- new

Changed files:
    mod_proxy_html.c -> 1.1
    mod_proxy_html.html -> 1.1

diff --git a/mod_proxy_html.c b/mod_proxy_html.c
new file mode 100644 (file)
index 0000000..5830516
--- /dev/null
+++ b/mod_proxy_html.c
@@ -0,0 +1,356 @@
+/*
+         Copyright (c) 2003, WebThing Ltd
+         Author: Nick Kew <nick@webthing.com>
+                 
+This program is free software; you can redistribute it and/or modify
+it under the terms of the GNU General Public License as published by
+the Free Software Foundation; either version 2 of the License, or
+(at your option) any later version.
+      
+This program is distributed in the hope that it will be useful,
+but WITHOUT ANY WARRANTY; without even the implied warranty of
+MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+GNU General Public License for more details.
+        
+You should have received a copy of the GNU General Public License
+along with this program; if not, write to the Free Software
+Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
+                   
+*/
+
+/* libxml */
+#include <libxml/HTMLparser.h>
+
+/* apache */
+#include <http_protocol.h>
+#include <http_config.h>
+#include <http_log.h>
+#include <apr_strings.h>
+
+module AP_MODULE_DECLARE_DATA proxy_html_module ;
+
+typedef struct {
+  struct urlmap* next ;
+  const char* from ;
+  const char* to ;
+} urlmap ;
+typedef struct {
+  urlmap* map ;
+  const char* doctype ;
+} proxy_html_conf ;
+typedef struct {
+  htmlSAXHandlerPtr sax ;
+  ap_filter_t* f ;
+  urlmap* map ;
+  htmlParserCtxtPtr parser ;
+  apr_bucket_brigade* bb ;
+} saxctxt ;
+
+static void pstartDocument(void* ctxt) {
+  saxctxt* ctx = (saxctxt*) ctxt ;
+
+  proxy_html_conf* cfg = ap_get_module_config(ctx->f->r->per_dir_config,&proxy_html_module);
+  apr_table_unset(ctx->f->r->headers_out, "Content-Length") ;
+  apr_table_unset(ctx->f->r->headers_out, "ETag") ;
+  ap_set_content_type(ctx->f->r, "text/html;charset=utf-8") ;
+  ap_fputs(ctx->f->next, ctx->bb, cfg->doctype) ;
+}
+static void pendDocument(void* ctxt) {
+  saxctxt* ctx = (saxctxt*) ctxt ;
+  APR_BRIGADE_INSERT_TAIL(ctx->bb,
+       apr_bucket_eos_create(ctx->bb->bucket_alloc) ) ;
+  ap_pass_brigade(ctx->f->next, ctx->bb) ;
+}
+typedef struct {
+       const char* name ;
+       const char** attrs ;
+} elt_t ;
+
+static void pstartElement(void* ctxt, const xmlChar* name,
+                       const xmlChar** attrs ) {
+
+  saxctxt* ctx = (saxctxt*) ctxt ;
+
+  static const char* href[] = { "href", NULL } ;
+  static const char* cite[] = { "cite", NULL } ;
+  static const char* action[] = { "action", NULL } ;
+  static const char* imgattr[] = { "src", "longdesc", "usemap", NULL } ;
+  static const char* inputattr[] = { "src", "usemap", NULL } ;
+  static const char* scriptattr[] = { "src", "for", NULL } ;
+  static const char* frameattr[] = { "src", "longdesc", NULL } ;
+  static const char* objattr[] = { "classid", "codebase", "data", "usemap", NULL } ;
+  static const char* profile[] = { "profile", NULL } ;
+  static const char* background[] = { "background", NULL } ;
+  static const char* codebase[] = { "codebase", NULL } ;
+
+  static elt_t linked_elts[] = {
