Index: include/sysinc.h
===================================================================
--- include/sysinc.h.orig	2022-12-05 09:13:13.147213258 +0100
+++ include/sysinc.h	2023-01-20 19:51:49.817570470 +0100
@@ -401,7 +401,90 @@
 #	else
 #		define ZBX_CURLOPT_ACCEPT_ENCODING	CURLOPT_ENCODING
 #	endif
+#	if 0x073700 <= LIBCURL_VERSION_NUM	/* version 7.55.0 */
+#		define ZBX_CURLINFO_SPEED_DOWNLOAD	CURLINFO_SPEED_DOWNLOAD_T
+#	else
+#		define ZBX_CURLINFO_SPEED_DOWNLOAD	CURLINFO_SPEED_DOWNLOAD
+#	endif
 #	define ZBX_CURLOPT_MAXREDIRS	10L
+#	if defined(NEED_FUNCTION_CURL_EASY_SETOPT_REDEFINE)
+#	undef curl_easy_setopt
+#	define curl_easy_setopt(handle, option, value)							\
+		__extension__({										\
+			CURLoption _curl_opt = (option);						\
+			if(__builtin_constant_p(_curl_opt)) {						\
+				CURL_IGNORE_DEPRECATION(						\
+					if(curlcheck_long_option(_curl_opt))				\
+						if(!curlcheck_long(value))				\
+							_curl_easy_setopt_err_long();			\
+					if(curlcheck_off_t_option(_curl_opt))				\
+						if(!curlcheck_off_t(value))				\
+							_curl_easy_setopt_err_curl_off_t();		\
+					if(curlcheck_string_option(_curl_opt))				\
+						if(!curlcheck_string(value))				\
+							_curl_easy_setopt_err_string();			\
+					if(curlcheck_write_cb_option(_curl_opt))			\
+						if(!curlcheck_write_cb(value))				\
+							_curl_easy_setopt_err_write_callback();		\
+					if((_curl_opt) == CURLOPT_RESOLVER_START_FUNCTION)		\
+						if(!curlcheck_resolver_start_callback(value))		\
+							_curl_easy_setopt_err_resolver_start_callback();\
+					if((_curl_opt) == CURLOPT_READFUNCTION)				\
+						if(!curlcheck_read_cb(value))				\
+							_curl_easy_setopt_err_read_cb();		\
+					if((_curl_opt) == CURLOPT_IOCTLFUNCTION)			\
+						if(!curlcheck_ioctl_cb(value))				\
+							_curl_easy_setopt_err_ioctl_cb();		\
+					if((_curl_opt) == CURLOPT_SOCKOPTFUNCTION)			\
+						if(!curlcheck_sockopt_cb(value))			\
+							_curl_easy_setopt_err_sockopt_cb();		\
+					if((_curl_opt) == CURLOPT_OPENSOCKETFUNCTION)			\
+						if(!curlcheck_opensocket_cb(value))			\
+							_curl_easy_setopt_err_opensocket_cb();		\
+					if((_curl_opt) == CURLOPT_PROGRESSFUNCTION)			\
+						if(!curlcheck_progress_cb(value))			\
+							_curl_easy_setopt_err_progress_cb();		\
+					if((_curl_opt) == CURLOPT_DEBUGFUNCTION)			\
+						if(!curlcheck_debug_cb(value))				\
+							_curl_easy_setopt_err_debug_cb();		\
+					if((_curl_opt) == CURLOPT_SSL_CTX_FUNCTION)			\
+						if(!curlcheck_ssl_ctx_cb(value))			\
+							_curl_easy_setopt_err_ssl_ctx_cb();		\
+					if(curlcheck_conv_cb_option(_curl_opt))				\
+						if(!curlcheck_conv_cb(value))				\
+							_curl_easy_setopt_err_conv_cb();		\
+					if((_curl_opt) == CURLOPT_SEEKFUNCTION)				\
+						if(!curlcheck_seek_cb(value))				\
+							_curl_easy_setopt_err_seek_cb();		\
+					if(curlcheck_cb_data_option(_curl_opt))				\
+						if(!curlcheck_cb_data(value))				\
+							_curl_easy_setopt_err_cb_data();		\
+					if((_curl_opt) == CURLOPT_ERRORBUFFER)				\
+						if(!curlcheck_error_buffer(value))			\
+							_curl_easy_setopt_err_error_buffer();		\
+					if((_curl_opt) == CURLOPT_STDERR)				\
+						if(!curlcheck_FILE(value))				\
+							_curl_easy_setopt_err_FILE();			\
+					if(curlcheck_postfields_option(_curl_opt))			\
+						if(!curlcheck_postfields(value))			\
+							_curl_easy_setopt_err_postfields();		\
+					if((_curl_opt) == CURLOPT_HTTPPOST)				\
+						if(!curlcheck_arr((value), struct curl_httppost))	\
+							_curl_easy_setopt_err_curl_httpost();		\
+					if((_curl_opt) == CURLOPT_MIMEPOST)				\
+						if(!curlcheck_ptr((value), curl_mime))			\
+							_curl_easy_setopt_err_curl_mimepost();		\
+					if(curlcheck_slist_option(_curl_opt))				\
+						if(!curlcheck_arr((value), struct curl_slist))		\
+							_curl_easy_setopt_err_curl_slist();		\
+					if((_curl_opt) == CURLOPT_SHARE)				\
+						if(!curlcheck_ptr((value), CURLSH))			\
+							_curl_easy_setopt_err_CURLSH();			\
+				)									\
+			}										\
+			curl_easy_setopt(handle, _curl_opt, value);					\
+		})
+#	endif
 #endif
 
 /* Required for advanced sigaction */
Index: m4/libcurl.m4
===================================================================
--- m4/libcurl.m4.orig	2022-12-01 08:47:13.072351692 +0100
+++ m4/libcurl.m4	2023-01-20 19:20:18.248255772 +0100
@@ -294,7 +294,27 @@ x=CURLOPT_VERBOSE;
 			LIBS="${LIBS} ${LIBCURL_LIBS}"
 			LDFLAGS="${LDFLAGS} ${LIBCURL_LDFLAGS}"
 			CFLAGS="${CFLAGS} ${LIBCURL_CFLAGS}"
+			# Does this version of curl ship with a broken curl_easy_setopt() wrapper?
+			# If this fails to compile, then yes and request to redefine it
+			AC_MSG_CHECKING([if curl/curl.h defines a broken curl_easy_setopt() wrapper])
+			AC_COMPILE_IFELSE([
+				AC_LANG_PROGRAM([[#include <curl/curl.h>]], [[
+CURL		*easyhandle;
+CURLoption	opt;
 
+(void)curl_easy_setopt(easyhandle, opt = CURLOPT_NOBODY, 1L);]]
+				)
+			], [
+				AC_MSG_RESULT(no)
+			], [
+				AC_MSG_RESULT(yes)
+				AC_DEFINE(NEED_FUNCTION_CURL_EASY_SETOPT_REDEFINE,1,
+					[Define to 1 if 'curl_easy_setopt' is broken and needs redefining.])
+			]
+			)
+
+			# Does curl_free() exist in this version of libcurl?
+			# If not, fake it with free()
 			AC_CHECK_FUNC(curl_free,,
 				AC_DEFINE(curl_free,free,
 					[Define curl_free() as free() if our version of curl lacks curl_free.]))