optimize CL/TE check;

replace the heavyhanded connection:close added in b4fddbc3d
with a comparison of content-length to num bytes consumed

this approach also covers incorrectly configured servers
where the reverseproxy was not detected

also adds explicit TE/CL handling, even though most
(all?) reverseproxies already prevent such issues

also adds explicit sanchk of up2k chunk-receiver,
in case any bugs are ever added there

copyparty/httpconn.py

@@ -222,6 +222,21 @@ class HttpConn(object):
             if not self.cli.run():
                 return
 
+            if self.sr.te == 1:
+                self.log("closing socket (leftover TE)", "90")
+                return
+
+            if (
+                "content-length" in self.cli.headers
+                and int(self.cli.headers["content-length"]) != self.sr.nb
+            ):
+                self.log("closing socket (CL mismatch)", "90")
+                return
+
+            # note: proxies reject PUT sans Content-Length; illegal for HTTP/1.1
+
+            self.sr.nb = self.sr.te = 0
+
             if self.u2idx:
                 self.hsrv.put_u2idx(str(self.addr), self.u2idx)
                 self.u2idx = None