Use case-insensitive comparison for headers fix #2100 (#2101)

* Use case-inseneitive comparison for headers

HTTP headers should be case-insensitive. Use case-insensitive string
comparisons when working with HTTP header responses to ensure
compatibility.

* Revert "Use case-inseneitive comparison for headers"

This reverts commit a02f591723506b62b7208449be6eef7122120398

* Ignore case when searching HTTP header responses

Looking up the Content-Length in the header returned by S3 storage
endpoints should ignore case. To guarantee portability implement a
function for case-insensitive string search, because it is non-standard.

* Add an _ after H5 for the strcasestr implementation

It is a private function and should sport that underscore.

* Remove author comment from the doc comment

* Use search function defined by system if available

Check whether the system provides a function implementing case
insensitive string searches. Only use the custom implementation if the
system does not provide the functionality.

* Add tests for case-insensitive search

Basic tests:
  - Search for empty string
  - Search with exact match
  - Search with case-insensitive match
  - search with no match

* Enforce clang-format style

Some variable definitions in the th5_system tests did not conform to
clang-format's expectations. Updated the offending lines.

* Correct comment describing test case

* Added some spaces to please clang-format

* Ignore discarding const

Ask the compiler to ignore discarding the const when retunring a match from H5_strcasestr

Co-authored-by: Frank Berghaus <frank.berghaus@mpcdf.mpg.de>

1 files changed, 1 insertions, 1 deletions

diff --git a/src/H5FDs3comms.c b/src/H5FDs3comms.c
index 1bf0a2f..628c55a 100644
--- a/src/H5FDs3comms.c
+++ b/src/H5FDs3comms.c
@@ -941,7 +941,7 @@ H5FD_s3comms_s3r_getsize(s3r_t *handle)
      * PARSE RESPONSE *
      ******************/
 
-    start = HDstrstr(headerresponse, "\r\nContent-Length: ");
+    start = HDstrcasestr(headerresponse, "\r\nContent-Length: ");
     if (start == NULL)
         HGOTO_ERROR(H5E_ARGS, H5E_BADVALUE, FAIL, "could not find \"Content-Length\" in response.");