+    { "a" , href } ,
+    { "form", action } ,
+    { "base" , href } ,
+    { "area" , href } ,
+    { "link" , href } ,
+    { "img" , imgattr } ,
+    { "input" , inputattr } ,
+    { "script" , scriptattr } ,
+    { "frame", frameattr } ,
+    { "iframe", frameattr } ,
+    { "object", objattr } ,
+    { "q" , cite } ,
+    { "blockquote" , cite } ,
+    { "ins" , cite } ,
+    { "del" , cite } ,
+    { "head" , profile } ,
+    { "body" , background } ,
+    { "applet", codebase } ,
+    { NULL, NULL }
+  } ;
+
+  ap_fputc(ctx->f->next, ctx->bb, '<') ;
+  ap_fputs(ctx->f->next, ctx->bb, name) ;
+
+  if ( attrs ) {
+    const char** linkattrs = 0 ;
+    const xmlChar** a ;
+    elt_t* elt ;
+    for ( elt = linked_elts;  elt->name != NULL ; ++elt )
+      if ( !strcmp(elt->name, name) ) {
+       linkattrs = elt->attrs ;
+       break ;
+      }
+    for ( a = attrs ; *a ; a += 2 ) {
+      const xmlChar* value = a[1] ;
+      if ( linkattrs && value ) {
+       int is_uri = 0 ;
+       const char** linkattr = linkattrs ;
+       do {
+         if ( !strcmp(*linkattr, *a) ) {
+           is_uri = 1 ;
+           break ;
+         }
+       } while ( *++linkattr ) ;
+       if ( is_uri ) {
+         urlmap* m ;
+         for ( m = ctx->map ; m ; m = (urlmap*)m->next ) {
+           if ( ! strncasecmp(value, m->from, strlen(m->from) ) ) {
+             value = apr_pstrcat(ctx->f->r->pool, m->to, value+strlen(m->from) , NULL) ;
+             break ;
+           }
+         }
+       }
+      }
+      if ( ! value )
+        ap_fputstrs(ctx->f->next, ctx->bb, " ", a[0], NULL) ;
+      else
+       ap_fputstrs(ctx->f->next, ctx->bb, " ", a[0], "=\"", value, "\"", NULL) ;
+    }
+  }
+  ap_fputc(ctx->f->next, ctx->bb, '>') ;
+}
+static void pendElement(void* ctxt, const xmlChar* name) {
+  const char** p ;
+  saxctxt* ctx = (saxctxt*) ctxt ;
+  static const char* empty_elts[] = {
+       "br" ,
+       "link" ,
+       "img" ,
+       "hr" ,
+       "input" ,
+       "meta" ,
+       "base" ,
+       "area" ,
+       "param" ,
+       "col" ,
+       "frame" ,
+       "isindex" ,
+       "basefont" ,
+       NULL
+  } ;
+  for ( p = empty_elts ; *p ; ++p )
+    if ( !strcmp( *p, name) )
+       return ;
+  ap_fprintf(ctx->f->next, ctx->bb, "</%s>", name) ;
+}
+#define FLUSH ap_fwrite(ctx->f->next, ctx->bb, (chars+begin), (i-begin)) ; begin = i+1
+static void pcharacters(void* ctxt, const xmlChar *chars, int length) {
+  saxctxt* ctx = (saxctxt*) ctxt ;
+  int i ;
+  int begin ;
+  for ( begin=i=0; i<length; i++ ) {
+    switch (chars[i]) {
+      case '&' : FLUSH ; ap_fputs(ctx->f->next, ctx->bb, "&amp;") ; break ;
+      case '<' : FLUSH ; ap_fputs(ctx->f->next, ctx->bb, "&lt;") ; break ;
+      case '>' : FLUSH ; ap_fputs(ctx->f->next, ctx->bb, "&gt;") ; break ;
+      case '"' : FLUSH ; ap_fputs(ctx->f->next, ctx->bb, "&quot;") ; break ;
+      default : break ;
+    }
+  }
+  FLUSH ;
+}
+static void pcdata(void* ctxt, const xmlChar *chars, int length) {
+  saxctxt* ctx = (saxctxt*) ctxt ;
+  ap_fwrite(ctx->f->next, ctx->bb, chars, length) ;
+}
+static void pcomment(void* ctxt, const xmlChar *chars) {
