Add user-callable SHA-2 functions

Add the user-callable functions sha224, sha256, sha384, sha512.  We
already had these in the C code to support SCRAM, but there was no test
coverage outside of the SCRAM tests.  Adding these as user-callable
functions allows writing some tests.  Also, we have a user-callable md5
function but no more modern alternative, which led to wide use of md5 as
a general-purpose hash function, which leads to occasional complaints
about using md5.

Also mark the existing md5 functions as leak-proof.

Reviewed-by: Michael Paquier <michael@paquier.xyz>

1 files changed, 169 insertions, 0 deletions

diff --git a/src/backend/utils/adt/cryptohashes.c b/src/backend/utils/adt/cryptohashes.c
new file mode 100644
index 00000000000..e1ff17590ea
--- /dev/null
+++ b/src/backend/utils/adt/cryptohashes.c
@@ -0,0 +1,169 @@
+/*-------------------------------------------------------------------------
+ *
+ * cryptohashes.c
+ *	  Cryptographic hash functions
+ *
+ * Portions Copyright (c) 2018, PostgreSQL Global Development Group
+ *
+ *
+ * IDENTIFICATION
+ *	  src/backend/utils/adt/cryptohashes.c
+ *
+ *-------------------------------------------------------------------------
+ */
+#include "postgres.h"
+
+#include "common/md5.h"
+#include "common/sha2.h"
+#include "utils/builtins.h"
+
+
+/*
+ * MD5
+ */
+
+/* MD5 produces a 16 byte (128 bit) hash; double it for hex */
+#define MD5_HASH_LEN  32
+
+/*
+ * Create an MD5 hash of a text value and return it as hex string.
+ */
+Datum
+md5_text(PG_FUNCTION_ARGS)
+{
+	text	   *in_text = PG_GETARG_TEXT_PP(0);
+	size_t		len;
+	char		hexsum[MD5_HASH_LEN + 1];
+
+	/* Calculate the length of the buffer using varlena metadata */
+	len = VARSIZE_ANY_EXHDR(in_text);
+
+	/* get the hash result */
+	if (pg_md5_hash(VARDATA_ANY(in_text), len, hexsum) == false)
+		ereport(ERROR,
+				(errcode(ERRCODE_OUT_OF_MEMORY),
+				 errmsg("out of memory")));
+
+	/* convert to text and return it */
+	PG_RETURN_TEXT_P(cstring_to_text(hexsum));
+}
+
+/*
+ * Create an MD5 hash of a bytea value and return it as a hex string.
+ */
+Datum
+md5_bytea(PG_FUNCTION_ARGS)
+{
+	bytea	   *in = PG_GETARG_BYTEA_PP(0);
+	size_t		len;
+	char		hexsum[MD5_HASH_LEN + 1];
+
+	len = VARSIZE_ANY_EXHDR(in);
+	if (pg_md5_hash(VARDATA_ANY(in), len, hexsum) == false)
+		ereport(ERROR,
+				(errcode(ERRCODE_OUT_OF_MEMORY),
+				 errmsg("out of memory")));
+
+	PG_RETURN_TEXT_P(cstring_to_text(hexsum));
+}
+
+
+/*
+ * SHA-2 variants
+ */
+
+Datum
+sha224_bytea(PG_FUNCTION_ARGS)
+{
+	bytea	   *in = PG_GETARG_BYTEA_PP(0);
+	const uint8 *data;
+	size_t		len;
+	pg_sha224_ctx ctx;
+	unsigned char buf[PG_SHA224_DIGEST_LENGTH];
+	bytea	   *result;
+
+	len = VARSIZE_ANY_EXHDR(in);
+	data = (unsigned char *) VARDATA_ANY(in);
+
+	pg_sha224_init(&ctx);
+	pg_sha224_update(&ctx, data, len);
+	pg_sha224_final(&ctx, buf);
+
+	result = palloc(sizeof(buf) + VARHDRSZ);
+	SET_VARSIZE(result, sizeof(buf) + VARHDRSZ);
+	memcpy(VARDATA(result), buf, sizeof(buf));
+
+	PG_RETURN_BYTEA_P(result);
+}
+
+Datum
+sha256_bytea(PG_FUNCTION_ARGS)
+{
+	bytea	   *in = PG_GETARG_BYTEA_PP(0);
+	const uint8 *data;
+	size_t		len;
+	pg_sha256_ctx ctx;
+	unsigned char buf[PG_SHA256_DIGEST_LENGTH];
+	bytea	   *result;
+
+	len = VARSIZE_ANY_EXHDR(in);
+	data = (unsigned char *) VARDATA_ANY(in);
+
+	pg_sha256_init(&ctx);
+	pg_sha256_update(&ctx, data, len);
+	pg_sha256_final(&ctx, buf);
+
+	result = palloc(sizeof(buf) + VARHDRSZ);
+	SET_VARSIZE(result, sizeof(buf) + VARHDRSZ);
+	memcpy(VARDATA(result), buf, sizeof(buf));
+
+	PG_RETURN_BYTEA_P(result);
+}
+
+Datum
+sha384_bytea(PG_FUNCTION_ARGS)
+{
+	bytea	   *in = PG_GETARG_BYTEA_PP(0);
+	const uint8 *data;
+	size_t		len;
+	pg_sha384_ctx ctx;
+	unsigned char buf[PG_SHA384_DIGEST_LENGTH];
+	bytea	   *result;
+
+	len = VARSIZE_ANY_EXHDR(in);
+	data = (unsigned char *) VARDATA_ANY(in);
+
+	pg_sha384_init(&ctx);
+	pg_sha384_update(&ctx, data, len);
+	pg_sha384_final(&ctx, buf);
+
+	result = palloc(sizeof(buf) + VARHDRSZ);
+	SET_VARSIZE(result, sizeof(buf) + VARHDRSZ);
+	memcpy(VARDATA(result), buf, sizeof(buf));
+
+	PG_RETURN_BYTEA_P(result);
+}
+
+Datum
+sha512_bytea(PG_FUNCTION_ARGS)
+{
+	bytea	   *in = PG_GETARG_BYTEA_PP(0);
+	const uint8 *data;
+	size_t		len;
+	pg_sha512_ctx ctx;
+	unsigned char buf[PG_SHA512_DIGEST_LENGTH];
+	bytea	   *result;
+
+	len = VARSIZE_ANY_EXHDR(in);
+	data = (unsigned char *) VARDATA_ANY(in);
+
+	pg_sha512_init(&ctx);
+	pg_sha512_update(&ctx, data, len);
+	pg_sha512_final(&ctx, buf);
+
+	result = palloc(sizeof(buf) + VARHDRSZ);
+	SET_VARSIZE(result, sizeof(buf) + VARHDRSZ);
+	memcpy(VARDATA(result), buf, sizeof(buf));
+
+	PG_RETURN_BYTEA_P(result);
+}