QUIC: ignore duplicate PATH_CHALLENGE frames. According to RFC 9000, an endpoint SHOULD NOT send multiple PATH_CHALLENGE frames in a single packet. The change adds a check to enforce this claim to optimize server behavior. Previously each PATH_CHALLENGE always resulted in a single response datagram being sent to client. The effect of this was however limited by QUIC flood protection. Also, PATH_CHALLENGE is explicitly disabled in Initial and Handshake levels, see RFC 9000, Table 3. However, technically it may be sent by client in 0-RTT over a new path without actual migration, even though the migration itself is prohibited during handshake. This allows client to coalesce multiple 0-RTT packets each carrying a PATH_CHALLENGE and end up with multiple PATH_CHALLENGEs per datagram. This again leads to suboptimal behavior, see above. Since the purpose of sending PATH_CHALLENGE frames in 0-RTT is unclear, these frames are now only allowed in 1-RTT. For 0-RTT they are silently ignored.

# Copyright (C) Igor Sysoev
# Copyright (C) Nginx, Inc.


have=NGX_WIN32 . auto/have_headers

CORE_INCS="$WIN32_INCS"
CORE_DEPS="$WIN32_DEPS"
CORE_SRCS="$WIN32_SRCS $IOCP_SRCS"
OS_CONFIG="$WIN32_CONFIG"
NGX_ICONS="$NGX_WIN32_ICONS"
SELECT_SRCS=$WIN32_SELECT_SRCS
POLL_SRCS=$WIN32_POLL_SRCS

ngx_pic_opt=
ngx_binext=".exe"

case "$NGX_CC_NAME" in

    gcc)
        CORE_LIBS="$CORE_LIBS -ladvapi32 -lws2_32"
        MAIN_LINK="$MAIN_LINK -Wl,--export-all-symbols"
        MAIN_LINK="$MAIN_LINK -Wl,--out-implib=$NGX_OBJS/libnginx.a"
        MODULE_LINK="-shared -L $NGX_OBJS -lnginx"
    ;;

    *)
        CORE_LIBS="$CORE_LIBS advapi32.lib ws2_32.lib"
    ;;

esac

EVENT_MODULES="$EVENT_MODULES $IOCP_MODULE"
#EVENT_FOUND=YES

have=NGX_HAVE_INET6 . auto/have

have=NGX_HAVE_IOCP . auto/have