iov: add iterator interface for giovec_t

This adds an iterator interface over giovec_t array, extracting a
fixed sized block.

Signed-off-by: Daiki Ueno <dueno@redhat.com>

7 files changed, 347 insertions, 2 deletions

diff --git a/.gitignore b/.gitignore
index e80cff4539..26d29fcf34 100644
--- a/.gitignore
+++ b/.gitignore
@@ -431,6 +431,7 @@ tests/infoaccess
 tests/init_fds
 tests/init_roundtrip
 tests/insecure_key
+tests/iov
 tests/ip-check
 tests/ip-utils
 tests/key-export-pkcs8
diff --git a/lib/Makefile.am b/lib/Makefile.am
index ffc72e4c2c..9fe78afbdc 100644
--- a/lib/Makefile.am
+++ b/lib/Makefile.am
@@ -80,7 +80,8 @@ COBJECTS = range.c record.c compress.c debug.c cipher.c gthreads.h handshake-tls
 	system-keys.h urls.c urls.h prf.c auto-verify.c dh-session.c \
 	cert-session.c handshake-checks.c dtls-sw.c dh-primes.c openpgp_compat.c \
 	crypto-selftests.c crypto-selftests-pk.c secrets.c extv.c extv.h \
-	hello_ext_lib.c hello_ext_lib.h ocsp-api.c stek.c cert-cred-rawpk.c
+	hello_ext_lib.c hello_ext_lib.h ocsp-api.c stek.c cert-cred-rawpk.c \
+	iov.c iov.h
 
