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zig/lib/std/crypto/Tls.zig
Andrew Kelley 02c33d02e0 std.crypto.Tls: parse encrypted extensions
2023-01-02 16:57:15 -07:00

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const std = @import("../std.zig");
const Tls = @This();
const net = std.net;
const mem = std.mem;
const crypto = std.crypto;
const assert = std.debug.assert;
application_cipher: ApplicationCipher,
read_seq: u64,
write_seq: u64,
/// The size is enough to contain exactly one TLSCiphertext record.
partially_read_buffer: [max_ciphertext_record_len]u8,
/// The number of partially read bytes inside `partiall_read_buffer`.
partially_read_len: u15,
eof: bool,
pub const ciphertext_record_header_len = 5;
pub const max_ciphertext_len = (1 << 14) + 256;
pub const max_ciphertext_record_len = max_ciphertext_len + ciphertext_record_header_len;
pub const hello_retry_request_sequence = [32]u8{
0xCF, 0x21, 0xAD, 0x74, 0xE5, 0x9A, 0x61, 0x11, 0xBE, 0x1D, 0x8C, 0x02, 0x1E, 0x65, 0xB8, 0x91,
0xC2, 0xA2, 0x11, 0x16, 0x7A, 0xBB, 0x8C, 0x5E, 0x07, 0x9E, 0x09, 0xE2, 0xC8, 0xA8, 0x33, 0x9C,
};
pub const ProtocolVersion = enum(u16) {
tls_1_2 = 0x0303,
tls_1_3 = 0x0304,
_,
};
pub const ContentType = enum(u8) {
invalid = 0,
change_cipher_spec = 20,
alert = 21,
handshake = 22,
application_data = 23,
_,
};
pub const HandshakeType = enum(u8) {
client_hello = 1,
server_hello = 2,
new_session_ticket = 4,
end_of_early_data = 5,
encrypted_extensions = 8,
certificate = 11,
certificate_request = 13,
certificate_verify = 15,
finished = 20,
key_update = 24,
message_hash = 254,
};
pub const ExtensionType = enum(u16) {
/// RFC 6066
server_name = 0,
/// RFC 6066
max_fragment_length = 1,
/// RFC 6066
status_request = 5,
/// RFC 8422, 7919
supported_groups = 10,
/// RFC 8446
signature_algorithms = 13,
/// RFC 5764
use_srtp = 14,
/// RFC 6520
heartbeat = 15,
/// RFC 7301
application_layer_protocol_negotiation = 16,
/// RFC 6962
signed_certificate_timestamp = 18,
/// RFC 7250
client_certificate_type = 19,
/// RFC 7250
server_certificate_type = 20,
/// RFC 7685
padding = 21,
/// RFC 8446
pre_shared_key = 41,
/// RFC 8446
early_data = 42,
/// RFC 8446
supported_versions = 43,
/// RFC 8446
cookie = 44,
/// RFC 8446
psk_key_exchange_modes = 45,
/// RFC 8446
certificate_authorities = 47,
/// RFC 8446
oid_filters = 48,
/// RFC 8446
post_handshake_auth = 49,
/// RFC 8446
signature_algorithms_cert = 50,
/// RFC 8446
key_share = 51,
};
pub const AlertLevel = enum(u8) {
warning = 1,
fatal = 2,
_,
};
pub const AlertDescription = enum(u8) {
close_notify = 0,
unexpected_message = 10,
bad_record_mac = 20,
record_overflow = 22,
handshake_failure = 40,
bad_certificate = 42,
unsupported_certificate = 43,
certificate_revoked = 44,
certificate_expired = 45,
certificate_unknown = 46,
illegal_parameter = 47,
unknown_ca = 48,
access_denied = 49,
decode_error = 50,
decrypt_error = 51,
protocol_version = 70,
insufficient_security = 71,
internal_error = 80,
inappropriate_fallback = 86,
user_canceled = 90,
missing_extension = 109,
unsupported_extension = 110,
unrecognized_name = 112,
bad_certificate_status_response = 113,
unknown_psk_identity = 115,
certificate_required = 116,
no_application_protocol = 120,
_,
};
pub const SignatureScheme = enum(u16) {
// RSASSA-PKCS1-v1_5 algorithms
rsa_pkcs1_sha256 = 0x0401,
rsa_pkcs1_sha384 = 0x0501,
rsa_pkcs1_sha512 = 0x0601,
// ECDSA algorithms
ecdsa_secp256r1_sha256 = 0x0403,
ecdsa_secp384r1_sha384 = 0x0503,
ecdsa_secp521r1_sha512 = 0x0603,
// RSASSA-PSS algorithms with public key OID rsaEncryption
rsa_pss_rsae_sha256 = 0x0804,
rsa_pss_rsae_sha384 = 0x0805,
rsa_pss_rsae_sha512 = 0x0806,
// EdDSA algorithms
ed25519 = 0x0807,
ed448 = 0x0808,
// RSASSA-PSS algorithms with public key OID RSASSA-PSS
rsa_pss_pss_sha256 = 0x0809,
rsa_pss_pss_sha384 = 0x080a,
rsa_pss_pss_sha512 = 0x080b,
// Legacy algorithms
rsa_pkcs1_sha1 = 0x0201,
ecdsa_sha1 = 0x0203,
_,
};
pub const NamedGroup = enum(u16) {
// Elliptic Curve Groups (ECDHE)
secp256r1 = 0x0017,
secp384r1 = 0x0018,
secp521r1 = 0x0019,
x25519 = 0x001D,
x448 = 0x001E,
// Finite Field Groups (DHE)
ffdhe2048 = 0x0100,
ffdhe3072 = 0x0101,
ffdhe4096 = 0x0102,
ffdhe6144 = 0x0103,
ffdhe8192 = 0x0104,
_,
};
// Plaintext:
// * type: ContentType
// * legacy_record_version: u16 = 0x0303,
// * length: u16,
// - The length (in bytes) of the following TLSPlaintext.fragment. The
// length MUST NOT exceed 2^14 bytes.
