Try to find out early if buffers get trashed or double-freed.

svn:r1225

3 files changed, 19 insertions, 5 deletions

diff --git a/src/or/buffers.c b/src/or/buffers.c
index 40d6b04d87..d4c3dd7875 100644
--- a/src/or/buffers.c
+++ b/src/or/buffers.c
@@ -6,7 +6,9 @@
 
 #include "or.h"
 
+#define BUFFER_MAGIC 0xB0FFF312u
 struct buf_t {
+  uint32_t magic; /* for debugging */
   char *mem;
   size_t len;
   size_t datalen;
@@ -118,6 +120,7 @@ int find_on_inbuf(char *string, int string_len, buf_t *buf) {
 buf_t *buf_new_with_capacity(size_t size) {
   buf_t *buf;
   buf = (buf_t*)tor_malloc(sizeof(buf_t));
+  buf->magic = BUFFER_MAGIC;
   buf->mem = (char *)tor_malloc(size);
   buf->len = size;
   buf->datalen = 0;
@@ -153,9 +156,10 @@ const char *_buf_peek_raw_buffer(const buf_t *buf)
 }
 
 void buf_free(buf_t *buf) {
-  assert(buf && buf->mem);
-  free(buf->mem);
-  free(buf);
+  assert_buf_ok(buf);
+  buf->magic = 0xDEADBEEF;
+  tor_free(buf->mem);
+  tor_free(buf);
 }
 
 /* read from socket s, writing onto end of buf.
@@ -576,6 +580,14 @@ int fetch_from_buf_socks(buf_t *buf, socks_request_t *req) {
   }
 }
 
+void assert_buf_ok(buf_t *buf)
+{
+  assert(buf);
+  assert(buf->magic == BUFFER_MAGIC);
+  assert(buf->mem);
+  assert(buf->datalen <= buf->len);
+}
+
 /*
   Local Variables:
   mode:c
diff --git a/src/or/connection.c b/src/or/connection.c
index c20a8b0418..c05736e02a 100644
--- a/src/or/connection.c
+++ b/src/or/connection.c
@@ -866,8 +866,8 @@ void assert_connection_ok(connection_t *conn, time_t now)
 
   /* buffers */
   if (!connection_is_listener(conn)) {
-    assert(conn->inbuf);
-    assert(conn->outbuf);
+    assert_buf_ok(conn->inbuf);
+    assert_buf_ok(conn->outbuf);
   }
 
   assert(!now || conn->timestamp_lastread <= now);
diff --git a/src/or/or.h b/src/or/or.h
index 97e74275de..ffae156f0e 100644
--- a/src/or/or.h
+++ b/src/or/or.h
@@ -572,6 +572,8 @@ int fetch_from_buf_http(buf_t *buf,
                         char **body_out, int max_bodylen);
 int fetch_from_buf_socks(buf_t *buf, socks_request_t *req);
 
+void assert_buf_ok(buf_t *buf);
+
 /********************************* circuit.c ***************************/
 
 void circuit_add(circuit_t *circ);