253 lines
8.3 KiB
C
253 lines
8.3 KiB
C
/*
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* PCO parsing related code
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* Copyright (C) 2002, 2003, 2004 Mondru AB.
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* Copyright (C) 2017-2019 by Harald Welte <laforge@gnumonks.org>
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* Copyright (C) 2019 sysmocom - s.f.m.c. GmbH <info@sysmocom.de>
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*
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* The contents of this file may be used under the terms of the GNU
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* General Public License Version 2, provided that the above copyright
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* notice and this permission notice is included in all copies or
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* substantial portions of the software.
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*
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*/
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#include <unistd.h>
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#include <string.h>
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#include <osmocom/core/msgb.h>
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#include <osmocom/gsm/tlv.h>
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#include "../lib/util.h"
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#include "pco.h"
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#include "ggsn.h"
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/* determine if IPCP contains given option */
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static const uint8_t *ipcp_contains_option(const struct ipcp_hdr *ipcp, size_t ipcp_len,
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enum ipcp_options opt, size_t opt_minlen)
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{
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const uint8_t *cur_opt = ipcp->options;
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/* iterate over Options and check if protocol contained */
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while (cur_opt + sizeof(struct ipcp_option_hdr) <= (uint8_t*)ipcp + ipcp_len) {
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const struct ipcp_option_hdr *cur_opt_hdr = (const struct ipcp_option_hdr *)cur_opt;
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/* length value includes 2 bytes type/length */
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if (cur_opt_hdr->len < sizeof(struct ipcp_option_hdr))
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return NULL;
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if (cur_opt_hdr->type == opt &&
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cur_opt_hdr->len >= sizeof(struct ipcp_option_hdr) + opt_minlen)
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return cur_opt;
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cur_opt += cur_opt_hdr->len;
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}
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return NULL;
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}
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static const char *pap_welcome = "Welcome to OsmoGGSN " PACKAGE_VERSION;
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/* Handle PAP protocol according to RFC 1334 */
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static void process_pco_element_pap(const struct pco_element *pco_in, struct msgb *resp,
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const struct apn_ctx *apn, struct pdp_t *pdp)
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{
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const struct pap_element *pap_in = (const struct pap_element *) pco_in->data;
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uint16_t pap_in_len;
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uint8_t peer_id_len;
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const uint8_t *peer_id;
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unsigned int pap_welcome_len;
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uint8_t pap_out_size;
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struct pap_element *pap_out;
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if (pco_in->length < sizeof(struct pap_element))
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goto ret_broken;
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pap_in_len = osmo_load16be(&pap_in->len);
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if (pco_in->length < pap_in_len)
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goto ret_broken;
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/* "pco_in->length > pap_in_len" is allowed: RFC1334 2.2 states:
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"Octets outside the range of the Length field should be treated as
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Data Link Layer padding and should be ignored on reception."
