nat: Extract the message re-writing from the utils to a dedicated file
Move the code around to make it more clear what the routines should do.
diff --git a/openbsc/src/osmo-bsc_nat/bsc_nat_rewrite.c b/openbsc/src/osmo-bsc_nat/bsc_nat_rewrite.c
new file mode 100644
index 0000000..79f03c2
--- /dev/null
+++ b/openbsc/src/osmo-bsc_nat/bsc_nat_rewrite.c
@@ -0,0 +1,628 @@
+/*
+ * Message rewriting functionality
+ */
+/*
+ * (C) 2010-2011 by Holger Hans Peter Freyther <zecke@selfish.org>
+ * (C) 2010-2011 by On-Waves
+ * All Rights Reserved
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU Affero General Public License as published by
+ * the Free Software Foundation; either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+ * GNU Affero General Public License for more details.
+ *
+ * You should have received a copy of the GNU Affero General Public License
+ * along with this program. If not, see <http://www.gnu.org/licenses/>.
+ *
+ */
+
+#include <openbsc/bsc_nat.h>
+#include <openbsc/bsc_nat_sccp.h>
+#include <openbsc/bsc_msc.h>
+#include <openbsc/gsm_data.h>
+#include <openbsc/debug.h>
+#include <openbsc/ipaccess.h>
+
+#include <osmocom/core/linuxlist.h>
+#include <osmocom/core/talloc.h>
+#include <osmocom/gsm/gsm0808.h>
+
+#include <osmocom/gsm/protocol/gsm_08_08.h>
+#include <osmocom/gsm/protocol/gsm_04_11.h>
+
+#include <osmocom/sccp/sccp.h>
+
+static char *match_and_rewrite_number(void *ctx, const char *number,
+ const char *imsi,
+ struct llist_head *list)
+{
+ struct bsc_nat_num_rewr_entry *entry;
+ char *new_number = NULL;
+
+ /* need to find a replacement and then fix it */
+ llist_for_each_entry(entry, list, list) {
+ regmatch_t matches[2];
+
+ /* check the IMSI match */
+ if (regexec(&entry->msisdn_reg, imsi, 0, NULL, 0) != 0)
+ continue;
+
+ /* this regexp matches... */
+ if (regexec(&entry->num_reg, number, 2, matches, 0) == 0 &&
+ matches[1].rm_eo != -1)
+ new_number = talloc_asprintf(ctx, "%s%s",
+ entry->replace,
+ &number[matches[1].rm_so]);
+ if (new_number)
+ break;
+ }
+
+ return new_number;
+}
+
+static char *rewrite_non_international(struct bsc_nat *nat, void *ctx, const char *imsi,
+ struct gsm_mncc_number *called)
+{
+ if (llist_empty(&nat->num_rewr))
+ return NULL;
+
+ if (called->plan != 1)
+ return NULL;
+ if (called->type == 1)
+ return NULL;
+
+ return match_and_rewrite_number(ctx, called->number,
+ imsi, &nat->num_rewr);
+}
+
+
+/**
+ * Rewrite non global numbers... according to rules based on the IMSI
+ */
+static struct msgb *rewrite_setup(struct bsc_nat *nat, struct msgb *msg,
+ struct bsc_nat_parsed *parsed, const char *imsi,
+ struct gsm48_hdr *hdr48, const uint32_t len)
+{
+ struct tlv_parsed tp;
+ unsigned int payload_len;
+ struct gsm_mncc_number called;
+ struct msgb *out;
+ char *new_number = NULL;
+ uint8_t *outptr;
+ const uint8_t *msgptr;
+ int sec_len;
+
+ /* decode and rewrite the message */
+ payload_len = len - sizeof(*hdr48);
+ tlv_parse(&tp, &gsm48_att_tlvdef, hdr48->data, payload_len, 0, 0);
+
+ /* no number, well let us ignore it */
+ if (!TLVP_PRESENT(&tp, GSM48_IE_CALLED_BCD))
+ return NULL;
+
+ memset(&called, 0, sizeof(called));
+ gsm48_decode_called(&called,
+ TLVP_VAL(&tp, GSM48_IE_CALLED_BCD) - 1);
+
+ /* check if it looks international and stop */
+ new_number = rewrite_non_international(nat, msg, imsi, &called);
+
+ if (!new_number) {
+ LOGP(DNAT, LOGL_DEBUG, "No IMSI match found, returning message.\n");
+ return NULL;
+ }
+
+ if (strlen(new_number) > sizeof(called.number)) {
+ LOGP(DNAT, LOGL_ERROR, "Number is too long for structure.\n");
+ talloc_free(new_number);
+ return NULL;
+ }
+
+ /*
+ * Need to create a new message now based on the old onew
+ * with a new number. We can sadly not patch this in place
+ * so we will need to regenerate it.
