nghttp3: required when ngtcp2 is used for QUIC

- checked for by configure
- updated docs/HTTP3.md
- shown in the version string

Closes #4210

configure.ac

@@ -3402,14 +3402,12 @@ if test X"$want_tcp2" != Xno; then
     AC_CHECK_LIB(ngtcp2, ngtcp2_conn_client_new,
       [
        AC_CHECK_HEADERS(ngtcp2/ngtcp2.h,
-          curl_h3_msg="enabled (ngtcp2)"
           NGTCP2_ENABLED=1
           AC_DEFINE(USE_NGTCP2, 1, [if ngtcp2 is in use])
           AC_SUBST(USE_NGTCP2, [1])
           CURL_LIBRARY_PATH="$CURL_LIBRARY_PATH:$DIR_TCP2"
           export CURL_LIBRARY_PATH
           AC_MSG_NOTICE([Added $DIR_TCP2 to CURL_LIBRARY_PATH])
-          experimental="$experimental HTTP3"
        )
       ],
         dnl not found, revert back to clean variables
@@ -3429,6 +3427,97 @@ if test X"$want_tcp2" != Xno; then
 
 fi
 
+dnl **********************************************************************
+dnl Check for nghttp3 (HTTP/3 with ngtcp2)
+dnl **********************************************************************
+
+OPT_NGHTTP3="yes"
+
+if test "x$NGTCP2_ENABLED" = "x"; then
+  # without ngtcp2, nghttp3 is of no use for us
+  OPT_NGHTTP3="no"
+fi
+
+AC_ARG_WITH(nghttp3,
+AC_HELP_STRING([--with-nghttp3=PATH],[Enable nghttp3 usage])
+AC_HELP_STRING([--without-nghttp3],[Disable nghttp3 usage]),
+  [OPT_NGHTTP3=$withval])
+case "$OPT_NGHTTP3" in
+  no)
+    dnl --without-nghttp3 option used
+    want_nghttp3="no"
+    ;;
+  yes)
+    dnl --with-nghttp3 option used without path
+    want_nghttp3="default"
+    want_nghttp3_path=""
+    ;;
+  *)
+    dnl --with-nghttp3 option used with path
+    want_nghttp3="yes"
+    want_nghttp3_path="$withval/lib/pkgconfig"
+    ;;
+esac
+
+curl_http3_msg="disabled (--with-nghttp3)"
+if test X"$want_nghttp3" != Xno; then
+  dnl backup the pre-nghttp3 variables
+  CLEANLDFLAGS="$LDFLAGS"
+  CLEANCPPFLAGS="$CPPFLAGS"
+  CLEANLIBS="$LIBS"
+
+  CURL_CHECK_PKGCONFIG(libnghttp3, $want_nghttp3_path)
+
+  if test "$PKGCONFIG" != "no" ; then
+    LIB_NGHTTP3=`CURL_EXPORT_PCDIR([$want_nghttp3_path])
+      $PKGCONFIG --libs-only-l libnghttp3`
+    AC_MSG_NOTICE([-l is $LIB_NGHTTP3])
+
+    CPP_NGHTTP3=`CURL_EXPORT_PCDIR([$want_nghttp3_path]) dnl
+      $PKGCONFIG --cflags-only-I libnghttp3`
+    AC_MSG_NOTICE([-I is $CPP_NGHTTP3])
+
+    LD_NGHTTP3=`CURL_EXPORT_PCDIR([$want_nghttp3_path])
+      $PKGCONFIG --libs-only-L libnghttp3`
+    AC_MSG_NOTICE([-L is $LD_NGHTTP3])
+
+    LDFLAGS="$LDFLAGS $LD_NGHTTP3"
+    CPPFLAGS="$CPPFLAGS $CPP_NGHTTP3"
+    LIBS="$LIB_NGHTTP3 $LIBS"
+
+    if test "x$cross_compiling" != "xyes"; then
+      DIR_NGHTTP3=`echo $LD_NGHTTP3 | $SED -e 's/-L//'`
+    fi
+    AC_CHECK_LIB(nghttp3, nghttp3_conn_client_new,
+      [
+       AC_CHECK_HEADERS(nghttp3/nghttp3.h,
+          curl_h3_msg="enabled (ngtcp2 + nghttp3)"
+          NGHTTP3_ENABLED=1
+          AC_DEFINE(USE_NGHTTP3, 1, [if nghttp3 is in use])
+          AC_SUBST(USE_NGHTTP3, [1])
+          CURL_LIBRARY_PATH="$CURL_LIBRARY_PATH:$DIR_NGHTTP3"
+          export CURL_LIBRARY_PATH
+          AC_MSG_NOTICE([Added $DIR_NGHTTP3 to CURL_LIBRARY_PATH])
+          experimental="$experimental HTTP3"
+       )
+      ],
+        dnl not found, revert back to clean variables
+        LDFLAGS=$CLEANLDFLAGS
+        CPPFLAGS=$CLEANCPPFLAGS
+        LIBS=$CLEANLIBS
+    )
+
+  else
+    dnl no nghttp3 pkg-config found, deal with it
+    if test X"$want_nghttp3" != Xdefault; then
+      dnl To avoid link errors, we do not allow --with-nghttp3 without
+      dnl a pkgconfig file
+      AC_MSG_ERROR([--with-nghttp3 was specified but could not find nghttp3 pkg-config file.])
+    fi
+  fi
+
+fi
+
 dnl **********************************************************************
 dnl Check for quiche (QUIC)
 dnl **********************************************************************

