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std.crypto.tls: send a legacy session id

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To support middlebox compatibility mode.
This commit is contained in:
Andrew Kelley 2022-12-18 18:14:37 -07:00
parent e2efba76aa
commit 7a23778384
1 changed files with 34 additions and 23 deletions
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57
lib/std/crypto/tls/Client.zig
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@ -36,9 +36,11 @@ pub fn init(stream: net.Stream, host: []const u8) !Client {
error.IdentityElement => return error.InsufficientEntropy,
};
// random (u32)
var rand_buf: [32]u8 = undefined;
crypto.random.bytes(&rand_buf);
// This is used both for the random bytes and for the legacy session id.
var random_buffer: [64]u8 = undefined;
crypto.random.bytes(&random_buffer);
const hello_rand = random_buffer[0..32].*;
const legacy_session_id = random_buffer[32..64].*;
const extensions_payload =
tls.extension(.supported_versions, [_]u8{
@ -86,8 +88,8 @@ pub fn init(stream: net.Stream, host: []const u8) !Client {
const client_hello =
int2(@enumToInt(tls.ProtocolVersion.tls_1_2)) ++
rand_buf ++
[1]u8{0} ++
hello_rand ++
[1]u8{32} ++ legacy_session_id ++
cipher_suites ++
int2(legacy_compression_methods) ++
extensions_header;
@ -152,46 +154,55 @@ pub fn init(stream: net.Stream, host: []const u8) !Client {
}
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].*;
var i: usize = 4;
const legacy_version = mem.readIntBig(u16, frag[i..][0..2]);
i += 2;
const random = frag[i..][0..32].*;
i += 32;
if (mem.eql(u8, &random, &tls.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 legacy_session_id_echo_len = frag[i];
i += 1;
if (legacy_session_id_echo_len != 32) return error.TlsIllegalParameter;
const legacy_session_id_echo = frag[i..][0..32];
if (!mem.eql(u8, legacy_session_id_echo, &legacy_session_id))
return error.TlsIllegalParameter;
i += 32;
const cipher_suite_int = mem.readIntBig(u16, frag[i..][0..2]);
i += 2;
const cipher_suite_tag = @intToEnum(CipherSuite, cipher_suite_int);
std.debug.print("server wants cipher suite {any}\n", .{cipher_suite_tag});
const legacy_compression_method = hello[37];
const legacy_compression_method = frag[i];
i += 1;
_ = 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;
const extensions_size = mem.readIntBig(u16, frag[i..][0..2]);
i += 2;
if (i + extensions_size != frag.len) return error.TlsBadLength;
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]);
while (i < frag.len) {
const et = mem.readIntBig(u16, frag[i..][0..2]);
i += 2;
const ext_size = mem.readIntBig(u16, hello[i..][0..2]);
const ext_size = mem.readIntBig(u16, frag[i..][0..2]);
i += 2;
const next_i = i + ext_size;
if (next_i > hello.len) return error.TlsBadLength;
if (next_i > frag.len) return error.TlsBadLength;
switch (et) {
@enumToInt(tls.ExtensionType.supported_versions) => {
if (supported_version != 0) return error.TlsIllegalParameter;
supported_version = mem.readIntBig(u16, hello[i..][0..2]);
supported_version = mem.readIntBig(u16, frag[i..][0..2]);
},
@enumToInt(tls.ExtensionType.key_share) => {
if (opt_x25519_server_pub_key != null) return error.TlsIllegalParameter;
const named_group = mem.readIntBig(u16, hello[i..][0..2]);
const named_group = mem.readIntBig(u16, frag[i..][0..2]);
i += 2;
switch (named_group) {
@enumToInt(tls.NamedGroup.x25519) => {
const key_size = mem.readIntBig(u16, hello[i..][0..2]);
const key_size = mem.readIntBig(u16, frag[i..][0..2]);
i += 2;
if (key_size != 32) return error.TlsBadLength;
opt_x25519_server_pub_key = hello[i..][0..32];
opt_x25519_server_pub_key = frag[i..][0..32];
},
else => {
std.debug.print("named group: {x}\n", .{named_group});