IPSec/strongswan failures and checkpoints

FAIL_CP_REQ
Add

leftsourceip=%config
leftdns=%dns

TS_UNACCEPTABLE
Check left|right subnet and proto settings.

NO_PROPOSAL_CHOSEN
check ike=XXX and esp=XXX

libopenikev2: openikev2::Payload_NOTIFY Class Reference
http://openikev2.sourceforge.net/libopenikev2_api/classopenikev2_1_1Payload__NOTIFY.html

UNSUPPORTED_CRITICAL_PAYLOAD	Unsupported critical payload.
INVALID_IKE_SPI	Invalid IKE SPI.
INVALID_MAJOR_VERSION	Invalid Major Version.
INVALID_SYNTAX	Invalid syntax.
INVALID_MESSAGE_ID	Invalid message ID.
INVALID_SPI	Invalid SPI.
NO_PROPOSAL_CHOSEN	No proposal chosen.
INVALID_KE_PAYLOAD	Invalid KE payload.
AUTHENTICATION_FAILED	Authentication failed.
SINGLE_PAIR_REQUIRED	Single pair required.
NO_ADDITIONAL_SAS	No additional SAs.
INTERNAL_ADDRESS_FAILURE	Internal address failure.
FAILED_CP_REQUIRED	Failed Configuration Payload required.
TS_UNACCEPTABLE	Traffic selector unacceptable.
INVALID_SELECTORS	Invalid selectors.
INITIAL_CONTACT	Initial contact.
SET_WINDOW_SIZE	Set window size.
ADDITIONAL_TS_POSSIBLE	Additional Traffic selector possible.
IPCOMP_SUPPORTED	IPcomp supported.
NAT_DETECTION_SOURCE_IP	NAT detection source ip.
NAT_DETECTION_DESTINATION_IP	NAT detection destination ip.
COOKIE	Cookie.
USE_TRANSPORT_MODE	Use transport mode.
HTTP_CERT_LOOKUP_SUPPORTED	HTTP certificate lookup supported.
REKEY_SA	Rekey SA.
ESP_TFC_PADDING_NOT_SUPPORTED	ESP TFC padding not supported.
NON_FIRST_FRAGMENT_ALSO	Non first fragment also.