bpo-21257: document http.client.parse_headers (GH-11443)
Document http.client.parse_headers
diff --git a/Doc/library/http.client.rst b/Doc/library/http.client.rst
index 3408c10..beaa720 100644
--- a/Doc/library/http.client.rst
+++ b/Doc/library/http.client.rst
@@ -115,6 +115,25 @@
The *strict* parameter was removed. HTTP 0.9 style "Simple Responses" are
no longer supported.
+This module provides the following function:
+
+.. function:: parse_headers(fp)
+
+ Parse the headers from a file pointer *fp* representing a HTTP
+ request/response. The file has to be a :class:`BufferedIOBase` reader
+ (i.e. not text) and must provide a valid :rfc:`2822` style header.
+
+ This function returns an instance of :class:`http.client.HTTPMessage`
+ that holds the header fields, but no payload
+ (the same as :attr:`HTTPResponse.msg`
+ and :attr:`http.server.BaseHTTPRequestHandler.headers`).
+ After returning, the file pointer *fp* is ready to read the HTTP body.
+
+ .. note::
+ :meth:`parse_headers` does not parse the start-line of a HTTP message;
+ it only parses the ``Name: value`` lines. The file has to be ready to
+ read these field lines, so the first line should already be consumed
+ before calling the function.
The following exceptions are raised as appropriate: