added asserts to catch broken peer allocations and frees as well as disk buffer corruption

examples/client_test.cpp

@@ -775,6 +775,7 @@ int main(int argc, char* argv[])
 			"  -O                    Disallow disk job reordering\n"
 			"  -P <host:port>        Use the specified SOCKS5 proxy\n"
 			"  -H                    Don't start DHT\n"
+			"  -W <num peers>        Set the max number of peers to keep in the peer list\n"
 			"  "
 			"\n\n"
 			"TORRENT is a path to a .torrent file\n"
@@ -895,6 +896,7 @@ int main(int argc, char* argv[])
 			case 't': poll_interval = atoi(arg); break;
 			case 'F': refresh_delay = atoi(arg); break;
 			case 'H': start_dht = false; --i; break;
+			case 'W': settings.max_peerlist_size = atoi(arg); break;
 			case 'x':
 				{
 					FILE* filter = fopen(arg, "r");

include/libtorrent/policy.hpp

@@ -310,6 +310,9 @@ namespace libtorrent
 			// this is set to true when this peer as been
 			// pinged by the DHT
 			bool added_to_dht:1;
+#endif
+#ifdef TORRENT_DEBUG
+			bool in_use:1;
 #endif
 		};
 

src/allocator.cpp

@@ -32,6 +32,7 @@ POSSIBILITY OF SUCH DAMAGE.
 
 #include "libtorrent/allocator.hpp"
 #include "libtorrent/config.hpp"
+#include "libtorrent/assert.hpp"
 
 #ifdef TORRENT_WINDOWS
 #include <Windows.h>
@@ -47,6 +48,18 @@ POSSIBILITY OF SUCH DAMAGE.
 #include <malloc.h> // memalign
 #endif
 
+#ifdef TORRENT_DEBUG_BUFFERS
+#include <sys/mman.h>
+#include "libtorrent/size_type.hpp"
+
+struct alloc_header
+{
+	libtorrent::size_type size;
+	int magic;
+};
+
+#endif
+
 namespace libtorrent
 {
 	int page_size()
@@ -71,6 +84,21 @@ namespace libtorrent
 
 	char* page_aligned_allocator::malloc(const size_type bytes)
 	{
+#ifdef TORRENT_DEBUG_BUFFERS
+		int page = page_size();
+		char* ret = (char*)valloc(bytes + 2 * page);
+		// make the two surrounding pages non-readable and -writable
+		TORRENT_ASSERT((bytes & (page-1)) == 0);
+		alloc_header* h = (alloc_header*)ret;
+		h->size = bytes;
+		h->magic = 0x1337;
+		mprotect(ret, page, PROT_READ);
+		mprotect(ret + page + bytes, page, PROT_READ);
+//		fprintf(stderr, "malloc: %p head: %p tail: %p size: %d\n", ret + page, ret, ret + page + bytes, int(bytes));
+
+		return ret + page;
+#endif
+
 #if TORRENT_USE_POSIX_MEMALIGN
 		void* ret;
 		if (posix_memalign(&ret, page_size(), bytes) != 0) ret = 0;
@@ -92,6 +120,22 @@ namespace libtorrent
 
 	void page_aligned_allocator::free(char* const block)
 	{
+
+#ifdef TORRENT_DEBUG_BUFFERS
+		int page = page_size();
+		// make the two surrounding pages non-readable and -writable
+		mprotect(block - page, page, PROT_READ | PROT_WRITE);
+		alloc_header* h = (alloc_header*)(block - page);
+		TORRENT_ASSERT((h->size & (page-1)) == 0);
+		TORRENT_ASSERT(h->magic == 0x1337);
+		mprotect(block + h->size, page, PROT_READ | PROT_WRITE);
+//		fprintf(stderr, "free: %p head: %p tail: %p size: %d\n", block, block - page, block + h->size, int(h->size));
+		h->magic = 0;
+
+		::free(block - page);
+		return;
+#endif
+
 #ifdef TORRENT_WINDOWS
 		VirtualFree(block, 0, MEM_RELEASE);
 #elif defined TORRENT_BEOS

src/policy.cpp

@@ -385,6 +385,11 @@ namespace libtorrent
 		if (m_round_robin > i - m_peers.begin()) --m_round_robin;
 		if (m_round_robin >= m_peers.size()) m_round_robin = 0;
 
+#ifdef TORRENT_DEBUG
+		TORRENT_ASSERT((*i)->in_use);
+		(*i)->in_use = false;
+#endif
+
 #if TORRENT_USE_IPV6
 		if ((*i)->is_v6_addr)
 		{
@@ -465,6 +470,7 @@ namespace libtorrent
 					{
 						if (erase_candidate > current) --erase_candidate;
 						TORRENT_ASSERT(current >= 0 && current < m_peers.size());
+						--round_robin;
 						erase_peer(m_peers.begin() + current);
 					}
 					else
@@ -601,6 +607,7 @@ namespace libtorrent
 					{
 						if (erase_candidate > current) --erase_candidate;
 						if (candidate > current) --candidate;
+						--m_round_robin;
 						erase_peer(m_peers.begin() + current);
 					}
 					else
@@ -805,6 +812,9 @@ namespace libtorrent
 #endif
 				(peer*)m_torrent->session().m_ipv4_peer_pool.malloc();
 			if (p == 0) return false;
+
+//			TORRENT_ASSERT(p->in_use == false);
+
 #if TORRENT_USE_IPV6
 			if (is_v6)
 				m_torrent->session().m_ipv6_peer_pool.set_next_size(500);
@@ -819,6 +829,10 @@ namespace libtorrent
 #endif
 				new (p) ipv4_peer(c.remote(), false, 0);
 
+#ifdef TORRENT_DEBUG
+			p->in_use = true;
+#endif
+
 			iter = m_peers.insert(iter, p);
 
 			if (m_round_robin >= iter - m_peers.begin()) ++m_round_robin;
@@ -1085,8 +1099,17 @@ namespace libtorrent
 			if (p == 0) return 0;
 			m_torrent->session().m_i2p_peer_pool.set_next_size(500);
 			new (p) i2p_peer(destination, true, src);
+
+#ifdef TORRENT_DEBUG
+			p->in_use = true;
+#endif
+
 			if (!insert_peer(p, iter, flags))
 			{
+#ifdef TORRENT_DEBUG
+				p->in_use = false;
+#endif
+
 				m_torrent->session().m_i2p_peer_pool.free((i2p_peer*)p);
 				return 0;
 			}
@@ -1188,8 +1211,15 @@ namespace libtorrent
 #endif
 				new (p) ipv4_peer(remote, true, src);
 
+#ifdef TORRENT_DEBUG
+			p->in_use = true;
+#endif
+
 			if (!insert_peer(p, iter, flags))
 			{
+#ifdef TORRENT_DEBUG
+				p->in_use = false;
+#endif
 #if TORRENT_USE_IPV6
 				if (is_v6) m_torrent->session().m_ipv6_peer_pool.free((ipv6_peer*)p);
 				else