 if WINDOWS
 COBJECTS += system/keys-win.c
diff --git a/lib/iov.c b/lib/iov.c
new file mode 100644
index 0000000000..5dc29c54bd
--- /dev/null
+++ b/lib/iov.c
@@ -0,0 +1,120 @@
+/*
+ * Copyright (C) 2019 Red Hat, Inc.
+ *
+ * Author: Daiki Ueno
+ *
+ * This file is part of GnuTLS.
+ *
+ * The GnuTLS is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU Lesser General Public License
+ * as published by the Free Software Foundation; either version 2.1 of
+ * the License, or (at your option) any later version.
+ *
+ * This library is distributed in the hope that it will be useful, but
+ * WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * Lesser General Public License for more details.
+ *
+ * You should have received a copy of the GNU Lesser General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>
+ *
+ */
+
+#include "gnutls_int.h"
+#include "iov.h"
+
+/**
+ * _gnutls_iov_iter_init:
+ * @iter: the iterator
+ * @iov: the data buffers
+ * @iov_count: the number of data buffers
+ * @block_size: block size to iterate
+ *
+ * Initialize the iterator.
+ *
+ * Returns: On success, %GNUTLS_E_SUCCESS (0) is returned, otherwise
+ *   an error code is returned
+ */
+int
+_gnutls_iov_iter_init(struct iov_iter_st *iter,
+		      const giovec_t *iov, size_t iov_count,
+		      size_t block_size)
+{
+	if (unlikely(block_size > MAX_CIPHER_BLOCK_SIZE))
+		return gnutls_assert_val(GNUTLS_E_INVALID_REQUEST);
+
+	iter->iov = iov;
+	iter->iov_count = iov_count;
+	iter->iov_index = 0;
+	iter->iov_offset = 0;
+	iter->block_size = block_size;
+	iter->block_offset = 0;
+	return 0;
+}
+
+/**
+ * _gnutls_iov_iter_next:
+ * @iter: the iterator
+ * @data: the return location of extracted data
+ *
+ * Retrieve block(s) pointed by @iter and advance it to the next
+ * position.  It returns the number of consecutive blocks in @data.
+ * At the end of iteration, 0 is returned.
+ *
+ * If the data stored in @iter is not multiple of the block size, the
+ * remaining data is stored in the "block" field of @iter with the
+ * size stored in the "block_offset" field.
+ *
+ * Returns: On success, a value greater than or equal to zero is
+ *   returned, otherwise a negative error code is returned
+ */
+ssize_t
+_gnutls_iov_iter_next(struct iov_iter_st *iter, uint8_t **data)
+{
+	while (iter->iov_index < iter->iov_count) {
+		const giovec_t *iov = &iter->iov[iter->iov_index];
+		uint8_t *p = iov->iov_base;
+		size_t len = iov->iov_len;
+		size_t block_left;
+
+		if (unlikely(len < iter->iov_offset))
+			return gnutls_assert_val(GNUTLS_E_UNEXPECTED_PACKET_LENGTH);
+		len -= iter->iov_offset;
+		p += iter->iov_offset;
+
+		/* We have at least one full block, return a whole set
+		 * of full blocks immediately. */
+		if (iter->block_offset == 0 && len >= iter->block_size) {
+			if ((len % iter->block_size) == 0) {
+				iter->iov_index++;
+				iter->iov_offset = 0;
+			} else
+				iter->iov_offset +=
+					len - (len % iter->block_size);
+
+			/* Return the blocks. */
+			*data = p;
+			return len / iter->block_size;
+		}
+
+		/* We can complete one full block to return. */
+		block_left = iter->block_size - iter->block_offset;
+		if (len >= block_left) {
+			memcpy(iter->block + iter->block_offset, p, block_left);
+			iter->iov_offset += block_left;
+			iter->block_offset = 0;
+
+			/* Return the filled block. */
+			*data = iter->block;
+			return 1;
+		}
+
+		/* Not enough data for a full block, store in temp
+		 * memory and continue. */
+		memcpy(iter->block + iter->block_offset, p, len);
+		iter->block_offset += len;
+		iter->iov_index++;
+		iter->iov_offset = 0;
+	}
+	return 0;
+}
diff --git a/lib/iov.h b/lib/iov.h
new file mode 100644
index 0000000000..47fba559ab
--- /dev/null
+++ b/lib/iov.h
@@ -0,0 +1,46 @@
+/*
+ * Copyright (C) 2019 Red Hat, Inc.
+ *
+ * Author: Daiki Ueno
+ *
+ * This file is part of GnuTLS.
+ *
+ * The GnuTLS is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU Lesser General Public License
+ * as published by the Free Software Foundation; either version 2.1 of
+ * the License, or (at your option) any later version.
+ *
+ * This library is distributed in the hope that it will be useful, but
+ * WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * Lesser General Public License for more details.
+ *
+ * You should have received a copy of the GNU Lesser General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>
+ *
+ */
+
+#ifndef GNUTLS_LIB_IOV_H
+#define GNUTLS_LIB_IOV_H
+
+#include "gnutls_int.h"
+
+struct iov_iter_st {
+	const giovec_t *iov;
+	size_t iov_count;	/* the number of iov */
+	size_t iov_index;	/* index of the current buffer */
+	size_t iov_offset;	/* byte offset in the current buffer */
+
+	uint8_t block[MAX_CIPHER_BLOCK_SIZE]; /* incomplete block for reading */
+	size_t block_size;	/* actual block size of the cipher */
+	size_t block_offset;	/* offset in block */
+
+};
+
+int _gnutls_iov_iter_init(struct iov_iter_st *iter,
+			  const giovec_t *iov, size_t iov_count,
+			  size_t block_size);
+
+ssize_t _gnutls_iov_iter_next(struct iov_iter_st *iter, uint8_t **data);
+
+#endif /* GNUTLS_LIB_IOV_H */
diff --git a/lib/libgnutls.map b/lib/libgnutls.map
index 0f31f4aef4..fc93c0857f 100644
--- a/lib/libgnutls.map
+++ b/lib/libgnutls.map
@@ -1384,4 +1384,7 @@ GNUTLS_PRIVATE_3_4 {
 	_gnutls_anti_replay_check;
 	# needed by gnutls-strcodes.c
 	_gnutls_ecc_curve_is_supported;
+	# needed by tests/iov:
+	_gnutls_iov_iter_init;
+	_gnutls_iov_iter_next;
 } GNUTLS_3_4;
diff --git a/tests/Makefile.am b/tests/Makefile.am
index a8c2d152ec..a2883570f3 100644
--- a/tests/Makefile.am
+++ b/tests/Makefile.am
@@ -214,7 +214,7 @@ ctests += mini-record-2 simple gnutls_hmac_fast set_pkcs12_cred cert certuniquei
 	 null_retrieve_function tls-record-size-limit tls-crt_type-neg \
 	 resume-with-stek-expiration resume-with-previous-stek rawpk-api \
 	 tls-record-size-limit-asym dh-compute ecdh-compute sign-verify-data-newapi \
-	 sign-verify-newapi sign-verify-deterministic
+	 sign-verify-newapi sign-verify-deterministic iov
 
