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Diffstat (limited to 'src/examples/asn1.cpp')
| -rw-r--r-- | src/examples/asn1.cpp | 319 |
1 files changed, 319 insertions, 0 deletions
diff --git a/src/examples/asn1.cpp b/src/examples/asn1.cpp new file mode 100644 index 000000000..40f597fc3 --- /dev/null +++ b/src/examples/asn1.cpp @@ -0,0 +1,319 @@ +#include "examples.h" + +#include <botan/bigint.h> +#include <botan/der_enc.h> +#include <botan/ber_dec.h> +#include <botan/asn1_time.h> +#include <botan/asn1_str.h> +#include <botan/oids.h> +#include <botan/pem.h> +#include <botan/charset.h> +using namespace Botan; + +#include <sstream> +#include <stdio.h> +#include <ctype.h> + +// Set this if your terminal understands UTF-8; otherwise output is in Latin-1 +#define UTF8_TERMINAL 1 + +/* + What level the outermost layer of stuff is at. Probably 0 or 1; asn1parse + uses 0 as the outermost, while 1 makes more sense to me. 2+ doesn't make + much sense at all. +*/ +#define INITIAL_LEVEL 0 + +void decode(BER_Decoder&, size_t); +void emit(const std::string&, size_t, size_t, const std::string& = ""); +std::string type_name(ASN1_Tag); + +namespace { + +std::string url_encode(const std::vector<byte>& in) + { + std::ostringstream out; + + for(size_t i = 0; i != in.size(); ++i) + { + const int c = in[i]; + if(isprint((int)c)) + out << (char)c; + else + out << "%" << std::hex << (int)c << std::dec; + } + return out.str(); + } + +} + +int asn1_example(int argc, char* argv[]) + { + if(argc != 2) + { + printf("Usage: %s <file>\n", argv[0]); + return 1; + } + + try { + DataSource_Stream in(argv[1]); + + if(!PEM_Code::matches(in)) + { + BER_Decoder decoder(in); + decode(decoder, INITIAL_LEVEL); + } + else + { + std::string label; // ignored + BER_Decoder decoder(PEM_Code::decode(in, label)); + decode(decoder, INITIAL_LEVEL); + } + + } + catch(std::exception& e) + { + printf("%s\n", e.what()); + return 1; + } + return 0; + } + +void decode(BER_Decoder& decoder, size_t level) + { + BER_Object obj = decoder.get_next_object(); + + while(obj.type_tag != NO_OBJECT) + { + const ASN1_Tag type_tag = obj.type_tag; + const ASN1_Tag class_tag = obj.class_tag; + const size_t length = obj.value.size(); + + /* hack to insert the tag+length back in front of the stuff now + that we've gotten the type info */ + DER_Encoder encoder; + encoder.add_object(type_tag, class_tag, obj.value); + std::vector<byte> bits = encoder.get_contents_unlocked(); + + BER_Decoder data(bits); + + if(class_tag & CONSTRUCTED) + { + BER_Decoder cons_info(obj.value); + if(type_tag == SEQUENCE) + { + emit("SEQUENCE", level, length); + decode(cons_info, level+1); + } + else if(type_tag == SET) + { + emit("SET", level, length); + decode(cons_info, level+1); + } + else + { + std::string name; + + if((class_tag & APPLICATION) || (class_tag & CONTEXT_SPECIFIC)) + { + name = "cons [" + std::to_string(type_tag) + "]"; + + if(class_tag & APPLICATION) + name += " appl"; + if(class_tag & CONTEXT_SPECIFIC) + name += " context"; + } + else + name = type_name(type_tag) + " (cons)"; + + emit(name, level, length); + decode(cons_info, level+1); + } + } + else if((class_tag & APPLICATION) || (class_tag & CONTEXT_SPECIFIC)) + { +#if 0 + std::vector<byte> bits; + data.decode(bits, type_tag); + + try + { + BER_Decoder inner(bits); + decode(inner, level + 1); + } + catch(...) + { + emit("[" + std::to_string(type_tag) + "]", level, length, + url_encode(bits)); + } +#else + emit("[" + std::to_string(type_tag) + "]", level, length, + url_encode(bits)); +#endif + } + else if(type_tag == OBJECT_ID) + { + OID oid; + data.decode(oid); + + std::string out = OIDS::lookup(oid); + if(out != oid.as_string()) + out += " [" + oid.as_string() + "]"; + + emit(type_name(type_tag), level, length, out); + } + else if(type_tag == INTEGER || type_tag == ENUMERATED) + { + BigInt number; + + if(type_tag == INTEGER) + data.decode(number); + else if(type_tag == ENUMERATED) + data.decode(number, ENUMERATED, class_tag); + + std::vector<byte> rep; + + /* If it's small, it's probably a number, not a hash */ + if(number.bits() <= 16) + rep = BigInt::encode(number, BigInt::Decimal); + else + rep = BigInt::encode(number, BigInt::Hexadecimal); + + std::string str; + for(size_t i = 0; i != rep.size(); ++i) + str += (char)rep[i]; + + emit(type_name(type_tag), level, length, str); + } + else if(type_tag == BOOLEAN) + { + bool boolean; + data.decode(boolean); + emit(type_name(type_tag), + level, length, (boolean ? "true" : "false")); + } + else if(type_tag == NULL_TAG) + { + emit(type_name(type_tag), level, length); + } + else if(type_tag == OCTET_STRING) + { + std::vector<byte> bits; + data.decode(bits, type_tag); + + try + { + BER_Decoder inner(bits); + decode(inner, level + 1); + } + catch(...) + { + emit(type_name(type_tag), level, length, + url_encode(bits)); + } + } + else if(type_tag == BIT_STRING) + { + std::vector<byte> bits; + data.decode(bits, type_tag); + + std::vector<bool> bit_set; + + for(size_t i = 0; i != bits.size(); ++i) + for(size_t j = 0; j != 8; ++j) + bit_set.push_back((bool)((bits[bits.size()-i-1] >> (7-j)) & 1)); + + std::string bit_str; + for(size_t i = 0; i != bit_set.size(); ++i) + { + bool the_bit = bit_set[bit_set.size()-i-1]; + + if(!the_bit && bit_str.size() == 0) + continue; + bit_str += (the_bit ? "1" : "0"); + } + + emit(type_name(type_tag), level, length, bit_str); + } + else if(type_tag == PRINTABLE_STRING || + type_tag == NUMERIC_STRING || + type_tag == IA5_STRING || + type_tag == T61_STRING || + type_tag == VISIBLE_STRING || + type_tag == UTF8_STRING || + type_tag == BMP_STRING) + { + ASN1_String str; + data.decode(str); + if(UTF8_TERMINAL) + emit(type_name(type_tag), level, length, + Charset::transcode(str.iso_8859(), + LATIN1_CHARSET, UTF8_CHARSET)); + else + emit(type_name(type_tag), level, length, str.iso_8859()); + } + else if(type_tag == UTC_TIME || type_tag == GENERALIZED_TIME) + { + X509_Time time; + data.decode(time); + emit(type_name(type_tag), level, length, time.readable_string()); + } + else + fprintf(stderr, "Unknown tag: class=%02X, type=%02X\n", + class_tag, type_tag); + + obj = decoder.get_next_object(); + } + } + +void emit(const std::string& type, size_t level, size_t length, + const std::string& value) + { + const size_t LIMIT = 128; + const size_t BIN_LIMIT = 64; + + int written = 0; + written += printf(" d=%2d, l=%4d: ", (int)level, (int)length); + for(size_t i = INITIAL_LEVEL; i != level; ++i) + written += printf(" "); + written += printf("%s ", type.c_str()); + + bool should_skip = false; + if(value.length() > LIMIT) should_skip = true; + if((type == "OCTET STRING" || type == "BIT STRING") && + value.length() > BIN_LIMIT) + should_skip = true; + + if(value != "" && !should_skip) + { + if(written % 2 == 0) printf(" "); + while(written < 50) written += printf(" "); + printf(":%s\n", value.c_str()); + } + else + printf("\n"); + } + +std::string type_name(ASN1_Tag type) + { + if(type == PRINTABLE_STRING) return "PRINTABLE STRING"; + if(type == NUMERIC_STRING) return "NUMERIC STRING"; + if(type == IA5_STRING) return "IA5 STRING"; + if(type == T61_STRING) return "T61 STRING"; + if(type == UTF8_STRING) return "UTF8 STRING"; + if(type == VISIBLE_STRING) return "VISIBLE STRING"; + if(type == BMP_STRING) return "BMP STRING"; + + if(type == UTC_TIME) return "UTC TIME"; + if(type == GENERALIZED_TIME) return "GENERALIZED TIME"; + + if(type == OCTET_STRING) return "OCTET STRING"; + if(type == BIT_STRING) return "BIT STRING"; + + if(type == ENUMERATED) return "ENUMERATED"; + if(type == INTEGER) return "INTEGER"; + if(type == NULL_TAG) return "NULL"; + if(type == OBJECT_ID) return "OBJECT"; + if(type == BOOLEAN) return "BOOLEAN"; + return "(UNKNOWN)"; + } |