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, 8 insertions, 0 deletions

diff --git a/src/H5private.h b/src/H5private.h
index c2ce4c1..f9ff043 100644
--- a/src/H5private.h
+++ b/src/H5private.h
@@ -593,6 +593,7 @@ H5_DLL herr_t   H5_timer_stop(H5_timer_t *timer /*in,out*/);
 H5_DLL herr_t   H5_timer_get_times(H5_timer_t timer, H5_timevals_t *times /*in,out*/);
 H5_DLL herr_t   H5_timer_get_total_times(H5_timer_t timer, H5_timevals_t *times /*in,out*/);
 H5_DLL char    *H5_timer_get_time_string(double seconds);
+H5_DLL char    *H5_strcasestr(const char *haystack, const char *needle);
 
 /* Depth of object copy */
 typedef enum {
@@ -1385,6 +1386,13 @@ H5_DLL H5_ATTR_CONST int Nflock(int fd, int operation);
 #ifndef HDstrcat
 #define HDstrcat(X, Y) strcat(X, Y)
 #endif
+#ifndef HDstrcasestr
+#if defined(H5_HAVE_STRCASESTR)
+#define HDstrcasestr(X, Y) strcasestr(X, Y)
+#else
+#define HDstrcasestr(X, Y) H5_strcasestr(X, Y)
+#endif
+#endif
 #ifndef HDstrchr
 #define HDstrchr(S, C) strchr(S, C)
 #endif