Use a compiler to marshall/unmarshall the sessions

This way changes are easier, all is needed is to change the session.asn1
file to add or remove elements, and different session types can also be
supported at the same time.

1 files changed, 283 insertions, 0 deletions

diff --git a/src/asn1c/ber_decoder.c b/src/asn1c/ber_decoder.c
new file mode 100644
index 0000000..0f99400
--- /dev/null
+++ b/src/asn1c/ber_decoder.c
@@ -0,0 +1,283 @@
+/*-
+ * Copyright (c) 2003, 2004 Lev Walkin <vlm@lionet.info>. All rights reserved.
+ * Redistribution and modifications are permitted subject to BSD license.
+ */
+#include <asn_internal.h>
+
+#undef	ADVANCE
+#define	ADVANCE(num_bytes)	do {					\
+		size_t num = num_bytes;					\
+		ptr = ((const char *)ptr) + num;			\
+		size -= num;						\
+		consumed_myself += num;					\
+	} while(0)
+#undef	RETURN
+#define	RETURN(_code)	do {						\
+		asn_dec_rval_t rval;					\
+		rval.code = _code;					\
+		if(opt_ctx) opt_ctx->step = step; /* Save context */	\
+		if(_code == RC_OK || opt_ctx)				\
+			rval.consumed = consumed_myself;		\
+		else							\
+			rval.consumed = 0;	/* Context-free */	\
+		return rval;						\
+	} while(0)
+
+/*
+ * The BER decoder of any type.
+ */
+asn_dec_rval_t
+ber_decode(asn_codec_ctx_t *opt_codec_ctx,
+	asn_TYPE_descriptor_t *type_descriptor,
+	void **struct_ptr, const void *ptr, size_t size) {
+	asn_codec_ctx_t s_codec_ctx;
+
+	/*
+	 * Stack checker requires that the codec context
+	 * must be allocated on the stack.
+	 */
+	if(opt_codec_ctx) {
+		if(opt_codec_ctx->max_stack_size) {
+			s_codec_ctx = *opt_codec_ctx;
+			opt_codec_ctx = &s_codec_ctx;
+		}
+	} else {
+		/* If context is not given, be security-conscious anyway */
+		memset(&s_codec_ctx, 0, sizeof(s_codec_ctx));
+		s_codec_ctx.max_stack_size = _ASN_DEFAULT_STACK_MAX;
+		opt_codec_ctx = &s_codec_ctx;
+	}
+
+	/*
+	 * Invoke type-specific decoder.
+	 */
+	return type_descriptor->ber_decoder(opt_codec_ctx, type_descriptor,
+		struct_ptr,	/* Pointer to the destination structure */
+		ptr, size,	/* Buffer and its size */
+		0		/* Default tag mode is 0 */
+		);
+}
+
+/*
+ * Check the set of <TL<TL<TL...>>> tags matches the definition.
+ */
+asn_dec_rval_t
+ber_check_tags(asn_codec_ctx_t *opt_codec_ctx,
+		asn_TYPE_descriptor_t *td, asn_struct_ctx_t *opt_ctx,
+		const void *ptr, size_t size, int tag_mode, int last_tag_form,
+		ber_tlv_len_t *last_length, int *opt_tlv_form) {
+	ssize_t consumed_myself = 0;
+	ssize_t tag_len;
+	ssize_t len_len;
+	ber_tlv_tag_t tlv_tag;
+	ber_tlv_len_t tlv_len;
+	ber_tlv_len_t limit_len = -1;
+	int expect_00_terminators = 0;
+	int tlv_constr = -1;	/* If CHOICE, opt_tlv_form is not given */
+	int step = opt_ctx ? opt_ctx->step : 0;	/* Where we left previously */
+	int tagno;
+
+	/*
+	 * Make sure we didn't exceed the maximum stack size.
+	 */
+	if(_ASN_STACK_OVERFLOW_CHECK(opt_codec_ctx))
+		RETURN(RC_FAIL);
+
+	/*
+	 * So what does all this implicit skip stuff mean?
+	 * Imagine two types,
+	 * 	A ::= [5] IMPLICIT	T
+	 * 	B ::= [2] EXPLICIT	T
+	 * Where T is defined as
+	 *	T ::= [4] IMPLICIT SEQUENCE { ... }
+	 * 
+	 * Let's say, we are starting to decode type A, given the
+	 * following TLV stream: <5> <0>. What does this mean?
+	 * It means that the type A contains type T which is,
+	 * in turn, empty.
+	 * Remember though, that we are still in A. We cannot
+	 * just pass control to the type T decoder. Why? Because
+	 * the type T decoder expects <4> <0>, not <5> <0>.
+	 * So, we must make sure we are going to receive <5> while
+	 * still in A, then pass control to the T decoder, indicating
+	 * that the tag <4> was implicitly skipped. The decoder of T
+	 * hence will be prepared to treat <4> as valid tag, and decode
+	 * it appropriately.
+	 */
+
+	tagno = step	/* Continuing where left previously */
+		+ (tag_mode==1?-1:0)
+		;
+	ASN_DEBUG("ber_check_tags(%s, size=%ld, tm=%d, step=%d, tagno=%d)",
+		td->name, (long)size, tag_mode, step, tagno);
+	/* assert(td->tags_count >= 1) May not be the case for CHOICE or ANY */
+
+	if(tag_mode == 0 && tagno == td->tags_count) {
+		/*
+		 * This must be the _untagged_ ANY type,
+		 * which outermost tag isn't known in advance.
