core: Add the ability to do explicit matching on weak and strong ETags

as per RFC2616 Section 13.3.3.

git-svn-id: https://svn.apache.org/repos/asf/httpd/httpd/trunk@1479528 13f79535-47bb-0310-9956-ffa450edef68

diff --git a/CHANGES b/CHANGES
index 9031485875d0ee5341c6c407fb5978d56a24ade9..39027d9769aa108892afe35d91429ddf1a5ac77d 100644 (file)
--- a/CHANGES
+++ b/CHANGES
@@ -1,6 +1,10 @@
                                                          -*- coding: utf-8 -*-
 Changes with Apache 2.5.0
 
+  *) core: Add the ability to do explicit matching on weak and strong ETags
+     as per RFC2616 Section 13.3.3. [Graham Leggett, Co-Advisor
+     <coad measurement-factory.com>]
+
   *) mod_cache: Ensure that updated responses to HEAD requests don't get
      mistakenly paired with a previously cached body. Ensure that any existing
      body is removed when a HEAD request is cached. [Graham Leggett,

diff --git a/include/ap_mmn.h b/include/ap_mmn.h
index 6aab61e32d49f8209e97e6bc64d79d04173b1df1..9d42cf0a9baeb2f6f63eeb31ac57e3223d63169f 100644 (file)
--- a/include/ap_mmn.h
+++ b/include/ap_mmn.h
@@ -422,6 +422,7 @@
  * 20121222.8 (2.5.0-dev)  Add dav_join_error()
  * 20121222.9 (2.5.0-dev)  Add conn_sense_e
  * 20121222.10 (2.5.0-dev) Add cache_control_t.invalidated
+ * 20121222.11 (2.5.0-dev) Add ap_find_etag_weak(), ap_find_etag_strong()
  */
 
 #define MODULE_MAGIC_COOKIE 0x41503235UL /* "AP25" */
@@ -429,7 +430,7 @@
 #ifndef MODULE_MAGIC_NUMBER_MAJOR
 #define MODULE_MAGIC_NUMBER_MAJOR 20121222
 #endif
-#define MODULE_MAGIC_NUMBER_MINOR 10                  /* 0...n */
+#define MODULE_MAGIC_NUMBER_MINOR 11                  /* 0...n */
 
 /**
  * Determine if the server's current MODULE_MAGIC_NUMBER is at least a

diff --git a/include/httpd.h b/include/httpd.h
index 2b8f08ab559bd5efce4fa4ba1b25ca6d0ab3dce8..efcb2907c98920a0b758759521b279b5c2ba2006 100644 (file)
--- a/include/httpd.h
+++ b/include/httpd.h
@@ -1519,6 +1519,24 @@ AP_DECLARE(char *) ap_get_list_item(apr_pool_t *p, const char **field);
  */
 AP_DECLARE(int) ap_find_list_item(apr_pool_t *p, const char *line, const char *tok);
 
+/**
+ * Do a weak ETag comparison within an HTTP field value list.
+ * @param p The pool to allocate from
+ * @param line The field value list to search
+ * @param tok The token to search for
+ * @return 1 if found, 0 if not found.
+ */
+AP_DECLARE(int) ap_find_etag_weak(apr_pool_t *p, const char *line, const char *tok);
+
+/**
+ * Do a strong ETag comparison within an HTTP field value list.
+ * @param p The pool to allocate from
+ * @param line The field value list to search
+ * @param tok The token to search for
+ * @return 1 if found, 0 if not found.
+ */
+AP_DECLARE(int) ap_find_etag_strong(apr_pool_t *p, const char *line, const char *tok);
+
 /**
  * Retrieve a token, spacing over it and adjusting the pointer to
  * the first non-white byte afterwards.  Note that these tokens

diff --git a/modules/http/http_protocol.c b/modules/http/http_protocol.c
index 2f7861230357e4087ba31a4dd09a15e2f0de8ddc..b25482dbcf92e16fbe47e0b89dad87c6f6e85c6f 100644 (file)
--- a/modules/http/http_protocol.c
+++ b/modules/http/http_protocol.c
@@ -345,8 +345,8 @@ AP_DECLARE(int) ap_meets_conditions(request_rec *r)
      */
     if ((if_match = apr_table_get(r->headers_in, "If-Match")) != NULL) {
         if (if_match[0] != '*'
-            && (etag == NULL || etag[0] == 'W'
-                || !ap_find_list_item(r->pool, if_match, etag))) {
+                && (etag == NULL
+                        || !ap_find_etag_strong(r->pool, if_match, etag))) {
             return HTTP_PRECONDITION_FAILED;
         }
     }
@@ -386,19 +386,18 @@ AP_DECLARE(int) ap_meets_conditions(request_rec *r)
             }
             else if (etag != NULL) {
                 if (apr_table_get(r->headers_in, "Range")) {
-                    not_modified = etag[0] != 'W'
-                                   && ap_find_list_item(r->pool,
-                                                        if_nonematch, etag);
+                    not_modified = ap_find_etag_strong(r->pool, if_nonematch,
+                            etag);
                 }
                 else {
-                    not_modified = ap_find_list_item(r->pool,
-                                                     if_nonematch, etag);
+                    not_modified = ap_find_etag_weak(r->pool, if_nonematch,
+                            etag);
                 }
             }
         }
         else if (if_nonematch[0] == '*'
-                 || (etag != NULL
-                     && ap_find_list_item(r->pool, if_nonematch, etag))) {
+                || (etag != NULL
+                        && ap_find_etag_strong(r->pool, if_nonematch, etag))) {
             return HTTP_PRECONDITION_FAILED;
         }
     }

