--- /dev/null
+ _ _
+ _ __ ___ ___ __| | ___ ___| |
+ | '_ ` _ \ / _ \ / _` | / __/ __| |
+ | | | | | | (_) | (_| | \__ \__ \ | ``mod_ssl combines the flexibility of
+ |_| |_| |_|\___/ \__,_|___|___/___/_| Apache with the security of OpenSSL.''
+ |_____|
+ mod_ssl ``Ralf Engelschall has released an
+ Apache Interface to OpenSSL excellent module that integrates
+ http://www.modssl.org/ Apache and SSLeay.''
+ Version 2.8 -- Tim J. Hudson
+
+ SYNOPSIS
+
+ This Apache module provides strong cryptography for the Apache 1.3 webserver
+ via the Secure Sockets Layer (SSL v2/v3) and Transport Layer Security (TLS
+ v1) protocols by the help of the SSL/TLS implementation library OpenSSL which
+ is based on SSLeay from Eric A. Young and Tim J. Hudson. The mod_ssl package
+ was created in April 1998 by Ralf S. Engelschall and was originally derived
+ from software developed by Ben Laurie for use in the Apache-SSL HTTP server
+ project.
+
+ SOURCES
+
+ Here is a short overview of the source files:
+
+ * README .................. This file ;)
+ # Makefile.in ............. Makefile template for Unix platform
+ # config.m4 ............... Autoconf stub for the Apache config mechanism
+ # mod_ssl.c ............... main source file containing API structures
+ # mod_ssl.h ............... common header file of mod_ssl
+ # ssl_engine_config.c ..... module configuration handling
+ # ssl_engine_dh.c ......... DSA/DH support
+ # ssl_engine_init.c ....... module initialization
+ # ssl_engine_io.c ......... I/O support
+ # ssl_engine_kernel.c ..... SSL engine kernel
+ # ssl_engine_log.c ........ logfile support
+ # ssl_engine_mutex.c ...... mutual exclusion support
+ # ssl_engine_pphrase.c .... pass-phrase handling
+ # ssl_engine_rand.c ....... PRNG support
+ # ssl_engine_vars.c ....... Variable Expansion support
+ # ssl_expr.c .............. expression handling main source
+ # ssl_expr.h .............. expression handling common header
+ # ssl_expr_scan.c ......... expression scanner automaton (pre-generated)
+ # ssl_expr_scan.l ......... expression scanner source
+ # ssl_expr_parse.c ........ expression parser automaton (pre-generated)
+ # ssl_expr_parse.h ........ expression parser header (pre-generated)
+ # ssl_expr_parse.y ........ expression parser source
+ # ssl_expr_eval.c ......... expression machine evaluation
+ # ssl_scache.c ............ session cache abstraction layer
+ # ssl_scache_dbm.c ........ session cache via DBM file
+ ~ ssl_scache_shmcb.c ...... session cache via shared memory cyclic buffer
+ ~ ssl_scache_shmht.c ...... session cache via shared memory hash table
+ # ssl_util.c .............. utility functions
+ # ssl_util_ssl.c .......... the OpenSSL companion source
+ # ssl_util_ssl.h .......... the OpenSSL companion header
+ # ssl_util_table.c ........ the hash table library source
+ # ssl_util_table.h ........ the hash table library header
+
+ Legend: # = already ported to Apache 2.0 and is cleaned up
+ * = ported to Apache 2.0 but still needs cleaning up
+ ~ = ported to Apache 2.0 but still needs work
+ - = port still not finished
+
+ The source files are written in clean ANSI C and pass the ``gcc -O -g
+ -ggdb3 -Wall -Wshadow -Wpointer-arith -Wcast-align -Wmissing-prototypes
+ -Wmissing-declarations -Wnested-externs -Winline'' compiler test
+ (assuming `gcc' is GCC 2.95.2 or newer) without any complains. When
+ you make changes or additions make sure the source still passes this
+ compiler test.
+
+ FUNCTIONS
+
+ Inside the source code you will be confronted with the following types of
+ functions which can be identified by their prefixes:
+
+ ap_xxxx() ............... Apache API function
+ ssl_xxxx() .............. mod_ssl function
+ SSL_xxxx() .............. OpenSSL function (SSL library)
+ OpenSSL_xxxx() .......... OpenSSL function (SSL library)
+ X509_xxxx() ............. OpenSSL function (Crypto library)
+ PEM_xxxx() .............. OpenSSL function (Crypto library)
+ EVP_xxxx() .............. OpenSSL function (Crypto library)
+ RSA_xxxx() .............. OpenSSL function (Crypto library)
+
+ DATA STRUCTURES
+
+ Inside the source code you will be confronted with the following
+ data structures:
+
+ server_rec .............. Apache (Virtual) Server
+ conn_rec ................ Apache Connection
+ request_rec ............. Apache Request
+ SSLModConfig ............ mod_ssl (Global) Module Configuration
+ SSLSrvConfig ............ mod_ssl (Virtual) Server Configuration
+ SSLDirConfig ............ mod_ssl Directory Configuration
+ SSLConnConfig ........... mod_ssl Connection Configuration
+ SSLFilterRec ............ mod_ssl Filter Context
+ SSL_CTX ................. OpenSSL Context
+ SSL_METHOD .............. OpenSSL Protocol Method
+ SSL_CIPHER .............. OpenSSL Cipher
+ SSL_SESSION ............. OpenSSL Session
+ SSL ..................... OpenSSL Connection
+ BIO ..................... OpenSSL Connection Buffer
+
+ For an overview how these are related and chained together have a look at the
+ page in README.dsov.{fig,ps}. It contains overview diagrams for those data
+ structures. It's designed for DIN A4 paper size, but you can easily generate
+ a smaller version inside XFig by specifing a magnification on the Export
+ panel.