docs/HTTP3.md

@@ -31,12 +31,42 @@ in the master branch using pull-requests, just like ordinary changes.
 
 ## Build
 
-1. clone ngtcp2 from git (the draft-22 branch)
-2. build and install ngtcp2's custom OpenSSL version (the quic-draft-22 branch)
-3. build and install nghttp3
-4. build and install ngtcp2 according to its instructions
-5. configure curl with ngtcp2 support: `./configure --with-ngtcp2=<install prefix>`
-6. build curl "normally"
+Build (patched) OpenSSL
+
+     % git clone --depth 1 -b quic-draft-22 https://github.com/tatsuhiro-t/openssl
+     % cd openssl
+     % ./config enable-tls1_3 --prefix=<somewhere1>
+     % make
+     % make install_sw
+
+Build nghttp3
+
+     % cd ..
+     % git clone https://github.com/ngtcp2/nghttp3
+     % cd nghttp3
+     % autoreconf -i
+     % ./configure --prefix=<somewhere2> --enable-lib-only
+     % make
+     % make install
+
+Build ngtcp2
+
+     % cd ..
+     % git clone -b draft-20 https://github.com/ngtcp2/ngtcp2
+     % cd ngtcp2
+     % autoreconf -i
+     % ./configure PKG_CONFIG_PATH=<somewhere1>/lib/pkgconfig:<somewhere2>/lib/pkgconfig LDFLAGS="-Wl,-rpath,<somehere1>/lib" --prefix==<somewhere3>
+     % make
+     % make install
+
+Build curl
+
+     % cd ..
+     % git clone https://github.com/curl/curl
+     % cd curl
+     % ./buildconf
+     % LDFLAGS="-Wl,-rpath,<somewhere1>/lib" ./configure -with-ssl=<somewhere1> --with-nghttp3=<somewhere2> --with-ngtcp2=<somewhere3>
+     % make
 
 ## Running
 

lib/vquic/ngtcp2.c

@@ -1055,7 +1055,7 @@ CURLcode Curl_quic_connect(struct connectdata *conn,
  */
 int Curl_quic_ver(char *p, size_t len)
 {
-  return msnprintf(p, len, " ngtcp2/blabla");
+  return msnprintf(p, len, " ngtcp2/blabla nghttp3/bloblo");
 }
 
 CURLcode Curl_quic_is_connected(struct connectdata *conn, int sockindex,