+ */
+
+ out = msgb_alloc_headroom(4096, 128, "changed-setup");
+ if (!out) {
+ LOGP(DNAT, LOGL_ERROR, "Failed to allocate.\n");
+ talloc_free(new_number);
+ return NULL;
+ }
+
+ /* copy the header */
+ outptr = msgb_put(out, sizeof(*hdr48));
+ memcpy(outptr, hdr48, sizeof(*hdr48));
+
+ /* copy everything up to the number */
+ sec_len = TLVP_VAL(&tp, GSM48_IE_CALLED_BCD) - 2 - &hdr48->data[0];
+ outptr = msgb_put(out, sec_len);
+ memcpy(outptr, &hdr48->data[0], sec_len);
+
+ /* create the new number */
+ if (strncmp(new_number, "00", 2) == 0) {
+ called.type = 1;
+ strncpy(called.number, new_number + 2, sizeof(called.number));
+ } else {
+ strncpy(called.number, new_number, sizeof(called.number));
+ }
+ gsm48_encode_called(out, &called);
+
+ /* copy thre rest */
+ msgptr = TLVP_VAL(&tp, GSM48_IE_CALLED_BCD) +
+ TLVP_LEN(&tp, GSM48_IE_CALLED_BCD);
+ sec_len = payload_len - (msgptr - &hdr48->data[0]);
+ outptr = msgb_put(out, sec_len);
+ memcpy(outptr, msgptr, sec_len);
+
+ talloc_free(new_number);
+ return out;
+}
+
+/**
+ * Find a new SMSC address, returns an allocated string that needs to be
+ * freed or is NULL.
+ */
+static char *find_new_smsc(struct bsc_nat *nat, void *ctx, const char *imsi,
+ const char *smsc_addr, const char *dest_nr)
+{
+ struct bsc_nat_num_rewr_entry *entry;
+ char *new_number = NULL;
+ uint8_t dest_match = llist_empty(&nat->tpdest_match);
+
+ /* We will find a new number now */
+ llist_for_each_entry(entry, &nat->smsc_rewr, list) {
+ regmatch_t matches[2];
+
+ /* check the IMSI match */
+ if (regexec(&entry->msisdn_reg, imsi, 0, NULL, 0) != 0)
+ continue;
+
+ /* this regexp matches... */
+ if (regexec(&entry->num_reg, smsc_addr, 2, matches, 0) == 0 &&
+ matches[1].rm_eo != -1)
+ new_number = talloc_asprintf(ctx, "%s%s",
+ entry->replace,
+ &smsc_addr[matches[1].rm_so]);
+ if (new_number)
+ break;
+ }
+
+ if (!new_number)
+ return NULL;
+
+ /*
+ * now match the number against another list
+ */
+ llist_for_each_entry(entry, &nat->tpdest_match, list) {
+ /* check the IMSI match */
+ if (regexec(&entry->msisdn_reg, imsi, 0, NULL, 0) != 0)
+ continue;
+
+ if (regexec(&entry->num_reg, dest_nr, 0, NULL, 0) == 0) {
+ dest_match = 1;
+ break;
+ }
+ }
+
+ if (!dest_match) {
+ talloc_free(new_number);
+ return NULL;
+ }
+
+ return new_number;
+}
+
+/**
+ * Clear the TP-SRR from the TPDU header
+ */
+static uint8_t sms_new_tpdu_hdr(struct bsc_nat *nat, const char *imsi,
+ const char *dest_nr, uint8_t hdr)
+{
+ struct bsc_nat_num_rewr_entry *entry;
+
+ /* We will find a new number now */
+ llist_for_each_entry(entry, &nat->sms_clear_tp_srr, list) {
+ /* check the IMSI match */
+ if (regexec(&entry->msisdn_reg, imsi, 0, NULL, 0) != 0)
+ continue;
+ if (regexec(&entry->num_reg, dest_nr, 0, NULL, 0) != 0)
+ continue;
+
+ /* matched phone number and imsi */
+ return hdr & ~0x20;
+ }
+
+ return hdr;
+}
+
+/**
+ * Check if we need to rewrite the number. For this SMS.
