SUCCESS);
+
+ closecontext:
+	CryptReleaseContext(hcryptprov, 0);
+
+ errout:
+	if (source != NULL)
+		isc_mem_put(ent->mctx, source, sizeof(isc_entropysource_t));
+
+	UNLOCK(&ent->lock);
+
+	return (ret);
+}