Desconstruindo a web

Desconstruindo a web
Willian Molinari (a.k.a PotHix)

https://www.youtube.com/watch?v=nG1oGfrDiUc

http://pothix.com
http://pothix.com

http://pothix.com
É uma URL?
http://pothix.com

“O que significa PotHix”
“O que significa PotHix”

http://pothix.com
É uma URL!
http://pothix.com

http://pothix.com
http://pothix.com
Tem HSTS?
Strict-Transport-Security

http://pothix.com
Tem cache?
Expires Cache-Control
http://pothix.com

Protocolo: http://
Domínio: pothix.com
Path: /
Tem cache de
DNS?

http://aosabook.org/en/posa/high-performance-networking-in-chrome.html

glibc -> /etc/hosts
nss/nss_files/files-hosts.c

glibc -> getaddrinfo()
sysdeps/posix/getaddrinfo.c
2321 getaddrinfo (const char *name, const char *service,
2322 const struct addrinfo *hints, struct addrinfo **pai)
2323 {

getaddrinfo()
Tem nscd para
cache de DNS?

Aplicação
Apresentação
Sessão
Transporte
Rede
Enlace
Físico
Modelo
OSI

Aplicação
Transporte
Rede
Enlace
Físico
Sessão
Apresentação

Aplicação
Transporte
Rede
Enlace
Físico

Aplicação
Transporte
Rede
Enlace
Físico
SO
user

TCP / UDP
DNSAplicação
Transporte
Rede
Enlace
Físico
IP
Ethernet / Wi-Fi
010101001011

DNS
TCP / UDP
Aplicação
Transporte
Rede
Enlace
Físico
IP
Ethernet / Wi-Fi
010101001011

código disponível em: chromium/src/net/dns

getaddrinfo()
__socket() & __connect()
sysdeps/posix/getaddrinfo.c
2515 fd = __socket (af, SOCK_DGRAM, IPPROTO_IP);
[...]
2526 [...] && __connect (fd, q->ai_addr, q->ai_addrlen) == 0

terminal
$ sudo strace -f -e bind,socket,fork,connect -p $(ps aux | grep chromium | grep
-v nacl | awk '{ print $2}' | xargs echo | sed 's/ /,/g')
[...]
[pid 8739] socket(PF_INET6, SOCK_DGRAM, IPPROTO_IP) = 134
[pid 8739] connect(134, {sa_family=AF_INET6, sin6_port=htons(53), inet_pton
(AF_INET6, "2001:4860:4860::8888", &sin6_addr), sin6_flowinfo=0,
sin6_scope_id=0}, 28) = -1 ENETUNREACH (Network is unreachable)
[pid 9010] socket(PF_INET, SOCK_DGRAM, IPPROTO_IP) = 134
[pid 9010] connect(134, {sa_family=AF_INET, sin_port=htons(0),
sin_addr=inet_addr("192.30.252.154")}, 16) = 0
[pid 8739] socket(PF_INET, SOCK_STREAM, IPPROTO_TCP) = 134
sin_addr=inet_addr("192.30.252.154")}, 16) = -1 EINPROGRESS (Operation now in
progress)
[...]
Syscalls in action! (*stripped)

terminal
$ sudo strace -f -e bind,socket,fork,connect -p $(ps aux | grep chromium | grep
-v nacl | awk '{ print $2}' | xargs echo | sed 's/ /,/g')
[...]
[pid 8739] socket(PF_INET6, SOCK_DGRAM, IPPROTO_IP) = 134
[pid 8739] connect(134, {sa_family=AF_INET6, sin6_port=htons(53), inet_pton
(AF_INET6, "2001:4860:4860::8888", &sin6_addr), sin6_flowinfo=0,
sin6_scope_id=0}, 28) = -1 ENETUNREACH (Network is unreachable)
[pid 9010] socket(PF_INET, SOCK_DGRAM, IPPROTO_IP) = 134
sin_addr=inet_addr("192.30.252.154")}, 16) = 0
[pid 8739] socket(PF_INET, SOCK_STREAM, IPPROTO_TCP) = 134
sin_addr=inet_addr("192.30.252.154")}, 16) = -1 EINPROGRESS (Operation now in
progress)
[...]
Syscalls in action! (*stripped)
UDP para ipv6
nope :(
UDP
ipv4
request