// * fragment: opaque
// - the data being transmitted
// Ciphertext
// * ContentType opaque_type = application_data; /* 23 */
// * ProtocolVersion legacy_record_version = 0x0303; /* TLS v1.2 */
// * uint16 length;
// * opaque encrypted_record[TLSCiphertext.length];
// Handshake:
// * type: HandshakeType
// * length: u24
// * data: opaque
// ServerHello:
// * ProtocolVersion legacy_version = 0x0303;
// * Random random;
// * opaque legacy_session_id_echo<0..32>;
// * CipherSuite cipher_suite;
// * uint8 legacy_compression_method = 0;
// * Extension extensions<6..2^16-1>;
// Extension:
// * ExtensionType extension_type;
// * opaque extension_data<0..2^16-1>;
pub const CipherSuite = enum(u16) {
TLS_AES_128_GCM_SHA256 = 0x1301,
TLS_AES_256_GCM_SHA384 = 0x1302,
TLS_CHACHA20_POLY1305_SHA256 = 0x1303,
TLS_AES_128_CCM_SHA256 = 0x1304,
TLS_AES_128_CCM_8_SHA256 = 0x1305,
};
pub const CipherParams = union(CipherSuite) {
TLS_AES_128_GCM_SHA256: struct {
const AEAD = crypto.aead.aes_gcm.Aes128Gcm;
const Hash = crypto.hash.sha2.Sha256;
const Hmac = crypto.auth.hmac.Hmac(Hash);
const Hkdf = crypto.kdf.hkdf.Hkdf(Hmac);
handshake_secret: [Hkdf.key_len]u8,
master_secret: [Hkdf.key_len]u8,
client_handshake_key: [AEAD.key_length]u8,
server_handshake_key: [AEAD.key_length]u8,
client_finished_key: [Hmac.key_length]u8,
server_finished_key: [Hmac.key_length]u8,
client_handshake_iv: [AEAD.nonce_length]u8,
server_handshake_iv: [AEAD.nonce_length]u8,
transcript_hash: Hash,
},
TLS_AES_256_GCM_SHA384: struct {
const AEAD = crypto.aead.aes_gcm.Aes256Gcm;
const Hash = crypto.hash.sha2.Sha384;
const Hmac = crypto.auth.hmac.Hmac(Hash);
const Hkdf = crypto.kdf.hkdf.Hkdf(Hmac);
handshake_secret: [Hkdf.key_len]u8,
master_secret: [Hkdf.key_len]u8,
client_handshake_key: [AEAD.key_length]u8,
server_handshake_key: [AEAD.key_length]u8,
client_finished_key: [Hmac.key_length]u8,
server_finished_key: [Hmac.key_length]u8,
client_handshake_iv: [AEAD.nonce_length]u8,
server_handshake_iv: [AEAD.nonce_length]u8,
transcript_hash: Hash,
},
TLS_CHACHA20_POLY1305_SHA256: void,
TLS_AES_128_CCM_SHA256: void,
TLS_AES_128_CCM_8_SHA256: void,
};
/// Encryption parameters for application traffic.
pub const ApplicationCipher = union(CipherSuite) {
TLS_AES_128_GCM_SHA256: struct {
const AEAD = crypto.aead.aes_gcm.Aes128Gcm;
const Hash = crypto.hash.sha2.Sha256;
const Hmac = crypto.auth.hmac.Hmac(Hash);
const Hkdf = crypto.kdf.hkdf.Hkdf(Hmac);
client_key: [AEAD.key_length]u8,
server_key: [AEAD.key_length]u8,
client_iv: [AEAD.nonce_length]u8,
server_iv: [AEAD.nonce_length]u8,
},
TLS_AES_256_GCM_SHA384: struct {
const AEAD = crypto.aead.aes_gcm.Aes256Gcm;
const Hash = crypto.hash.sha2.Sha384;
const Hmac = crypto.auth.hmac.Hmac(Hash);
const Hkdf = crypto.kdf.hkdf.Hkdf(Hmac);
client_key: [AEAD.key_length]u8,
server_key: [AEAD.key_length]u8,
client_iv: [AEAD.nonce_length]u8,
server_iv: [AEAD.nonce_length]u8,
},
TLS_CHACHA20_POLY1305_SHA256: void,
TLS_AES_128_CCM_SHA256: void,
TLS_AES_128_CCM_8_SHA256: void,
};
const cipher_suites = blk: {
const fields = @typeInfo(CipherSuite).Enum.fields;
var result: [(fields.len + 1) * 2]u8 = undefined;
mem.writeIntBig(u16, result[0..2], result.len - 2);
for (fields) |field, i| {
const int = @enumToInt(@field(CipherSuite, field.name));
result[(i + 1) * 2] = @truncate(u8, int >> 8);
result[(i + 1) * 2 + 1] = @truncate(u8, int);
}
break :blk result;
};
/// `host` is only borrowed during this function call.
