/* * Message rewriting functionality */ /* * (C) 2010-2013 by Holger Hans Peter Freyther * (C) 2010-2013 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 . * */ #include #include #include #include #include #include #include #include #include #include #include #include #include #include static char *trie_lookup(struct nat_rewrite *trie, const char *number, regoff_t off, void *ctx) { struct nat_rewrite_rule *rule; if (!trie) { LOGP(DCC, LOGL_ERROR, "Asked to do a table lookup but no table.\n"); return NULL; } rule = nat_rewrite_lookup(trie, number); if (!rule) { LOGP(DCC, LOGL_DEBUG, "Couldn't find a prefix rule for %s\n", number); return NULL; } return talloc_asprintf(ctx, "%s%s", rule->rewrite, &number[off]); } static char *match_and_rewrite_number(void *ctx, const char *number, const char *imsi, struct llist_head *list, struct nat_rewrite *trie) { 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) { if (entry->is_prefix_lookup) new_number = trie_lookup(trie, number, matches[1].rm_so, ctx); else new_number = talloc_asprintf(ctx, "%s%s", entry->replace, &number[matches[1].rm_so]); } if (new_number) break; } return new_number; } static char *rewrite_isdn_number(struct bsc_nat *nat, struct llist_head *rewr_list, void *ctx, const char *imsi, struct gsm_mncc_number *called) { char int_number[sizeof(called->number) + 2]; char *number = called->number; if (llist_empty(&nat->num_rewr)) { LOGP(DCC, LOGL_DEBUG, "Rewrite rules empty.\n"); return NULL; } /* only ISDN plan */ if (called->plan != 1) { LOGP(DCC, LOGL_DEBUG, "Called plan is not 1 it was %d\n", called->plan); return NULL; } /* international, prepend */ if (called->type == 1) { int_number[0] = '+'; memcpy(&int_number[1], number, strlen(number) + 1); number = int_number; } return match_and_rewrite_number(ctx, number, imsi, rewr_list, nat->num_rewr_trie); } static void update_called_number(struct gsm_mncc_number *called, const char *chosen_number) { if (strncmp(chosen_number, "00", 2) == 0) { called->type = 1; strncpy(called->number, chosen_number + 2, sizeof(called->number)); } else { /* rewrite international to unknown */ if (called->type == 1) called->type = 0; strncpy(called->number, chosen_number, sizeof(called->number)); } called->number[sizeof(called->number) - 1] = '\0'; } /** * 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_pre = NULL, *new_number_post = NULL, *chosen_number; 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 */ LOGP(DCC, LOGL_DEBUG, "Pre-Rewrite for IMSI(%s) Plan(%d) Type(%d) Number(%s)\n", imsi, called.plan, called.type, called.number); new_number_pre = rewrite_isdn_number(nat, &nat->num_rewr, msg, imsi, &called); if (!new_number_pre) { LOGP(DCC, LOGL_DEBUG, "No IMSI(%s) match found, returning message.\n", imsi); return NULL; } if (strlen(new_number_pre) > sizeof(called.number)) { LOGP(DCC, LOGL_ERROR, "Number %s is too long for structure.\n", new_number_pre); talloc_free(new_number_pre); return NULL; } update_called_number(&called, new_number_pre); /* another run through the re-write engine with other rules */ LOGP(DCC, LOGL_DEBUG, "Post-Rewrite for IMSI(%s) Plan(%d) Type(%d) Number(%s)\n", imsi, called.plan, called.type, called.number); new_number_post = rewrite_isdn_number(nat, &nat->num_rewr_post, msg, imsi, &called); chosen_number = new_number_post ? new_number_post : new_number_pre; if (strlen(chosen_number) > sizeof(called.number)) { LOGP(DCC, LOGL_ERROR, "Number %s is too long for structure.\n", chosen_number); talloc_free(new_number_pre); talloc_free(new_number_post); 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(DCC, LOGL_ERROR, "Failed to allocate.\n"); talloc_free(new_number_pre); talloc_free(new_number_post); 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 */ update_called_number(&called, chosen_number); LOGP(DCC, LOGL_DEBUG, "Chosen number for IMSI(%s) is Plan(%d) Type(%d) Number(%s)\n", imsi, called.plan, called.type, 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_pre); talloc_free(new_number_post); 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, NULL); } /** * 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; } ipa_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, "Allocation 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; } if (strcmp("prefix_lookup", entry->replace) == 0) entry->is_prefix_lookup = 1; /* 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); } }