dfilter: Remove redundant STTYPE_CHARCONST syntax node

A charconst uses the same semantic rules as unparsed so just
use the latter to avoid redundancies.

We keep the use of TOKEN_CHARCONST as an optimization to avoid
an unnecessary name resolution (lookup for a registered field with
the same name as the charconst).

9 files changed, 29 insertions, 86 deletions

diff --git a/doc/README.display_filter b/doc/README.display_filter
index 50ec94d02e..c266f1174f 100644
--- a/doc/README.display_filter
+++ b/doc/README.display_filter
@@ -222,28 +222,8 @@ with a central engine.
 Each node (stnode_t) in the syntax tree has a type (sttype).
 These sttypes are very much related to ftypes (field types), but there
 is not a one-to-one correspondence. The syntax tree nodes are slightly
-high-level. For example, there is only a single INTEGER sttype, unlike
-the ftype system that has a type for UINT64, UINT32, UINT16, UINT8, etc.
-(INTEGER removed in 2c701ddf - dfilter: Improve grammar to parse ranges)
-
-typedef enum {
-	STTYPE_UNINITIALIZED,
-	STTYPE_TEST,
-	STTYPE_UNPARSED,
-	STTYPE_STRING,
-	STTYPE_CHARCONST,
-	STTYPE_FIELD,
-	STTYPE_FVALUE,
-	STTYPE_RANGE,
-	STTYPE_FUNCTION,
-	STTYPE_SET,
-	STTYPE_PCRE,
-	STTYPE_NUM_TYPES
-} sttype_id_t;
-
-
-The root node of the syntax tree is the main test or comparison
-being done.
+higher-level abstractions. The root node of the syntax tree is the main
+test or comparison being done.
 
 Semantic Check
 --------------
diff --git a/epan/dfilter/grammar.lemon b/epan/dfilter/grammar.lemon
index 84567569c9..59d9120d09 100644
--- a/epan/dfilter/grammar.lemon
+++ b/epan/dfilter/grammar.lemon
@@ -144,7 +144,8 @@ entity(E) ::= STRING(S).
 }
 entity(E) ::= CHARCONST(C).
 {
-	E = stnode_new(STTYPE_CHARCONST, df_lval_value(C));
+	/* A charconst uses "unparsed" semantic rules. */
+	E = stnode_new(STTYPE_UNPARSED, df_lval_value(C));
 	df_lval_free(C);
 }
 entity(E) ::= UNPARSED(U).
diff --git a/epan/dfilter/semcheck.c b/epan/dfilter/semcheck.c
index 4057cb0010..cd575c81f0 100644
--- a/epan/dfilter/semcheck.c
+++ b/epan/dfilter/semcheck.c
@@ -438,7 +438,6 @@ check_exists(dfwork_t *dfw, stnode_t *st_arg1)
 			/* This is OK */
 			break;
 		case STTYPE_STRING:
-		case STTYPE_CHARCONST:
 		case STTYPE_UNPARSED:
 			dfilter_fail(dfw, "\"%s\" is neither a field nor a protocol name.",
 					(char *)stnode_data(st_arg1));
@@ -560,31 +559,6 @@ check_function(dfwork_t *dfw, stnode_t *st_node)
 	}
 }
 
