#5964: Another follow-up commit for #5456 (encrypted communication with libevent...

Decrypt only what is asked for, not more. This fixes previous commit
which changed semantics by processing the buffer to the very end,
starting with correct offset though.

Refactor encryption/decryption to a single function which callback.

diff --git a/libtransmission/peer-io.c b/libtransmission/peer-io.c
index 98f80662471e7da8fcfbbb0ad67f86e23105b7fa..79cb0f8c291a80d24d71ce8c0506c40dd8c5d634 100644 (file)
--- a/libtransmission/peer-io.c
+++ b/libtransmission/peer-io.c
@@ -1041,6 +1041,33 @@ tr_peerIoSetEncryption (tr_peerIo * io, tr_encryption_type encryption_type)
 ***
 **/
 
+static inline void
+processBuffer (tr_crypto        * crypto,
+               struct evbuffer  * buffer,
+               size_t             offset,
+               size_t             size,
+               void            (* callback) (tr_crypto *, size_t, const void *, void *))
+{
+    struct evbuffer_ptr pos;
+    struct evbuffer_iovec iovec;
+
+    evbuffer_ptr_set (buffer, &pos, offset, EVBUFFER_PTR_SET);
+
+    do
+    {
+        if (evbuffer_peek (buffer, size, &pos, &iovec, 1) <= 0)
+            break;
+
+        callback (crypto, iovec.iov_len, iovec.iov_base, iovec.iov_base);
+
+        assert (size >= iovec.iov_len);
+        size -= iovec.iov_len;
+    }
+    while (!evbuffer_ptr_set (buffer, &pos, iovec.iov_len, EVBUFFER_PTR_ADD));
+
+    assert (size == 0);
+}
+
 static void
 addDatatype (tr_peerIo * io, size_t byteCount, bool isPieceData)
 {
@@ -1051,27 +1078,21 @@ addDatatype (tr_peerIo * io, size_t byteCount, bool isPieceData)
     peer_io_push_datatype (io, d);
 }
 
-static void
-maybeEncryptBuffer (tr_peerIo * io, struct evbuffer * buf)
+static inline void
+maybeEncryptBuffer (tr_peerIo       * io,
+                    struct evbuffer * buf,
+                    size_t            offset,
+                    size_t            size)
 {
     if (io->encryption_type == PEER_ENCRYPTION_RC4)
-    {
-        struct evbuffer_ptr pos;
-        struct evbuffer_iovec iovec;
-        evbuffer_ptr_set (buf, &pos, 0, EVBUFFER_PTR_SET);
-        do {
-            if (evbuffer_peek (buf, -1, &pos, &iovec, 1) != 1)
-              break;
-            tr_cryptoEncrypt (&io->crypto, iovec.iov_len, iovec.iov_base, iovec.iov_base);
-        } while (!evbuffer_ptr_set (buf, &pos, iovec.iov_len, EVBUFFER_PTR_ADD));
-    }
+        processBuffer (&io->crypto, buf, offset, size, &tr_cryptoEncrypt);
 }
 
 void
 tr_peerIoWriteBuf (tr_peerIo * io, struct evbuffer * buf, bool isPieceData)
 {
     const size_t byteCount = evbuffer_get_length (buf);
-    maybeEncryptBuffer (io, buf);
+    maybeEncryptBuffer (io, buf, 0, byteCount);
     evbuffer_add_buffer (io->outbuf, buf);
     addDatatype (io, byteCount, isPieceData);
 }
@@ -1127,6 +1148,16 @@ evbuffer_add_uint64 (struct evbuffer * outbuf, uint64_t addme_hll)
 ****
 ***/
 
+static inline void
+maybeDecryptBuffer (tr_peerIo       * io,
+                    struct evbuffer * buf,
+                    size_t            offset,
+                    size_t            size)
+{
+    if (io->encryption_type == PEER_ENCRYPTION_RC4)
+        processBuffer (&io->crypto, buf, offset, size, &tr_cryptoDecrypt);
+}
+
 void
 tr_peerIoReadBytesToBuf (tr_peerIo * io, struct evbuffer * inbuf, struct evbuffer * outbuf, size_t byteCount)
 {
@@ -1142,18 +1173,7 @@ tr_peerIoReadBytesToBuf (tr_peerIo * io, struct evbuffer * inbuf, struct evbuffe
     evbuffer_add_buffer (outbuf, tmp);
     evbuffer_free (tmp);
 
-    /* decrypt if needed */
-    if (io->encryption_type == PEER_ENCRYPTION_RC4) {
-        struct evbuffer_ptr pos;
-        struct evbuffer_iovec iovec;
-        evbuffer_ptr_set (outbuf, &pos, old_length, EVBUFFER_PTR_SET);
-        do {
-            if (evbuffer_peek (outbuf, -1, &pos, &iovec, 1) != 1)
-              break;
-            tr_cryptoDecrypt (&io->crypto, iovec.iov_len, iovec.iov_base, iovec.iov_base);
-            byteCount -= iovec.iov_len;
-        } while (!evbuffer_ptr_set (outbuf, &pos, iovec.iov_len, EVBUFFER_PTR_ADD));
-    }
+    maybeDecryptBuffer (io, outbuf, old_length, byteCount);
 }
 
 void