nat: Implement rewriting, have a very basic test for that feature
diff --git a/openbsc/include/openbsc/bsc_nat.h b/openbsc/include/openbsc/bsc_nat.h
index 0494217..9f26c87 100644
--- a/openbsc/include/openbsc/bsc_nat.h
+++ b/openbsc/include/openbsc/bsc_nat.h
@@ -343,6 +343,6 @@
int bsc_ussd_init(struct bsc_nat *nat);
int bsc_check_ussd(struct sccp_connections *con, struct bsc_nat_parsed *parsed, struct msgb *msg);
-struct msgb *bsc_nat_rewrite_setup(struct bsc_nat *nat, struct msgb *msg, struct bsc_nat_parsed *);
+struct msgb *bsc_nat_rewrite_setup(struct bsc_nat *nat, struct msgb *msg, struct bsc_nat_parsed *, const char *imsi);
#endif
diff --git a/openbsc/src/nat/bsc_nat.c b/openbsc/src/nat/bsc_nat.c
index dcacfb9..0a58515 100644
--- a/openbsc/src/nat/bsc_nat.c
+++ b/openbsc/src/nat/bsc_nat.c
@@ -864,7 +864,7 @@
* replace the msg and the parsed structure becomes
* invalid.
*/
- msg = bsc_nat_rewrite_setup(bsc->nat, msg, parsed);
+ msg = bsc_nat_rewrite_setup(bsc->nat, msg, parsed, con->imsi);
talloc_free(parsed);
parsed = NULL;
}
diff --git a/openbsc/src/nat/bsc_nat_utils.c b/openbsc/src/nat/bsc_nat_utils.c
index a3fd97a..59c92a3 100644
--- a/openbsc/src/nat/bsc_nat_utils.c
+++ b/openbsc/src/nat/bsc_nat_utils.c
@@ -724,7 +724,146 @@
/**
* Rewrite non global numbers... according to rules based on the IMSI
*/
-struct msgb *bsc_nat_rewrite_setup(struct bsc_nat *nat, struct msgb *msg, struct bsc_nat_parsed *pa)
+struct msgb *bsc_nat_rewrite_setup(struct bsc_nat *nat, struct msgb *msg, struct bsc_nat_parsed *parsed, const char *imsi)
{
- return msg;
+ struct tlv_parsed tp;
+ struct gsm48_hdr *hdr48;
+ uint32_t len;
+ uint8_t msg_type;
+ unsigned int payload_len;
+ struct gsm_mncc_number called;
+ struct msg_entry *entry;
+ char *new_number = NULL;
+ struct msgb *out, *sccp;
+ uint8_t *outptr;
+ const uint8_t *msgptr;
+ int sec_len;
+
+ if (!imsi || strlen(imsi) < 5)
+ return msg;
+
+ if (!nat->num_rewr)
+ 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;
+
+ msg_type = hdr48->msg_type & 0xbf;
+ if (hdr48->proto_discr != GSM48_PDISC_CC ||
+ msg_type != GSM48_MT_CC_SETUP)
+ return msg;
+
+ /* 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 msg;
+
+ memset(&called, 0, sizeof(called));
+ gsm48_decode_called(&called,
+ TLVP_VAL(&tp, GSM48_IE_CALLED_BCD) - 1);
+
+ /* check if it looks international and stop */
+ if (strncmp(called.number, "+", 1) == 0)
+ return msg;
+ if (strncmp(called.number, "00", 2) == 0)
+ return msg;
+
+ /* need to find a replacement and then fix it */
+ llist_for_each_entry(entry, &nat->num_rewr->entry, list) {
+ regex_t reg;
+ regmatch_t matches[2];
+
+ if (strncmp(entry->mcc, imsi, 3) != 0)
+ continue;
+ if (strncmp(entry->mnc, imsi + 3, 2) != 0)
+ continue;
+
+ /* We have an entry for the IMSI. Need to match now */
+ if (regcomp(®, entry->option, REG_EXTENDED) != 0) {
+ LOGP(DNAT, LOGL_ERROR,
+ "Regexp '%s' is not valid.\n", entry->option);
+ continue;
+ }
+
+ /* this regexp matches... */
+ if (regexec(®, called.number, 2, matches, 0) == 0 &&
+ matches[1].rm_eo != -1)
+ new_number = talloc_asprintf(msg, "%s%s",
+ entry->text,
+ &called.number[matches[1].rm_so]);
+ regfree(®);
+
+ if (new_number)
+ break;
+ }
+
+ if (!new_number) {
+ LOGP(DNAT, LOGL_DEBUG, "No IMSI match found, returning message.\n");
+ return msg;
+ }
+
+ /*
+ * 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 msg;
+ }
+
+ /* 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 */
+ 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);
+
+ /* wrap with DTAP, SCCP, then IPA. TODO: Stop copying */