pub fn init(stream: net.Stream, host: []const u8) !Tls {
var x25519_priv_key: [32]u8 = undefined;
crypto.random.bytes(&x25519_priv_key);
const x25519_pub_key = crypto.dh.X25519.recoverPublicKey(x25519_priv_key) catch |err| {
switch (err) {
// Only possible to happen if the private key is all zeroes.
error.IdentityElement => return error.InsufficientEntropy,
}
};
// random (u32)
var rand_buf: [32]u8 = undefined;
crypto.random.bytes(&rand_buf);
const extensions_header = [_]u8{
// Extensions byte length
undefined, undefined,
// Extension: supported_versions (only TLS 1.3)
0, 43, // ExtensionType.supported_versions
0x00, 0x05, // byte length of this extension payload
0x04, // byte length of supported versions
0x03, 0x04, // TLS 1.3
0x03, 0x03, // TLS 1.2
// Extension: signature_algorithms
0, 13, // ExtensionType.signature_algorithms
0x00, 0x22, // byte length of this extension payload
0x00, 0x20, // byte length of signature algorithms list
0x04, 0x01, // rsa_pkcs1_sha256
0x05, 0x01, // rsa_pkcs1_sha384
0x06, 0x01, // rsa_pkcs1_sha512
0x04, 0x03, // ecdsa_secp256r1_sha256
0x05, 0x03, // ecdsa_secp384r1_sha384
0x06, 0x03, // ecdsa_secp521r1_sha512
0x08, 0x04, // rsa_pss_rsae_sha256
0x08, 0x05, // rsa_pss_rsae_sha384
0x08, 0x06, // rsa_pss_rsae_sha512
0x08, 0x07, // ed25519
0x08, 0x08, // ed448
0x08, 0x09, // rsa_pss_pss_sha256
0x08, 0x0a, // rsa_pss_pss_sha384
0x08, 0x0b, // rsa_pss_pss_sha512
0x02, 0x01, // rsa_pkcs1_sha1
0x02, 0x03, // ecdsa_sha1
// Extension: supported_groups
0, 10, // ExtensionType.supported_groups
0x00, 0x0c, // byte length of this extension payload
0x00, 0x0a, // byte length of supported groups list
0x00, 0x17, // secp256r1
0x00, 0x18, // secp384r1
0x00, 0x19, // secp521r1
0x00, 0x1D, // x25519
0x00, 0x1E, // x448
// Extension: key_share
0, 51, // ExtensionType.key_share
0, 38, // byte length of this extension payload
0, 36, // byte length of client_shares
0x00, 0x1D, // NamedGroup.x25519
0, 32, // byte length of key_exchange
} ++ x25519_pub_key ++ [_]u8{
// Extension: server_name
0, 0, // ExtensionType.server_name
undefined, undefined, // byte length of this extension payload
undefined, undefined, // server_name_list byte count
0x00, // name_type
undefined, undefined, // host name len
};
var hello_header = [_]u8{
// Plaintext header
@enumToInt(ContentType.handshake),
0x03, 0x01, // legacy_record_version
undefined, undefined, // Plaintext fragment length (u16)
// Handshake header
@enumToInt(HandshakeType.client_hello),
undefined, undefined, undefined, // handshake length (u24)
// ClientHello
0x03, 0x03, // legacy_version
} ++ rand_buf ++ [1]u8{0} ++ cipher_suites ++ [_]u8{
0x01, 0x00, // legacy_compression_methods
} ++ extensions_header;
mem.writeIntBig(u16, hello_header[3..][0..2], @intCast(u16, hello_header.len - 5 + host.len));
mem.writeIntBig(u24, hello_header[6..][0..3], @intCast(u24, hello_header.len - 9 + host.len));
mem.writeIntBig(
u16,
hello_header[hello_header.len - extensions_header.len ..][0..2],
@intCast(u16, extensions_header.len - 2 + host.len),
);
mem.writeIntBig(u16, hello_header[hello_header.len - 7 ..][0..2], @intCast(u16, 5 + host.len));
mem.writeIntBig(u16, hello_header[hello_header.len - 5 ..][0..2], @intCast(u16, 3 + host.len));
mem.writeIntBig(u16, hello_header[hello_header.len - 2 ..][0..2], @intCast(u16, 0 + host.len));
{
var iovecs = [_]std.os.iovec_const{
.{
.iov_base = &hello_header,
.iov_len = hello_header.len,
},
.{
.iov_base = host.ptr,
.iov_len = host.len,
},
};
try stream.writevAll(&iovecs);
}
const client_hello_bytes1 = hello_header[5..];
var cipher_params: CipherParams = undefined;
var handshake_buf: [8000]u8 = undefined;
var len: usize = 0;
var i: usize = i: {
const plaintext = handshake_buf[0..5];
len = try stream.readAtLeast(&handshake_buf, plaintext.len);
if (len < plaintext.len) return error.EndOfStream;
const ct = @intToEnum(ContentType, plaintext[0]);
const frag_len = mem.readIntBig(u16, plaintext[3..][0..2]);
const end = plaintext.len + frag_len;
if (end > handshake_buf.len) return error.TlsRecordOverflow;
if (end > len) {
len += try stream.readAtLeast(handshake_buf[len..], end - len);
if (end > len) return error.EndOfStream;
}
const frag = handshake_buf[plaintext.len..end];
switch (ct) {
.alert => {
const level = @intToEnum(AlertLevel, frag[0]);
const desc = @intToEnum(AlertDescription, frag[1]);
std.debug.print("alert: {s} {s}\n", .{ @tagName(level), @tagName(desc) });
return error.TlsAlert;
},
.handshake => {
if (frag[0] != @enumToInt(HandshakeType.server_hello)) {
return error.TlsUnexpectedMessage;
}
const length = mem.readIntBig(u24, frag[1..4]);
if (4 + length != frag.len) return error.TlsBadLength;
const hello = frag[4..];
const legacy_version = mem.readIntBig(u16, hello[0..2]);
const random = hello[2..34].*;
if (mem.eql(u8, &random, &hello_retry_request_sequence)) {
@panic("TODO handle HelloRetryRequest");
}
const legacy_session_id_echo_len = hello[34];
if (legacy_session_id_echo_len != 0) return error.TlsIllegalParameter;
const cipher_suite_int = mem.readIntBig(u16, hello[35..37]);
const cipher_suite_tag = std.meta.intToEnum(CipherSuite, cipher_suite_int) catch
return error.TlsIllegalParameter;
std.debug.print("server wants cipher suite {s}\n", .{@tagName(cipher_suite_tag)});
const legacy_compression_method = hello[37];
_ = legacy_compression_method;
const extensions_size = mem.readIntBig(u16, hello[38..40]);
if (40 + extensions_size != hello.len) return error.TlsBadLength;
var i: usize = 40;
var supported_version: u16 = 0;
var opt_x25519_server_pub_key: ?*[32]u8 = null;
while (i < hello.len) {
const et = mem.readIntBig(u16, hello[i..][0..2]);
i += 2;
const ext_size = mem.readIntBig(u16, hello[i..][0..2]);
i += 2;
const next_i = i + ext_size;
if (next_i > hello.len) return error.TlsBadLength;
switch (et) {
@enumToInt(ExtensionType.supported_versions) => {
if (supported_version != 0) return error.TlsIllegalParameter;
supported_version = mem.readIntBig(u16, hello[i..][0..2]);
},
@enumToInt(ExtensionType.key_share) => {
if (opt_x25519_server_pub_key != null) return error.TlsIllegalParameter;
const named_group = mem.readIntBig(u16, hello[i..][0..2]);
i += 2;
switch (named_group) {
@enumToInt(NamedGroup.x25519) => {
const key_size = mem.readIntBig(u16, hello[i..][0..2]);
i += 2;
if (key_size != 32) return error.TlsBadLength;
opt_x25519_server_pub_key = hello[i..][0..32];
},
else => {
std.debug.print("named group: {x}\n", .{named_group});
return error.TlsIllegalParameter;
},
}
},
else => {
std.debug.print("unexpected extension: {x}\n", .{et});
},
}
i = next_i;
}
const x25519_server_pub_key = opt_x25519_server_pub_key orelse
return error.TlsIllegalParameter;
const tls_version = if (supported_version == 0) legacy_version else supported_version;
switch (tls_version) {
@enumToInt(ProtocolVersion.tls_1_2) => {
std.debug.print("server wants TLS v1.2\n", .{});
},
@enumToInt(ProtocolVersion.tls_1_3) => {
std.debug.print("server wants TLS v1.3\n", .{});
},
else => return error.TlsIllegalParameter,
}
const shared_key = crypto.dh.X25519.scalarmult(
x25519_priv_key,
x25519_server_pub_key.*,
) catch return error.TlsDecryptFailure;
switch (cipher_suite_tag) {
inline .TLS_AES_128_GCM_SHA256, .TLS_AES_256_GCM_SHA384 => |tag| {
const P = std.meta.TagPayload(CipherParams, tag);
cipher_params = @unionInit(CipherParams, @tagName(tag), .{
.handshake_secret = undefined,
.master_secret = undefined,
.client_handshake_key = undefined,
.server_handshake_key = undefined,
.client_finished_key = undefined,
.server_finished_key = undefined,
.client_handshake_iv = undefined,
.server_handshake_iv = undefined,
.transcript_hash = P.Hash.init(.{}),
});
const p = &@field(cipher_params, @tagName(tag));
p.transcript_hash.update(client_hello_bytes1); // Client Hello part 1
p.transcript_hash.update(host); // Client Hello part 2
p.transcript_hash.update(frag); // Server Hello
const hello_hash = p.transcript_hash.peek();
const zeroes = [1]u8{0} ** P.Hash.digest_length;
const early_secret = P.Hkdf.extract(&[1]u8{0}, &zeroes);
const empty_hash = emptyHash(P.Hash);
const hs_derived_secret = hkdfExpandLabel(P.Hkdf, early_secret, "derived", &empty_hash, P.Hash.digest_length);
p.handshake_secret = P.Hkdf.extract(&hs_derived_secret, &shared_key);
const ap_derived_secret = hkdfExpandLabel(P.Hkdf, p.handshake_secret, "derived", &empty_hash, P.Hash.digest_length);
p.master_secret = P.Hkdf.extract(&ap_derived_secret, &zeroes);
const client_secret = hkdfExpandLabel(P.Hkdf, p.handshake_secret, "c hs traffic", &hello_hash, P.Hash.digest_length);
const server_secret = hkdfExpandLabel(P.Hkdf, p.handshake_secret, "s hs traffic", &hello_hash, P.Hash.digest_length);
p.client_finished_key = hkdfExpandLabel(P.Hkdf, client_secret, "finished", "", P.Hmac.key_length);
p.server_finished_key = hkdfExpandLabel(P.Hkdf, server_secret, "finished", "", P.Hmac.key_length);
p.client_handshake_key = hkdfExpandLabel(P.Hkdf, client_secret, "key", "", P.AEAD.key_length);
