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440 lines
17 KiB
440 lines
17 KiB
diff --git a/docs/manual/mod/mod_rewrite.html.en b/docs/manual/mod/mod_rewrite.html.en
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index 2b8ed35..b7f1c31 100644
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--- a/docs/manual/mod/mod_rewrite.html.en
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+++ b/docs/manual/mod/mod_rewrite.html.en
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@@ -1403,6 +1403,16 @@ cannot use <code>$N</code> in the substitution string!
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<td>Force the <a class="glossarylink" href="../glossary.html#mime-type" title="see glossary">MIME-type</a> of the target file
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to be the specified type. <em><a href="../rewrite/flags.html#flag_t">details ...</a></em></td>
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</tr>
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+<tr>
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+ <td>UnsafeAllow3F</td>
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+ <td>Allows substitutions from URL's that may be unsafe.
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+ <em><a href="../rewrite/flags.html#flag_unsafe_allow_3f">details ...</a></em></td>
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+ </tr>
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+<tr>
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+ <td>UnsafePrefixStat</td>
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+ <td>Allows potentially unsafe substitutions from a leading variable or backreference to a filesystem path.
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+ <em><a href="../rewrite/flags.html#flag_unsafe_prefix_stat">details ...</a></em></td>
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+ </tr>
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</table>
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<div class="note"><h3>Home directory expansion</h3>
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diff --git a/docs/manual/rewrite/flags.html.en b/docs/manual/rewrite/flags.html.en
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index 734809a..30d549d 100644
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--- a/docs/manual/rewrite/flags.html.en
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+++ b/docs/manual/rewrite/flags.html.en
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@@ -768,6 +768,30 @@ re-processing (including subsequent rounds of mod_rewrite processing).
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The <code>L</code> flag can be useful in this context to end the
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<em>current</em> round of mod_rewrite processing.</p>
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+</div>
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+
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+<div class="section">
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+<h2><a name="flag_unsafe_allow_3f" id="flag_unsafe_allow_3f">UnsafeAllow3F</a></h2>
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+
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+<p>
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+Setting this flag is required to allow a rewrite to continue If the
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+HTTP request being written has an encoded question mark, '%3f', and the
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+rewritten result has a '?' in the substiution. This protects from a malicious
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+URL taking advantage of a capture and re-substitution of the encoded
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+question mark.</p>
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+
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+</div>
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+<div class="section">
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+<h2><a name="flag_unsafe_prefix_status" id="flag_unsafe_prefix_status">UnsafePrefixStat</a></h2>
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+
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+<p>
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+Setting this flag is required in server-scoped substitutions
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+start with a variable or backreference and resolve to a filesystem path.
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+These substitutions are not prefixed with the document root.
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+This protects from a malicious URL causing the expanded substitution to
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+map to an unexpected filesystem location.
