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e3da7c9934
In the past only GTPv2C was supported, and had the "gtp" generic prefix. Later on, GTPv1C support was added, and "gtp1" prefix was used. Let's move GTPv2C specific bits to have "gtp2" prefix too, and leave "gtp" prefix for generic stuff among different GTP versions.
103 lines
2.9 KiB
C
103 lines
2.9 KiB
C
/*
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* Copyright (C) 2019 by Sukchan Lee <acetcom@gmail.com>
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*
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* This file is part of Open5GS.
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*
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* This program is free software: you can redistribute it and/or modify
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* it under the terms of the GNU Affero General Public License as published by
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* the Free Software Foundation, either version 3 of the License, or
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* (at your option) any later version.
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*
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* This program is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU General Public License for more details.
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*
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* You should have received a copy of the GNU General Public License
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* along with this program. If not, see <https://www.gnu.org/licenses/>.
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*/
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#include "ogs-gtp.h"
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int ogs_gtpu_header_len(ogs_pkbuf_t *pkbuf)
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{
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ogs_gtp2_header_t *gtp_h = NULL;
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uint8_t *ext_h = NULL;
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uint16_t len = 0;
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ogs_assert(pkbuf);
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ogs_assert(pkbuf->data);
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gtp_h = (ogs_gtp2_header_t *)pkbuf->data;
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len = OGS_GTPV1U_HEADER_LEN;
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if (pkbuf->len < len) return -1;
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if (gtp_h->flags & OGS_GTPU_FLAGS_E) {
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len += OGS_GTPV1U_EXTENSION_HEADER_LEN;
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if (pkbuf->len < len) return -1;
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/*
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* TS29.281
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* 5.2.1 General format of the GTP-U Extension Header
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*
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* If no such Header follows,
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* then the value of the Next Extension Header Type shall be 0. */
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while (*(ext_h = (((uint8_t *)gtp_h) + len - 1))) {
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/*
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* The length of the Extension header shall be defined
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* in a variable length of 4 octets, i.e. m+1 = n*4 octets,
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* where n is a positive integer.
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*/
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len += (*(++ext_h)) * 4;
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if (pkbuf->len < len) return -1;
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}
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} else if (gtp_h->flags & (OGS_GTPU_FLAGS_S|OGS_GTPU_FLAGS_PN)) {
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/*
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* If and only if one or more of these three flags are set,
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* the fields Sequence Number, N-PDU and Extension Header
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* shall be present. The sender shall set all the bits of
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* the unused fields to zero. The receiver shall not evaluate
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* the unused fields.
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* For example, if only the E flag is set to 1, then
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* the N-PDU Number and Sequence Number fields shall also be present,
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* but will not have meaningful values and shall not be evaluated.
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*/
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len += 4;
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}
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if (pkbuf->len < len) return -1;
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return len;
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}
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uint16_t ogs_in_cksum(uint16_t *addr, int len)
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{
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int nleft = len;
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uint32_t sum = 0;
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uint16_t *w = addr;
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uint16_t answer = 0;
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// Adding 16 bits sequentially in sum
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while (nleft > 1) {
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sum += *w;
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nleft -= 2;
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w++;
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}
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// If an odd byte is left
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if (nleft == 1) {
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*(uint8_t *) (&answer) = *(uint8_t *) w;
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sum += answer;
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}
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sum = (sum >> 16) + (sum & 0xffff);
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sum += (sum >> 16);
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answer = ~sum;
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return answer;
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}
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