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*/
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switch (pap_in->code) {
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case PAP_CODE_AUTH_REQ:
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if (pap_in_len < sizeof(struct pap_element) + 1)
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goto ret_broken_auth;
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peer_id_len = pap_in->data[0];
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if (pap_in_len < sizeof(struct pap_element) + 1 + peer_id_len)
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goto ret_broken_auth;
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peer_id = &pap_in->data[1];
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LOGPPDP(LOGL_DEBUG, pdp, "PCO PAP PeerId = %s, ACKing\n",
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osmo_quote_str((const char *)peer_id, peer_id_len));
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/* Password-Length + Password following here, but we don't care */
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/* Prepare response, we ACK all of them: */
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pap_welcome_len = strlen(pap_welcome);
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/* +1: Length field of pap_welcome Message */
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pap_out_size = sizeof(struct pap_element) + 1 + pap_welcome_len;
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pap_out = alloca(pap_out_size);
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pap_out->code = PAP_CODE_AUTH_ACK;
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pap_out->id = pap_in->id;
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pap_out->len = htons(pap_out_size);
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pap_out->data[0] = pap_welcome_len;
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memcpy(pap_out->data+1, pap_welcome, pap_welcome_len);
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msgb_t16lv_put(resp, PCO_P_PAP, pap_out_size, (uint8_t *) pap_out);
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break;
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case PAP_CODE_AUTH_ACK:
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case PAP_CODE_AUTH_NAK:
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default:
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LOGPPDP(LOGL_NOTICE, pdp, "Unsupported PAP PCO Code %u, ignoring\n", pap_in->code);
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break;
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}
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return;
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ret_broken_auth:
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LOGPPDP(LOGL_NOTICE, pdp, "Invalid PAP AuthenticateReq: %s, ignoring\n",
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osmo_hexdump_nospc((const uint8_t *)pco_in, pco_in->length));
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return;
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ret_broken:
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LOGPPDP(LOGL_NOTICE, pdp, "Invalid PAP PCO Length: %s, ignoring\n",
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osmo_hexdump_nospc((const uint8_t *)pco_in, pco_in->length));
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}
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static void process_pco_element_ipcp(const struct pco_element *pco_elem, struct msgb *resp,
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const struct apn_ctx *apn, struct pdp_t *pdp)
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{
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struct ippoolm_t *peer_v4 = pdp_get_peer_ipv(pdp, false);
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const struct in46_addr *dns1 = &apn->v4.cfg.dns[0];
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const struct in46_addr *dns2 = &apn->v4.cfg.dns[1];
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uint8_t *start = resp->tail;
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const struct ipcp_hdr *ipcp;
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uint16_t ipcp_len;
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uint8_t *len1, *len2;
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unsigned int len_appended;
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ptrdiff_t consumed;
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size_t remain;
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if (!peer_v4) {
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LOGPPDP(LOGL_ERROR, pdp, "IPCP but no IPv4 type ?!?\n");
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return;
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}
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ipcp = (const struct ipcp_hdr *)pco_elem->data;
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consumed = (pco_elem->data - &pdp->pco_req.v[0]);
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remain = sizeof(pdp->pco_req.v) - consumed;
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ipcp_len = osmo_load16be(&ipcp->len);
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if (remain < 0 || remain < ipcp_len) {
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LOGPPDP(LOGL_ERROR, pdp, "Malformed IPCP, ignoring\n");
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return;
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}
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/* Three byte T16L header */
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msgb_put_u16(resp, 0x8021); /* IPCP */
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len1 = msgb_put(resp, 1); /* Length of contents: delay */
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msgb_put_u8(resp, 0x02); /* ACK */
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msgb_put_u8(resp, ipcp->id); /* ID: Needs to match request */
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msgb_put_u8(resp, 0x00); /* Length MSB */
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len2 = msgb_put(resp, 1); /* Length LSB: delay */
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if (dns1->len == 4 && ipcp_contains_option(ipcp, ipcp_len, IPCP_OPT_PRIMARY_DNS, 4)) {
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msgb_put_u8(resp, 0x81); /* DNS1 Tag */
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msgb_put_u8(resp, 2 + dns1->len); /* DNS1 Length, incl. TL */
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msgb_put_u32(resp, ntohl(dns1->v4.s_addr));
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}
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if (dns2->len == 4 && ipcp_contains_option(ipcp, ipcp_len, IPCP_OPT_SECONDARY_DNS, 4)) {
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msgb_put_u8(resp, 0x83); /* DNS2 Tag */
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msgb_put_u8(resp, 2 + dns2->len); /* DNS2 Length, incl. TL */
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msgb_put_u32(resp, ntohl(dns2->v4.s_addr));
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}