p.server_handshake_key = hkdfExpandLabel(P.Hkdf, server_secret, "key", "", P.AEAD.key_length);
p.client_handshake_iv = hkdfExpandLabel(P.Hkdf, client_secret, "iv", "", P.AEAD.nonce_length);
p.server_handshake_iv = hkdfExpandLabel(P.Hkdf, server_secret, "iv", "", P.AEAD.nonce_length);
//std.debug.print("shared_key: {}\nhello_hash: {}\nearly_secret: {}\nempty_hash: {}\nderived_secret: {}\nhandshake_secret: {}\n client_secret: {}\n server_secret: {}\nclient_handshake_iv: {}\nserver_handshake_iv: {}\n", .{
// std.fmt.fmtSliceHexLower(&shared_key),
// std.fmt.fmtSliceHexLower(&hello_hash),
// std.fmt.fmtSliceHexLower(&early_secret),
// std.fmt.fmtSliceHexLower(&empty_hash),
// std.fmt.fmtSliceHexLower(&hs_derived_secret),
// std.fmt.fmtSliceHexLower(&p.handshake_secret),
// std.fmt.fmtSliceHexLower(&client_secret),
// std.fmt.fmtSliceHexLower(&server_secret),
// std.fmt.fmtSliceHexLower(&p.client_handshake_iv),
// std.fmt.fmtSliceHexLower(&p.server_handshake_iv),
//});
},
.TLS_CHACHA20_POLY1305_SHA256 => {
@panic("TODO");
},
.TLS_AES_128_CCM_SHA256 => {
@panic("TODO");
},
.TLS_AES_128_CCM_8_SHA256 => {
@panic("TODO");
},
}
},
else => return error.TlsUnexpectedMessage,
}
break :i end;
};
var read_seq: u64 = 0;
while (true) {
const end_hdr = i + 5;
if (end_hdr > handshake_buf.len) return error.TlsRecordOverflow;
if (end_hdr > len) {
len += try stream.readAtLeast(handshake_buf[len..], end_hdr - len);
if (end_hdr > len) return error.EndOfStream;
}
const ct = @intToEnum(ContentType, handshake_buf[i]);
i += 1;
const legacy_version = mem.readIntBig(u16, handshake_buf[i..][0..2]);
i += 2;
_ = legacy_version;
const record_size = mem.readIntBig(u16, handshake_buf[i..][0..2]);
i += 2;
const end = i + record_size;
if (end > handshake_buf.len) return error.TlsRecordOverflow;
if (end > len) {
len += try stream.readAtLeast(handshake_buf[len..], end - len);
if (end > len) return error.EndOfStream;
}
switch (ct) {
.change_cipher_spec => {
if (record_size != 1) return error.TlsUnexpectedMessage;
if (handshake_buf[i] != 0x01) return error.TlsUnexpectedMessage;
},
.application_data => {
var cleartext_buf: [8000]u8 = undefined;
const cleartext = switch (cipher_params) {
inline .TLS_AES_128_GCM_SHA256, .TLS_AES_256_GCM_SHA384 => |*p| c: {
const P = @TypeOf(p.*);
const ciphertext_len = record_size - P.AEAD.tag_length;
const ciphertext = handshake_buf[i..][0..ciphertext_len];
i += ciphertext.len;
if (ciphertext.len > cleartext_buf.len) return error.TlsRecordOverflow;
const cleartext = cleartext_buf[0..ciphertext.len];
const auth_tag = handshake_buf[i..][0..P.AEAD.tag_length].*;
const V = @Vector(P.AEAD.nonce_length, u8);
const pad = [1]u8{0} ** (P.AEAD.nonce_length - 8);
const operand: V = pad ++ @bitCast([8]u8, big(read_seq));
read_seq += 1;
const nonce: [P.AEAD.nonce_length]u8 = @as(V, p.server_handshake_iv) ^ operand;
const ad = handshake_buf[end_hdr - 5 ..][0..5];
P.AEAD.decrypt(cleartext, ciphertext, auth_tag, ad, nonce, p.server_handshake_key) catch
return error.TlsBadRecordMac;
p.transcript_hash.update(cleartext[0 .. cleartext.len - 1]);
break :c cleartext;
},
.TLS_CHACHA20_POLY1305_SHA256 => {
@panic("TODO");
},
.TLS_AES_128_CCM_SHA256 => {
@panic("TODO");
},
.TLS_AES_128_CCM_8_SHA256 => {
@panic("TODO");
},
};
const inner_ct = @intToEnum(ContentType, cleartext[cleartext.len - 1]);
switch (inner_ct) {
.handshake => {
var ct_i: usize = 0;
while (true) {
const handshake_type = cleartext[ct_i];
ct_i += 1;
const handshake_len = mem.readIntBig(u24, cleartext[ct_i..][0..3]);
ct_i += 3;
const next_handshake_i = ct_i + handshake_len;
if (next_handshake_i > cleartext.len - 1)
return error.TlsBadLength;
switch (handshake_type) {
@enumToInt(HandshakeType.encrypted_extensions) => {
const total_ext_size = mem.readIntBig(u16, cleartext[ct_i..][0..2]);
ct_i += 2;
const end_ext_i = ct_i + total_ext_size;
while (ct_i < end_ext_i) {
const et = mem.readIntBig(u16, cleartext[ct_i..][0..2]);
ct_i += 2;
const ext_size = mem.readIntBig(u16, cleartext[ct_i..][0..2]);
ct_i += 2;
const next_ext_i = ct_i + ext_size;
switch (et) {
@enumToInt(ExtensionType.server_name) => {},
else => {
std.debug.print("encrypted extension: {any}\n", .{
et,
});
},
}
ct_i = next_ext_i;
}
},
@enumToInt(HandshakeType.certificate) => {
std.debug.print("cool certificate bro\n", .{});
},
@enumToInt(HandshakeType.certificate_verify) => {
std.debug.print("the certificate came with a fancy signature\n", .{});
},
@enumToInt(HandshakeType.finished) => {
// This message is to trick buggy proxies into behaving correctly.