+ */
+static char *sms_new_dest_nr(struct bsc_nat *nat, void *ctx,
+ const char *imsi, const char *dest_nr)
+{
+ return match_and_rewrite_number(ctx, dest_nr, imsi,
+ &nat->sms_num_rewr);
+}
+
+/**
+ * This is a helper for GSM 04.11 8.2.5.2 Destination address element
+ */
+void sms_encode_addr_element(struct msgb *out, const char *new_number,
+ int format, int tp_data)
+{
+ uint8_t new_addr_len;
+ uint8_t new_addr[26];
+
+ /*
+ * Copy the new number. We let libosmocore encode it, then set
+ * the extension followed after the length. Depending on if
+ * we want to write RP we will let the TLV code add the
+ * length for us or we need to use strlen... This is not very clear
+ * as of 03.40 and 04.11.
+ */
+ new_addr_len = gsm48_encode_bcd_number(new_addr, ARRAY_SIZE(new_addr),
+ 1, new_number);
+ new_addr[1] = format;
+ if (tp_data) {
+ uint8_t *data = msgb_put(out, new_addr_len);
+ memcpy(data, new_addr, new_addr_len);
+ data[0] = strlen(new_number);
+ } else {
+ msgb_lv_put(out, new_addr_len - 1, new_addr + 1);
+ }
+}
+
+static struct msgb *sms_create_new(uint8_t type, uint8_t ref,
+ struct gsm48_hdr *old_hdr48,
+ const uint8_t *orig_addr_ptr,
+ int orig_addr_len, const char *new_number,
+ const uint8_t *data_ptr, int data_len,
+ uint8_t tpdu_first_byte,
+ const int old_dest_len, const char *new_dest_nr)
+{
+ struct gsm48_hdr *new_hdr48;
+ struct msgb *out;
+
+ /*
+ * We need to re-create the patched structure. This is why we have
+ * saved the above pointers.
+ */
+ out = msgb_alloc_headroom(4096, 128, "changed-smsc");
+ if (!out) {
+ LOGP(DNAT, LOGL_ERROR, "Failed to allocate.\n");
+ return NULL;
+ }
+
+ out->l2h = out->data;
+ msgb_v_put(out, GSM411_MT_RP_DATA_MO);
+ msgb_v_put(out, ref);
+ msgb_lv_put(out, orig_addr_len, orig_addr_ptr);
+
+ sms_encode_addr_element(out, new_number, 0x91, 0);
+
+
+ /* Patch the TPDU from here on */
+
+ /**
+ * Do we need to put a new TP-Destination-Address (TP-DA) here or
+ * can we copy the old thing? For the TP-DA we need to find out the
+ * new size.