Happy eyebals (rfc6555): https://www.ietf.org/mail-
archive/web/v6ops/current/msg22455.html

AAAA
A
Browser
sitev6
sitev4
de acordo com a rfc6555

AAAA
A
Browser
sitev6
sitev4RST
de acordo com a rfc6555

DNSAplicação
Transporte
Rede
Enlace
Físico
TCP / UDP
IP
Ethernet / Wi-Fi
010101001011

UDP/IP
linux/blob/master/net/ipv4/udp.c

DNSAplicação
Transporte
Rede
Enlace
Físico
TCP / UDP
IP
Mágica, bro!

A visual explanation of how dns lookups work

Via dnstracer: `dnstracer -s . -4 -o pothix.com`
A.ROOT-SERVERS.NET [.] (198.41.0.4)
a.gtld-servers.net [com] (192.5.6.30)
ns1.dreamhost.com [pothix.com]
(66.33.206.206) Got authoritative answer
ns1.dreamhost.com (66.33.206.206)
pothix.com -> 192.30.252.153
ns1.dreamhost.com (66.33.206.206)
pothix.com -> 192.30.252.154

Internet
glibc
DNS
TCP/IP
UDP/IP
POSIX

Internet
glibc
DNS
TCP/IP
UDP/IP
POSIX
HTTP

HTTP/HTTPS
TCP / UDP
IP
Ethernet / Wi-Fi
010101001011
Aplicação
Transporte
Rede
Enlace
Físico

TCP
linux/blob/master/net/ipv4/tcp.c

https://en.wikipedia.org/wiki/Transmission_Control_Protocol

ACK
SYN + ACK
ACK
Three way handshake

SYN+ACK
LISTEN
SYN
RECEIVED
SYNSENT

SYN
RECEIVED
SYNSENTESTABLISHED
ACK

ESTABLISHEDSYNSENTESTABLISHED
É NÓIS! É NÓIS!

TLS = fork(SSLv3)
SSLv3 is no longer supported in chrome

HTTP/HTTPS
TCP / UDP
IP
Ethernet / Wi-Fi
010101001011
Aplicação
Transporte
Rede
Enlace
Físico
TLS

conexão estabelecida
client hello
(CIPHERS, URL)
Os primeiros milisegundos de uma conexão HTTPS

https://cc.dcsec.uni-hannover.de/

Server hello
(certificado, CIPHER)
TLS_RSA_WITH_RC4_128_MD5
public
key
crypt hash

Data válida?
CA confiável?
Assinatura válida?
URL esperada?

Gerei uma parada aqui
(pre_master secret)
!^*@#$&!@(#$&!@#)$^$^

!!@U#$N!Y*@#$*
master secret

É NÓIS!
criptografia
dos dados
verificação contra
conteúdo “batizado”
É NÓIS!

TLSHTTP HTTP
Internet
headers
url
cookies
headers
url
cookies

HTTP/HTTP2
chromium - net/http & net/spdy

Rafael Rinaldi
Dissecando o protocolo HTTP/2

HTTP 1x via telnet
$ telnet pothix.com 80
Trying 192.30.252.153...
Connected to pothix.com.
Escape character is '^]'.
GET /index.html HTTP/1.1
Host: pothix.com
HTTP/1.1 200 OK
Server: GitHub.com
...
terminal

papers/Vipin_Analysis_of_open_source_WLAN_driver_paper.pdf
➔ net/ipv4/tcp.c
➔ include/net/cfg80211.h
➔ net/wireless/nl80211.c
➔ include/net/mac80211.h
➔ drivers/net/wireless/iwlwifi/