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+</p>
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+
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</div></div>
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<div class="bottomlang">
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<p><span>Available Languages: </span><a href="../en/rewrite/flags.html" title="English"> en </a> |
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diff --git a/modules/mappers/mod_rewrite.c b/modules/mappers/mod_rewrite.c
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index b71c67c..797f093 100644
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--- a/modules/mappers/mod_rewrite.c
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+++ b/modules/mappers/mod_rewrite.c
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@@ -172,6 +172,8 @@ static const char* really_last_key = "rewrite_really_last";
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#define RULEFLAG_QSLAST (1<<19)
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#define RULEFLAG_QSNONE (1<<20) /* programattic only */
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#define RULEFLAG_ESCAPECTLS (1<<21)
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+#define RULEFLAG_UNSAFE_PREFIX_STAT (1<<22)
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+#define RULEFLAG_UNSAFE_ALLOW3F (1<<23)
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/* return code of the rewrite rule
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* the result may be escaped - or not
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@@ -179,7 +181,7 @@ static const char* really_last_key = "rewrite_really_last";
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#define ACTION_NORMAL (1<<0)
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#define ACTION_NOESCAPE (1<<1)
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#define ACTION_STATUS (1<<2)
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-
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+#define ACTION_STATUS_SET (1<<3)
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#define MAPTYPE_TXT (1<<0)
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#define MAPTYPE_DBM (1<<1)
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@@ -203,6 +205,7 @@ static const char* really_last_key = "rewrite_really_last";
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#define OPTION_IGNORE_INHERIT (1<<8)
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#define OPTION_IGNORE_CONTEXT_INFO (1<<9)
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#define OPTION_LEGACY_PREFIX_DOCROOT (1<<10)
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+#define OPTION_UNSAFE_PREFIX_STAT (1<<12)
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#ifndef RAND_MAX
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#define RAND_MAX 32767
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@@ -296,6 +299,14 @@ typedef enum {
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CONDPAT_AP_EXPR
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} pattern_type;
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+typedef enum {
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+ RULE_RC_NOMATCH = 0, /* the rule didn't match */
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+ RULE_RC_MATCH = 1, /* a matching rule w/ substitution */
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+ RULE_RC_NOSUB = 2, /* a matching rule w/ no substitution */
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+ RULE_RC_STATUS_SET = 3 /* a matching rule that has set an HTTP error
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+ to be returned in r->status */
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+} rule_return_type;
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+
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typedef struct {
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char *input; /* Input string of RewriteCond */
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char *pattern; /* the RegExp pattern string */
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@@ -927,10 +938,15 @@ static void fully_qualify_uri(request_rec *r)
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return;
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}
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+static int startsWith(request_rec *r, const char *haystack, const char *needle) {
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+ int rc = (ap_strstr_c(haystack, needle) == haystack);
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+ rewritelog((r, 5, NULL, "prefix_stat startsWith(%s, %s) %d", haystack, needle, rc));
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+ return rc;
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+}
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/*
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- * stat() only the first segment of a path
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+ * stat() only the first segment of a path, and only if it matches the output of the last matching rule
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*/
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-static int prefix_stat(const char *path, apr_pool_t *pool)
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+static int prefix_stat(request_rec *r, const char *path, apr_pool_t *pool, rewriterule_entry *lastsub)
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{
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const char *curpath = path;
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const char *root;
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@@ -964,10 +980,36 @@ static int prefix_stat(const char *path, apr_pool_t *pool)
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apr_finfo_t sb;
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if (apr_stat(&sb, statpath, APR_FINFO_MIN, pool) == APR_SUCCESS) {
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- return 1;
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+ if (!lastsub) {
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+ rewritelog((r, 3, NULL, "prefix_stat no lastsub subst prefix %s", statpath));
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+ return 1;
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+ }
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+
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+ rewritelog((r, 3, NULL, "prefix_stat compare statpath %s and lastsub output %s STATOK %d ",
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+ statpath, lastsub->output, lastsub->flags & RULEFLAG_UNSAFE_PREFIX_STAT));
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+ if (lastsub->flags & RULEFLAG_UNSAFE_PREFIX_STAT) {
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+ return 1;
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+ }
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+ else {
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+ const char *docroot = ap_document_root(r);
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+ const char *context_docroot = ap_context_document_root(r);
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+ /*
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+ * As an example, path (r->filename) is /var/foo/bar/baz.html
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+ * even if the flag is not set, we can accept a rule that
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+ * began with a literal /var (stapath), or if the entire path
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+ * starts with the docroot or context document root
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+ */
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+ if (startsWith(r, lastsub->output, statpath) ||
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+ startsWith(r, path, docroot) ||
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+ ((docroot != context_docroot) &&
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+ startsWith(r, path, context_docroot))) {
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+ return 1;
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+ }
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+ }
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}
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}
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+ /* prefix will be added */
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return 0;
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}