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/* patch in length values */
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len_appended = resp->tail - start;
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*len1 = len_appended - 3;
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*len2 = len_appended - 3;
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}
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static void process_pco_element_dns_ipv6(const struct pco_element *pco_elem, struct msgb *resp,
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const struct apn_ctx *apn, struct pdp_t *pdp)
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{
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unsigned int i;
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const uint8_t *tail = resp->tail;
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for (i = 0; i < ARRAY_SIZE(apn->v6.cfg.dns); i++) {
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const struct in46_addr *i46a = &apn->v6.cfg.dns[i];
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if (i46a->len != 16)
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continue;
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msgb_t16lv_put(resp, PCO_P_DNS_IPv6_ADDR, i46a->len, i46a->v6.s6_addr);
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}
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if (resp->tail == tail)
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LOGPPDP(LOGL_NOTICE, pdp, "MS requested IPv6 DNS, but APN has none configured\n");
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}
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static void process_pco_element_dns_ipv4(const struct pco_element *pco_elem, struct msgb *resp,
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const struct apn_ctx *apn, struct pdp_t *pdp)
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{
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unsigned int i;
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const uint8_t *tail = resp->tail;
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for (i = 0; i < ARRAY_SIZE(apn->v4.cfg.dns); i++) {
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const struct in46_addr *i46a = &apn->v4.cfg.dns[i];
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if (i46a->len != 4)
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continue;
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msgb_t16lv_put(resp, PCO_P_DNS_IPv4_ADDR, i46a->len, (uint8_t *)&i46a->v4);
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}
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if (resp->tail == tail)
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LOGPPDP(LOGL_NOTICE, pdp, "MS requested IPv4 DNS, but APN has none configured\n");
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}
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static void process_pco_element(const struct pco_element *pco_elem, struct msgb *resp,
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const struct apn_ctx *apn, struct pdp_t *pdp)
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{
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uint16_t protocol_id = osmo_load16be(&pco_elem->protocol_id);
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LOGPPDP(LOGL_DEBUG, pdp, "PCO Protocol 0x%04x\n", protocol_id);
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switch (protocol_id) {
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case PCO_P_PAP:
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process_pco_element_pap(pco_elem, resp, apn, pdp);
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break;
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case PCO_P_IPCP:
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process_pco_element_ipcp(pco_elem, resp, apn, pdp);
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break;
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case PCO_P_DNS_IPv6_ADDR:
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process_pco_element_dns_ipv6(pco_elem, resp, apn, pdp);
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break;
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case PCO_P_DNS_IPv4_ADDR:
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process_pco_element_dns_ipv4(pco_elem, resp, apn, pdp);
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break;
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default:
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LOGPPDP(LOGL_INFO, pdp, "Unknown/Unimplemented PCO Protocol 0x%04x: %s\n",
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protocol_id, osmo_hexdump_nospc(pco_elem->data, pco_elem->length));
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break;
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}
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}
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/* process one PCO request from a MS/UE, putting together the proper responses */
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void process_pco(const struct apn_ctx *apn, struct pdp_t *pdp)
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{
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struct msgb *resp = msgb_alloc(256, "PCO.resp");
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const struct ul255_t *pco = &pdp->pco_req;
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const struct pco_element *pco_elem;
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const uint8_t *cur;
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/* build the header of the PCO response */
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OSMO_ASSERT(resp);
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msgb_put_u8(resp, 0x80); /* ext-bit + configuration protocol byte */
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/* iterate over the PCO elements in the request; call process_pco_element() for each */
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for (cur = pco->v + 1, pco_elem = (const struct pco_element *) cur;
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cur + sizeof(struct pco_element) <= pco->v + pco->l;
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cur += pco_elem->length + sizeof(*pco_elem), pco_elem = (const struct pco_element *) cur) {
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process_pco_element(pco_elem, resp, apn, pdp);
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}
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/* copy the PCO response msgb and copy its contents over to the PDP context */
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if (msgb_length(resp) > 1) {
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memcpy(pdp->pco_neg.v, msgb_data(resp), msgb_length(resp));
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pdp->pco_neg.l = msgb_length(resp);
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} else
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pdp->pco_neg.l = 0;
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msgb_free(resp);
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}
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