Since (length url-request-data) returns characters in the string
instead of bytes, shouldn't it be (string-bytes url-request-data)
instead?

Additionally, what happens if you post using Unicode?

Does the following patch help any?

--- url-http.el	28 Nov 2004 19:13:50 -0000	1.6
+++ url-http.el	30 Nov 2004 17:16:09 -0000
@@ -259,7 +259,7 @@
 	   (if url-request-data
 	       (concat
 		"Content-length: " (number-to-string
-				    (length url-request-data))
+				    (string-bytes url-request-data))
 		"\r\n"))
 	   ;; End request
 	   "\r\n"
@@ -1060,6 +1060,9 @@
 	(set-process-buffer connection buffer)
 	(set-process-sentinel connection 'url-http-end-of-document-sentinel)
 	(set-process-filter connection 'url-http-generic-filter)
+	(set-process-coding-system connection
+				   (detect-coding-string url-request-data t)
+				   url-request-coding-system)
 	(process-send-string connection (url-http-create-request url))))
     buffer))
 
--- url-vars.el	19 Oct 2004 21:37:18 -0000	1.8
+++ url-vars.el	30 Nov 2004 17:16:09 -0000
@@ -218,6 +218,8 @@
 
 (defvar url-request-data nil "Any data to send with the next request.")
 
+(defvar url-request-coding-system 'binary "The coding system to use for the request.")
+
 (defvar url-request-extra-headers nil
   "A list of extra headers to send with the next request.
 Should be an assoc list of headers/contents.")
 
 

-- 
A choice between one man and a shovel, or a dozen men with teaspoons
is clear to me, and I'm sure it is clear to you also.
    -- Zimran Ahmed <http://www.winterspeak.com/>