 if HAVE_SECCOMP_TESTS
 ctests += dtls-with-seccomp tls-with-seccomp dtls-client-with-seccomp tls-client-with-seccomp
@@ -460,6 +460,10 @@ tls13_anti_replay_CPPFLAGS = $(AM_CPPFLAGS) \
 	-I$(top_builddir)/gl	\
 	$(NETTLE_CFLAGS)
 
+iov_CPPFLAGS = $(AM_CPPFLAGS) \
+	-I$(top_srcdir)/gl	\
+	-I$(top_builddir)/gl
+
 if ENABLE_PKCS11
 if !WINDOWS
 ctests += tls13/post-handshake-with-cert-pkcs11 pkcs11/tls-neg-pkcs11-no-key
diff --git a/tests/iov.c b/tests/iov.c
new file mode 100644
index 0000000000..eda5583a77
--- /dev/null
+++ b/tests/iov.c
@@ -0,0 +1,170 @@
+/*
+ * Copyright (C) 2019 Red Hat, Inc.
+ *
+ * Author: Daiki Ueno
+ *
+ * This file is part of GnuTLS.
+ *
+ * GnuTLS is free software; you can redistribute it and/or modify it
+ * under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * GnuTLS is distributed in the hope that it will be useful, but
+ * WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * General Public License for more details.
+ *
+ * You should have received a copy of the GNU Lesser General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>
+ */
+
+#ifdef HAVE_CONFIG_H
+#include <config.h>
+#endif
+
+#include "gnutls_int.h"
+#include "../lib/iov.h"
+
+#include "utils.h"
+
+struct exp_st {
+	ssize_t ret;
+	size_t iov_index;
+	size_t iov_offset;
+	size_t block_offset;
+};
+
+struct test_st {
+	const char *name;
+	const giovec_t *iov;
+	size_t iovcnt;
+	size_t block_size;
+	const struct exp_st *exp;
+	size_t expcnt;
+	size_t remaining;
+};
+
+static const giovec_t iov16[] = {
+	{(void *) "0123456789abcdef", 16},
+	{(void *) "0123456789abcdef", 16},
+	{(void *) "0123456789abcdef", 16},
+	{(void *) "0123456789abcdef", 16}
+};
+
+static const struct exp_st exp16_64[] = {
+	{1, 3, 16, 0},
+	{0, 0, 0, 0}
+};
+
+static const struct exp_st exp16_32[] = {
+	{1, 1, 16, 0},
+	{1, 3, 16, 0},
+	{0, 0, 0, 0}
+};
+
+static const struct exp_st exp16_16[] = {
+	{1, 1, 0, 0},
+	{1, 2, 0, 0},
+	{1, 3, 0, 0},
+	{1, 4, 0, 0},
+	{0, 0, 0, 0}
+};
+
+static const struct exp_st exp16_4[] = {
+	{4, 1, 0, 0},
+	{4, 2, 0, 0},
+	{4, 3, 0, 0},
+	{4, 4, 0, 0},
+	{0, 0, 0, 0}
+};
+
+static const struct exp_st exp16_3[] = {
+	{5, 0, 15, 0},
+	{1, 1, 2, 0},
+	{4, 1, 14, 0},
+	{1, 2, 1, 0},
+	{5, 3, 0, 0},
+	{5, 3, 15, 0},
+	{0, 0, 0, 1}
+};
+
+static const giovec_t iov8[] = {
+	{(void *) "01234567", 8},
+	{(void *) "01234567", 8},
+	{(void *) "01234567", 8},
+	{(void *) "01234567", 8}
+};
+
+static const struct exp_st exp8_64[] = {
+	{0, 0, 0, 32}
+};
