libzfs: add keylocation=https://, backed by fetch(3) or libcurl

Signed-off-by: Ahelenia Ziemiańska <nabijaczleweli@nabijaczleweli.xyz>
Ref: openzfs#9543
Closes openzfs#9947

.github/workflows/zfs-tests-functional.yml

@@ -17,6 +17,13 @@ jobs:
         ref: ${{ github.event.pull_request.head.sha }}
     - name: Install dependencies
       run: |
+        libcurl_dev_variant () {
+          case "$(tr -cd 'gno' < /dev/urandom | head -c1)" in
+            g) echo libcurl4-gnutls-dev ;;
+            n) echo libcurl4-nss-dev ;;
+            o) echo libcurl4-openssl-dev ;;
+          esac
+        }
         sudo apt-get update
         sudo apt-get install --yes -qq build-essential autoconf libtool gdb lcov \
           git alien fakeroot wget curl bc fio acl \
@@ -26,7 +33,7 @@ jobs:
           xfslibs-dev libattr1-dev libacl1-dev libudev-dev libdevmapper-dev \
           libssl-dev libffi-dev libaio-dev libelf-dev libmount-dev \
           libpam0g-dev pamtester python-dev python-setuptools python-cffi \
-          python3 python3-dev python3-setuptools python3-cffi
+          python3 python3-dev python3-setuptools python3-cffi "$(libcurl_dev_variant)"
     - name: Autogen.sh
       run: |
         sh autogen.sh

.github/workflows/zfs-tests-sanity.yml

@@ -13,6 +13,13 @@ jobs:
         ref: ${{ github.event.pull_request.head.sha }}
     - name: Install dependencies
       run: |
+        libcurl_dev_variant () {
+          case "$(tr -cd 'gno' < /dev/urandom | head -c1)" in
+            g) echo libcurl4-gnutls-dev ;;
+            n) echo libcurl4-nss-dev ;;
+            o) echo libcurl4-openssl-dev ;;
+          esac
+        }
         sudo apt-get update
         sudo apt-get install --yes -qq build-essential autoconf libtool gdb lcov \
           git alien fakeroot wget curl bc fio acl \
@@ -22,7 +29,7 @@ jobs:
           xfslibs-dev libattr1-dev libacl1-dev libudev-dev libdevmapper-dev \
           libssl-dev libffi-dev libaio-dev libelf-dev libmount-dev \
           libpam0g-dev pamtester python-dev python-setuptools python-cffi \
-          python3 python3-dev python3-setuptools python3-cffi
+          python3 python3-dev python3-setuptools python3-cffi "$(libcurl_dev_variant)"
     - name: Autogen.sh
       run: |
         sh autogen.sh

