Add code to generate universally unique identifiers.

We create type 4, variant 1 uuids (random).

MANIFEST

@@ -240,6 +240,7 @@ lib/util/ttysize.c
 lib/util/unlinkat.c
 lib/util/util.exp.in
 lib/util/utimens.c
+lib/util/uuid.c
 lib/util/vsyslog.c
 lib/zlib/Makefile.in
 lib/zlib/adler32.c

include/sudo_util.h

@@ -315,4 +315,10 @@ __dso_public char *sudo_ttyname_dev_v1(dev_t tdev, char *name, size_t namelen);
 __dso_public void sudo_get_ttysize_v1(int *rowp, int *colp);
 #define sudo_get_ttysize(_a, _b) sudo_get_ttysize_v1((_a), (_b))
 
+/* uuid.c */
+__dso_public void sudo_uuid_create_v1(unsigned char uuid_out[16]);
+#define sudo_uuid_create(_a) sudo_uuid_create_v1((_a))
+__dso_public char *sudo_uuid_to_string_v1(unsigned char uuid[16], char *dst, size_t dstsiz);
+#define sudo_uuid_to_string(_a, _b, _c) sudo_uuid_to_string_v1((_a), (_b), (_c))
+
 #endif /* SUDO_UTIL_H */

lib/util/Makefile.in

@@ -124,7 +124,7 @@ LTOBJS = @DIGEST@ event.lo fatal.lo key_val.lo gethostname.lo gettime.lo \
          roundup.lo secure_path.lo setgroups.lo strsplit.lo strtobool.lo \
          strtoid.lo strtomode.lo strtonum.lo sudo_conf.lo \
 	 sudo_debug.lo sudo_dso.lo term.lo ttyname_dev.lo \
-	 ttysize.lo @COMMON_OBJS@ @LTLIBOBJS@
+	 ttysize.lo uuid.lo @COMMON_OBJS@ @LTLIBOBJS@
 
 IOBJS = $(LTOBJS:.lo=.i)
 
@@ -1347,6 +1347,14 @@ utimens.i: $(srcdir)/utimens.c $(incdir)/compat/stdbool.h \
 	$(CC) -E -o $@ $(CPPFLAGS) $<
 utimens.plog: utimens.i
 	rm -f $@; pvs-studio --cfg $(PVS_CFG) --sourcetree-root $(top_srcdir) --skip-cl-exe yes --source-file $(srcdir)/utimens.c --i-file $< --output-file $@
+uuid.lo: $(srcdir)/uuid.c $(incdir)/compat/stdbool.h $(incdir)/sudo_compat.h \
+         $(incdir)/sudo_rand.h $(incdir)/sudo_util.h $(top_builddir)/config.h
+	$(LIBTOOL) $(LTFLAGS) --mode=compile $(CC) -c -o $@ $(CPPFLAGS) $(CFLAGS) $(ASAN_CFLAGS) $(PIE_CFLAGS) $(SSP_CFLAGS) $(srcdir)/uuid.c
+uuid.i: $(srcdir)/uuid.c $(incdir)/compat/stdbool.h $(incdir)/sudo_compat.h \
+         $(incdir)/sudo_rand.h $(incdir)/sudo_util.h $(top_builddir)/config.h
+	$(CC) -E -o $@ $(CPPFLAGS) $<
+uuid.plog: uuid.i
+	rm -f $@; pvs-studio --cfg $(PVS_CFG) --sourcetree-root $(top_srcdir) --skip-cl-exe yes --source-file $(srcdir)/uuid.c --i-file $< --output-file $@
 vsyslog.lo: $(srcdir)/vsyslog.c $(incdir)/sudo_compat.h $(top_builddir)/config.h
 	$(LIBTOOL) $(LTFLAGS) --mode=compile $(CC) -c -o $@ $(CPPFLAGS) $(CFLAGS) $(ASAN_CFLAGS) $(PIE_CFLAGS) $(SSP_CFLAGS) $(srcdir)/vsyslog.c
 vsyslog.i: $(srcdir)/vsyslog.c $(incdir)/sudo_compat.h $(top_builddir)/config.h