+
+static const struct test_st tests[] = {
+	{ "16/64", iov16, sizeof(iov16)/sizeof(iov16[0]), 64,
+	  exp16_64, sizeof(exp16_64)/sizeof(exp16_64[0]), 0 },
+	{ "16/32", iov16, sizeof(iov16)/sizeof(iov16[0]), 32,
+	  exp16_32, sizeof(exp16_32)/sizeof(exp16_32[0]), 0 },
+	{ "16/16", iov16, sizeof(iov16)/sizeof(iov16[0]), 16,
+	  exp16_16, sizeof(exp16_16)/sizeof(exp16_16[0]), 0 },
+	{ "16/4", iov16, sizeof(iov16)/sizeof(iov16[0]), 4,
+	  exp16_4, sizeof(exp16_4)/sizeof(exp16_4[0]), 0 },
+	{ "16/3", iov16, sizeof(iov16)/sizeof(iov16[0]), 3,
+	  exp16_3, sizeof(exp16_3)/sizeof(exp16_3[0]), 1 },
+	{ "8/64", iov8, sizeof(iov8)/sizeof(iov8[0]), 64,
+	  exp8_64, sizeof(exp8_64)/sizeof(exp8_64[0]), 32 }
+};
+
+void
+doit (void)
+{
+	size_t i;
+
+	for (i = 0; i < sizeof(tests)/sizeof(tests[0]); i++) {
+		struct iov_iter_st iter;
+		const struct exp_st *exp = tests[i].exp;
+		uint8_t *data;
+		size_t j;
+
+		success("%s\n", tests[i].name);
+		assert(_gnutls_iov_iter_init(&iter,
+					     tests[i].iov, tests[i].iovcnt,
+					     tests[i].block_size) == 0);
+		for (j = 0; j < tests[i].expcnt; j++) {
+			ssize_t ret;
+
+			ret = _gnutls_iov_iter_next(&iter, &data);
+			if (ret != exp[j].ret)
+				fail("iov_iter_next: %d != %d\n",
+				     (int) ret, (int) exp[j].ret);
+			else if (debug)
+				success("iov_iter_next: %d == %d\n",
+					(int) ret, (int) exp[j].ret);
+			if (ret == 0)
+				break;
+			if (ret > 0) {
+				if (iter.iov_index != exp[j].iov_index)
+					fail("iter.iov_index: %u != %u\n",
+					     (unsigned) iter.iov_index, (unsigned) exp[j].iov_index);
+				else if (debug)
+					success("iter.iov_index: %u == %u\n",
+					     (unsigned) iter.iov_index, (unsigned) exp[j].iov_index);
+				if (iter.iov_offset != exp[j].iov_offset)
+					fail("iter.iov_offset: %u != %u\n",
+					     (unsigned) iter.iov_offset, (unsigned) exp[j].iov_offset);
+				else if (debug)
+					success("iter.iov_offset: %u == %u\n",
+					     (unsigned) iter.iov_offset, (unsigned) exp[j].iov_offset);
+				if (iter.block_offset != exp[j].block_offset)
+					fail("iter.block_offset: %u != %u\n",
+					     (unsigned) iter.block_offset, (unsigned) exp[j].block_offset);
+				else if (debug)
+					success("iter.block_offset: %u == %u\n",
+					     (unsigned) iter.block_offset, (unsigned) exp[j].block_offset);
+			}
+		}
+		if (iter.block_offset != tests[i].remaining)
+			fail("remaining: %u != %u\n",
+			     (unsigned) iter.block_offset, (unsigned) tests[i].remaining);
+	}
+}