const client_change_cipher_spec_msg = [_]u8{
@enumToInt(ContentType.change_cipher_spec),
0x03, 0x03, // legacy protocol version
0x00, 0x01, // length
0x01,
};
const app_cipher = switch (cipher_params) {
inline .TLS_AES_128_GCM_SHA256, .TLS_AES_256_GCM_SHA384 => |*p, tag| c: {
const P = @TypeOf(p.*);
// TODO verify the server's data
const handshake_hash = p.transcript_hash.finalResult();
const verify_data = hmac(P.Hmac, &handshake_hash, p.client_finished_key);
const out_cleartext = [_]u8{
@enumToInt(HandshakeType.finished),
0, 0, verify_data.len, // length
} ++ verify_data ++ [1]u8{@enumToInt(ContentType.handshake)};
const wrapped_len = out_cleartext.len + P.AEAD.tag_length;
var finished_msg = [_]u8{
@enumToInt(ContentType.application_data),
0x03, 0x03, // legacy protocol version
0, wrapped_len, // byte length of encrypted record
} ++ ([1]u8{undefined} ** wrapped_len);
const ad = finished_msg[0..5];
const ciphertext = finished_msg[5..][0..out_cleartext.len];
const auth_tag = finished_msg[finished_msg.len - P.AEAD.tag_length ..];
const nonce = p.client_handshake_iv;
P.AEAD.encrypt(ciphertext, auth_tag, &out_cleartext, ad, nonce, p.client_handshake_key);
const both_msgs = client_change_cipher_spec_msg ++ finished_msg;
try stream.writeAll(&both_msgs);
const client_secret = hkdfExpandLabel(P.Hkdf, p.master_secret, "c ap traffic", &handshake_hash, P.Hash.digest_length);
const server_secret = hkdfExpandLabel(P.Hkdf, p.master_secret, "s ap traffic", &handshake_hash, P.Hash.digest_length);
//std.debug.print("master_secret={}\nclient_secret={}\nserver_secret={}\n", .{
// std.fmt.fmtSliceHexLower(&p.master_secret),
// std.fmt.fmtSliceHexLower(&client_secret),
// std.fmt.fmtSliceHexLower(&server_secret),
//});
break :c @unionInit(ApplicationCipher, @tagName(tag), .{
.client_key = hkdfExpandLabel(P.Hkdf, client_secret, "key", "", P.AEAD.key_length),
.server_key = hkdfExpandLabel(P.Hkdf, server_secret, "key", "", P.AEAD.key_length),
.client_iv = hkdfExpandLabel(P.Hkdf, client_secret, "iv", "", P.AEAD.nonce_length),
.server_iv = hkdfExpandLabel(P.Hkdf, server_secret, "iv", "", P.AEAD.nonce_length),
});
},
.TLS_CHACHA20_POLY1305_SHA256 => {
@panic("TODO");
},
.TLS_AES_128_CCM_SHA256 => {
@panic("TODO");
},
.TLS_AES_128_CCM_8_SHA256 => {
@panic("TODO");
},
};
std.debug.print("remaining bytes: {d}\n", .{len - end});
return .{
.application_cipher = app_cipher,
.read_seq = 0,
.write_seq = 0,
.partially_read_buffer = undefined,
.partially_read_len = 0,
.eof = false,
};
},
else => {
std.debug.print("handshake type: {d}\n", .{cleartext[0]});
return error.TlsUnexpectedMessage;
},
}
ct_i = next_handshake_i;
if (ct_i >= cleartext.len - 1) break;
}
},
else => {
std.debug.print("inner content type: {any}\n", .{inner_ct});
return error.TlsUnexpectedMessage;
},
}
},
else => {
std.debug.print("content type: {s}\n", .{@tagName(ct)});
return error.TlsUnexpectedMessage;
},
}
i = end;
}
return error.TlsHandshakeFailure;
}
pub fn write(tls: *Tls, stream: net.Stream, bytes: []const u8) !usize {
var ciphertext_buf: [max_ciphertext_record_len * 4]u8 = undefined;
// Due to the trailing inner content type byte in the ciphertext, we need
// an additional buffer for storing the cleartext into before encrypting.