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@@ -3046,6 +3088,9 @@ static const char *cmd_rewriteoptions(cmd_parms *cmd,
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else if (!strcasecmp(w, "legacyprefixdocroot")) {
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options |= OPTION_LEGACY_PREFIX_DOCROOT;
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}
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+ else if (!strcasecmp(w, "UnsafePrefixStat")) {
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+ options |= OPTION_UNSAFE_PREFIX_STAT;
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+ }
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else {
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return apr_pstrcat(cmd->pool, "RewriteOptions: unknown option '",
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w, "'", NULL);
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@@ -3752,6 +3797,18 @@ static const char *cmd_rewriterule_setflag(apr_pool_t *p, void *_cfg,
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++error;
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}
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break;
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+ case 'u':
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+ case 'U':
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+ if (!strcasecmp(key, "nsafePrefixStat")){
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+ cfg->flags |= (RULEFLAG_UNSAFE_PREFIX_STAT);
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+ }
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+ else if(!strcasecmp(key, "nsafeAllow3F")) {
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+ cfg->flags |= RULEFLAG_UNSAFE_ALLOW3F;
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+ }
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+ else {
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+ ++error;
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+ }
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+ break;
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default:
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++error;
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break;
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@@ -4102,7 +4159,8 @@ static APR_INLINE void force_type_handler(rewriterule_entry *p,
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/*
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* Apply a single RewriteRule
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*/
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-static int apply_rewrite_rule(rewriterule_entry *p, rewrite_ctx *ctx)
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+static rule_return_type apply_rewrite_rule(rewriterule_entry *p,
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+ rewrite_ctx *ctx)
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{
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ap_regmatch_t regmatch[AP_MAX_REG_MATCH];
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apr_array_header_t *rewriteconds;
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@@ -4153,7 +4211,7 @@ static int apply_rewrite_rule(rewriterule_entry *p, rewrite_ctx *ctx)
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rc = !ap_regexec(p->regexp, ctx->uri, AP_MAX_REG_MATCH, regmatch, 0);
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if (! (( rc && !(p->flags & RULEFLAG_NOTMATCH)) ||
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(!rc && (p->flags & RULEFLAG_NOTMATCH)) ) ) {
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- return 0;
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+ return RULE_RC_NOMATCH;
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}
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/* It matched, wow! Now it's time to prepare the context structure for
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@@ -4204,7 +4262,7 @@ static int apply_rewrite_rule(rewriterule_entry *p, rewrite_ctx *ctx)
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}
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}
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else if (!rc) {
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- return 0;
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+ return RULE_RC_NOMATCH;
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}
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/* If some HTTP header was involved in the condition, remember it
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@@ -4224,6 +4282,15 @@ static int apply_rewrite_rule(rewriterule_entry *p, rewrite_ctx *ctx)
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newuri = do_expand(p->output, ctx, p);
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rewritelog((r, 2, ctx->perdir, "rewrite '%s' -> '%s'", ctx->uri,
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newuri));
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+ if (!(p->flags & RULEFLAG_UNSAFE_ALLOW3F) &&
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+ ap_strcasestr(r->unparsed_uri, "%3f") &&
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+ ap_strchr_c(newuri, '?')) {
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+ ap_log_rerror(APLOG_MARK, APLOG_ERR, 0, r, APLOGNO()
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+ "Unsafe URL with %%3f URL rewritten without "
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+ "UnsafeAllow3F");
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+ r->status = HTTP_FORBIDDEN;
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+ return RULE_RC_STATUS_SET;
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+ }
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}
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/* expand [E=var:val] and [CO=<cookie>] */
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@@ -4241,7 +4308,7 @@ static int apply_rewrite_rule(rewriterule_entry *p, rewrite_ctx *ctx)
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r->status = p->forced_responsecode;
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}
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- return 2;
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+ return RULE_RC_NOSUB;
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}
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/* Now adjust API's knowledge about r->filename and r->args */
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@@ -4293,7 +4360,7 @@ static int apply_rewrite_rule(rewriterule_entry *p, rewrite_ctx *ctx)
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r->filename));
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r->filename = apr_pstrcat(r->pool, "proxy:", r->filename, NULL);
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- return 1;
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+ return RULE_RC_MATCH;
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}
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/* If this rule is explicitly forced for HTTP redirection
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@@ -4308,7 +4375,7 @@ static int apply_rewrite_rule(rewriterule_entry *p, rewrite_ctx *ctx)
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r->filename));
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r->status = p->forced_responsecode;
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- return 1;
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+ return RULE_RC_MATCH;
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}
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/* Special Rewriting Feature: Self-Reduction
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@@ -4330,7 +4397,7 @@ static int apply_rewrite_rule(rewriterule_entry *p, rewrite_ctx *ctx)
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"with %s", p->forced_responsecode, r->filename));
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r->status = p->forced_responsecode;
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- return 1;
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+ return RULE_RC_MATCH;
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}
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/* Finally remember the forced mime-type */
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@@ -4339,7 +4406,7 @@ static int apply_rewrite_rule(rewriterule_entry *p, rewrite_ctx *ctx)
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/* Puuhhhhhhhh... WHAT COMPLICATED STUFF ;_)
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* But now we're done for this particular rule.
