http: limit the initial send amount to used upload buffer size

Previously this logic would cap the send to CURL_MAX_WRITE_SIZE bytes,
but for the situations where a larger upload buffer has been set, this
function can benefit from sending more bytes. With default size used,
this does the same as before.

Also changed the storage of the size to an 'unsigned int' as it is not
allowed to be set larger than 2M.

Also added cautions to the man pages about changing buffer sizes in
run-time.

Closes #7022

1 files changed, 8 insertions, 8 deletions

diff --git a/lib/http.c b/lib/http.c
index eece05513..4d8d94596 100644
--- a/lib/http.c
+++ b/lib/http.c
@@ -1273,14 +1273,6 @@ CURLcode Curl_buffer_send(struct dynbuf *in,
     else
       sendsize = size;
 
-    /* We never send more than CURL_MAX_WRITE_SIZE bytes in one single chunk
-       when we speak HTTPS, as if only a fraction of it is sent now, this data
-       needs to fit into the normal read-callback buffer later on and that
-       buffer is using this size.
-    */
-    if(sendsize > CURL_MAX_WRITE_SIZE)
-      sendsize = CURL_MAX_WRITE_SIZE;
-
     /* OpenSSL is very picky and we must send the SAME buffer pointer to the
        library when we attempt to re-send this buffer. Sending the same data
        is not enough, we must use the exact same address. For this reason, we
@@ -1293,6 +1285,14 @@ CURLcode Curl_buffer_send(struct dynbuf *in,
       Curl_dyn_free(in);
       return result;
     }
+    /* We never send more than upload_buffer_size bytes in one single chunk
+       when we speak HTTPS, as if only a fraction of it is sent now, this data
+       needs to fit into the normal read-callback buffer later on and that
+       buffer is using this size.
+    */
+    if(sendsize > (size_t)data->set.upload_buffer_size)
+      sendsize = (size_t)data->set.upload_buffer_size;
+
     memcpy(data->state.ulbuf, ptr, sendsize);
     ptr = data->state.ulbuf;
   }