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add learnings from Ep3 Trial Edition download quest

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This commit is contained in:
Martin Michelsen
2023-09-28 14:48:26 -07:00
parent 5c5da8e10b
commit fbdfdb085a
11 changed files with 269 additions and 90 deletions
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src/Quest.cc
+74 -46
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@@ -83,7 +83,8 @@ struct PSOGCIDLQFileEncryptedHeader : PSOMemCardDLQFileEncryptedHeader<true> {
} __attribute__((packed));
template <bool IsBigEndian>
string decrypt_download_quest_data_section(const void* data_section, size_t size, uint32_t seed) {
string decrypt_download_quest_data_section(
const void* data_section, size_t size, uint32_t seed, bool skip_checksum = false, bool is_ep3_trial = false) {
string decrypted = decrypt_data_section<IsBigEndian>(data_section, size, seed);
size_t orig_size = decrypted.size();
@@ -99,41 +100,67 @@ string decrypt_download_quest_data_section(const void* data_section, size_t size
round2_crypt.encrypt_t<IsBigEndian>(
decrypted.data() + 4, (decrypted.size() - 4));
if (header->decompressed_size & 0xFFF00000) {
throw runtime_error(string_printf(
"decompressed_size too large (%08" PRIX32 ")", header->decompressed_size.load()));
if (is_ep3_trial) {
StringReader r(decrypted);
r.skip(16);
if (r.readx(15) != "SONICTEAM,SEGA.") {
throw runtime_error("Episode 3 GCI file is not a quest");
}
r.skip(9);
// Some Ep3 trial download quests don't have a stop opcode in the PRS
// stream; it seems the client just automatically stops when the correct
// amount of data has been produced. To handle this, we allow the PRS stream
// to be unterminated here.
size_t decompressed_size = prs_decompress_size(
r.getv(r.remaining(), false), r.remaining(), sizeof(Episode3::MapDefinitionTrial), true);
if (decompressed_size < sizeof(Episode3::MapDefinitionTrial)) {
throw runtime_error(string_printf(
"decompressed size (%zu) does not match expected size (%zu)",
decompressed_size, sizeof(Episode3::MapDefinitionTrial)));
}
return decrypted.substr(0x28);
} else {
if (header->decompressed_size & 0xFFF00000) {
throw runtime_error(string_printf(
"decompressed_size too large (%08" PRIX32 ")", header->decompressed_size.load()));
}
if (!skip_checksum) {
uint32_t expected_crc = header->checksum;
header->checksum = 0;
uint32_t actual_crc = crc32(decrypted.data(), orig_size);
header->checksum = expected_crc;
if (expected_crc != actual_crc && expected_crc != bswap32(actual_crc)) {
throw runtime_error(string_printf(
"incorrect decrypted data section checksum: expected %08" PRIX32 "; received %08" PRIX32,
expected_crc, actual_crc));
}
}
// Unlike the above rounds, round 3 is always little-endian (it corresponds to
// the round of encryption done on the server before sending the file to the
// client in the first place)
PSOV2Encryption(header->round3_seed).decrypt(decrypted.data() + sizeof(HeaderT), decrypted.size() - sizeof(HeaderT));
decrypted.resize(orig_size);
// Some download quest GCI files have decompressed_size fields that are 8
// bytes smaller than the actual decompressed size of the data. They seem to
// work fine, so we accept both cases as correct.
size_t decompressed_size = prs_decompress_size(
decrypted.data() + sizeof(HeaderT),
decrypted.size() - sizeof(HeaderT));
size_t expected_decompressed_size = header->decompressed_size.load();
if ((decompressed_size != expected_decompressed_size) &&
(decompressed_size != expected_decompressed_size - 8)) {
throw runtime_error(string_printf(
"decompressed size (%zu) does not match expected size (%zu)",
decompressed_size, expected_decompressed_size));
}
return decrypted.substr(sizeof(HeaderT));
}
uint32_t expected_crc = header->checksum;
header->checksum = 0;
uint32_t actual_crc = crc32(decrypted.data(), orig_size);
header->checksum = expected_crc;
if (expected_crc != actual_crc && expected_crc != bswap32(actual_crc)) {
throw runtime_error(string_printf(
"incorrect decrypted data section checksum: expected %08" PRIX32 "; received %08" PRIX32,
expected_crc, actual_crc));
}
// Unlike the above rounds, round 3 is always little-endian (it corresponds to
// the round of encryption done on the server before sending the file to the
// client in the first place)
PSOV2Encryption(header->round3_seed).decrypt(decrypted.data() + sizeof(HeaderT), decrypted.size() - sizeof(HeaderT));
decrypted.resize(orig_size);
// Some download quest GCI files have decompressed_size fields that are 8
// bytes smaller than the actual decompressed size of the data. They seem to
// work fine, so we accept both cases as correct.