+  saxctxt* ctx = (saxctxt*) ctxt ;
+  ap_fputstrs(ctx->f->next, ctx->bb, "<!--", chars, "-->", NULL) ;
+}
+static htmlSAXHandlerPtr setupSAX(apr_pool_t* pool) {
+  htmlSAXHandlerPtr sax = apr_pcalloc(pool, sizeof(htmlSAXHandler) ) ;
+  sax->startDocument = pstartDocument ;
+  sax->endDocument = pendDocument ;
+  sax->startElement = pstartElement ;
+  sax->endElement = pendElement ;
+  sax->characters = pcharacters ;
+  sax->comment = pcomment ;
+  sax->cdataBlock = pcdata ;
+  return sax ;
+}
+static char* ctype2encoding(apr_pool_t* pool, const char* in) {
+  char* x ;
+  char* ptr ;
+  char* ctype ;
+  if ( ! in )
+    return 0 ;
+  ctype = strdup(in) ;
+  for ( ptr = ctype ; *ptr; ++ptr)
+    if ( isupper(*ptr) )
+      *ptr = tolower(*ptr) ;
+
+  if ( ptr = strstr(ctype, "charset=") , ptr > 0 ) {
+    ptr += 8 ;  // jump over "charset=" and chop anything that follows charset
+    if ( x = strchr(ptr, ' ') , x )
+      *x = 0 ;
+    if ( x = strchr(ptr, ';') , x )
+      *x = 0 ;
+  }
+  x =  ptr ? apr_pstrdup(pool, ptr) : 0 ;
+  free (ctype ) ;
+  return x ;
+}
+
+static int proxy_html_filter_init(ap_filter_t* f) {
+  saxctxt* fctx ;
+
+  xmlCharEncoding enc
+       = xmlParseCharEncoding(ctype2encoding(f->r->pool, f->r->content_type)) ;
+
+/* remove content-length filter */
+  ap_filter_rec_t* clf = ap_get_output_filter_handle("CONTENT_LENGTH") ;
+  ap_filter_t* ff = f->next ;
+
+  do {
+    ap_filter_t* fnext = ff->next ;
+    if ( ff->frec == clf )
+      ap_remove_output_filter(ff) ;
+    ff = fnext ;
+  } while ( ff ) ;
+
+  fctx = f->ctx = apr_pcalloc(f->r->pool, sizeof(saxctxt)) ;
+  fctx->sax = setupSAX(f->r->pool) ;
+  fctx->f = f ;
+  fctx->bb = apr_brigade_create(f->r->pool, f->r->connection->bucket_alloc) ;
+  fctx->map = ap_get_module_config(f->r->per_dir_config,&proxy_html_module);
+
+  if ( f->r->proto_num >= 1001 ) {
+    if ( ! f->r->main && ! f->r->prev )
+      f->r->chunked = 1 ;
+  }
+  fctx->parser = htmlCreatePushParserCtxt
+       ( fctx->sax , fctx, "    ", 4, 0, enc) ;
+  return OK ;
+}
+static saxctxt* check_filter_init (ap_filter_t* f) {
+
+  if ( f->r->proxyreq && f->r->content_type ) {
+    if ( strncasecmp(f->r->content_type, "text/html", 9) &&
+       strncasecmp(f->r->content_type, "application/xhtml+xml", 21) ) {
+      ap_remove_output_filter(f) ;
+      return NULL ;
+    }
+  }
+
+  if ( ! f->ctx )
+    proxy_html_filter_init(f) ;
+  return f->ctx ;
+}
+static int proxy_html_filter(ap_filter_t* f, apr_bucket_brigade* bb) {
+  apr_bucket* b ;
+  const char* buf = 0 ;
+  apr_size_t bytes = 0 ;
+
+  saxctxt* ctxt = check_filter_init(f) ;
+  if ( ! ctxt )
+    return ap_pass_brigade(f->next, bb) ;
+
+  for ( b = APR_BRIGADE_FIRST(bb) ;
+       b != APR_BRIGADE_SENTINEL(bb) ;
+       b = APR_BUCKET_NEXT(b) ) {
+    if ( APR_BUCKET_IS_EOS(b) ) {
+      htmlParseChunk(ctxt->parser, buf, 0, 1) ;
+      htmlFreeParserCtxt(ctxt->parser) ;
+    } else if ( apr_bucket_read(b, &buf, &bytes, APR_BLOCK_READ)
+             == APR_SUCCESS ) {
+      htmlParseChunk(ctxt->parser, buf, bytes, 0) ;
+    } else {
+      ap_log_rerror(APLOG_MARK, APLOG_ERR, 0, f->r, "Error in bucket read") ;
+    }
+  }