var cleartext_buf: [max_ciphertext_len]u8 = undefined;
var iovecs_buf: [5]std.os.iovec_const = undefined;
var ciphertext_end: usize = 0;
var iovec_end: usize = 0;
var bytes_i: usize = 0;
// How many bytes are taken up by overhead per record.
const overhead_len: usize = switch (tls.application_cipher) {
inline .TLS_AES_128_GCM_SHA256, .TLS_AES_256_GCM_SHA384 => |*p| l: {
const P = @TypeOf(p.*);
const V = @Vector(P.AEAD.nonce_length, u8);
const overhead_len = ciphertext_record_header_len + P.AEAD.tag_length + 1;
while (true) {
const encrypted_content_len = @intCast(u16, @min(
@min(bytes.len - bytes_i, max_ciphertext_len - 1),
ciphertext_buf.len -
ciphertext_record_header_len - P.AEAD.tag_length - ciphertext_end - 1,
));
if (encrypted_content_len == 0) break :l overhead_len;
mem.copy(u8, &cleartext_buf, bytes[bytes_i..][0..encrypted_content_len]);
cleartext_buf[encrypted_content_len] = @enumToInt(ContentType.application_data);
bytes_i += encrypted_content_len;
const ciphertext_len = encrypted_content_len + 1;
const cleartext = cleartext_buf[0..ciphertext_len];
const record_start = ciphertext_end;
const ad = ciphertext_buf[ciphertext_end..][0..5];
ad.* =
[_]u8{@enumToInt(ContentType.application_data)} ++
int2(@enumToInt(ProtocolVersion.tls_1_2)) ++
int2(ciphertext_len + P.AEAD.tag_length);
ciphertext_end += ad.len;
const ciphertext = ciphertext_buf[ciphertext_end..][0..ciphertext_len];
ciphertext_end += ciphertext_len;
const auth_tag = ciphertext_buf[ciphertext_end..][0..P.AEAD.tag_length];
ciphertext_end += auth_tag.len;
const pad = [1]u8{0} ** (P.AEAD.nonce_length - 8);
const operand: V = pad ++ @bitCast([8]u8, big(tls.write_seq));
tls.write_seq += 1;
const nonce: [P.AEAD.nonce_length]u8 = @as(V, p.client_iv) ^ operand;
P.AEAD.encrypt(ciphertext, auth_tag, cleartext, ad, nonce, p.client_key);
//std.debug.print("seq: {d} nonce: {} client_key: {} client_iv: {} ad: {} auth_tag: {}\nserver_key: {} server_iv: {}\n", .{
// tls.write_seq - 1,
// std.fmt.fmtSliceHexLower(&nonce),
// std.fmt.fmtSliceHexLower(&p.client_key),
// std.fmt.fmtSliceHexLower(&p.client_iv),
// std.fmt.fmtSliceHexLower(ad),
// std.fmt.fmtSliceHexLower(auth_tag),
// std.fmt.fmtSliceHexLower(&p.server_key),
// std.fmt.fmtSliceHexLower(&p.server_iv),
//});
const record = ciphertext_buf[record_start..ciphertext_end];
iovecs_buf[iovec_end] = .{
.iov_base = record.ptr,
.iov_len = record.len,
};
iovec_end += 1;
}
},
.TLS_CHACHA20_POLY1305_SHA256 => {
@panic("TODO");
},
.TLS_AES_128_CCM_SHA256 => {
@panic("TODO");
},
.TLS_AES_128_CCM_8_SHA256 => {
@panic("TODO");
},
};
// Ideally we would call writev exactly once here, however, we must ensure
// that we don't return with a record partially written.
var i: usize = 0;
var total_amt: usize = 0;
while (true) {
var amt = try stream.writev(iovecs_buf[i..iovec_end]);
while (amt >= iovecs_buf[i].iov_len) {
const encrypted_amt = iovecs_buf[i].iov_len;
total_amt += encrypted_amt - overhead_len;
amt -= encrypted_amt;
i += 1;
// Rely on the property that iovecs delineate records, meaning that
// if amt equals zero here, we have fortunately found ourselves
// with a short read that aligns at the record boundary.
if (i >= iovec_end or amt == 0) return total_amt;
}
iovecs_buf[i].iov_base += amt;
iovecs_buf[i].iov_len -= amt;
}
}
pub fn writeAll(tls: *Tls, stream: net.Stream, bytes: []const u8) !void {
var index: usize = 0;
while (index < bytes.len) {
index += try tls.write(stream, bytes[index..]);
}
}
/// Returns number of bytes that have been read, which are now populated inside
/// `buffer`. A return value of zero bytes does not necessarily mean end of
/// stream.
pub fn read(tls: *Tls, stream: net.Stream, buffer: []u8) !usize {
const prev_len = tls.partially_read_len;
var in_buf: [max_ciphertext_len * 4]u8 = undefined;
mem.copy(u8, &in_buf, tls.partially_read_buffer[0..prev_len]);
// Capacity of output buffer, in records, rounded up.