Internetglibc
DNS
TCP/IP
UDP/IP
HTTP
POSIX

Carrier
Sense
Multiple
Access
Collision
Avoidance

glibc
DNS
TCP/IP
UDP/IP
HTTP
POSIX
Internet

# traceroute -T pothix.com
traceroute to pothix.com (192.30.252.153), 30 hops max, 60 byte packets
1 palantir (192.168.1.1) 8.718 ms 8.769 ms 8.868 ms
2 10.18.128.1 (10.18.128.1) 25.058 ms 25.673 ms 27.189 ms
3 c8bd5001.virtua.com.br (200.189.80.1) 29.071 ms 29.073 ms 29.068 ms
4 embratel-T0-7-2-0-tacc01.spoph.embratel.net.br (200.178.127.57) 32.917 ms
embratel-T0-4-1-0-uacc03.spomb.embratel.net.br (189.42.182.37) 31.734 ms
embratel-T0-1-0-2-uacc04.spoph.embratel.net.br (201.56.189.9) 36.481 ms
5 ebt-H0-1-0-0-tcore01.spolp.embratel.net.br (200.230.1.242) 37.800 ms
200.244.212.73 (200.244.212.73) 37.803 ms
200.244.212.81 (200.244.212.81) 41.446 ms
6 ebt-BP1082-intl02.nyk.embratel.net.br (200.230.220.30) 204.822 ms
ebt-B11121-intl02.nyk.embratel.net.br (200.230.251.254) 192.381 ms
ebt-BP11521-intl02.nyk.embratel.net.br (200.230.220.174) 189.936 ms
7 fa-0-0-0.r23.nycmny01.us.bb.gin.ntt.net (129.250.202.185) 192.297 ms 172.074 ms 172.013 ms
8 ae-9.r22.asbnva02.us.bb.gin.ntt.net (129.250.2.149) 171.973 ms 167.012 ms 166.951 ms
9 ae-44.r06.asbnva02.us.bb.gin.ntt.net (129.250.6.113) 166.888 ms 166.873 ms
ae-45.r05.asbnva02.us.bb.gin.ntt.net (129.250.5.137) 212.669 ms
10 xe-0-3-0-18.r05.asbnva02.us.ce.gin.ntt.net (129.250.197.70) 202.448 ms
xe-0-9-0-16.r06.asbnva02.us.ce.gin.ntt.net (129.250.197.74) 201.593 ms 202.489 ms
11 pages.github.com (192.30.252.153) 171.337 ms * *
TCP meu router
github pages
USA backbone
backbone
embratel
NET

Nginx conf file
upstream backend {
server backend1.example.com weight=5;
server backend2.example.com:8080;
server unix:/tmp/backend3;
server backup1.example.com:8080 backup;
server backup2.example.com:8080 backup;
}
...
http://nginx.org/en/docs/http/ngx_http_upstream_module.html#server
TCP
Unix Socket

Internet
assets
TCP
http://12factor.net/port-binding

HTTP parsing
ragel vindo lá do velho mongrel*
*de acordo com o documento de design do unicorn

Webserver -> Framework
baseado no PEP3333

lib/rails/application.rb
Rack -> Rails
mais informações no post do timaro no omniref

É um Rack application
...
# Implements call according to the Rack API. It simply
# dispatches the request to the underlying middleware stack.
def call(env)
env["ORIGINAL_FULLPATH"] = build_original_fullpath(env)
env["ORIGINAL_SCRIPT_NAME"] = env["SCRIPT_NAME"]
super(env)
end
...