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*/
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- return 1;
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+ return RULE_RC_MATCH;
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}
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/*
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@@ -4347,13 +4414,13 @@ static int apply_rewrite_rule(rewriterule_entry *p, rewrite_ctx *ctx)
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* i.e. a list of rewrite rules
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*/
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static int apply_rewrite_list(request_rec *r, apr_array_header_t *rewriterules,
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- char *perdir)
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+ char *perdir, rewriterule_entry **lastsub)
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{
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rewriterule_entry *entries;
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rewriterule_entry *p;
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int i;
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int changed;
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- int rc;
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+ rule_return_type rc;
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int s;
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rewrite_ctx *ctx;
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int round = 1;
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@@ -4361,6 +4428,7 @@ static int apply_rewrite_list(request_rec *r, apr_array_header_t *rewriterules,
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ctx = apr_palloc(r->pool, sizeof(*ctx));
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ctx->perdir = perdir;
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ctx->r = r;
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+ *lastsub = NULL;
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/*
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* Iterate over all existing rules
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@@ -4388,7 +4456,12 @@ static int apply_rewrite_list(request_rec *r, apr_array_header_t *rewriterules,
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ctx->vary = NULL;
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rc = apply_rewrite_rule(p, ctx);
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- if (rc) {
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+ if (rc != RULE_RC_NOMATCH) {
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+
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+ if (!(p->flags & RULEFLAG_NOSUB)) {
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+ rewritelog((r, 2, perdir, "setting lastsub to rule with output %s", p->output));
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+ *lastsub = p;
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+ }
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/* Catch looping rules with pathinfo growing unbounded */
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if ( strlen( r->filename ) > 2*r->server->limit_req_line ) {
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@@ -4408,6 +4481,12 @@ static int apply_rewrite_list(request_rec *r, apr_array_header_t *rewriterules,
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apr_table_merge(r->headers_out, "Vary", ctx->vary);
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}
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+
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+ /* Error while evaluating rule, r->status set */
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+ if (RULE_RC_STATUS_SET == rc) {
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+ return ACTION_STATUS_SET;
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+ }
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+
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/*
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* The rule sets the response code (implies match-only)
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*/
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@@ -4418,7 +4497,7 @@ static int apply_rewrite_list(request_rec *r, apr_array_header_t *rewriterules,
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/*
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* Indicate a change if this was not a match-only rule.
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*/
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- if (rc != 2) {
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+ if (rc != RULE_RC_NOSUB) {
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changed = ((p->flags & RULEFLAG_NOESCAPE)
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? ACTION_NOESCAPE : ACTION_NORMAL);
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}
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@@ -4607,6 +4686,7 @@ static int hook_uri2file(request_rec *r)
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int rulestatus;
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void *skipdata;
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const char *oargs;
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+ rewriterule_entry *lastsub = NULL;
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/*
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* retrieve the config structures
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@@ -4718,7 +4798,7 @@ static int hook_uri2file(request_rec *r)
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/*
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* now apply the rules ...
