WEB?

HTTPApacheNginx

HTTP

Text based protocl defined in 1991

V0.9 defined default port 80

uses TCP/IP connection but should be able to run on any connection oriented protocol

RFCs 2616, 5785, 6266, 6585, 3986, 6874

HTTP vs. Gopher

HTTP defines HTML as formatting for documents

Gopher defines menu style format

HTTP does not define any easy for searching and indexing pages

Trough its simple structure, gopher allows easy search and indexing

HTTP80rfc2616 Gopher70rfc1436

Gopher defined the URI standard

HTTP

Methods

Requests

Responses

Headers

URI/URL

CGI

HTTP Methods

Method URI Proto GET /lib/ana/sex.txtHTTP/1.0

GET

HEAD

POST

OPTIONS

TRACE

PUT

DELETE

HTTP Requests

Method URI Proto + CRLFHEADER + CRLFHEADER + CRLFCRLFGET /pics/ana/naked.jpg HTTP/1.0 + CRLFRange: 2400-2600,2900-3200 + CRLFCRLF

HTTP Responses

GET /pics/ana/naked.jpg HTTP/1.0 + CRLFRange: 2400-2600,2900-3200 + CRLFCRLF
ProtoStatusReasonHTTP/1.0200OK + CRLFResponse headers + CRLFCRLF.... binary data here .....

HTTP proto differences

HTTP/1.0close connection after each request

HTTP/1.1Host header

Connection: keep-alive

CONNECT method

Uniform Resource Identifier
(URI)

UR Locator - URL

Protocols: file, http, https, ftp, ftps, mailto, telnet, ssh, smb, irc

proto :// user:pass @ host : port / path ? params

params: param=value & param=value

Common Gateway Interface
(CGI)

CGI is not Computer Generated Imagery :)

Web ServerDynamic Content Generator(CGI script)

SERVER_SOFTWARESERVER_NAMEGATEWAY_INTERFACE

SERVER_PROTOCOLSERVER_PORTREQUEST_METHODPATH_INFO - request pathPATH_TRANSLATED - full fs pathSCRIPT_NAME - request pathQUERY_STRINGREMOTE_HOSTREMOTE_ADDRAUTH_TYPEREMOTE_USERREMOTE_IDENTCONTENT_TYPECONTENT_LENGTH

Common Gateway Interface
(CGI)

CGI is not Computer Generated Imagery :)

Web ServerDynamic Content Generator(CGI script)

/bin/sh + special environment variables1. Create a new environment2. Create a new shell process3. Execute the scriptNote: the script must be executable and must be able to produce the required output.

Responses must start with: Content-type: some-type + CRLF

Responses may include Status codes:
200 OK + CRLF

Apache

Documentation

Module architecture

Multi-processing Modules (MPMs)

Additional Modules

MPMs - Prefork

mpm_common

Prefork

Worker

Event

Child

ChildChild

MemoryMemoryMemoryMemoryMainProcess

MPMs - Worker

mpm_common

Prefork

Worker

Event

ChildChildChildMain Process

Memory

MPMs - event

mpm_common

Prefork

Worker

Event

desc_ready = select(1, &rfds, NULL, NULL, &tv);for (i=0; i 0; ++i) {

VS.

for (;;) { nfds = epoll_wait(epollfd, events, MAX_EVENTS, -1);

Module structure - Startup

Pre-Config

Test Configuration

Post Configuration

Open Logs

Child Init

Note that all of these are performed at least two times!

Module structure - Request

Pre-Connection

Create Connection

Process Connection

Create Request

Post-Read Request

Header Parse

HTTP Scheme

Default Port

Quick Handler

Translate Name

Map to Storage

Check Access

Verify User ID

Verify User Access

Check Type

Fixups

Insert Filters

Content Handlers

Logging

Insert Errors

Apache - Content handlers

module_namemodule_filemime_typepriority

cgi_modulemod_cgi.c.cgi .pl .sh10

php_modulemod_php.c.php .php510

perl_modulemod_perl.c.pl .pm10

Apache - CGI execution

Apache

Child

mod_php

Child

mod_cgi

root

nobody

nobody

Child

mod_cgi

Child

mod_suphp

index.phpindex.phpsuexecindex.php/bin/sh/bin/sh

suphpindex.php/bin/sh

user

user

Apache - CGI execution

Apache

Child

mod_fcgid

Child

mod_fcgid

root

nobody

user

index.phpFastCGIdaemonchildchildchild

index.phpindex.php

suexec

Apache structure

bin/httpd - the server

ab - Apache Bench

apxs - externel module builder

htpasswd

suexec

conf/httpd.conf

mime.typs + magic

modules/ (libexec on 1.3)

logs/