Remove Edge Side Include (ESI) protocol (#1905)

ESI feature has a number of bugs and security vulnerabilities.
It is also rarely used and a survey of active community members
has not revealed a need to keep maintaining this code.

CREDITS

@@ -1522,15 +1522,6 @@ src/auth/ntlm/smb_lm/:
 
 ==============================================================================
 
-src/esi/Libxml2Parser.cc,
-src/esi/Libxml2Parser.h:
-
- * The ESI Libxml2 parser is Copyright (c) 2004 by Joachim Bauch
- * http://www.joachim-bauch.de
- * [email protected]
-
-==============================================================================
-
 src/external_acl.c:
 
  Copyright (C) 2002 MARA Systems AB, Sweden <[email protected]>

configure.ac

@@ -817,38 +817,6 @@ AC_ARG_ENABLE(delay-pools,
 dnl disable generic/common adaptation support by default
 squid_opt_use_adaptation=no
 
-AH_TEMPLATE([USE_SQUID_ESI],[whether to enable ESI processing])
-AC_ARG_ENABLE(esi,[
-  AS_HELP_STRING([--enable-esi],
-                 [Enable ESI for accelerators. ESI requires expat or xml2 library.
-                  Enabling ESI will cause squid reverse proxies to be capable
-                  of the Edge Acceleration Specification (www.esi.org).])
-],[
-  SQUID_DEFINE_BOOL(USE_SQUID_ESI,$enable_esi)
-])
-AC_MSG_NOTICE([Enable ESI processor: ${enable_esi:=no (auto)}])
-
-# ESI support libraries: expat
-SQUID_AUTO_LIB(expat,[ESI expat library],[LIBEXPAT])
-SQUID_CHECK_LIB_WORKS(expat,[
-  PKG_CHECK_MODULES([LIBEXPAT],[expat],[:],[:])
-  CPPFLAGS="$LIBEXPAT_CFLAGS $CPPFLAGS"
-  AC_CHECK_HEADERS(expat.h)
-])
-
-# ESI support libraries: xml2
-SQUID_AUTO_LIB(xml2,[ESI xml2 library],[LIBXML2])
-SQUID_CHECK_LIB_WORKS(xml2,[
-  PKG_CHECK_MODULES([LIBXML2],[libxml-2.0],[:],[:])
-  CPPFLAGS="$LIBXML2_CFLAGS $CPPFLAGS"
-  AC_CHECK_HEADERS(libxml/parser.h libxml/HTMLparser.h libxml/HTMLtree.h)
-])
-
-AS_IF([test "x$enable_esi" = "xyes" -a "x$LIBXML2_LIBS" = "x" -a "x$LIBEXPAT_LIBS" = "x"],[
-  AC_MSG_ERROR([ESI processor requires libxml2 or libexpat])
-])
-AM_CONDITIONAL(ENABLE_ESI,[test "x$enable_esi" = "xyes"])
-
 AC_ARG_ENABLE(icap-client,
   AS_HELP_STRING([--disable-icap-client],[Disable the ICAP client.]),[
   SQUID_YESNO([$enableval],[--enable-icap-client])
@@ -2519,8 +2487,6 @@ AC_CONFIG_FILES([
 	errors/Makefile
 	icons/Makefile
 	lib/Makefile
-	lib/libTrie/Makefile
-	lib/libTrie/test/Makefile
 	lib/ntlmauth/Makefile
 	lib/rfcnb/Makefile
 	lib/smblib/Makefile
@@ -2587,7 +2553,6 @@ AC_CONFIG_FILES([
 	src/DiskIO/IpcIo/Makefile
 	src/DiskIO/Mmapped/Makefile
 	src/error/Makefile
-	src/esi/Makefile
 	src/eui/Makefile
 	src/format/Makefile
 	src/fs/Makefile

doc/Programming-Guide/03_MajorComponents.dox

@@ -338,11 +338,4 @@ TODO: get RFCs linked from ietf
 	see (http://squid.nlanr.net/Squid/urn-support.html) URN Support in Squid
 	.
 
-\section ESI ESI
-\par
-	ESI is an implementation of Edge Side Includes (http://www.esi.org).
-	ESI is implemented as a client side stream and a small
-	modification to client_side_reply.c to check whether
-	ESI should be inserted into the reply stream or not.
-
  */

doc/debug-sections.txt

@@ -138,8 +138,6 @@ section 83    TLS Server/Peer negotiation
 section 83    TLS session management
 section 84    Helper process maintenance
 section 85    Client-side Request Routines
-section 86    ESI Expressions
-section 86    ESI processing
 section 87    Client-side Stream routines.
 section 88    Client-side Reply Routines
 section 89    EUI-48 Lookup

doc/release-notes/release-7.sgml.in

@@ -199,6 +199,9 @@ This section gives an account of those changes in three categories:
 <sect1>Removed directives<label id="removeddirectives">
 <p>
 <descrip>
+	<tag>esi_parser</tag>
+	<p>Edge Side Includes (ESI) protocol is no longer supported natively.
+
 	<tag>mcast_miss_addr</tag>
 	<p>The corresponding code has not built for many years, indicating that the
 	feature is unused.
@@ -257,9 +260,7 @@ This section gives an account of those changes in three categories:
 <sect1>Changes to existing options<label id="modifiedoptions">
 <p>
 <descrip>
-	<tag>--disable-esi</tag>
-	<p>The ESI feature is now disabled by default.
-	   Use <em>--enable-esi</em> if needed.
+	<p>No build options have changed behaviour in this version.
 
 </descrip>
 </p>
@@ -270,9 +271,18 @@ This section gives an account of those changes in three categories:
 	<tag>--enable-cachemgr-hostname=</tag>
 	<p>The <em>cachemgr.cgi</em> tool this option relates to has been removed.
 
+	<tag>--enable-esi</tag>
+	<p>Edge Side Includes (ESI) protocol is no longer supported natively.
+
+	<tag>--without-expat</tag>
+	<p>The ESI feature using libexpat has been removed.
+
 	<tag>--without-gnugss</tag>
 	<p>Renamed to <em>--without-gss</em>.
 
+	<tag>--without-xml2</tag>
+	<p>The ESI feature using libxml2 has been removed.
+
 	<tag>CPPFLAGS=-DHEADERS_LOG</tag>
 	<p>The code enabled by this preprocessor macro has not built for many
 	   years, indicating that the feature is unused.

lib/Makefile.am

@@ -10,9 +10,6 @@ include $(top_srcdir)/src/Common.am
 SUBDIRS=
 EXTRA_DIST=
 
-if ENABLE_ESI
-SUBDIRS += libTrie
-endif
 if ENABLE_SNMP
 SUBDIRS += snmplib
 endif