fix: quiet -Walloc-size-larger-than and -Wformat-truncation warnings (#436)

* fix: quiet -Walloc-size-larger-than and -Wformat-truncation warnings

OPENDMARC_MAX_SHELVES_LG2 was derived from sizeof(size_t) under the
assumption that OPENDMARC_HASH_SHELF is <= 32 bytes, but it actually
holds a pthread_mutex_t and runs 48-72 bytes depending on platform,
so the theoretical max calloc() request could exceed the allocator
limit. The only real caller asks for 8192 buckets, so cap the table
size at a fixed, generous bound instead.

MAXHEADER was sized so that a maxed-out authservid_hdr plus a
maxed-out From-domain could together exceed the malloc'd header
buffer, risking silent truncation of the Authentication-Results
header in pathological cases. Double it so the worst case fits.

* fix: enable subdir-objects to quiet automake forward-incompat warning

test_arcares and test_spf_parse pull source files from
$(top_srcdir)/opendmarc/, which automake warns will become a hard
error in a future release without subdir-objects enabled. Verified
make check still passes (13/13) with objects now placed in a path
mirroring their source tree instead of being flattened.

Author: thegushi

libopendmarc/opendmarc_internal.h

@@ -209,10 +209,15 @@ typedef struct {
 #define	OPENDMARC_MIN_SHELVES	(1 << OPENDMARC_MIN_SHELVES_LG2)
 
 /*
- * max * sizeof internal_entry must fit into size_t.
- * assumes internal_entry is <= 32 (2^5) bytes.
+ * Largest table size opendmarc_hash_init() will honor. The real
+ * caller (opendmarc_tld.c) only ever asks for 8192; this just keeps a
+ * runaway or hostile tablesize argument from reaching calloc(). Fixed
+ * well below any allocator limit rather than derived from sizeof(size_t),
+ * since the size of OPENDMARC_HASH_SHELF (which includes a pthread_mutex_t)
+ * varies by platform and a sizeof-derived bound can creep past what
+ * calloc() will actually allocate.
  */
-#define	OPENDMARC_MAX_SHELVES_LG2	(sizeof (size_t) * 8 - 1 - 5)
+#define	OPENDMARC_MAX_SHELVES_LG2	24
 #define	OPENDMARC_MAX_SHELVES	((size_t)1 << OPENDMARC_MAX_SHELVES_LG2)
 
 typedef struct {

libopendmarc/tests/Makefile.am

@@ -1,3 +1,4 @@
+AUTOMAKE_OPTIONS = subdir-objects
 SUBDIRS=testfiles
 LDADD = ../libopendmarc.la $(LIBRESOLV)
 AM_CPPFLAGS = -I.. -I../..

opendmarc/opendmarc.h

@@ -37,7 +37,7 @@
 #define	REPORTCMD_EXIT_SUPPRESSED	2	/* ReportCommand sent nothing; all recipients were suppressed by policy (e.g. NoReportsList/StaleMARC), not an error */
 #define	JOBIDUNKNOWN	"(unknown-jobid)"
 #define	MAXARGV		65536
-#define	MAXHEADER	4096
+#define	MAXHEADER	8192
 #define	TEMPFILE	"/var/tmp/dmarcXXXXXX"
 
 #define AUTHRESULTSHDR	"Authentication-Results"