diff --git a/src/utils/Makefile b/src/utils/Makefile
index 0f1f191..940b4d8 100644
--- a/src/utils/Makefile
+++ b/src/utils/Makefile
@@ -14,6 +14,7 @@
 
 LIB_OBJS= \
 	base64.o \
+	bitfield.o \
 	common.o \
 	ip_addr.o \
 	radiotap.o \
diff --git a/src/utils/bitfield.c b/src/utils/bitfield.c
new file mode 100644
index 0000000..f90e4be
--- /dev/null
+++ b/src/utils/bitfield.c
@@ -0,0 +1,89 @@
+/*
+ * Bitfield
+ * Copyright (c) 2013, Jouni Malinen <j@w1.fi>
+ *
+ * This software may be distributed under the terms of the BSD license.
+ * See README for more details.
+ */
+
+#include "includes.h"
+
+#include "common.h"
+#include "bitfield.h"
+
+
+struct bitfield {
+	u8 *bits;
+	size_t max_bits;
+};
+
+
+struct bitfield * bitfield_alloc(size_t max_bits)
+{
+	struct bitfield *bf;
+
+	bf = os_zalloc(sizeof(*bf) + (max_bits + 7) / 8);
+	if (bf == NULL)
+		return NULL;
+	bf->bits = (u8 *) (bf + 1);
+	bf->max_bits = max_bits;
+	return bf;
+}
+
+
+void bitfield_free(struct bitfield *bf)
+{
+	os_free(bf);
+}
+
+
+void bitfield_set(struct bitfield *bf, size_t bit)
+{
+	if (bit >= bf->max_bits)
+		return;
+	bf->bits[bit / 8] |= BIT(bit % 8);
+}
+
+
+void bitfield_clear(struct bitfield *bf, size_t bit)
+{
+	if (bit >= bf->max_bits)
+		return;
+	bf->bits[bit / 8] &= ~BIT(bit % 8);
+}
+
+
+int bitfield_is_set(struct bitfield *bf, size_t bit)
+{
+	if (bit >= bf->max_bits)
+		return 0;
+	return !!(bf->bits[bit / 8] & BIT(bit % 8));
+}
+
+
+static int first_zero(u8 val)
+{
+	int i;
+	for (i = 0; i < 8; i++) {
+		if (!(val & 0x01))
+			return i;
+		val >>= 1;
+	}
+	return -1;
+}
+
+
+int bitfield_get_first_zero(struct bitfield *bf)
+{
+	size_t i;
+	for (i = 0; i <= (bf->max_bits + 7) / 8; i++) {
+		if (bf->bits[i] != 0xff)
+			break;
+	}
+	if (i > (bf->max_bits + 7) / 8)
+		return -1;
+	i = i * 8 + first_zero(bf->bits[i]);
+	if (i >= bf->max_bits)
+		return -1;
+	return i;
+}
diff --git a/src/utils/bitfield.h b/src/utils/bitfield.h
new file mode 100644
index 0000000..7050a20
--- /dev/null
+++ b/src/utils/bitfield.h
@@ -0,0 +1,21 @@
+/*
+ * Bitfield
+ * Copyright (c) 2013, Jouni Malinen <j@w1.fi>
+ *
+ * This software may be distributed under the terms of the BSD license.
+ * See README for more details.
+ */
+
+#ifndef BITFIELD_H
+#define BITFIELD_H
+
+struct bitfield;
+
+struct bitfield * bitfield_alloc(size_t max_bits);
+void bitfield_free(struct bitfield *bf);
+void bitfield_set(struct bitfield *bf, size_t bit);
+void bitfield_clear(struct bitfield *bf, size_t bit);
+int bitfield_is_set(struct bitfield *bf, size_t bit);
+int bitfield_get_first_zero(struct bitfield *bf);
+
+#endif /* BITFIELD_H */
diff --git a/src/utils/common.c b/src/utils/common.c
index e636984..bf326cd 100644
--- a/src/utils/common.c
+++ b/src/utils/common.c
@@ -517,11 +517,9 @@
 		if (pos == NULL || pos[1] != '\0')
 			return NULL;
 		*len = pos - value;
-		str = os_malloc(*len + 1);
+		str = dup_binstr(value, *len);
 		if (str == NULL)
 			return NULL;
-		os_memcpy(str, value, *len);
-		str[*len] = '\0';
 		return str;
 	} else if (*value == 'P' && value[1] == '"') {
 		const char *pos;
@@ -532,11 +530,9 @@
 		if (pos == NULL || pos[1] != '\0')
 			return NULL;
 		tlen = pos - value;
-		tstr = os_malloc(tlen + 1);
+		tstr = dup_binstr(value, tlen);
 		if (tstr == NULL)
 			return NULL;
-		os_memcpy(tstr, value, tlen);
-		tstr[tlen] = '\0';
 
 		str = os_malloc(tlen + 1);
 		if (str == NULL) {
@@ -610,3 +606,19 @@
 
 	return len;
 }
+
+
+char * dup_binstr(const void *src, size_t len)
+{
+	char *res;
+
+	if (src == NULL)
+		return NULL;
+	res = os_malloc(len + 1);
+	if (res == NULL)
+		return NULL;
+	os_memcpy(res, src, len);
+	res[len] = '\0';
+
+	return res;
+}
diff --git a/src/utils/common.h b/src/utils/common.h
index a859042..e4f7031 100644
--- a/src/utils/common.h
+++ b/src/utils/common.h
@@ -487,6 +487,7 @@
 size_t merge_byte_arrays(u8 *res, size_t res_len,
 			 const u8 *src1, size_t src1_len,
 			 const u8 *src2, size_t src2_len);
+char * dup_binstr(const void *src, size_t len);
 
 static inline int is_zero_ether_addr(const u8 *a)
 {