[PATCH 4/5] [NET] Add skb_find_text() to search for a text pattern in skbs

[Thomas Graf <tgraf@xxxxxxx>]

Adds the function skb_find_text() to search for text patterns
in both, linear and non-linear skbs.

Signed-off-by: Thomas Graf <tgraf@xxxxxxx>

---
commit 4fdcfba0bf99efed709bc8ebaeda0d5ed7e9cc67
tree 13ce1cd98014267f2a353b96e813c1e70bbe9c3b
parent 81553cdea2a7ff762cb44aeced743d3a77efd2d7
author Thomas Graf <tgraf@xxxxxxx> Fri, 27 May 2005 23:44:50 +0200
committer Thomas Graf <tgraf@xxxxxxx> Fri, 27 May 2005 23:44:50 +0200

 include/linux/skbuff.h |    4 ++
 net/core/skbuff.c      |   83 +++++++++++++++++++++++++++++++++++++++++++++++++
 2 files changed, 87 insertions(+)

Index: include/linux/skbuff.h
===================================================================
--- 266c4ad512e5ae71bd7cd88c94bfb18fb2f761d6/include/linux/skbuff.h  
(mode:100644)
+++ 13ce1cd98014267f2a353b96e813c1e70bbe9c3b/include/linux/skbuff.h  
(mode:100644)
@@ -28,6 +28,7 @@
 #include <linux/poll.h>
 #include <linux/net.h>
 #include <net/checksum.h>
+#include <linux/textsearch.h>
 
 #define HAVE_ALLOC_SKB         /* For the drivers to know */
 #define HAVE_ALIGNABLE_SKB     /* Ditto 8)                */
@@ -1187,6 +1188,9 @@
 extern void           skb_split(struct sk_buff *skb,
                                 struct sk_buff *skb1, const u32 len);
 
+extern int skb_find_text(struct sk_buff *skb, int from, int to,
+                        struct ts_config *config, struct ts_state *state);
+
 static inline void *skb_header_pointer(const struct sk_buff *skb, int offset,
                                       int len, void *buffer)
 {
Index: net/core/skbuff.c
===================================================================
--- 266c4ad512e5ae71bd7cd88c94bfb18fb2f761d6/net/core/skbuff.c  (mode:100644)
+++ 13ce1cd98014267f2a353b96e813c1e70bbe9c3b/net/core/skbuff.c  (mode:100644)
@@ -1506,6 +1506,88 @@
                skb_split_no_header(skb, skb1, len, pos);
 }
 
+static int get_skb_text(int offset, unsigned char **text,
+                       struct ts_config *conf, struct ts_state *state)
+{
+       /* args[0]: lower limit
+        * args[1]: upper limit
+        * args[2]: skb
+        * args[3]: fragment index
+        * args[4]: current fragment data buffer
+        * args[5]: octets consumed up to previous fragment */
+       int from = state->args[0], to = state->args[1];
+       struct sk_buff *skb = (struct sk_buff *) state->args[2];
+       int limit = min_t(int, skb_headlen(skb), to);
+       int real_offset = offset + from;
+       skb_frag_t *f;
+
+       if (!skb_is_nonlinear(skb)) {
+               if (real_offset < limit) {
+linear:
+                       *text = skb->data + real_offset;
+                       return limit - real_offset;
+               }
+
+               return 0;
+       }
+
+       if (real_offset < limit)
+               goto linear;
+
+next_fragment:
+       f = &skb_shinfo(skb)->frags[state->args[3]];
+       limit = min_t(int, f->size + state->args[5], to);
+
+       if (!state->args[4])
+               state->args[4] = (long) kmap_skb_frag(f);
+
+       if (real_offset < limit) {
+               *text = (unsigned char *) state->args[4] + f->page_offset +
+                       (real_offset - (int) state->args[5]);
+               return limit - real_offset;
+       }
+
+       kunmap_skb_frag((void *) state->args[4]);
+       state->args[3]++;
+       state->args[4] = (long) NULL;
+       state->args[5] += f->size;
+
+       if (state->args[3] >= skb_shinfo(skb)->nr_frags)
+               return 0;
+
+       goto next_fragment;
+}
+
+static void get_skb_text_finish(struct ts_config *conf, struct ts_state *state)
+{
+       if (state->args[4])
+               kunmap_skb_frag((void *) state->args[4]);
+}
+
+/**
+ * skb_find_text - Find a text pattern in skb data
+ * @skb: the buffer to look in
+ * @from: search offset
+ * @to: search limit
+ * @config: textsearch configuration
+ * @state: empty textsearch state variable
+ */
+int skb_find_text(struct sk_buff *skb, int from, int to,
+                 struct ts_config *config, struct ts_state *state)
+{
+       config->get_text = get_skb_text;
+       config->finish = get_skb_text_finish;
+       state->args[0] = from;
+       state->args[1] = to;
+       state->args[2] = (long) skb;
+       state->args[3] = 0;
+       state->args[4] = 0;
+       state->args[5] = skb_headlen(skb);
+
+       return textsearch_find(config, state);
+}
+
+
 void __init skb_init(void)
 {
        skbuff_head_cache = kmem_cache_create("skbuff_head_cache",
@@ -1544,3 +1626,4 @@
 EXPORT_SYMBOL(skb_unlink);
 EXPORT_SYMBOL(skb_append);
 EXPORT_SYMBOL(skb_split);
+EXPORT_SYMBOL(skb_find_text);