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[DO NOT MERGE YET] add options for testing retransmission behavior #498

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[DO NOT MERGE YET] add options for testing retransmission behavior #498

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30bccca
add option to intentionally fragment payload
kazuho Dec 5, 2021
6fa59fb
add option to destroy packets being sent at a specified ratio
kazuho Dec 5, 2021
ebf401e
use xorshift64 for repeatability
kazuho Dec 5, 2021
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11 changes: 11 additions & 0 deletions include/quicly.h
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Original file line number Diff line number Diff line change
Expand Up @@ -315,10 +315,21 @@ struct st_quicly_context_t {
* will request the peer to send one ACK every 1/8 RTT (or CWND). 0 disables the use of the delayed-ack extension.
*/
uint16_t ack_frequency;
/**
* destroy the packet being sent at given ratio (xorshift with given seed is used for each connection)
*/
struct {
uint16_t ratio;
uint64_t seed;
} destroy_packet;
/**
* expand client hello so that it does not fit into one datagram
*/
unsigned expand_client_hello : 1;
/**
* intentionally fragment stream payload; this is useful for testing retransmission
*/
unsigned fragment_payload : 1;
/**
*
*/
Expand Down
5 changes: 5 additions & 0 deletions lib/defaults.c
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Original file line number Diff line number Diff line change
Expand Up @@ -28,6 +28,7 @@
#define DEFAULT_MAX_CRYPTO_BYTES 65536
#define DEFAULT_INITCWND_PACKETS 10
#define DEFAULT_PRE_VALIDATION_AMPLIFICATION_LIMIT 3
#define DEFAULT_DESTROY_PACKET_SEED 88172645463325252

/* profile that employs IETF specified values */
const quicly_context_t quicly_spec_context = {NULL, /* tls */
Expand All @@ -45,7 +46,9 @@ const quicly_context_t quicly_spec_context = {NULL,
QUICLY_PROTOCOL_VERSION_1,
DEFAULT_PRE_VALIDATION_AMPLIFICATION_LIMIT,
0, /* ack_frequency */
{0, DEFAULT_DESTROY_PACKET_SEED}, /* destroy_packet */
0, /* enlarge_client_hello */
0, /* fragment_payload */
NULL,
NULL, /* on_stream_open */
&quicly_default_stream_scheduler,
Expand Down Expand Up @@ -73,7 +76,9 @@ const quicly_context_t quicly_performant_context = {NULL,
QUICLY_PROTOCOL_VERSION_1,
DEFAULT_PRE_VALIDATION_AMPLIFICATION_LIMIT,
0, /* ack_frequency */
{0, DEFAULT_DESTROY_PACKET_SEED}, /* destroy_packet */
0, /* enlarge_client_hello */
0, /* fragment_payload */
NULL,
NULL, /* on_stream_open */
&quicly_default_stream_scheduler,
Expand Down
32 changes: 32 additions & 0 deletions lib/quicly.c
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Original file line number Diff line number Diff line change
Expand Up @@ -242,6 +242,10 @@ struct st_quicly_conn_t {
* next PN to be skipped
*/
uint64_t next_pn_to_skip;
/**
* RNG used to determine if packet should be destroyed
*/
uint64_t destroy_packet_rng;
/**
*
*/
Expand Down Expand Up @@ -454,6 +458,12 @@ static const quicly_transport_parameters_t default_transport_params = {.max_udp_
.active_connection_id_limit =
QUICLY_DEFAULT_ACTIVE_CONNECTION_ID_LIMIT};

static void xorshift64(uint64_t *x)
{
*x = *x ^ (*x << 7);
*x = *x ^ (*x >> 9);
}

static const struct st_ptls_salt_t *get_salt(uint32_t protocol_version)
{
static const struct st_ptls_salt_t
Expand Down Expand Up @@ -2115,6 +2125,7 @@ static quicly_conn_t *create_connection(quicly_context_t *ctx, uint32_t protocol
&conn->super.remote.transport_params.max_ack_delay, &conn->super.remote.transport_params.ack_delay_exponent);
conn->egress.next_pn_to_skip =
calc_next_pn_to_skip(conn->super.ctx->tls, 0, initcwnd, conn->super.ctx->initial_egress_max_udp_payload_size);
conn->egress.destroy_packet_rng = conn->super.ctx->destroy_packet.seed;
conn->egress.max_udp_payload_size = conn->super.ctx->initial_egress_max_udp_payload_size;
init_max_streams(&conn->egress.max_streams.uni);
init_max_streams(&conn->egress.max_streams.bidi);
Expand Down Expand Up @@ -3111,6 +3122,13 @@ static int commit_send_packet(quicly_conn_t *conn, quicly_send_context_t *s, int
s->dst_payload_from - s->payload_buf.datagram, conn->egress.packet_number,
coalesced);

