decoding dynamic types

include/libtcap.h

@@ -9,6 +9,7 @@
 
 TCMessage_t *tcap_decode(const char *buf, size_t len);
 void *inap_decode(Invoke_t *invoke, asn_TYPE_descriptor_t **);
+int tcap_extract(const char *buf, size_t len, const char *spec);
 
 
 #endif

src/tcap.c

@@ -3,6 +3,7 @@
 #include <stdio.h>
 #include <stdlib.h>
 #include <sys/types.h>
+#include <string.h>
 
 #include "TCMessage.h"
 #include "Invoke.h"
@@ -72,3 +73,46 @@ nothing:
 	*type = NULL;
 	return NULL;
 }
+
+int tcap_extract(const char *buf, size_t len, const char *spec) {
+	void *element;
+	asn_TYPE_descriptor_t *type;
+	const char *c;
+	const char *token;
+	int token_len, i;
+	asn_TYPE_member_t *member;
+
+	element = tcap_decode(buf, len);
+	if (!element)
+		goto error;
+	type = &asn_DEF_TCMessage;
+
+	token = spec;
+
+	while (1) {
+		c = strchr(token, '.');
+		if (!c)
+			goto done;
+		token_len = c - spec;
+
+		/* has to be a CHOICE, SET or SEQUENCE */
+		for (i = 0; i < type->elements_count; i++) {
+			member = &type->elements[i];
+			if (!strncmp(token, member->name, token_len))
+				goto found_member;
+		}
+
+		goto error;
+
+found_member:
+		type = member->type;
+		element = *((void **) (element + member->memb_offset));
+
+		token = c + 1;
+	}
+
+done:
+	return 0;
+error:
+	return -1;
+}

tests/basic.c

@@ -89,5 +89,8 @@ int main() {
 		}
 	}
 
+	i = tcap_extract(tcap, tcap_len, "end.components");
+	printf("extract: %i\n", i);
+
 	return 0;
 }