+  apr_brigade_destroy(bb) ;
+  return APR_SUCCESS ;
+}
+static const char* DEFAULT_DOCTYPE =
+       "<!DOCTYPE html PUBLIC \"-//W3C//DTD HTML 4.01//EN\">\n" ;
+
+static void* proxy_html_config(apr_pool_t* pool, char* x) {
+  proxy_html_conf* ret = apr_pcalloc(pool, sizeof(proxy_html_conf) ) ;
+  ret->doctype = DEFAULT_DOCTYPE ;
+  return ret ;
+}
+static void* proxy_html_merge(apr_pool_t* pool, void* BASE, void* ADD) {
+  proxy_html_conf* base = (proxy_html_conf*) BASE ;
+  proxy_html_conf* add = (proxy_html_conf*) ADD ;
+  proxy_html_conf* conf = apr_palloc(pool, sizeof(proxy_html_conf)) ;
+  conf->map = add->map ? add->map : base->map ;
+  if ( add->map && base->map ) {
+    urlmap* newmap = add->map ;
+    while ( newmap->next )
+       newmap = (urlmap*)newmap->next ;
+    newmap->next = (struct urlmap*) base->map ;
+  }
+  conf->doctype = ( add->doctype == DEFAULT_DOCTYPE )
+               ? base->doctype : add->doctype ;
+  return conf ;
+}
+static const char* set_urlmap(cmd_parms* cmd, void* CFG,
+       const char* from, const char* to) {
+  proxy_html_conf* cfg = (proxy_html_conf*)CFG ;
+  urlmap* newmap = apr_palloc(cmd->pool, sizeof(urlmap) ) ;
+  newmap->from = apr_pstrdup(cmd->pool, from) ;
+  newmap->to = apr_pstrdup(cmd->pool, to) ;
+  newmap->next = (struct urlmap*) cfg->map ;
+  cfg->map = newmap ;
+  return NULL ;
+}
+static const char* set_doctype(cmd_parms* cmd, void* CFG, const char* t) {
+  proxy_html_conf* cfg = (proxy_html_conf*)CFG ;
+  cfg->doctype = apr_pstrdup(cmd->pool, t) ;
+  return NULL ;
+}
+static const command_rec proxy_html_cmds[] = {
+  AP_INIT_TAKE2("ProxyHTMLURLMap", set_urlmap, NULL, OR_ALL, "Map URL From To" ) ,
+  AP_INIT_TAKE1("ProxyHTMLDoctype", set_doctype, NULL, OR_ALL, "Set Doctype for URL mapped documents" ) ,
+  { NULL }
+} ;
+static void proxy_html_hooks(apr_pool_t* p) {
+  ap_register_output_filter("proxy-html", proxy_html_filter,
+       proxy_html_filter_init, AP_FTYPE_RESOURCE) ;
+}
+module AP_MODULE_DECLARE_DATA proxy_html_module = {
+       STANDARD20_MODULE_STUFF,
+       proxy_html_config,
+       proxy_html_merge,
+       NULL,
+       NULL,
+       proxy_html_cmds,
+       proxy_html_hooks
+} ;

diff --git a/mod_proxy_html.html b/mod_proxy_html.html
new file mode 100644 (file)
index 0000000..7580f56
--- /dev/null
+++ b/mod_proxy_html.html
@@ -0,0 +1,81 @@
+<?xml version="1.0" encoding="utf-8"?><!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Strict//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-strict.dtd">
+<html lang="en"><head>
+<title>mod_proxy_html</title>
+<style type="text/css">
+@import url(/index.css) ;
+</style>
+</head><body>
+<div id="apache">
+<h1><a href="./">mod_proxy_html</a></h1>
+<div class="notice">
+<h2>Notice</h2>
+<p>Users of mod_proxy_html should upgrade to <a href="http://xmlsoft.org/">libxml2 version 2.5.10</a> or later.
+This fixes bugs in earlier versions that
+can in some cases have a severe impact on performance.</p>
+</div>
+
+<p>mod_proxy_html is based on one specific capability of
+<a href="../mod_accessibility/">mod_accessibility</a>, namely that of
+rewriting HTML links so that they don't break in a reverse proxy.