size_t decompressed_size = prs_decompress_size(
decrypted.data() + sizeof(HeaderT),
decrypted.size() - sizeof(HeaderT));
if ((decompressed_size != header->decompressed_size) &&
(decompressed_size != header->decompressed_size - 8)) {
throw runtime_error(string_printf(
"decompressed size (%zu) does not match size in header (%" PRId32 ")",
decompressed_size, header->decompressed_size.load()));
}
return decrypted.substr(sizeof(HeaderT));
}
string decrypt_vms_v1_data_section(const void* data_section, size_t size) {
@@ -160,16 +187,17 @@ string decrypt_vms_v1_data_section(const void* data_section, size_t size) {
template <bool IsBigEndian>
string find_seed_and_decrypt_download_quest_data_section(
const void* data_section, size_t size, size_t num_threads) {
const void* data_section, size_t size, bool skip_checksum, bool is_ep3_trial, size_t num_threads) {
mutex result_lock;
string result;
uint64_t result_seed = parallel_range<uint64_t>([&](uint64_t seed, size_t) {
try {
string ret = decrypt_download_quest_data_section<IsBigEndian>(data_section, size, seed);
string ret = decrypt_download_quest_data_section<IsBigEndian>(
data_section, size, seed, skip_checksum, is_ep3_trial);
lock_guard<mutex> g(result_lock);
result = std::move(ret);
return true;
} catch (const runtime_error&) {
} catch (const runtime_error& e) {
return false;
}
},
@@ -474,7 +502,7 @@ shared_ptr<const string> Quest::dat_contents() const {
}
string Quest::decode_gci_file(
const string& filename, ssize_t find_seed_num_threads, int64_t known_seed) {
const string& filename, ssize_t find_seed_num_threads, int64_t known_seed, bool skip_checksum) {
string data = load_file(filename);
StringReader r(data);
@@ -489,11 +517,11 @@ string Quest::decode_gci_file(
if (dlq_header.round2_seed || dlq_header.checksum || dlq_header.round3_seed) {
if (known_seed >= 0) {
return decrypt_download_quest_data_section<true>(
r.getv(header.data_size), header.data_size, known_seed);
r.getv(header.data_size), header.data_size, known_seed, skip_checksum, false);
} else if (header.embedded_seed != 0) {
return decrypt_download_quest_data_section<true>(
r.getv(header.data_size), header.data_size, header.embedded_seed);
r.getv(header.data_size), header.data_size, header.embedded_seed, skip_checksum, false);
} else {
if (find_seed_num_threads < 0) {
@@ -503,7 +531,7 @@ string Quest::decode_gci_file(
find_seed_num_threads = thread::hardware_concurrency();
}
return find_seed_and_decrypt_download_quest_data_section<true>(
r.getv(header.data_size), header.data_size, find_seed_num_threads);
r.getv(header.data_size), header.data_size, skip_checksum, false, find_seed_num_threads);
}
} else { // Unencrypted GCI format
@@ -525,7 +553,7 @@ string Quest::decode_gci_file(
if (header.is_trial()) {
if (known_seed >= 0) {
return decrypt_download_quest_data_section<true>(
r.getv(header.data_size), header.data_size, known_seed);
r.getv(header.data_size), header.data_size, known_seed, true, true);
} else {
if (find_seed_num_threads < 0) {
throw runtime_error("file is encrypted");
@@ -534,7 +562,7 @@ string Quest::decode_gci_file(
find_seed_num_threads = thread::hardware_concurrency();
}
return find_seed_and_decrypt_download_quest_data_section<true>(
r.getv(header.data_size), header.data_size, find_seed_num_threads);
r.getv(header.data_size), header.data_size, true, true, find_seed_num_threads);
}
} else {
@@ -575,7 +603,7 @@ string Quest::decode_gci_file(
}
string Quest::decode_vms_file(
const string& filename, ssize_t find_seed_num_threads, int64_t known_seed) {
const string& filename, ssize_t find_seed_num_threads, int64_t known_seed, bool skip_checksum) {
string data = load_file(filename);
StringReader r(data);
@@ -603,7 +631,7 @@ string Quest::decode_vms_file(
find_seed_num_threads = thread::hardware_concurrency();
}
return find_seed_and_decrypt_download_quest_data_section<false>(
data_section, header.data_size, find_seed_num_threads);
data_section, header.data_size, skip_checksum, 0, find_seed_num_threads);
}
}