diff --git a/e2ap/lib/constraints.c b/e2ap/lib/constraints.c
new file mode 100644
index 0000000..df3c6c1
--- /dev/null
+++ b/e2ap/lib/constraints.c
@@ -0,0 +1,93 @@
+#include <asn_internal.h>
+#include <constraints.h>
+
+int
+asn_generic_no_constraint(const asn_TYPE_descriptor_t *type_descriptor,
+                          const void *struct_ptr,
+                          asn_app_constraint_failed_f *cb, void *key) {
+    (void)type_descriptor;	/* Unused argument */
+	(void)struct_ptr;	/* Unused argument */
+	(void)cb;	/* Unused argument */
+	(void)key;	/* Unused argument */
+
+	/* Nothing to check */
+	return 0;
+}
+
+int
+asn_generic_unknown_constraint(const asn_TYPE_descriptor_t *type_descriptor,
+                               const void *struct_ptr,
+                               asn_app_constraint_failed_f *cb, void *key) {
+    (void)type_descriptor;	/* Unused argument */
+	(void)struct_ptr;	/* Unused argument */
+	(void)cb;	/* Unused argument */
+	(void)key;	/* Unused argument */
+
+	/* Unknown how to check */
+	return 0;
+}
+
+struct errbufDesc {
+    const asn_TYPE_descriptor_t *failed_type;
+    const void *failed_struct_ptr;
+	char *errbuf;
+	size_t errlen;
+};
+
+static void
+_asn_i_ctfailcb(void *key, const asn_TYPE_descriptor_t *td, const void *sptr,
+                const char *fmt, ...) {
+    struct errbufDesc *arg = key;
+	va_list ap;
+	ssize_t vlen;
+	ssize_t maxlen;
+
+	arg->failed_type = td;
+	arg->failed_struct_ptr = sptr;
+
+	maxlen = arg->errlen;
+	if(maxlen <= 0)
+		return;
+
+	va_start(ap, fmt);
+	vlen = vsnprintf(arg->errbuf, maxlen, fmt, ap);
+	va_end(ap);
+	if(vlen >= maxlen) {
+		arg->errbuf[maxlen-1] = '\0';	/* Ensuring libc correctness */
+		arg->errlen = maxlen - 1;	/* Not counting termination */
+		return;
+	} else if(vlen >= 0) {
+		arg->errbuf[vlen] = '\0';	/* Ensuring libc correctness */
+		arg->errlen = vlen;		/* Not counting termination */
+	} else {
+		/*
+		 * The libc on this system is broken.
+		 */
+		vlen = sizeof("<broken vsnprintf>") - 1;
+		maxlen--;
+		arg->errlen = vlen < maxlen ? vlen : maxlen;
+		memcpy(arg->errbuf, "<broken vsnprintf>", arg->errlen);
+		arg->errbuf[arg->errlen] = 0;
+	}
+
+	return;
+}
+
+int
+asn_check_constraints(const asn_TYPE_descriptor_t *type_descriptor,
+                      const void *struct_ptr, char *errbuf, size_t *errlen) {
+    struct errbufDesc arg;
+    int ret;
+
+    arg.failed_type = 0;
+    arg.failed_struct_ptr = 0;
+    arg.errbuf = errbuf;
+    arg.errlen = errlen ? *errlen : 0;
+
+    ret = type_descriptor->encoding_constraints.general_constraints(
+        type_descriptor, struct_ptr, _asn_i_ctfailcb, &arg);
+    if(ret == -1 && errlen) *errlen = arg.errlen;
+
+    return ret;
+}
+