GRUB's HTTP module declares support for HTTP/1.1, which defaults to
Connection:keepalive. At the end of the content, the server holds the TCP
connection open waiting for the next request.
It seems that grub_net_poll_cards() is watching for the HTTP module to set
net->stall, and otherwise waits the full 400ms GRUB_NET_INTERVAL to return
to processing. However, HTTP module only sets that flag in specific
conditions:
- parse_line detects that we are at the end of downloading a chunked
Transfer-Encoding
- http_err detects a problem with the underlying TCP connection
- http_receive has queued 20 netbuffer packets for processing
If the file is small and takes less than 20 packets, and the server is not
using chunked encoding, grub_net_poll_cards() will wait the full 400ms
before continuing to process and finish the file download.
This patch sets Connection:close, which will tell the server to close the
connection as soon as it has finished sending the file. GRUB closes any
connections that are left open (in http_seek), so it does not change
performance. When the server disconnects, I think it triggers http_err and
then quits out of grub_net_poll_cards early.
---
diff --git a/grub-core/net/http.c b/grub-core/net/http.c
index 5aa4ad3..a5d64f6 100644
--- a/grub-core/net/http.c
+++ b/grub-core/net/http.c
@@ -318,6 +318,7 @@ http_establish (struct grub_file *file, grub_off_t
offset, int initial)
+ grub_strlen (data->filename)
+ sizeof (" HTTP/1.1\r\nHost: ") - 1
+ grub_strlen (file->device->net->server)
+ + sizeof ("\r\nConnection: close") - 1
+ sizeof ("\r\nUser-Agent: " PACKAGE_STRING
"\r\n") - 1
+ sizeof ("Range: bytes=XXXXXXXXXXXXXXXXXXXX"
@@ -366,6 +367,17 @@ http_establish (struct grub_file *file, grub_off_t
offset, int initial)
grub_strlen (file->device->net->server));
ptr = nb->tail;
+ err = grub_netbuff_put (nb,
+ sizeof ("\r\nConnection: close")
+ - 1);
+ if (err)
+ {
+ grub_netbuff_free (nb);
+ return err;
+ }
+ grub_memcpy (ptr, "\r\nConnection: close",
+ sizeof ("\r\nConnection: close") - 1);
+ ptr = nb->tail;
err = grub_netbuff_put (nb,
sizeof ("\r\nUser-Agent: " PACKAGE_STRING "\r\n")
- 1);
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