diff --git a/server/util.c b/server/util.c
index 676759fe48724acb90cc67713180ffb5e15bd2b5..6be14736b77c4cc7acc68044cb0eeda63a05679e 100644 (file)
--- a/server/util.c
+++ b/server/util.c
@@ -1287,27 +1287,58 @@ AP_DECLARE(char *) ap_get_list_item(apr_pool_t *p, const char **field)
     return token;
 }
 
+typedef enum ap_etag_e {
+    AP_ETAG_NONE,
+    AP_ETAG_WEAK,
+    AP_ETAG_STRONG
+} ap_etag_e;
+
 /* Find an item in canonical form (lowercase, no extra spaces) within
  * an HTTP field value list.  Returns 1 if found, 0 if not found.
  * This would be much more efficient if we stored header fields as
  * an array of list items as they are received instead of a plain string.
  */
-AP_DECLARE(int) ap_find_list_item(apr_pool_t *p, const char *line,
-                                  const char *tok)
+static int find_list_item(apr_pool_t *p, const char *line,
+                                  const char *tok, ap_etag_e type)
 {
     const unsigned char *pos;
     const unsigned char *ptr = (const unsigned char *)line;
     int good = 0, addspace = 0, in_qpair = 0, in_qstr = 0, in_com = 0;
 
-    if (!line || !tok)
+    if (!line || !tok) {
+        return 0;
+    }
+    if (type == AP_ETAG_STRONG && *tok != '\"') {
         return 0;
+    }
+    if (type == AP_ETAG_WEAK) {
+        if (*tok == 'W' && (*(tok+1)) == '/' && (*(tok+2)) == '\"') {
+            tok += 2;
+        }
+        else if (*tok != '\"') {
+            return 0;
+        }
+    }
 
     do {  /* loop for each item in line's list */
 
         /* Find first non-comma, non-whitespace byte */
-
-        while (*ptr == ',' || apr_isspace(*ptr))
+        while (*ptr == ',' || apr_isspace(*ptr)) {
             ++ptr;
+        }
+
+        /* Account for strong or weak Etags, depending on our search */
+        if (type == AP_ETAG_STRONG && *ptr != '\"') {
+            break;
+        }
+        if (type == AP_ETAG_WEAK) {
+            if (*ptr == 'W' && (*(ptr+1)) == '/' && (*(ptr+2)) == '\"') {
+                ptr += 2;
+            }
+            else if (*ptr != '\"') {
+                break;
+            }
+        }
 
         if (*ptr)
             good = 1;  /* until proven otherwise for this item */
@@ -1375,7 +1406,8 @@ AP_DECLARE(int) ap_find_list_item(apr_pool_t *p, const char *line,
                                if (in_com || in_qstr)
                                    good = good && (*pos++ == *ptr);
                                else
-                                   good = good && (*pos++ == apr_tolower(*ptr));
+                                   good = good
+                                       && (apr_tolower(*pos++) == apr_tolower(*ptr));
                                addspace = 0;
                                break;
                 }
@@ -1389,6 +1421,34 @@ AP_DECLARE(int) ap_find_list_item(apr_pool_t *p, const char *line,
     return good;
 }
 
+/* Find an item in canonical form (lowercase, no extra spaces) within
+ * an HTTP field value list.  Returns 1 if found, 0 if not found.
+ * This would be much more efficient if we stored header fields as
+ * an array of list items as they are received instead of a plain string.
+ */
+AP_DECLARE(int) ap_find_list_item(apr_pool_t *p, const char *line,
+                                  const char *tok)
+{
+    return find_list_item(p, line, tok, AP_ETAG_NONE);
+}
+
+/* Find a strong Etag in canonical form (lowercase, no extra spaces) within
+ * an HTTP field value list.  Returns 1 if found, 0 if not found.
+ */
+AP_DECLARE(int) ap_find_etag_strong(apr_pool_t *p, const char *line,
+                                    const char *tok)
+{
+    return find_list_item(p, line, tok, AP_ETAG_STRONG);
+}
+
+/* Find a weak ETag in canonical form (lowercase, no extra spaces) within
+ * an HTTP field value list.  Returns 1 if found, 0 if not found.
+ */
+AP_DECLARE(int) ap_find_etag_weak(apr_pool_t *p, const char *line,
+                                  const char *tok)
+{
+    return find_list_item(p, line, tok, AP_ETAG_WEAK);
+}
 
 /* Retrieve a token, spacing over it and returning a pointer to
  * the first non-white byte afterwards.  Note that these tokens