# Copyright (c) 2017 - 2020 LiteSpeed Technologies Inc. See LICENSE. LSQUIC Examples =============== LSQUIC comes with several examples of how the library is used. The client and server programs described below are built on a common framework and share many options. Echo client and server ---------------------- Echo client and server (see bin/echo_{client,server}.c) are for simple line-based request and reply communication. Only one stream per connection is supported for simplicity. The client reads input from stdin. MD5 client and server --------------------- See bin/md5_{client,server}.c MD5 server accepts connections, computes MD5 sum of streams' (one or more) payload, and sends back the checksum. MD5 client sends one or more file contents to the server. Both client and server support various options to exercise different aspects of LSQUIC. HTTP client and server ---------------------- See bin/http_{client,server}.c This pair of programs is to demonstrate how to use HTTP features of QUIC. HTTP server is interoperable with proto-quic's quic_client. Usage Examples -------------- Fetch Google's home page: ./http_client -s www.google.com -p / The default port number is 443, but it can be specified after colon using the -s flag. The value of the `host' header as well as the SNI value defaults to the host part of the -s option. -H option can be used to override it. For example: ./http_client -H www.youtube.com -s www.google.com:443 -p / -M HEAD The host part can be an IP address. Both IPv4 and IPv6 are supported. See ./http_client -h for a (long) list of different flags. POST a file to calculate its CRC32 checksum: ./http_client -H www.litespeedtech.com -s 443 \ -p /cgi-bin/crc32.cgi -P file-256M -M POST HTTP/1.1 200 OK content-type: text/plain date: Fri, 09 Jun 2017 08:40:45 GMT server: LiteSpeed alt-svc: quic=":443"; v="35,37" CRC32: 2A0E7DBB This is a good way to check that the payload gets to the other side correctly. The CGI script is: #!/usr/bin/perl use String::CRC32; printf "Content-type: text/plain\r\n\r\nCRC32: %X\n", crc32(*STDIN) On the command line, I do alias crc32="perl -MString::CRC32 -e'printf qq(%X\n), crc32(<>)'" To submit several requests concurrently, one can use -n and -r options: ./http_client -H www.litespeedtech.com -s 443 \ -p /cgi-bin/crc32.cgi -P file-256M -M POST -n 3 -r 10 This will open three parallel connections which will make ten POST requests together. To perform load testing, it is good to mix sending and receiving data: for i in {1..100}; do ./http_client $COMMON_OPTS -p /cgi-bin/crc32.cgi -P file-256M \ -M POST >out-post.$i & ./http_client $COMMON_OPTS -p /docs/file-256M >out-get.$i & sleep 1 done If you don't want to create a hundred 256-megabyte out-get.* files, use -K flag to discard output. Testing Large Packet Sizes --------------------------------- IETF QUIC supports all valid UDP packet sizes. This section outlines the environment setup and testing parameters necessary to test this feature. Compilation - Make sure to compile the library in DEBUG mode so that the NDEBUG define is off. - Build both the http_client and http_server test programs. Running Instructions - On the server side, define the environment variable LSQUIC_CN_PACK_SIZE and set it to the intended packet size. Valid sizes are up to 65507 (IPv4). - Use the -W flag for http_client and http_server for the ability to send packets of large size. - On the client side, use the -z flag to specify the maximum size of packet that the client will accept. Example Usage ./http_client -p /file-1M -H www.litespeedtech.com -s 192.168.0.85:5443 -o version=FF000014 -z 65507 -W ./http_server -c www.litespeedtech.com,certschain,privkey -s 0.0.0.0:5443 -W Additional Notes Since this feature does not have MTU discovery enabled at the time of writing, make sure to use client and server machines that share a path with the intended MTU. Control QUIC Settings via -o Flag --------------------------------- Most of the settings in struct squic_engine_settings can be controlled via -o flag. With exception of es_versions, which is a bit mask, other es_* options can be mapped to corresponding -o value via s/^es_//: es_cfcw => -o cwcf=12345 es_max_streams_in => -o max_streams_in=123 And so on. For example, to test version negotiation: ./http_server -c www.litespeedtech.com,certschain,privkey \ -o version=Q035 -L debug 