+The need for it was identified in <a href="http://groups.google.com/groups?dq=&amp;hl=en&amp;lr=&amp;ie=UTF-8&amp;th=f71d3dfe32c6387f&amp;seekm=slrnbhi6p4.4pb.wizball%40babar.foo.com&amp;frame=off">a Usenet thread</a>.</p>
+<p>The problem arises when links such as <code>&lt;a
+href="http://private-address.example.com/"></code> are used in
+a proxied page, when the server <code>private-address.example.com</code>
+needs to be proxied (for example, because its address is not valid
+beyond a private network).  <code>mod_proxy_html</code> rewrites
+such URLs into the proxy's own namespace.</p>
+<p>The key directive required for this is <tt>ProxyHTMLURLMap</tt>.
+This is functionally identical to <tt>AccessibilityURLMap</tt>,
+which is documented in the
+<a href="../mod_accessibility/">mod_accessibility</a> pages.</p>
+<h3>Example: how to use it</h3>
+<p>In this case, the proxy is serving pages from two internal servers
+<tt>internal.example.org</tt> and <tt>other.example.org</tt>
+neither of which is accessible directly from the outside world.
+The directives for this are:</p>
+<dl>
+<dt><code>ProxyPass    /internal.example.org/  http://internal.example.org/</code>
+<br/><code>ProxyPass   /other.example.org/     http://other.example.org/</code>
+<dd>Map the URLs to the proxy's address space, as documented in Apache's
+<tt>mod_proxy</tt> documentation.</dd>
+<dt><code>ProxyHTMLURLMap      http://internal.example.org     /internal.example.org</code>
+<br/><code>ProxyHTMLURLMap     http://other.example.org        /other.example.org</code></dt>
+<dd>This causes mod_proxy_html to rewrite all absolute URLs for
+the internal domains to the proxy's address space.  These directives
+<em>could</em> go inside the Location directives below, but putting them
+at top level saves repeating them at different Locations.
+<strong>NOTE:</strong> because the pattern matching used is starts-with,
+it is best to omit any trailing slash from the above URL.
+</dd>
+<dt><code>&lt;Location /internal.example.org/></code></dt>
+<dd>Specifies directives that will apply (only) under 
+<tt>/internal.example.org</tt></dd>
+<dt><code>ProxyPassReverse     /</code></dt>
+<dd>Rewrite URLs in HTTP Headers (mod_proxy)</dd>
+<dt><code>SetOutputFilter      proxy-html</code></dt>
+<dd>Inserts (activates) the proxy-html output filter</dd>
+<dt><code>ProxyHTMLURLMap      /       /internal.example.org/</code></dt>
+<dd>Rewrites URLs starting with a <tt>/</tt> into the proxy's address space.</dd>
+<dt><code>ProxyHTMLURLMap      /internal.example.org/  /internal.example.org/</code></dt>
+<dd>This is necessary to prevent the previous rule rewriting relative URLs
+already in the Proxy's address space.  It must come after the previous rule.</dd>
+<dt><code>&lt;/Location></code></dt>
+<dd>Ends directives for <tt>/internal.example.org</tt>.  Equivalent directives
+are of course also required for <tt>/other.example.org</tt>, but are
+omitted (for brevity) from this page.</dd>
+</dl>
+<h2>Availability</h2>
+<p><a href="mod_proxy_html.c">mod_proxy_html.c source code</a> is available
+under the <a href="http://www.fsf.org/licenses/gpl.html">GNU
+General Public License (GPL)</a>.  As with other opensource modules,
+we can consider alternative licenses by request.</p>
+</div>
+<div id="navbar"><a class="internal" href="./" title="Up">Up</a>
+*
+<a class="internal" href="/" title="WebThing Apache Centre">Home</a>
+*
+<a class="internal" href="/contact.html" title="Contact WebThing">Contact</a>
+*
+<a class="external" href="http://www.webthing.com/" title="WebThing Ltd">WebÞing</a>
+*
+<a class="external" href="http://www.apache.org/" title="Apache Software Foundation">Apache</a></div></body></html>