+		 * Fetch the tag and length separately.
+		 */
+		tag_len = ber_fetch_tag(ptr, size, &tlv_tag);
+		switch(tag_len) {
+		case -1: RETURN(RC_FAIL);
+		case 0: RETURN(RC_WMORE);
+		}
+		tlv_constr = BER_TLV_CONSTRUCTED(ptr);
+		len_len = ber_fetch_length(tlv_constr,
+			(const char *)ptr + tag_len, size - tag_len, &tlv_len);
+		switch(len_len) {
+		case -1: RETURN(RC_FAIL);
+		case 0: RETURN(RC_WMORE);
+		}
+		ASN_DEBUG("Advancing %ld in ANY case",
+			(long)(tag_len + len_len));
+		ADVANCE(tag_len + len_len);
+	} else {
+		assert(tagno < td->tags_count);	/* At least one loop */
+	}
+	for((void)tagno; tagno < td->tags_count; tagno++, step++) {
+
+		/*
+		 * Fetch and process T from TLV.
+		 */
+		tag_len = ber_fetch_tag(ptr, size, &tlv_tag);
+			ASN_DEBUG("Fetching tag from {%p,%ld}: "
+				"len %ld, step %d, tagno %d got %s",
+				ptr, (long)size,
+				(long)tag_len, step, tagno,
+				ber_tlv_tag_string(tlv_tag));
+		switch(tag_len) {
+		case -1: RETURN(RC_FAIL);
+		case 0: RETURN(RC_WMORE);
+		}
+
+		tlv_constr = BER_TLV_CONSTRUCTED(ptr);
+
+		/*
+		 * If {I}, don't check anything.
+		 * If {I,B,C}, check B and C unless we're at I.
+		 */
+		if(tag_mode != 0 && step == 0) {
+			/*
+			 * We don't expect tag to match here.
+			 * It's just because we don't know how the tag
+			 * is supposed to look like.
+			 */
+		} else {
+		    assert(tagno >= 0);	/* Guaranteed by the code above */
+		    if(tlv_tag != td->tags[tagno]) {
+			/*
+			 * Unexpected tag. Too bad.
+			 */
+		    	ASN_DEBUG("Expected: %s, "
+				"expectation failed (tn=%d, tm=%d)",
+				ber_tlv_tag_string(td->tags[tagno]),
+				tagno, tag_mode
+			);
+			RETURN(RC_FAIL);
+		    }
+		}
+
+		/*
+		 * Attention: if there are more tags expected,
+		 * ensure that the current tag is presented
+		 * in constructed form (it contains other tags!).
+		 * If this one is the last one, check that the tag form
+		 * matches the one given in descriptor.
+		 */
+		if(tagno < (td->tags_count - 1)) {
+			if(tlv_constr == 0) {
+				ASN_DEBUG("tlv_constr = %d, expfail",
+					tlv_constr);
+				RETURN(RC_FAIL);
+			}
+		} else {
+			if(last_tag_form != tlv_constr
+			&& last_tag_form != -1) {
+				ASN_DEBUG("last_tag_form %d != %d",
+					last_tag_form, tlv_constr);
+				RETURN(RC_FAIL);
+			}
+		}
+
+		/*
+		 * Fetch and process L from TLV.
+		 */
+		len_len = ber_fetch_length(tlv_constr,
+			(const char *)ptr + tag_len, size - tag_len, &tlv_len);
+		ASN_DEBUG("Fetching len = %ld", (long)len_len);
+		switch(len_len) {
+		case -1: RETURN(RC_FAIL);
+		case 0: RETURN(RC_WMORE);
+		}
+
+		/*
+		 * FIXME
+		 * As of today, the chain of tags
+		 * must either contain several indefinite length TLVs,
+		 * or several definite length ones.
+		 * No mixing is allowed.
+		 */
+		if(tlv_len == -1) {
+			/*
+			 * Indefinite length.
+			 */
+			if(limit_len == -1) {
+				expect_00_terminators++;
+			} else {
+				ASN_DEBUG("Unexpected indefinite length "
+					"in a chain of definite lengths");
+				RETURN(RC_FAIL);
+			}
+			ADVANCE(tag_len + len_len);
+			continue;
+		} else {
+			if(expect_00_terminators) {
+				ASN_DEBUG("Unexpected definite length "
+					"in a chain of indefinite lengths");
+				RETURN(RC_FAIL);
+			}
+		}
+
+		/*
+		 * Check that multiple TLVs specify ever decreasing length,
+		 * which is consistent.
+		 */
+		if(limit_len == -1) {
+			limit_len    = tlv_len + tag_len + len_len;
+			if(limit_len < 0) {
+				/* Too great tlv_len value? */
+				RETURN(RC_FAIL);
+			}
+		} else if(limit_len != tlv_len + tag_len + len_len) {
+			/*
+			 * Inner TLV specifies length which is inconsistent
+			 * with the outer TLV's length value.
+			 */
+			ASN_DEBUG("Outer TLV is %ld and inner is %ld",
+				(long)limit_len, (long)tlv_len);
+			RETURN(RC_FAIL);
+		}
+
+		ADVANCE(tag_len + len_len);
+
+		limit_len -= (tag_len + len_len);
+		if((ssize_t)size > limit_len) {
+			/*
+			 * Make sure that we won't consume more bytes
+			 * from the parent frame than the inferred limit.
+			 */
+			size = limit_len;
+		}
+	}
+
+	if(opt_tlv_form)
+		*opt_tlv_form = tlv_constr;
+	if(expect_00_terminators)
+		*last_length = -expect_00_terminators;
+	else
+		*last_length = tlv_len;
+
+	RETURN(RC_OK);
+}