+ */
+ if (new_dest_nr) {
+ uint8_t *data, *new_size;
+
+ /* reserve the size and write the header */
+ new_size = msgb_put(out, 1);
+ out->l3h = new_size + 1;
+ msgb_v_put(out, tpdu_first_byte);
+ msgb_v_put(out, data_ptr[1]);
+
+ /* encode the new number and put it */
+ if (strncmp(new_dest_nr, "00", 2) == 0)
+ sms_encode_addr_element(out, new_dest_nr + 2, 0x91, 1);
+ else
+ sms_encode_addr_element(out, new_dest_nr, 0x81, 1);
+
+ /* Copy the rest after the TP-DS */
+ data = msgb_put(out, data_len - 2 - 1 - old_dest_len);
+ memcpy(data, &data_ptr[2 + 1 + old_dest_len], data_len - 2 - 1 - old_dest_len);
+
+ /* fill in the new size */
+ new_size[0] = msgb_l3len(out);
+ } else {
+ msgb_v_put(out, data_len);
+ msgb_tv_fixed_put(out, tpdu_first_byte, data_len - 1, &data_ptr[1]);
+ }
+
+ /* prepend GSM 04.08 header */
+ new_hdr48 = (struct gsm48_hdr *) msgb_push(out, sizeof(*new_hdr48) + 1);
+ memcpy(new_hdr48, old_hdr48, sizeof(*old_hdr48));
+ new_hdr48->data[0] = msgb_l2len(out);
+
+ return out;
+}
+
+/**
+ * Parse the SMS and check if it needs to be rewritten
+ */
+static struct msgb *rewrite_sms(struct bsc_nat *nat, struct msgb *msg,
+ struct bsc_nat_parsed *parsed, const char *imsi,
+ struct gsm48_hdr *hdr48, const uint32_t len)
+{
+ unsigned int payload_len;
+ unsigned int cp_len;
+
+ uint8_t ref;
+ uint8_t orig_addr_len, *orig_addr_ptr;
+ uint8_t dest_addr_len, *dest_addr_ptr;
+ uint8_t data_len, *data_ptr;
+ char smsc_addr[30];
+
+
+ uint8_t dest_len, orig_dest_len;
+ char _dest_nr[30];
+ char *dest_nr;
+ char *new_dest_nr;
+
+ char *new_number = NULL;
+ uint8_t tpdu_hdr;
+ struct msgb *out;
+
+ payload_len = len - sizeof(*hdr48);
+ if (payload_len < 1) {
+ LOGP(DNAT, LOGL_ERROR, "SMS too short for things. %d\n", payload_len);
+ return NULL;
+ }
+
+ cp_len = hdr48->data[0];
+ if (payload_len + 1 < cp_len) {
+ LOGP(DNAT, LOGL_ERROR, "SMS RPDU can not fit in: %d %d\n", cp_len, payload_len);
+ return NULL;
+ }
+
+ if (hdr48->data[1] != GSM411_MT_RP_DATA_MO)
+ return NULL;
+
+ if (cp_len < 5) {
+ LOGP(DNAT, LOGL_ERROR, "RD-DATA can not fit in the CP len: %d\n", cp_len);
+ return NULL;
+ }
+
+ /* RP */
+ ref = hdr48->data[2];
+ orig_addr_len = hdr48->data[3];
+ orig_addr_ptr = &hdr48->data[4];
+
+ /* the +1 is for checking if the following element has some space */
+ if (cp_len < 3 + orig_addr_len + 1) {
+ LOGP(DNAT, LOGL_ERROR, "RP-Originator addr does not fit: %d\n", orig_addr_len);
+ return NULL;
+ }
+
+ dest_addr_len = hdr48->data[3 + orig_addr_len + 1];
+ dest_addr_ptr = &hdr48->data[3 + orig_addr_len + 2];
+
+ if (cp_len < 3 + orig_addr_len + 1 + dest_addr_len + 1) {
+ LOGP(DNAT, LOGL_ERROR, "RP-Destination addr does not fit: %d\n", dest_addr_len);
+ return NULL;
+ }
+ gsm48_decode_bcd_number(smsc_addr, ARRAY_SIZE(smsc_addr), dest_addr_ptr - 1, 1);
+
+ data_len = hdr48->data[3 + orig_addr_len + 1 + dest_addr_len + 1];
+ data_ptr = &hdr48->data[3 + orig_addr_len + 1 + dest_addr_len + 2];
+
+ if (cp_len < 3 + orig_addr_len + 1 + dest_addr_len + 1 + data_len) {
+ LOGP(DNAT, LOGL_ERROR, "RP-Data does not fit: %d\n", data_len);
+ return NULL;
+ }
+
+ if (data_len < 3) {
+ LOGP(DNAT, LOGL_ERROR, "SMS-SUBMIT is too short.\n");
+ return NULL;
+ }
+
+ /* TP-PDU starts here */
+ if ((data_ptr[0] & 0x03) != GSM340_SMS_SUBMIT_MS2SC)
+ return NULL;
+
+ /*
+ * look into the phone number. The length is in semi-octets, we will
+ * need to add the byte for the number type as well.