-/* Convert a character constant to a 1-byte BYTE_STRING containing the
- * character. */
-WS_RETNONNULL
-static fvalue_t *
-dfilter_fvalue_from_charconst_string(dfwork_t *dfw, ftenum_t ftype, stnode_t *st, gboolean allow_partial_value)
-{
-	fvalue_t *fvalue;
-	const char *s = stnode_data(st);
-
-	fvalue = fvalue_from_unparsed(FT_CHAR, s, allow_partial_value,
-			dfw->error_message == NULL ? &dfw->error_message : NULL);
-	if (fvalue == NULL)
-		THROW(TypeError);
-
-	char *temp_string;
-	/* It's valid. Create a 1-byte BYTE_STRING from its value. */
-	temp_string = g_strdup_printf("%02x", fvalue->value.uinteger);
-	FVALUE_FREE(fvalue);
-	fvalue = fvalue_from_unparsed(ftype, temp_string, allow_partial_value, NULL);
-	ws_assert(fvalue);
-	g_free(temp_string);
-
-	return fvalue;
-}
-
 /* If the LHS of a relation test is a FIELD, run some checks
  * and possibly some modifications of syntax tree nodes. */
 static void
@@ -633,8 +607,7 @@ check_relation_LHS_FIELD(dfwork_t *dfw, const char *relation_string,
 			THROW(TypeError);
 		}
 	}
-	else if (type2 == STTYPE_STRING || type2 == STTYPE_UNPARSED ||
-	         type2 == STTYPE_CHARCONST) {
+	else if (type2 == STTYPE_STRING || type2 == STTYPE_UNPARSED) {
 		/* Skip incompatible fields */
 		while (hfinfo1->same_name_prev_id != -1 &&
 				((type2 == STTYPE_STRING && ftype1 != FT_STRING && ftype1!= FT_STRINGZ) ||
@@ -646,13 +619,6 @@ check_relation_LHS_FIELD(dfwork_t *dfw, const char *relation_string,
 		if (type2 == STTYPE_STRING) {
 			fvalue = dfilter_fvalue_from_string(dfw, ftype1, st_arg2, hfinfo1);
 		}
-		else if (type2 == STTYPE_CHARCONST &&
-		    strcmp(relation_string, "contains") == 0) {
-			/* The RHS should be the same type as the LHS,
-			 * but a character is just a one-byte byte
-			 * string. */
-			fvalue = dfilter_fvalue_from_charconst_string(dfw, ftype1, st_arg2, allow_partial_value);
-		}
 		else {
 			fvalue = dfilter_fvalue_from_unparsed(dfw, ftype1, st_arg2, allow_partial_value, hfinfo1);
 		}
@@ -771,8 +737,7 @@ check_relation_LHS_STRING(dfwork_t *dfw, const char* relation_string,
 		fvalue = dfilter_fvalue_from_string(dfw, ftype2, st_arg1, hfinfo2);
 		stnode_replace(st_arg1, STTYPE_FVALUE, fvalue);
 	}
-	else if (type2 == STTYPE_STRING || type2 == STTYPE_UNPARSED ||
-	         type2 == STTYPE_CHARCONST) {
+	else if (type2 == STTYPE_STRING || type2 == STTYPE_UNPARSED) {
 		/* Well now that's silly... */
 		dfilter_fail(dfw, "Neither \"%s\" nor \"%s\" are field or protocol names.",
 				(char *)stnode_data(st_arg1),
@@ -839,8 +804,7 @@ check_relation_LHS_UNPARSED(dfwork_t *dfw, const char* relation_string,
 		fvalue = dfilter_fvalue_from_unparsed(dfw, ftype2, st_arg1, allow_partial_value, hfinfo2);
 		stnode_replace(st_arg1, STTYPE_FVALUE, fvalue);
 	}
-	else if (type2 == STTYPE_STRING || type2 == STTYPE_UNPARSED ||
-	         type2 == STTYPE_CHARCONST) {
+	else if (type2 == STTYPE_STRING || type2 == STTYPE_UNPARSED) {
 		/* Well now that's silly... */
 		dfilter_fail(dfw, "Neither \"%s\" nor \"%s\" are field or protocol names.",
 				(char *)stnode_data(st_arg1),
@@ -921,13 +885,6 @@ check_relation_LHS_RANGE(dfwork_t *dfw, const char *relation_string,
 		fvalue = dfilter_fvalue_from_unparsed(dfw, FT_BYTES, st_arg2, allow_partial_value, NULL);
 		stnode_replace(st_arg2, STTYPE_FVALUE, fvalue);
 	}
-	else if (type2 == STTYPE_CHARCONST) {
-		ws_debug("5 check_relation_LHS_RANGE(type2 = STTYPE_CHARCONST)");
-		/* The RHS should be FT_BYTES, but a character is just a
-		 * one-byte byte string. */
-		fvalue = dfilter_fvalue_from_charconst_string(dfw, FT_BYTES, st_arg2, allow_partial_value);
-		stnode_replace(st_arg2, STTYPE_FVALUE, fvalue);
-	}
 	else if (type2 == STTYPE_RANGE) {
 		ws_debug("5 check_relation_LHS_RANGE(type2 = STTYPE_RANGE)");
 		check_drange_sanity(dfw, st_arg2);
@@ -971,7 +928,7 @@ check_param_entity(dfwork_t *dfw, stnode_t *st_node)
 
 	e_type = stnode_type_id(st_node);
 	/* If there's an unparsed string, change it to an FT_STRING */
-	if (e_type == STTYPE_UNPARSED || e_type == STTYPE_CHARCONST) {
+	if (e_type == STTYPE_UNPARSED) {
 		fvalue = dfilter_fvalue_from_unparsed(dfw, FT_STRING, st_node, TRUE, NULL);
 		new_st = stnode_new(STTYPE_FVALUE, fvalue);
 		stnode_free(st_node);
@@ -1033,7 +990,7 @@ check_relation_LHS_FUNCTION(dfwork_t *dfw, const char *relation_string,
 		fvalue = dfilter_fvalue_from_string(dfw, ftype1, st_arg2, NULL);
 		stnode_replace(st_arg2, STTYPE_FVALUE, fvalue);
 	}
-	else if (type2 == STTYPE_UNPARSED || type2 == STTYPE_CHARCONST) {
+	else if (type2 == STTYPE_UNPARSED) {
 		fvalue = dfilter_fvalue_from_unparsed(dfw, ftype1, st_arg2, allow_partial_value, NULL);
 		stnode_replace(st_arg2, STTYPE_FVALUE, fvalue);
 	}
@@ -1148,7 +1105,6 @@ check_relation(dfwork_t *dfw, const char *relation_string,
 					allow_partial_value, st_node, st_arg1, st_arg2);
 			break;
 		case STTYPE_UNPARSED:
-		case STTYPE_CHARCONST:
 			check_relation_LHS_UNPARSED(dfw, relation_string, can_func,
 					allow_partial_value, st_node, st_arg1, st_arg2);
 			break;
diff --git a/epan/dfilter/sttype-string.c b/epan/dfilter/sttype-string.c
index 0bd88c38bd..770d0765fb 100644
--- a/epan/dfilter/sttype-string.c
+++ b/epan/dfilter/sttype-string.c
@@ -48,15 +48,6 @@ sttype_register_string(void)
 		string_tostr
 	};
 