lib/util/util.exp.in

@@ -122,6 +122,8 @@ sudo_term_noecho_v1
 sudo_term_raw_v1
 sudo_term_restore_v1
 sudo_ttyname_dev_v1
+sudo_uuid_create_v1
+sudo_uuid_to_string_v1
 sudo_vfatal_nodebug_v1
 sudo_vfatalx_nodebug_v1
 sudo_vwarn_nodebug_v1

lib/util/uuid.c

@@ -0,0 +1,112 @@
+/*
+ * SPDX-License-Identifier: ISC
+ *
+ * Copyright (c) 2020 Todd C. Miller <Todd.Miller@sudo.ws>
+ *
+ * Permission to use, copy, modify, and distribute this software for any
+ * purpose with or without fee is hereby granted, provided that the above
+ * copyright notice and this permission notice appear in all copies.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
+ * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
+ * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
+ * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
+ * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
+ * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
+ * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
+ */
+
+/*
+ * This is an open source non-commercial project. Dear PVS-Studio, please check it.
+ * PVS-Studio Static Code Analyzer for C, C++ and C#: http://www.viva64.com
+ */
+
+#include <config.h>
+
+#include <sys/types.h>
+#include <stdlib.h>
+#if defined(HAVE_STDINT_H)
+# include <stdint.h>
+#elif defined(HAVE_INTTYPES_H)
+# include <inttypes.h>
+#endif
+#include <string.h>
+#include <arpa/inet.h>
+
+#include "sudo_compat.h"
+#include "sudo_util.h"
+#include "sudo_rand.h"
+
+struct uuid {
+    uint32_t time_low;
+    uint16_t time_mid;
+    uint16_t time_high_and_version;
+    uint16_t clock_seq_and_variant;
+    unsigned char node[6];
+};
+
+/*
+ * Create a type 4 (random), variant 1 universally unique identifier (UUID).
+ */
+void
+sudo_uuid_create_v1(unsigned char uuid_out[16])
+{
+    union {
+	struct uuid id;
+	unsigned char u8[16];
+    } uuid;
+
+    arc4random_buf(&uuid, sizeof(uuid));
+
+    /* Convert fields to host by order. */
+    uuid.id.time_low = ntohl(uuid.id.time_low);
+    uuid.id.time_mid = ntohs(uuid.id.time_mid);
+    uuid.id.time_high_and_version = ntohs(uuid.id.time_high_and_version);
+    uuid.id.clock_seq_and_variant = ntohs(uuid.id.clock_seq_and_variant);
+
+    /* Set version to 4 (random) in the high nibble. */
+    uuid.id.time_high_and_version &= 0x0fff;
+    uuid.id.time_high_and_version |= 0x4000;
+
+    /* Set variant to 1 (first two bits are 10) */
+    uuid.id.clock_seq_and_variant &= 0x3fff;
+    uuid.id.clock_seq_and_variant |= 0x8000;
+
+    /* Store fields in network byte order (big endian). */
+    uuid.id.time_low = htonl(uuid.id.time_low);
+    uuid.id.time_mid = htons(uuid.id.time_mid);
+    uuid.id.time_high_and_version = htons(uuid.id.time_high_and_version);
+    uuid.id.clock_seq_and_variant = htons(uuid.id.clock_seq_and_variant);
+    memcpy(uuid_out, &uuid, 16);
+}
+
+/*
+ * Format a uuid as a 36-byte string (plus one for the NUL).
+ */
+char *
+sudo_uuid_to_string_v1(unsigned char uuid[16], char *dst, size_t dstsiz)
+{
+    const char hex[] = "0123456789abcdef";
+    char *cp = dst;
+    int i;
+
+    if (dstsiz < sizeof("123e4567-e89b-12d3-a456-426655440000"))
+	return NULL;
+
+    for (i = 0; i < 16; i++) {
+	*cp++ = hex[uuid[i] >> 4];
+	*cp++ = hex[uuid[i] & 0x0f];
+
+	switch (i) {
+	case 4:
+	case 6:
+	case 8:
+	case 10:
+	    *cp++ = '-';
+	    break;
+	}
+    }
+    *cp = '\0';
+
+    return dst;
+}