Support large file uploads

If the declaration file is larger than ~64KiB, upload it in multiple
separately-deflated chunks.

diff --git a/rnetclient.c b/rnetclient.c
index a58b62b..d264c72 100644 (file)
--- a/rnetclient.c
+++ b/rnetclient.c
@@ -180,12 +180,51 @@ static void usage(void)
 
 static int rnet_send(gnutls_session_t session, char *buffer, size_t len, int header)
 {
-       char *out;
-       size_t olen;
-       deflateRecord(buffer, len, &out, &olen, header);
-       gnutls_record_send(session, out, olen);
-       free(out);
-       return 0;
+       int r = 0;
+       /* Large files have to be uploaded as multiple
+          separately-deflated chunks, because the compressed and
+          uncompressed lengths in each record are encoded in unsigned
+          16-bit integers each.
+
+          The header can't be split into multiple chunks, and it
+          should never have to, since it won't ever get even close to
+          64KiB.
+
+          The uploaded file may be larger: to upload such large
+          files, it suffices to send multiple records till the entire
+          file is transferred, without waiting for a response.  Since
+          we've alread informed the server of the file size in the
+          header, it knows exactly how much data to expect before
+          sending a response.  It will only send an error message
+          before that if it times us out.
+
+          Odds are that any reasonably large size will do, but it
+          can't be too close to 64KiB, otherwise there won't be room
+          for the compressed length should it not compress well,
+          which should never happen for capital-ASCII-only
+          declaration files, but who knows?
+
+          This chunk size worked at the first try, uploading a
+          ~100KiB file, so let's stick with it.  */
+       const int maxc = 64472;
+       if (header && len > maxc)
+               return -1;
+
+       do {
+               char *out = NULL;
+               size_t olen;
+               size_t clen = len < maxc ? len : maxc;
+               r = deflateRecord(buffer, clen, &out, &olen, header);
+               if (!r) {
+                       size_t n = gnutls_record_send(session, out, olen);
+                       if (n != olen)
+                               r = -1;
+               }
+               free(out);
+               buffer += clen;
+               len -= clen;
+       } while (len && !r);
+       return r;
 }
 
 static int rnet_recv(gnutls_session_t session, struct rnet_message **message)