-	static sttype_t charconst_type = {
-		STTYPE_CHARCONST,
-		"CHARCONST",
-		string_new,
-		string_free,
-		string_dup,
-		string_tostr
-	};
-
 	static sttype_t unparsed_type = {
 		STTYPE_UNPARSED,
 		"UNPARSED",
@@ -67,7 +58,6 @@ sttype_register_string(void)
 	};
 
 	sttype_register(&string_type);
-	sttype_register(&charconst_type);
 	sttype_register(&unparsed_type);
 }
 
diff --git a/epan/dfilter/syntax-tree.h b/epan/dfilter/syntax-tree.h
index 96c6ad30c7..45e37a8beb 100644
--- a/epan/dfilter/syntax-tree.h
+++ b/epan/dfilter/syntax-tree.h
@@ -24,7 +24,6 @@ typedef enum {
 	STTYPE_TEST,
 	STTYPE_UNPARSED,
 	STTYPE_STRING,
-	STTYPE_CHARCONST,
 	STTYPE_FIELD,
 	STTYPE_FVALUE,
 	STTYPE_RANGE,
diff --git a/epan/ftypes/ftype-bytes.c b/epan/ftypes/ftype-bytes.c
index d5b37bca5b..f78d535160 100644
--- a/epan/ftypes/ftype-bytes.c
+++ b/epan/ftypes/ftype-bytes.c
@@ -239,6 +239,20 @@ byte_array_from_unparsed(const char *s, gchar **err_msg)
 	GByteArray	*bytes;
 	gboolean	res;
 
+	if (s[0] == '\'') {
+		/*
+		 * byte array with length 1 represented as a C-style character constant.
+		 */
+		unsigned long value;
+		if (!parse_charconst(s, &value, err_msg))
+			return FALSE;
+		ws_assert(value <= UINT8_MAX);
+		uint8_t one_byte = (uint8_t)value;
+		bytes = g_byte_array_new();
+		g_byte_array_append(bytes, &one_byte, 1);
+		return bytes;
+	}
+
 	/*
 	 * Special case where the byte string is specified using a one byte
 	 * hex literal. We can't allow this for byte strings that are longer
diff --git a/epan/ftypes/ftype-integer.c b/epan/ftypes/ftype-integer.c
index a099e033f6..22f365e156 100644
--- a/epan/ftypes/ftype-integer.c
+++ b/epan/ftypes/ftype-integer.c
@@ -48,7 +48,7 @@ get_sinteger(fvalue_t *fv)
 	return fv->value.sinteger;
 }
 
-static gboolean
+gboolean
 parse_charconst(const char *s, unsigned long *valuep, gchar **err_msg)
 {
 	const char *cp;
diff --git a/epan/ftypes/ftypes-int.h b/epan/ftypes/ftypes-int.h
index 2059c17bc4..757405c07d 100644
--- a/epan/ftypes/ftypes-int.h
+++ b/epan/ftypes/ftypes-int.h
@@ -134,6 +134,9 @@ struct _ftype_t {
 
 GByteArray *byte_array_from_unparsed(const char *s, gchar **err_msg);
 
+gboolean
+parse_charconst(const char *s, unsigned long *valuep, gchar **err_msg);
+
 #endif /* FTYPES_INT_H */
 
 /*
diff --git a/test/suite_dfilter/group_syntax.py b/test/suite_dfilter/group_syntax.py
index ffc339f5d9..dbd162177b 100644
--- a/test/suite_dfilter/group_syntax.py
+++ b/test/suite_dfilter/group_syntax.py
@@ -91,11 +91,11 @@ class case_syntax(unittest.TestCase):
         dfilter = "bootp"
         checkDFilterSucceed(dfilter, "Deprecated tokens: \"bootp\"")
 
-    def test_charconst_1(self, checkDFilterCount):
+    def test_charconst_bytes_1(self, checkDFilterCount):
         # Bytes as a character constant.
         dfilter = "frame contains 'H'"
         checkDFilterCount(dfilter, 1)
 
-    def test_charconst_2(self, checkDFilterCount):
+    def test_charconst_bytes_2(self, checkDFilterCount):
         dfilter = "frame[54] == 'H'"
         checkDFilterCount(dfilter, 1)