+ */
+ orig_dest_len = data_ptr[2];
+ dest_len = ((orig_dest_len + 1) / 2) + 1;
+ if (data_len < dest_len + 3 || dest_len < 2) {
+ LOGP(DNAT, LOGL_ERROR, "SMS-SUBMIT can not have TP-DestAddr.\n");
+ return NULL;
+ }
+
+ if ((data_ptr[3] & 0x80) == 0) {
+ LOGP(DNAT, LOGL_ERROR, "TP-DestAddr has extension. Not handled.\n");
+ return NULL;
+ }
+
+ if ((data_ptr[3] & 0x0F) == 0) {
+ LOGP(DNAT, LOGL_ERROR, "TP-DestAddr is of unknown type.\n");
+ return NULL;
+ }
+
+ /**
+ * Besides of what I think I read in GSM 03.40 and 04.11 the TP-DA
+ * contains the semi-octets as length (strlen), change it to the
+ * the number of bytes, but then change it back.
+ */
+ data_ptr[2] = dest_len;
+ gsm48_decode_bcd_number(_dest_nr + 2, ARRAY_SIZE(_dest_nr) - 2,
+ &data_ptr[2], 1);
+ data_ptr[2] = orig_dest_len;
+ if ((data_ptr[3] & 0x70) == 0x10) {
+ _dest_nr[0] = _dest_nr[1] = '0';
+ dest_nr = &_dest_nr[0];
+ } else {
+ dest_nr = &_dest_nr[2];
+ }
+
+ /**
+ * Call functions to rewrite the data
+ */
+ tpdu_hdr = sms_new_tpdu_hdr(nat, imsi, dest_nr, data_ptr[0]);
+ new_number = find_new_smsc(nat, msg, imsi, smsc_addr, dest_nr);
+ new_dest_nr = sms_new_dest_nr(nat, msg, imsi, dest_nr);
+
+ if (tpdu_hdr == data_ptr[0] && !new_number && !new_dest_nr)
+ return NULL;
+
+ out = sms_create_new(GSM411_MT_RP_DATA_MO, ref, hdr48,
+ orig_addr_ptr, orig_addr_len,
+ new_number ? new_number : smsc_addr,
+ data_ptr, data_len, tpdu_hdr,
+ dest_len, new_dest_nr);
+ talloc_free(new_number);
+ talloc_free(new_dest_nr);
+ return out;
+}
+
+struct msgb *bsc_nat_rewrite_msg(struct bsc_nat *nat, struct msgb *msg, struct bsc_nat_parsed *parsed, const char *imsi)
+{
+ struct gsm48_hdr *hdr48;
+ uint32_t len;
+ uint8_t msg_type, proto;
+ struct msgb *new_msg = NULL, *sccp;
+ uint8_t link_id;
+
+ if (!imsi || strlen(imsi) < 5)
+ return msg;
+
+ /* only care about DTAP messages */
+ if (parsed->bssap != BSSAP_MSG_DTAP)
+ return msg;
+ if (!parsed->dest_local_ref)
+ return msg;
+
+ hdr48 = bsc_unpack_dtap(parsed, msg, &len);
+ if (!hdr48)
+ return msg;
+
+ link_id = msg->l3h[1];
+ proto = hdr48->proto_discr & 0x0f;
+ msg_type = hdr48->msg_type & 0xbf;
+
+ if (proto == GSM48_PDISC_CC && msg_type == GSM48_MT_CC_SETUP)
+ new_msg = rewrite_setup(nat, msg, parsed, imsi, hdr48, len);
+ else if (proto == GSM48_PDISC_SMS && msg_type == GSM411_MT_CP_DATA)
+ new_msg = rewrite_sms(nat, msg, parsed, imsi, hdr48, len);
+
+ if (!new_msg)
+ return msg;
+
+ /* wrap with DTAP, SCCP, then IPA. TODO: Stop copying */