config/user-libfetch.m4

@@ -0,0 +1,69 @@
+dnl #
+dnl # Check for a libfetch - either fetch(3) or libcurl.
+dnl #
+dnl # There are two configuration dimensions:
+dnl #   * fetch(3) vs libcurl
+dnl #   * static vs dynamic
+dnl #
+dnl # fetch(3) is only dynamic, we use sover 6,
+dnl # which first appeared in 8.0-RELEASE.
+dnl #
+dnl # libcurl development packages include curl-config(1) – we want:
+dnl #   * HTTPS support
+dnl #   * version at least 7.10 ("October 2006"), for sover 4
+dnl #   * to decide if it's static or not
+dnl #
+AC_DEFUN([ZFS_AC_CONFIG_USER_LIBFETCH], [
+	AC_MSG_CHECKING([for libfetch])
+	LIBFETCH_LIBS=
+	LIBFETCH_IS_FETCH=0
+	LIBFETCH_IS_LIBCURL=0
+	LIBFETCH_DYNAMIC=0
+	LIBFETCH_SONAME=
+	have_libfetch=
+
+	saved_libs="$LIBS"
+	LIBS="$LIBS -lfetch"
+	AC_LINK_IFELSE([AC_LANG_PROGRAM([[
+		#include <sys/param.h>
+		#include <stdio.h>
+		#include <fetch.h>
+	]], [fetchGetURL("", "");])], [
+		have_libfetch=1
+		LIBFETCH_IS_FETCH=1
+		LIBFETCH_DYNAMIC=1
+		LIBFETCH_SONAME='"libfetch.so.6"'
+		LIBFETCH_LIBS="-ldl"
+		AC_MSG_RESULT([fetch(3)])
+	], [])
+	LIBS="$saved_libs"
+
+	if test -z "$have_libfetch"; then
+		if curl-config --protocols 2>/dev/null | grep -q HTTPS &&
+		    test "$(("0x$(curl-config --vernum)"))" -ge "$((0x071000))"; then
+			have_libfetch=1
+			LIBFETCH_IS_LIBCURL=1
+			if test "$(curl-config --built-shared)" = "yes"; then
+				LIBFETCH_DYNAMIC=1
+				LIBFETCH_SONAME='"libcurl.so.4"'
+				LIBFETCH_LIBS="-ldl"
+				AC_MSG_RESULT([libcurl])
+			else
+				LIBFETCH_LIBS="$(curl-config --libs)"
+				AC_MSG_RESULT([libcurl (static)])
+			fi
+
+			CCFLAGS="$CCFLAGS $(curl-config --cflags)"
+		fi
+	fi
+
+	if test -z "$have_libfetch"; then
+		AC_MSG_RESULT([none])
+	fi
+
+	AC_SUBST([LIBFETCH_LIBS])
+	AC_DEFINE_UNQUOTED([LIBFETCH_IS_FETCH], [$LIBFETCH_IS_FETCH], [libfetch is fetch(3)])
+	AC_DEFINE_UNQUOTED([LIBFETCH_IS_LIBCURL], [$LIBFETCH_IS_LIBCURL], [libfetch is libcurl])
+	AC_DEFINE_UNQUOTED([LIBFETCH_DYNAMIC], [$LIBFETCH_DYNAMIC], [whether the chosen libfetch is to be loaded at run-time])
+	AC_DEFINE_UNQUOTED([LIBFETCH_SONAME], [$LIBFETCH_SONAME], [soname of chosen libfetch])
+])

config/user.m4

@@ -22,6 +22,7 @@ AC_DEFUN([ZFS_AC_CONFIG_USER], [
 	ZFS_AC_CONFIG_USER_LIBCRYPTO
 	ZFS_AC_CONFIG_USER_LIBAIO
 	ZFS_AC_CONFIG_USER_LIBATOMIC
+	ZFS_AC_CONFIG_USER_LIBFETCH
 	ZFS_AC_CONFIG_USER_CLOCK_GETTIME
 	ZFS_AC_CONFIG_USER_PAM
 	ZFS_AC_CONFIG_USER_RUNSTATEDIR

include/libzfs_impl.h

@@ -69,6 +69,8 @@ struct libzfs_handle {
 	boolean_t libzfs_prop_debug;
 	regex_t libzfs_urire;
 	uint64_t libzfs_max_nvlist;
+	void *libfetch;
+	char *libfetch_load_error;
 };
 
 struct zfs_handle {

lib/libzfs/Makefile.am

@@ -75,7 +75,7 @@ libzfs_la_LIBADD = \
 	$(abs_top_builddir)/lib/libnvpair/libnvpair.la \
 	$(abs_top_builddir)/lib/libuutil/libuutil.la
 
-libzfs_la_LIBADD += -lm $(LIBCRYPTO_LIBS) $(ZLIB_LIBS) $(LTLIBINTL)
+libzfs_la_LIBADD += -lm $(LIBCRYPTO_LIBS) $(ZLIB_LIBS) $(LIBFETCH_LIBS) $(LTLIBINTL)
 
 libzfs_la_LDFLAGS = -pthread