ggsn.c: Refactor PCO processing during PDP activation
The existing PCO processing is implemented in a rather convoluted way. We scan the list of PCO elements several times for different PCO protocols. Let's change to a straight-forward model where we simply do one iteration over the list of PCO elements and generate responses step by step. Change-Id: I4a7d09279b6b259e2b95f1f51159b16838b2d94c
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f653c5bc33
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9272d212c3
180
ggsn/ggsn.c
180
ggsn/ggsn.c
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@ -470,22 +470,6 @@ struct pco_element {
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uint8_t data[0];
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} __attribute__((packed));
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/* determine if PCO contains given protocol */
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static const struct pco_element *pco_contains_proto(const struct ul255_t *pco, size_t offset,
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uint16_t prot, size_t prot_minlen)
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{
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const uint8_t *cur = pco->v + 1 /*length*/ + offset;
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/* iterate over PCO and check if protocol contained */
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while (cur + sizeof(struct pco_element) <= pco->v + pco->l) {
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const struct pco_element *elem = (const struct pco_element *)cur;
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if (ntohs(elem->protocol_id) == prot && elem->length >= prot_minlen)
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return elem;
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cur += elem->length + sizeof(struct pco_element);
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}
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return NULL;
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}
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/*! Get the peer of pdp based on IP version used.
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* \param[in] pdp PDP context to select the peer from.
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* \param[in] v4v6 IP version to select. Valid values are 4 and 6.
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@ -510,101 +494,127 @@ static struct ippoolm_t *pdp_get_peer_ipv(struct pdp_t *pdp, bool is_ipv6) {
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return NULL;
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}
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/* construct an IPCP PCO response from request*/
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static void build_ipcp_pco(const struct apn_ctx *apn, struct pdp_t *pdp, struct msgb *msg)
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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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const struct pco_element *pco_ipcp;
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uint8_t *start = resp->tail;
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const uint8_t *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, offset = 0;
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size_t remain;
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/* pco_contains_proto() returns a potentially unaligned pointer into pco_req->v (see OS#3194) */
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pco_ipcp = pco_contains_proto(&pdp->pco_req, offset, PCO_P_IPCP, sizeof(struct ipcp_hdr));
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while (pco_ipcp) {
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uint8_t *start = msg->tail;
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if (!peer_v4)
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return;
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ipcp = pco_ipcp->data;
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consumed = (ipcp - &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 + 2); /* 1=code + 1=id */
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if (remain < 0 || remain < ipcp_len)
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return;
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ipcp = pco_elem->data;
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consumed = (ipcp - &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 + 2); /* 1=code + 1=id */
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if (remain < 0 || remain < ipcp_len)
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return;
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/* Three byte T16L header */
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msgb_put_u16(msg, 0x8021); /* IPCP */
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len1 = msgb_put(msg, 1); /* Length of contents: delay */
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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(msg, 0x02); /* ACK */
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msgb_put_u8(msg, ipcp[1]); /* ID: Needs to match request */
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msgb_put_u8(msg, 0x00); /* Length MSB */
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len2 = msgb_put(msg, 1); /* Length LSB: delay */
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msgb_put_u8(resp, 0x02); /* ACK */
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msgb_put_u8(resp, ipcp[1]); /* 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(msg, 0x81); /* DNS1 Tag */
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msgb_put_u8(msg, 2 + dns1->len);/* DNS1 Length, incl. TL */
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msgb_put_u32(msg, 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(msg, 0x83); /* DNS2 Tag */
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msgb_put_u8(msg, 2 + dns2->len);/* DNS2 Length, incl. TL */
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msgb_put_u32(msg, ntohl(dns2->v4.s_addr));
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}
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/* patch in length values */
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len_appended = msg->tail - start;
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*len1 = len_appended - 3;
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*len2 = len_appended - 3;
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offset += sizeof(pco_ipcp) + pco_ipcp->length;
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pco_ipcp = pco_contains_proto(&pdp->pco_req, offset, PCO_P_IPCP, sizeof(struct ipcp_hdr));
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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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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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}
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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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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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}
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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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switch (ntohs(pco_elem->protocol_id)) {
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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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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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static void process_pco(const struct apn_ctx *apn, struct pdp_t *pdp)
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{
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struct msgb *msg = msgb_alloc(256, "PCO");
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struct ippoolm_t *peer_v4 = pdp_get_peer_ipv(pdp, false);
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unsigned int i;
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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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OSMO_ASSERT(msg);
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msgb_put_u8(msg, 0x80); /* ext-bit + configuration protocol byte */
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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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if (peer_v4)
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build_ipcp_pco(apn, pdp, msg);
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if (pco_contains_proto(&pdp->pco_req, 0, PCO_P_DNS_IPv6_ADDR, 0)) {
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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(msg, PCO_P_DNS_IPv6_ADDR, i46a->len, i46a->v6.s6_addr);
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}
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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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if (pco_contains_proto(&pdp->pco_req, 0, PCO_P_DNS_IPv4_ADDR, 0)) {
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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(msg, PCO_P_DNS_IPv4_ADDR, i46a->len, (uint8_t *)&i46a->v4);
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}
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}
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if (msgb_length(msg) > 1) {
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memcpy(pdp->pco_neg.v, msgb_data(msg), msgb_length(msg));
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pdp->pco_neg.l = msgb_length(msg);
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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(msg);
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msgb_free(resp);
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}
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static bool apn_supports_ipv4(const struct apn_ctx *apn)
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