diff options
Diffstat (limited to 'skeletons/der_encoder.c')
-rw-r--r-- | skeletons/der_encoder.c | 143 |
1 files changed, 143 insertions, 0 deletions
diff --git a/skeletons/der_encoder.c b/skeletons/der_encoder.c new file mode 100644 index 00000000..f275f9c1 --- /dev/null +++ b/skeletons/der_encoder.c @@ -0,0 +1,143 @@ +/*- + * Copyright (c) 2003, 2004 Lev Walkin <vlm@lionet.info>. All rights reserved. + * Redistribution and modifications are permitted subject to BSD license. + */ +#include <constr_TYPE.h> +#include <assert.h> + +static ssize_t der_write_TL(ber_tlv_tag_t tag, ber_tlv_len_t len, + asn_app_consume_bytes_f *cb, void *app_key, int constructed); + +/* + * The DER encoder of any type. + */ +der_enc_rval_t +der_encode(asn1_TYPE_descriptor_t *type_descriptor, void *struct_ptr, + asn_app_consume_bytes_f *consume_bytes, void *app_key) { + + ASN_DEBUG("DER encoder invoked for %s", + type_descriptor->name); + + /* + * Invoke type-specific encoder. + */ + return type_descriptor->der_encoder(type_descriptor, + struct_ptr, /* Pointer to the destination structure */ + 0, 0, + consume_bytes, app_key); +} + +/* + * Write out leading TL[v] sequence according to the type definition. + */ +ssize_t +der_write_tags(asn1_TYPE_descriptor_t *sd, + size_t struct_length, + int tag_mode, + ber_tlv_tag_t tag, /* EXPLICIT or IMPLICIT tag */ + asn_app_consume_bytes_f *cb, + void *app_key) { + ber_tlv_tag_t *tags; /* Copy of tags stream */ + int tags_count; /* Number of tags */ + size_t overall_length; + ssize_t *lens; + int i; + + if(tag_mode) { + /* + * Instead of doing shaman dance like we do in ber_check_tags(), + * allocate a small array on the stack + * and initialize it appropriately. + */ + tags = alloca((sd->tags_count + (tag_mode?1:0)) + * sizeof(ber_tlv_tag_t)); + if(tags == NULL) return -1; /* Impossible on i386 */ + tags_count = sd->tags_count + + 1 /* EXPLICIT or IMPLICIT tag is given */ + - ((tag_mode==-1)?sd->tags_impl_skip:0); + /* Copy tags over */ + tags[0] = tag; + for(i = 1; i < tags_count; i++) + tags[i] = sd->tags[i - 1 + sd->tags_impl_skip]; + } else { + tags = sd->tags; + tags_count = sd->tags_count; + } + + /* No tags to write */ + if(tags_count == 0) + return 0; + + lens = alloca(tags_count * sizeof(lens[0])); + if(lens == NULL) return -1; + + /* + * Array of tags is initialized. + * Now, compute the size of the TLV pairs, from right to left. + */ + overall_length = struct_length; + for(i = tags_count - 1; i >= 0; --i) { + lens[i] = der_write_TL(tags[i], overall_length, 0, 0, 0); + if(lens[i] == -1) return -1; + overall_length += lens[i]; + lens[i] = overall_length - lens[i]; + } + + if(!cb) return overall_length - struct_length; + + ASN_DEBUG("%s %s TL sequence (%d elements)", + cb?"Encoding":"Estimating", sd->name, tags_count); + + /* + * Encode the TL sequence for real. + */ + for(i = 0; i < tags_count; i++) { + ssize_t len; + int _constr; + + /* If this one happens to be constructed, do it. */ + if(i < (tags_count - 1) || sd->last_tag_form == 1) + _constr = 1; + else _constr = 0; + + len = der_write_TL(tags[i], lens[i], cb, app_key, _constr); + if(len == -1) return -1; + } + + return overall_length - struct_length; +} + +static ssize_t +der_write_TL(ber_tlv_tag_t tag, ber_tlv_len_t len, + asn_app_consume_bytes_f *cb, void *app_key, + int constructed) { + uint8_t buf[32]; + size_t size = 0; + int buf_size = cb?sizeof(buf):0; + ssize_t tmp; + + /* Serialize tag (T from TLV) into possibly zero-length buffer */ + tmp = der_tlv_tag_serialize(tag, buf, buf_size); + if(tmp == -1 || tmp > sizeof(buf)) return -1; + size += tmp; + + /* Serialize length (L from TLV) into possibly zero-length buffer */ + tmp = der_tlv_length_serialize(len, buf+size, buf_size?buf_size-size:0); + if(tmp == -1) return -1; + size += tmp; + + if(size > sizeof(buf)) + return -1; + + /* + * If callback is specified, invoke it, and check its return value. + */ + if(cb) { + if(constructed) *buf |= 0x20; + if(cb(buf, size, app_key) == -1) { + return -1; + } + } + + return size; +} |