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*/
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- rulestatus = apply_rewrite_list(r, conf->rewriterules, NULL);
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+ rulestatus = apply_rewrite_list(r, conf->rewriterules, NULL, &lastsub);
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apr_table_setn(r->notes, "mod_rewrite_rewritten",
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apr_psprintf(r->pool,"%d",rulestatus));
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}
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@@ -4756,6 +4836,9 @@ static int hook_uri2file(request_rec *r)
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r->status = HTTP_OK;
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return n;
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}
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+ else if (ACTION_STATUS_SET == rulestatus) {
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+ return r->status;
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+ }
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if (to_proxyreq) {
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/* it should be go on as an internal proxy request */
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@@ -4875,23 +4958,29 @@ static int hook_uri2file(request_rec *r)
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return HTTP_BAD_REQUEST;
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}
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- /* if there is no valid prefix, we call
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- * the translator from the core and
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- * prefix the filename with document_root
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+ /* We have r->filename as a path in a server-context rewrite without
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+ * the PT flag. The historical behavior is to treat it as a verbatim
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+ * filesystem path iff the first component of the path exists and is
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+ * readable by httpd. Otherwise, it is interpreted as DocumentRoot
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+ * relative.
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*
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* NOTICE:
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* We cannot leave out the prefix_stat because
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- * - when we always prefix with document_root
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- * then no absolute path can be created, e.g. via
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- * emulating a ScriptAlias directive, etc.
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- * - when we always NOT prefix with document_root
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+ * - If we always prefix with document_root
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+ * then no absolute path can could ever be used in
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+ * a substitution. e.g. emulating an Alias.
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+ * - If we never prefix with document_root
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* then the files under document_root have to
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* be references directly and document_root
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* gets never used and will be a dummy parameter -
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- * this is also bad
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+ * this is also bad.
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+ * - Later addition: This part is questionable.
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+ * If we had never prefixed, users would just
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+ * need %{DOCUMENT_ROOT} in substitutions or the
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+ * [PT] flag.
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*
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* BUT:
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- * Under real Unix systems this is no problem,
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+ * Under real Unix systems this is no perf problem,
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* because we only do stat() on the first directory
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* and this gets cached by the kernel for along time!
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*/
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@@ -4900,7 +4989,9 @@ static int hook_uri2file(request_rec *r)
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uri_reduced = apr_table_get(r->notes, "mod_rewrite_uri_reduced");
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}
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- if (!prefix_stat(r->filename, r->pool) || uri_reduced != NULL) {
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+ if (!prefix_stat(r, r->filename, r->pool,
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+ conf->options & OPTION_UNSAFE_PREFIX_STAT ? NULL : lastsub)
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+ || uri_reduced != NULL) {
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int res;
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char *tmp = r->uri;
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@@ -4945,6 +5036,7 @@ static int hook_fixup(request_rec *r)
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char *ofilename, *oargs;
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int is_proxyreq;
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void *skipdata;
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+ rewriterule_entry *lastsub;
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dconf = (rewrite_perdir_conf *)ap_get_module_config(r->per_dir_config,
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&rewrite_module);
|
|
@@ -5029,7 +5121,7 @@ static int hook_fixup(request_rec *r)
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/*
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* now apply the rules ...
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*/
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- rulestatus = apply_rewrite_list(r, dconf->rewriterules, dconf->directory);
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+ rulestatus = apply_rewrite_list(r, dconf->rewriterules, dconf->directory, &lastsub);
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if (rulestatus) {
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unsigned skip_absolute = is_absolute_uri(r->filename, NULL);
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int to_proxyreq = 0;
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@@ -5058,6 +5150,9 @@ static int hook_fixup(request_rec *r)
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r->status = HTTP_OK;
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return n;
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}
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+ else if (ACTION_STATUS_SET == rulestatus) {
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+ return r->status;
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+ }
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if (to_proxyreq) {
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/* it should go on as an internal proxy request */
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