Fix data corruption.

This was caused by the code handling incoming retransmissions not reading
from the receive buffer correctly after the change to ringbuffers.

diff --git a/utcp.c b/utcp.c
index 3d0971a37ba359716533ddaeab9b03874473d510..0d102b4c7bcd063ff388209e7e8c1b9ff4c50fd3 100644 (file)
--- a/utcp.c
+++ b/utcp.c
@@ -320,6 +320,44 @@ static ssize_t buffer_copy(struct buffer *buf, void *data, size_t offset, size_t
        return len;
 }
 
+// Copy data from the buffer without removing it.
+static ssize_t buffer_call(struct buffer *buf, utcp_recv_t cb, void *arg, size_t offset, size_t len) {
+       // Ensure we don't copy more than is actually stored in the buffer
+       if(offset >= buf->used) {
+               return 0;
+       }
+
+       if(buf->used - offset < len) {
+               len = buf->used - offset;
+       }
+
+       uint32_t realoffset = buf->offset + offset;
+
+       if(buf->size - buf->offset < offset) {
+               // The offset wrapped
+               realoffset -= buf->size;
+       }
+
+       if(buf->size - realoffset < len) {
+               // The data is wrapped
+               ssize_t rx1 = cb(arg, buf->data + realoffset, buf->size - realoffset);
+
+               if(rx1 < buf->size - realoffset) {
+                       return rx1;
+               }
+
+               ssize_t rx2 = cb(arg, buf->data, len - (buf->size - realoffset));
+
+               if(rx2 < 0) {
+                       return rx2;
+               } else {
+                       return rx1 + rx2;
+               }
+       } else {
+               return cb(arg, buf->data + realoffset, len);
+       }
+}
+
 // Discard data from the buffer.
 static ssize_t buffer_discard(struct buffer *buf, size_t len) {
        if(buf->used < len) {
@@ -1024,23 +1062,32 @@ static void handle_out_of_order(struct utcp_connection *c, uint32_t offset, cons
 }
 
 static void handle_in_order(struct utcp_connection *c, const void *data, size_t len) {
-       // Check if we can process out-of-order data now.
-       if(c->sacks[0].len && len >= c->sacks[0].offset) { // TODO: handle overlap with second SACK
-               debug(c, "incoming packet len %lu connected with SACK at %u\n", (unsigned long)len, c->sacks[0].offset);
-               buffer_put_at(&c->rcvbuf, 0, data, len); // TODO: handle return value
-               len = max(len, c->sacks[0].offset + c->sacks[0].len);
-               data = c->rcvbuf.data;
-       }
-
        if(c->recv) {
                ssize_t rxd = c->recv(c, data, len);
 
-               if(rxd < 0 || (size_t)rxd != len) {
+               if(rxd != (ssize_t)len) {
                        // TODO: handle the application not accepting all data.
                        abort();
                }
        }
 
+       // Check if we can process out-of-order data now.
+       if(c->sacks[0].len && len >= c->sacks[0].offset) {
+               debug(c, "incoming packet len %lu connected with SACK at %u\n", (unsigned long)len, c->sacks[0].offset);
+
+               if(len < c->sacks[0].offset + c->sacks[0].len) {
+                       size_t offset = len;
+                       len = c->sacks[0].offset + c->sacks[0].len;
+                       size_t remainder = len - offset;
+                       ssize_t rxd = buffer_call(&c->rcvbuf, c->recv, c, offset, remainder);
+
+                       if(rxd != (ssize_t)remainder) {
+                               // TODO: handle the application not accepting all data.
+                               abort();
+                       }
+               }
+       }
+
        if(c->rcvbuf.used) {
                sack_consume(c, len);
        }