ggsn: Move PCO handling code into its own file

This way ggsn.c is shrinked in size and get rid of a lot of code there,
which is of no interest unless the reader is interested in that really
specific part.

Change-Id: Ieaa7e71f17c7fd9377c76ef53362eab596d669a6
diff --git a/ggsn/pco.h b/ggsn/pco.h
new file mode 100644
index 0000000..7ebe05a
--- /dev/null
+++ b/ggsn/pco.h
@@ -0,0 +1,81 @@
+#pragma once
+
+#include <stdint.h>
+
+#include "../gtp/pdp.h"
+
+/* 3GPP TS 24.008 10.6.5.3 */
+enum pco_protocols {
+	PCO_P_LCP		= 0xC021,
+	PCO_P_PAP		= 0xC023,
+	PCO_P_CHAP		= 0xC223,
+	PCO_P_IPCP		= 0x8021,
+	PCO_P_PCSCF_ADDR	= 0x0001,
+	PCO_P_IM_CN_SS_F	= 0x0002,
+	PCO_P_DNS_IPv6_ADDR	= 0x0003,
+	PCO_P_POLICY_CTRL_REJ	= 0x0004,	/* only in Network->MS */
+	PCO_P_MS_SUP_NETREQ_BCI	= 0x0005,
+	/* reserved */
+	PCO_P_DSMIPv6_HA_ADDR	= 0x0007,
+	PCO_P_DSMIPv6_HN_PREF	= 0x0008,
+	PCO_P_DSMIPv6_v4_HA_ADDR= 0x0009,
+	PCO_P_IP_ADDR_VIA_NAS	= 0x000a,	/* only MS->Network */
+	PCO_P_IPv4_ADDR_VIA_DHCP= 0x000b,	/* only MS->Netowrk */
+	PCO_P_PCSCF_IPv4_ADDR	= 0x000c,
+	PCO_P_DNS_IPv4_ADDR	= 0x000d,
+	PCO_P_MSISDN		= 0x000e,
+	PCO_P_IFOM_SUPPORT	= 0x000f,
+	PCO_P_IPv4_LINK_MTU	= 0x0010,
+	PCO_P_MS_SUPP_LOC_A_TFT	= 0x0011,
+	PCO_P_PCSCF_RESEL_SUP	= 0x0012,	/* only MS->Network */
+	PCO_P_NBIFOM_REQ	= 0x0013,
+	PCO_P_NBIFOM_MODE	= 0x0014,
+	PCO_P_NONIP_LINK_MTU	= 0x0015,
+	PCO_P_APN_RATE_CTRL_SUP	= 0x0016,
+	PCO_P_PS_DATA_OFF_UE	= 0x0017,
+	PCO_P_REL_DATA_SVC	= 0x0018,
+};
+
+struct pco_element {
+	uint16_t protocol_id;	/* network byte order */
+	uint8_t length;		/* length of data below */
+	uint8_t data[0];
+} __attribute__((packed));
+
+
+/* RFC 1332 */
+enum ipcp_options {
+	IPCP_OPT_IPADDR = 3,
+	IPCP_OPT_PRIMARY_DNS = 129,
+	IPCP_OPT_SECONDARY_DNS = 131,
+};
+
+struct ipcp_option_hdr {
+	uint8_t type;
+	uint8_t len;
+	uint8_t data[0];
+} __attribute__ ((packed));
+
+struct ipcp_hdr {
+	uint8_t code;
+	uint8_t id;
+	uint16_t len;
+	uint8_t options[0];
+} __attribute__ ((packed));
+
+/* RFC 1334, section 3.2. Packet Format */
+struct pap_element {
+	uint8_t code;
+	uint8_t id;
+	uint16_t len; /* length including header */
+	uint8_t data[0];
+} __attribute__((packed));
+
+enum pap_code {
+	PAP_CODE_AUTH_REQ = 1,
+	PAP_CODE_AUTH_ACK = 2,
+	PAP_CODE_AUTH_NAK = 3,
+};
+
+struct apn_ctx;
+void process_pco(const struct apn_ctx *apn, struct pdp_t *pdp);