+
+ EXPERIMENTAL CODE
+
+ Experimental code is always encapsulated as following:
+
+ | #ifdef SSL_EXPERIMENTAL_xxxx
+ | ...
+ | #endif
+
+ This way it is only compiled in when this define is enabled with
+ the APACI --enable-rule=SSL_EXPERIMENTAL option and as long as the
+ C pre-processor variable SSL_EXPERIMENTAL_xxxx_IGNORE is _NOT_
+ defined (via CFLAGS). Or in other words: SSL_EXPERIMENTAL enables all
+ SSL_EXPERIMENTAL_xxxx variables, except if SSL_EXPERIMENTAL_xxxx_IGNORE
+ is already defined. Currently the following features are experimental:
+
+ o SSL_EXPERIMENTAL_ENGINE
+ The ability to support the new forthcoming OpenSSL ENGINE stuff.
+ Until this development branch of OpenSSL is merged into the main
+ stream, you have to use openssl-engine-0.9.x.tar.gz for this.
+ mod_ssl automatically recognizes this OpenSSL variant and then can
+ activate external crypto devices through SSLCryptoDevice directive.
+
+ INCOMPATIBILITIES
+
+ The following intentional incompatibilities exist between mod_ssl 2.x
+ from Apache 1.3 and this mod_ssl version for Apache 2.0:
+
+ o The complete EAPI-based SSL_VENDOR stuff was removed.
+ o The complete EAPI-based SSL_COMPAT stuff was removed.
+ o The <IfDefine> variable MOD_SSL is no longer provided automatically
+
+ MAJOR CHANGES
+
+ The following major changes were made between mod_ssl 2.x
+ from Apache 1.3 and this mod_ssl version for Apache 2.0:
+
+ o The DBM based session cache is now based on APR's DBM API only.
+ o The shared memory based session cache is now based on APR's APIs.
+ o SSL I/O is now implemented in terms of filters rather than BUFF
+ o Eliminated ap_global_ctx. Storing Persistant information in
+ process_rec->pool->user_data. The ssl_pphrase_Handle_CB() and
+ ssl_config_global_* () functions have an extra parameter now -
+ "server_rec *" - which is used to retrieve the SSLModConfigRec.
+ o Properly support restarts, allowing mod_ssl to be added to a server
+ that is already running and to change server certs/keys on restart
+ o Various performance enhancements
+ o proxy support is no longer an "extension", much of the mod_ssl core
+ was re-written (ssl_engine_{init,kernel,config}.c) to be generic so
+ it could be re-used in proxy mode.
+ - the optional function ssl_proxy_enable is provide for mod_proxy
+ to enable proxy support
+ - proxy support now requires 'SSLProxyEngine on' to be configured
+ - proxy now supports SSLProxyCARevocation{Path,File} in addition to
+ the original SSLProxy* directives
+ o per-directory SSLCACertificate{File,Path} is now thread-safe but
+ requires SSL_set_cert_store patch to OpenSSL
+ o RSA sslc is supported via ssl_toolkit_compat.h
+ o the ssl_engine_{ds,ext}.c source files are obsolete and no longer
+ exist
+
+ TODO
+
+ o SSL renegotiations in combination with POST request
+ o Port all remaining code (code inside #if 0...#endif blocks)
+ o Do we need SSL_set_read_ahead()?
+ o the ssl_expr api is NOT THREAD SAFE. race conditions exist:
+ -in ssl_expr_comp() if SSLRequire is used in .htaccess
+ (ssl_expr_info is global)
+ -is ssl_expr_eval() if there is an error
+ (ssl_expr_error is global)
+ o SSLRequire directive (parsing of) leaks memory
+ o Diffie-Hellman-Parameters for temporary keys are hardcoded in
+ ssl_engine_dh.c, while the comment in ssl_engine_kernel.c says:
+ "it is suggested that keys be changed daily or every 500
+ transactions, and more often if possible."
+ o ssl_var_lookup could be rewritten to be MUCH faster
+ o CRL callback should be pluggable
+ o session cache store should be pluggable
+ o init functions should return status code rather than ssl_die()
+ o ssl_engine_pphrase.c needs to be reworked so it is generic enough
+ to also decrypt proxy keys
+ o the shmcb code should just align its memory segment rather than
+ jumping through all the "safe" memcpy and memset hoops
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