/* packet drill: intentionally destroy the packet at given ratio */
if (conn->super.ctx->destroy_packet.ratio > 0) {
xorshift64(&conn->egress.destroy_packet_rng);
if (conn->egress.destroy_packet_rng % 1024 < conn->super.ctx->destroy_packet.ratio)
s->dst[-1] ^= 1;
}

/* update CC, commit sentmap */
if (s->target.ack_eliciting) {
packet_bytes_in_flight = s->dst - s->target.first_byte_at;
Expand Down Expand Up @@ -3665,8 +3683,22 @@ int quicly_send_stream(quicly_stream_t *stream, quicly_send_context_t *s)
}
assert(len != 0);

/* [fragment] trim output to cause fragmentation at the receiver */
if (stream->conn->super.ctx->fragment_payload) {
size_t new_len = len < 4 ? 1 : len / 4;
if (new_len < len)
wrote_all = 0;
len = new_len;
}

adjust_stream_frame_layout(&s->dst, s->dst_end, &len, &wrote_all, &frame_type_at);

/* [fragment] append PADDING to prevent more frames from getting added to the same packet */
if (stream->conn->super.ctx->fragment_payload && s->dst < s->dst_end) {
memset(s->dst, QUICLY_FRAME_TYPE_PADDING, s->dst_end - s->dst);
s->dst = s->dst_end;
}

/* determine if the frame incorporates FIN */
if (off + len == stream->sendstate.final_size) {
assert(!quicly_sendstate_is_open(&stream->sendstate));
Expand Down
16 changes: 15 additions & 1 deletion src/cli.c
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Original file line number Diff line number Diff line change
Expand Up @@ -1022,6 +1022,7 @@ static void usage(const char *cmd)
" -E expand Client Hello (sends multiple client Initials)\n"
" -f fraction increases the induced ack frequency to specified\n"
" fraction of CWND (default: 0)\n"
" -F introduce fragmentation\n"
" -G enable UDP generic segmentation offload\n"
" -i interval interval to reissue requests (in milliseconds)\n"
" -I timeout idle timeout (in milliseconds; default: 600,000)\n"
Expand Down Expand Up @@ -1051,6 +1052,8 @@ static void usage(const char *cmd)
" -x named-group named group to be used (default: secp256r1)\n"
" -X max bidirectional stream count (default: 100)\n"
" -y cipher-suite cipher-suite to be used (default: all)\n"
" -Y ratio destroy the packet being sent at given ratio\n"
" (default: 0)\n"
" -h print this help\n"
"\n",
cmd);
Expand Down Expand Up @@ -1094,7 +1097,7 @@ int main(int argc, char **argv)
address_token_aead.dec = ptls_aead_new(&ptls_openssl_aes128gcm, &ptls_openssl_sha256, 0, secret, "");
}

while ((ch = getopt(argc, argv, "a:b:B:c:C:Dd:k:Ee:f:Gi:I:K:l:M:m:NnOp:P:Rr:S:s:u:U:Vvw:W:x:X:y:h")) != -1) {
while ((ch = getopt(argc, argv, "a:b:B:c:C:Dd:k:Ee:Ff:Gi:I:K:l:M:m:NnOp:P:Rr:S:s:u:U:Vvw:W:x:X:Y:y:h")) != -1) {
switch (ch) {
case 'a':
assert(negotiated_protocols.count < PTLS_ELEMENTSOF(negotiated_protocols.list));
Expand Down Expand Up @@ -1156,6 +1159,9 @@ int main(int argc, char **argv)
}
setvbuf(quicly_trace_fp, NULL, _IONBF, 0);
break;
case 'F':
ctx.fragment_payload = 1;
break;
case 'f': {
double fraction;
if (sscanf(optarg, "%lf", &fraction) != 1) {
Expand Down Expand Up @@ -1291,6 +1297,14 @@ int main(int argc, char **argv)
exit(1);
}
break;
case 'Y': {
double ratio;
if (sscanf(optarg, "%lf", &ratio) != 1 || !(0 <= ratio && ratio <= 1)) {
fprintf(stderr, "failed to parse packet destroy ratio (-Y): %s\n", optarg);
exit(1);
}
ctx.destroy_packet.ratio = (uint16_t)(ratio * 1024);
} break;
case 'y': {
size_t i;
for (i = 0; cipher_suites[i] != NULL; ++i)
Expand Down