Informações do Rack
{"GATEWAY_INTERFACE"=>"CGI/1.1",
"PATH_INFO"=>"/favicon.ico",
"QUERY_STRING"=>"",
"REMOTE_ADDR"=>"127.0.0.1",
"REMOTE_HOST"=>"localhost.localdomain",
"REQUEST_METHOD"=>"GET",
"REQUEST_URI"=>"http://localhost:9292/favicon.
ico",
"SCRIPT_NAME"=>"",
"SERVER_NAME"=>"localhost",
"SERVER_PORT"=>"9292",
"SERVER_PROTOCOL"=>"HTTP/1.1",
"SERVER_SOFTWARE"=>"WEBrick/1.3.1 (Ruby/2.2.3
/2015-08-18)",
"HTTP_HOST"=>"localhost:9292",
"HTTP_CONNECTION"=>"keep-alive",
"HTTP_USER_AGENT"=>"Mozilla/5.0 (X11; Linux
x86_64) AppleWebKit/537.36 (KHTML, like Gecko)
Chrome/46.0.2490.71 Safari/537.36",
"HTTP_ACCEPT"=>"*/*",
"HTTP_REFERER"=>"http://localhost:9292/",
"HTTP_ACCEPT_ENCODING"=>"gzip, deflate, sdch",
"HTTP_ACCEPT_LANGUAGE"=>"en-US,en;q=0.8,pt-BR;q=0.
6,pt;q=0.4,es;q=0.2,eo;q=0.2", "rack.version"=>[1,
2],
"rack.multithread"=>true, "rack.multiprocess"
=>false, "rack.run_once"=>false, "rack.url_scheme"
=>"http", "HTTP_VERSION"=>"HTTP/1.1",
"REQUEST_PATH"=>"/favicon.ico"}

Rails::Engine
Todas as apps são Engines

Rack middlewares
[
Rack::Sendfile,
ActionDispatch::Static, Rack::Lock,
#<ActiveSupport::Cache::Strategy::LocalCache::
Middleware:0x000000028fa168>,
Rack::Runtime, Rack::MethodOverride,
ActionDispatch::RequestId,
Rails::Rack::Logger,
ActionDispatch::ShowExceptions,
WebConsole::Middleware,
ActionDispatch::DebugExceptions,
ActionDispatch::RemoteIp,
ActionDispatch::Reloader,
ActionDispatch::Callbacks,
ActiveRecord::Migration::CheckPending,
ActiveRecord::ConnectionAdapters::
ConnectionManagement,
ActiveRecord::QueryCache,
ActionDispatch::Cookies,
ActionDispatch::Session::CookieStore,
ActionDispatch::Flash,
ActionDispatch::ParamsParser,
Rack::Head,
Rack::ConditionalGet,
Rack::ETag
]

ActionDispatch
::Journey::Router
a primeira parte do seu código a ser tocada
req.path_parameters
=> {:controller=>"pages", :action=>"home"}

ActionDispatch::Routing
::RouteSet::Dispatcher
achando o controller via rotas
ActiveSupport::Dependencies.constantize("#{params[:controller].camelize}Controller")
=> PagesController

ActionController::Metal
prepara o request e manda processar
def dispatch(name, request) #:nodoc:
[...]
process(name)

AbstractController::Base
encaminha para o seu controller
def process(action, *args)
[...]
process_action(action_name, *args) # que no fim é só um `send`

pega aí Rack -> [status, header, body]
ActionDispatch
::Journey::Router

glibc
DNS
TCP/IP
UDP/IP
HTTP
POSIX
Internet
c-c-c-combo breaker

exemplos retirados do post “How browsers work”
algoritmo de parsing
implementado no webkit do chrome
HEAD

algoritmo de parsing
implementado no webkit do chrome

<img src=”http://pothix.com/avatar.gif”> thread
<img src=”http://pothix.com/esperanto.png”> thread
<img src=”http://pothix.com/fotodasferias.scr”> thread
<script src=”http://pothix.com/marotagem.js”> sincrono
<script src=”http://pothix.com/estiloso.css”> thread
<script src=”http://pothix.com/javaescrito.js”> sincrono
<img src=”http://pothix.com/fotodasferias.jpg”>

Diego Eis: DOM, CSSOM e RenderThree - Introdução ao Browser Render Path

glibc
MV
VM
C
Internet
Internet

Não acredite em mágica
entenda como funciona de verdade
ceeeeerto.

Seja curioso
conhecimento nunca é demais

Perguntas?
Willian Molinari
@PotHix
pothix@pothix.com
Slides: https://goo.gl/cC36RM

Desconstruindo a web

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