const buf_cap = (buffer.len +| (max_ciphertext_len - 1)) / max_ciphertext_len;
const wanted_read_len = buf_cap * (max_ciphertext_len + ciphertext_record_header_len);
const ask_slice = in_buf[prev_len..@min(wanted_read_len, in_buf.len)];
const actual_read_len = try stream.read(ask_slice);
const frag = in_buf[0 .. prev_len + actual_read_len];
if (frag.len == 0) {
tls.eof = true;
return 0;
}
var in: usize = 0;
var out: usize = 0;
while (true) {
if (in + ciphertext_record_header_len > frag.len) {
return finishRead(tls, frag, in, out);
}
const ct = @intToEnum(ContentType, frag[in]);
in += 1;
const legacy_version = mem.readIntBig(u16, frag[in..][0..2]);
in += 2;
_ = legacy_version;
const record_size = mem.readIntBig(u16, frag[in..][0..2]);
in += 2;
const end = in + record_size;
if (end > frag.len) {
if (record_size > max_ciphertext_len) return error.TlsRecordOverflow;
return finishRead(tls, frag, in, out);
}
switch (ct) {
.alert => {
@panic("TODO handle an alert here");
},
.application_data => {
const cleartext_len = switch (tls.application_cipher) {
inline .TLS_AES_128_GCM_SHA256, .TLS_AES_256_GCM_SHA384 => |*p| c: {
const P = @TypeOf(p.*);
const V = @Vector(P.AEAD.nonce_length, u8);
const ad = frag[in - 5 ..][0..5];
const ciphertext_len = record_size - P.AEAD.tag_length;
const ciphertext = frag[in..][0..ciphertext_len];
in += ciphertext_len;
const auth_tag = frag[in..][0..P.AEAD.tag_length].*;
const cleartext = buffer[out..][0..ciphertext_len];
const pad = [1]u8{0} ** (P.AEAD.nonce_length - 8);
const operand: V = pad ++ @bitCast([8]u8, big(tls.read_seq));
tls.read_seq += 1;
const nonce: [P.AEAD.nonce_length]u8 = @as(V, p.server_iv) ^ operand;
//std.debug.print("seq: {d} nonce: {} server_key: {} server_iv: {}\n", .{
// tls.read_seq - 1,
// std.fmt.fmtSliceHexLower(&nonce),
// std.fmt.fmtSliceHexLower(&p.server_key),
// std.fmt.fmtSliceHexLower(&p.server_iv),
//});
P.AEAD.decrypt(cleartext, ciphertext, auth_tag, ad, nonce, p.server_key) catch
return error.TlsBadRecordMac;
break :c cleartext.len;
},
.TLS_CHACHA20_POLY1305_SHA256 => {
@panic("TODO");
},
.TLS_AES_128_CCM_SHA256 => {
@panic("TODO");
},
.TLS_AES_128_CCM_8_SHA256 => {
@panic("TODO");
},
};
const inner_ct = @intToEnum(ContentType, buffer[out + cleartext_len - 1]);
switch (inner_ct) {
.alert => {
const level = @intToEnum(AlertLevel, buffer[out]);
const desc = @intToEnum(AlertDescription, buffer[out + 1]);
if (desc == .close_notify) {
tls.eof = true;
return out;
}
std.debug.print("alert: {s} {s}\n", .{ @tagName(level), @tagName(desc) });
return error.TlsAlert;
},
.handshake => {
std.debug.print("the server wants to keep shaking hands\n", .{});
},
.application_data => {
out += cleartext_len - 1;
},
else => {
std.debug.print("inner content type: {d}\n", .{inner_ct});
return error.TlsUnexpectedMessage;
},
}
},
else => {
std.debug.print("unexpected ct: {any}\n", .{ct});
return error.TlsUnexpectedMessage;
},
}
in = end;
}
}
fn finishRead(tls: *Tls, frag: []const u8, in: usize, out: usize) usize {
const saved_buf = frag[in..];
mem.copy(u8, &tls.partially_read_buffer, saved_buf);
tls.partially_read_len = @intCast(u15, saved_buf.len);
return out;
}
fn hkdfExpandLabel(
comptime Hkdf: type,
key: [Hkdf.prk_length]u8,
label: []const u8,
context: []const u8,
comptime len: usize,
) [len]u8 {
const max_label_len = 255;
const max_context_len = 255;
const tls13 = "tls13 ";
var buf: [2 + 1 + tls13.len + max_label_len + 1 + max_context_len]u8 = undefined;
mem.writeIntBig(u16, buf[0..2], len);
buf[2] = @intCast(u8, tls13.len + label.len);
buf[3..][0..tls13.len].* = tls13.*;
var i: usize = 3 + tls13.len;
mem.copy(u8, buf[i..], label);
i += label.len;
buf[i] = @intCast(u8, context.len);
i += 1;
mem.copy(u8, buf[i..], context);
i += context.len;
var result: [len]u8 = undefined;
Hkdf.expand(&result, buf[0..i], key);
return result;
}
fn emptyHash(comptime Hash: type) [Hash.digest_length]u8 {
var result: [Hash.digest_length]u8 = undefined;
Hash.hash(&.{}, &result, .{});
return result;
}
fn hmac(comptime Hmac: type, message: []const u8, key: [Hmac.key_length]u8) [Hmac.mac_length]u8 {
var result: [Hmac.mac_length]u8 = undefined;
Hmac.create(&result, message, &key);
return result;
}
const builtin = @import("builtin");
const native_endian = builtin.cpu.arch.endian();
inline fn big(x: anytype) @TypeOf(x) {
return switch (native_endian) {
.Big => x,
.Little => @byteSwap(x),
};
}
inline fn int2(x: u16) [2]u8 {
return .{
@truncate(u8, x >> 8),
@truncate(u8, x),
};
}
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