2>server.out & ./http_client -H www.litespeedtech.com -p Makefile -L debug 2>client.out Above, the client will start with the default, which is the highest supported QUIC version, which the server should negotiate down. You should see it from the log files. The code to set options via -o flag lives in set_engine_option(). It is good to update this function at the same time as member fields are added to struct lsquic_engine_settings. Control LSQUIC Behavior via Environment Variables ------------------------------------------------- LSQUIC_PACKET_OUT_LIMIT If set, the value of this environment variable is the maximum number of packets that can be sent out in one shot. The limit is in the test program framework's ea_packets_out() callback. It is not applicable when sendmmsg(2) is used. Note 1: sendmmsg can be enabled using -g option, if available for your platform. Note 2: see -m option for a related packet-out limitation. LSQUIC_LOSE_PACKETS_RE If set, this regular expression specifies the numbers of packets which the sender will lose on purpose. For example: export LSQUIC_LOSE_PACKETS_RE='^(3|5|10)$' The act of losing a packet is performed by changing its payload to zero-filled buffer of the same size, which is almost as good as not sending anything. The latter is difficult to implement without negatively affecting the regular code flow. Only available in debug builds. LSQUIC_PACER_INTERTICK Number of microsecods to use as constant intertick time in lieu of the pacer's dynamic intertick time approximation. Only available in debug builds. LSQUIC_CUBIC_SAMPLING_RATE Number of microseconds between times CWND is logged at info level. Only available in debug builds. LSQUIC_RANDOM_SEND_FAILURE Frequency with which sending of packets fails: one out of this many times on average. Only available when compiled with -DLSQUIC_RANDOM_SEND_FAILURE=1 LSQUIC_LOG_SECRETS If set to true value, crypto secrets will be logged. Applies to IETF QUIC only. LSQUIC_COALESCE If set to false, packets are not coalesced. Defaults to true. LSQUIC_USE_POOLS If set to false, all memory pooling code is replaced with calls to malloc() and free(). This facilitates debugging memory issues. The default is true. LSQUIC_ACK_ATTACK If set to true, generate optimistic ACKs. Control Network-Related Stuff ----------------------------- -D Set `do not fragment' flag on outgoing UDP packets. -z BYTES Maximum size of outgoing UDP packets. The default is 1370 bytes for IPv4 socket and 1350 bytes for IPv6 socket. -S opt=val Socket options. Supported options: sndbuf=12345 # Sets SO_SNDBUF rcvbuf=12345 # Sets SO_RCVBUF -g Use sendmmsg() to send packets. This is only compiled in if available. More Compilation Options ------------------------ -DLSQUIC_CONN_STATS=1 Track some statistics about connections -- packets in, sent, delayed, stream payload per packet size ratio, and some others -- and print them at NOTICE level when connection is destroyed. Cumulative connections statistics are printed by the engine when it is destroyed if lsquic_engine_api.ea_stats_fh is set. The HTTP client programs sets it when -t or -T command-line option is used. -DLSQUIC_PACKINTS_SANITY_CHECK=1 Turn on sanity checking for packet interval code. The packet interval code, shared by both send and receive history modules, contained a bug which prompted me to add a checking function. -DLSQUIC_SEND_STATS=0 Turn off statistics collection performed by the send controller: number of packets sent, resent, and delayed. -DLOG_PACKET_CHECKSUM=1 When turned on, CRC32 checksum of each sent and received packet is logged as an event. -DLSQUIC_LOWEST_LOG_LEVEL=LSQ_LOG_WARN If you want to go even faster: compile out some log levels entirely. -DLSQUIC_EXTRA_CHECKS=1 Add relatively expensive run-time sanity checks -DLSQUIC_RANDOM_SEND_FAILURE=1 Simulate failure to send packets to test send resumption logic. When this flag is specified, sending of packets will randomly fail, about one out of every 10 attempts. Set environment variable LSQUIC_RANDOM_SEND_FAILURE to change this frequency. -DLSQUIC_ECN_BLACK_HOLE=1 When compiled with this flag, setting environment variable LSQUIC_ECN_BLACK_HOLE to 1 will emulate ECN black hole: all received packets with ECN markings are dropped on the floor. -DLSQUIC_ACK_ATTACK=1 Enable ACK attack mode. See LSQUIC_ACK_ATTACK environment variable entry above.