/* cbs_find_ber walks an ASN.1 structure in |orig_in| and sets |*ber_found| * depending on whether an indefinite length element was found. The value of * |in| is not changed. It returns one on success (i.e. |*ber_found| was set) * and zero on error. */ static int cbs_find_ber(CBS *orig_in, char *ber_found, unsigned depth) { CBS in; if (depth > kMaxDepth) { return 0; } CBS_init(&in, CBS_data(orig_in), CBS_len(orig_in)); *ber_found = 0; while (CBS_len(&in) > 0) { CBS contents; unsigned tag; size_t header_len; if (!CBS_get_any_ber_asn1_element(&in, &contents, &tag, &header_len)) { return 0; } if (CBS_len(&contents) == header_len && header_len > 0 && CBS_data(&contents)[header_len-1] == 0x80) { *ber_found = 1; return 1; } if (tag & CBS_ASN1_CONSTRUCTED) { if (!CBS_skip(&contents, header_len) || !cbs_find_ber(&contents, ber_found, depth + 1)) { return 0; } } } return 1; }
/* cbs_find_ber walks an ASN.1 structure in |orig_in| and sets |*ber_found| * depending on whether an indefinite length element or constructed string was * found. The value of |orig_in| is not changed. It returns one on success (i.e. * |*ber_found| was set) and zero on error. */ static int cbs_find_ber(const CBS *orig_in, char *ber_found, unsigned depth) { CBS in; if (depth > kMaxDepth) { return 0; } CBS_init(&in, CBS_data(orig_in), CBS_len(orig_in)); *ber_found = 0; while (CBS_len(&in) > 0) { CBS contents; unsigned tag; size_t header_len; if (!CBS_get_any_ber_asn1_element(&in, &contents, &tag, &header_len)) { return 0; } if (CBS_len(&contents) == header_len && header_len > 0 && CBS_data(&contents)[header_len-1] == 0x80) { /* Found an indefinite-length element. */ *ber_found = 1; return 1; } if (tag & CBS_ASN1_CONSTRUCTED) { if (is_string_type(tag)) { /* Constructed strings are only legal in BER and require conversion. */ *ber_found = 1; return 1; } if (!CBS_skip(&contents, header_len) || !cbs_find_ber(&contents, ber_found, depth + 1)) { return 0; } } } return 1; }
/* cbs_convert_ber reads BER data from |in| and writes DER data to |out|. If * |string_tag| is non-zero, then all elements must match |string_tag| up to the * constructed bit and primitive element bodies are written to |out| without * element headers. This is used when concatenating the fragments of a * constructed string. If |looking_for_eoc| is set then any EOC elements found * will cause the function to return after consuming it. It returns one on * success and zero on error. */ static int cbs_convert_ber(CBS *in, CBB *out, unsigned string_tag, char looking_for_eoc, unsigned depth) { assert(!(string_tag & CBS_ASN1_CONSTRUCTED)); if (depth > kMaxDepth) { return 0; } while (CBS_len(in) > 0) { CBS contents; unsigned tag, child_string_tag = string_tag; size_t header_len; CBB *out_contents, out_contents_storage; if (!CBS_get_any_ber_asn1_element(in, &contents, &tag, &header_len)) { return 0; } if (is_eoc(header_len, &contents)) { return looking_for_eoc; } if (string_tag != 0) { /* This is part of a constructed string. All elements must match * |string_tag| up to the constructed bit and get appended to |out| * without a child element. */ if ((tag & ~CBS_ASN1_CONSTRUCTED) != string_tag) { return 0; } out_contents = out; } else { unsigned out_tag = tag; if ((tag & CBS_ASN1_CONSTRUCTED) && is_string_type(tag)) { /* If a constructed string, clear the constructed bit and inform * children to concatenate bodies. */ out_tag &= ~CBS_ASN1_CONSTRUCTED; child_string_tag = out_tag; } if (!CBB_add_asn1(out, &out_contents_storage, out_tag)) { return 0; } out_contents = &out_contents_storage; } if (CBS_len(&contents) == header_len && header_len > 0 && CBS_data(&contents)[header_len - 1] == 0x80) { /* This is an indefinite length element. */ if (!cbs_convert_ber(in, out_contents, child_string_tag, 1 /* looking for eoc */, depth + 1) || !CBB_flush(out)) { return 0; } continue; } if (!CBS_skip(&contents, header_len)) { return 0; } if (tag & CBS_ASN1_CONSTRUCTED) { /* Recurse into children. */ if (!cbs_convert_ber(&contents, out_contents, child_string_tag, 0 /* not looking for eoc */, depth + 1)) { return 0; } } else { /* Copy primitive contents as-is. */ if (!CBB_add_bytes(out_contents, CBS_data(&contents), CBS_len(&contents))) { return 0; } } if (!CBB_flush(out)) { return 0; } } return looking_for_eoc == 0; }
/* cbs_convert_ber reads BER data from |in| and writes DER data to |out|. If * |squash_header| is set then the top-level of elements from |in| will not * have their headers written. This is used when concatenating the fragments of * an indefinite length, primitive value. If |looking_for_eoc| is set then any * EOC elements found will cause the function to return after consuming it. * It returns one on success and zero on error. */ static int cbs_convert_ber(CBS *in, CBB *out, char squash_header, char looking_for_eoc, unsigned depth) { if (depth > kMaxDepth) { return 0; } while (CBS_len(in) > 0) { CBS contents; unsigned tag; size_t header_len; CBB *out_contents, out_contents_storage; if (!CBS_get_any_ber_asn1_element(in, &contents, &tag, &header_len)) { return 0; } out_contents = out; if (CBS_len(&contents) == header_len) { if (is_eoc(header_len, &contents)) { return looking_for_eoc; } if (header_len > 0 && CBS_data(&contents)[header_len - 1] == 0x80) { /* This is an indefinite length element. If it's a SEQUENCE or SET then * we just need to write the out the contents as normal, but with a * concrete length prefix. * * If it's a something else then the contents will be a series of BER * elements of the same type which need to be concatenated. */ const char context_specific = (tag & 0xc0) == 0x80; char squash_child_headers = is_primitive_type(tag); /* This is a hack, but it sufficies to handle NSS's output. If we find * an indefinite length, context-specific tag with a definite, primitive * tag inside it, then we assume that the context-specific tag is * implicit and the tags within are fragments of a primitive type that * need to be concatenated. */ if (context_specific && (tag & CBS_ASN1_CONSTRUCTED)) { CBS in_copy, inner_contents; unsigned inner_tag; size_t inner_header_len; CBS_init(&in_copy, CBS_data(in), CBS_len(in)); if (!CBS_get_any_ber_asn1_element(&in_copy, &inner_contents, &inner_tag, &inner_header_len)) { return 0; } if (CBS_len(&inner_contents) > inner_header_len && is_primitive_type(inner_tag)) { squash_child_headers = 1; } } if (!squash_header) { unsigned out_tag = tag; if (squash_child_headers) { out_tag &= ~CBS_ASN1_CONSTRUCTED; } if (!CBB_add_asn1(out, &out_contents_storage, out_tag)) { return 0; } out_contents = &out_contents_storage; } if (!cbs_convert_ber(in, out_contents, squash_child_headers, 1 /* looking for eoc */, depth + 1)) { return 0; } if (out_contents != out && !CBB_flush(out)) { return 0; } continue; } } if (!squash_header) { if (!CBB_add_asn1(out, &out_contents_storage, tag)) { return 0; } out_contents = &out_contents_storage; } if (!CBS_skip(&contents, header_len)) { return 0; } if (tag & CBS_ASN1_CONSTRUCTED) { if (!cbs_convert_ber(&contents, out_contents, 0 /* don't squash header */, 0 /* not looking for eoc */, depth + 1)) { return 0; } } else { if (!CBB_add_bytes(out_contents, CBS_data(&contents), CBS_len(&contents))) { return 0; } } if (out_contents != out && !CBB_flush(out)) { return 0; } } return looking_for_eoc == 0; }