+ gsm0808_prepend_dtap_header(new_msg, link_id);
+ sccp = sccp_create_dt1(parsed->dest_local_ref, new_msg->data, new_msg->len);
+ talloc_free(new_msg);
+
+ if (!sccp) {
+ LOGP(DNAT, LOGL_ERROR, "Failed to allocate.\n");
+ return msg;
+ }
+
+ ipaccess_prepend_header(sccp, IPAC_PROTO_SCCP);
+
+ /* the parsed hangs off from msg but it needs to survive */
+ talloc_steal(sccp, parsed);
+ msgb_free(msg);
+ return sccp;
+}
+
+static void num_rewr_free_data(struct bsc_nat_num_rewr_entry *entry)
+{
+ regfree(&entry->msisdn_reg);
+ regfree(&entry->num_reg);
+ talloc_free(entry->replace);
+}
+
+void bsc_nat_num_rewr_entry_adapt(void *ctx, struct llist_head *head,
+ const struct osmo_config_list *list)
+{
+ struct bsc_nat_num_rewr_entry *entry, *tmp;
+ struct osmo_config_entry *cfg_entry;
+
+ /* free the old data */
+ llist_for_each_entry_safe(entry, tmp, head, list) {
+ num_rewr_free_data(entry);
+ llist_del(&entry->list);
+ talloc_free(entry);
+ }
+
+
+ if (!list)
+ return;
+
+ llist_for_each_entry(cfg_entry, &list->entry, list) {
+ char *regexp;
+ if (cfg_entry->text[0] == '+') {
+ LOGP(DNAT, LOGL_ERROR,
+ "Plus is not allowed in the number\n");
+ continue;
+ }
+
+ entry = talloc_zero(ctx, struct bsc_nat_num_rewr_entry);
+ if (!entry) {
+ LOGP(DNAT, LOGL_ERROR,
+ "Allication of the num_rewr entry failed.\n");
+ continue;
+ }
+
+ entry->replace = talloc_strdup(entry, cfg_entry->text);
+ if (!entry->replace) {
+ LOGP(DNAT, LOGL_ERROR,
+ "Failed to copy the replacement text.\n");
+ talloc_free(entry);
+ continue;
+ }
+
+ /* we will now build a regexp string */
+ if (cfg_entry->mcc[0] == '^') {
+ regexp = talloc_strdup(entry, cfg_entry->mcc);
+ } else {
+ regexp = talloc_asprintf(entry, "^%s%s",
+ cfg_entry->mcc[0] == '*' ?
+ "[0-9][0-9][0-9]" : cfg_entry->mcc,
+ cfg_entry->mnc[0] == '*' ?
+ "[0-9][0-9]" : cfg_entry->mnc);
+ }
+
+ if (!regexp) {
+ LOGP(DNAT, LOGL_ERROR, "Failed to create a regexp string.\n");
+ talloc_free(entry);
+ continue;
+ }
+
+ if (regcomp(&entry->msisdn_reg, regexp, 0) != 0) {
+ LOGP(DNAT, LOGL_ERROR,
+ "Failed to compile regexp '%s'\n", regexp);
+ talloc_free(regexp);
+ talloc_free(entry);
+ continue;
+ }
+
+ talloc_free(regexp);
+ if (regcomp(&entry->num_reg, cfg_entry->option, REG_EXTENDED) != 0) {
+ LOGP(DNAT, LOGL_ERROR,
+ "Failed to compile regexp '%s'\n", cfg_entry->option);
+ regfree(&entry->msisdn_reg);
+ talloc_free(entry);
+ continue;
+ }
+
+ /* we have copied the number */
+ llist_add_tail(&entry->list, head);
+ }
+}