+ gsm0808_prepend_dtap_header(out, 0);
+ sccp = sccp_create_dt1(parsed->dest_local_ref, out->data, out->len);
+ if (!sccp) {
+ LOGP(DNAT, LOGL_ERROR, "Failed to allocate.\n");
+ talloc_free(new_number);
+ talloc_free(out);
+ return msg;
+ }
+
+ ipaccess_prepend_header(sccp, IPAC_PROTO_SCCP);
+
+ /* give up memory, we are done */
+ talloc_free(new_number);
+ /* the parsed hangs off from msg but it needs to survive */
+ talloc_steal(sccp, parsed);
+ msgb_free(msg);
+ msgb_free(out);
+ out = NULL;
+ return sccp;
}
+
diff --git a/openbsc/tests/bsc-nat/bsc_data.c b/openbsc/tests/bsc-nat/bsc_data.c
index f4dba0a..3cc22af 100644
--- a/openbsc/tests/bsc-nat/bsc_data.c
+++ b/openbsc/tests/bsc-nat/bsc_data.c
@@ -160,3 +160,28 @@
.port = 5555,
},
};
+
+/* CC Setup messages */
+static const uint8_t cc_setup_national[] = {
+ 0x00, 0x20, 0xfd, 0x06, 0x01, 0x12,
+ 0x6d, 0x00, 0x01, 0x19, 0x01, 0x00, 0x16, 0x03,
+ 0x05, 0x04, 0x06, 0x60, 0x04, 0x02, 0x00, 0x05,
+ 0x81, 0x5e, 0x06, 0x81, 0x10, 0x27, 0x33, 0x63,
+ 0x66, 0x15, 0x02, 0x11, 0x01
+};
+
+static const uint8_t cc_setup_national_patched[] = {
+ 0x00, 0x22, 0xfd, 0x06, 0x01, 0x12,
+ 0x6d, 0x00, 0x01, 0x1b, 0x01, 0x00, 0x18, 0x03,
+ 0x05, 0x04, 0x06, 0x60, 0x04, 0x02, 0x00, 0x05,
+ 0x81, 0x5e, 0x08, 0x81, 0x00, 0x94, 0x71, 0x32,
+ 0x33, 0x66, 0xf6, 0x15, 0x02, 0x11, 0x01
+};
+
+static const uint8_t cc_setup_international[] = {
+ 0x00, 0x22, 0xfd, 0x06, 0x01, 0x13,
+ 0xe7, 0x00, 0x01, 0x1b, 0x01, 0x00, 0x18, 0x03,
+ 0x45, 0x04, 0x06, 0x60, 0x04, 0x02, 0x00, 0x05,
+ 0x81, 0x5e, 0x08, 0x81, 0x00, 0x94, 0x71, 0x33,
+ 0x63, 0x66, 0x03, 0x15, 0x02, 0x11, 0x01
+};
diff --git a/openbsc/tests/bsc-nat/bsc_nat_test.c b/openbsc/tests/bsc-nat/bsc_nat_test.c
index 141775c..7a2557f 100644
--- a/openbsc/tests/bsc-nat/bsc_nat_test.c
+++ b/openbsc/tests/bsc-nat/bsc_nat_test.c
@@ -799,6 +799,87 @@
}
}
+static void test_setup_rewrite()
+{
+ struct msgb *msg = msgb_alloc(4096, "test_dt_filter");
+ struct msgb *out;
+ struct bsc_nat_parsed *parsed;
+ const char *imsi = "27408000001234";
+
+ struct bsc_nat *nat = bsc_nat_alloc();
+
+ /* a fake list */
+ struct msg_entries entries;
+ struct msg_entry entry;
+
+ INIT_LLIST_HEAD(&entries.entry);
+ entry.mcc = "274";
+ entry.mnc = "08";
+ entry.option = "^0([1-9])";
+ entry.text = "0049";
+ llist_add_tail(&entry.list, &entries.entry);
+ nat->num_rewr = &entries;
+
+ /* verify that nothing changed */
+ msgb_reset(msg);
+ copy_to_msg(msg, cc_setup_international, ARRAY_SIZE(cc_setup_international));
+ parsed = bsc_nat_parse(msg);
+ if (!parsed) {
+ fprintf(stderr, "FAIL: Could not parse ID resp\n");
+ abort();
+ }
+
+ out = bsc_nat_rewrite_setup(nat, msg, parsed, imsi);
+ if (msg != out) {
+ fprintf(stderr, "FAIL: The message should not have been changed\n");
+ abort();
+ }
+
+ if (out->len != ARRAY_SIZE(cc_setup_international)) {
+ fprintf(stderr, "FAIL: Length of message changed\n");
+ abort();
+ }
+
+ if (memcmp(out->data, cc_setup_international, out->len) != 0) {
+ fprintf(stderr, "FAIL: Content modified..\n");
+ abort();
+ }
+ talloc_free(parsed);
+
+ /* verify that something in the message changes */
+ msgb_reset(msg);
+ copy_to_msg(msg, cc_setup_national, ARRAY_SIZE(cc_setup_national));
+ parsed = bsc_nat_parse(msg);
+ if (!parsed) {
+ fprintf(stderr, "FAIL: Could not parse ID resp\n");
+ abort();
+ }
+
+ out = bsc_nat_rewrite_setup(nat, msg, parsed, imsi);
+ if (!out) {
+ fprintf(stderr, "FAIL: A new message should be created.\n");
+ abort();
+ }
+
+ if (msg == out) {
+ fprintf(stderr, "FAIL: The message should have changed\n");
+ abort();
+ }
+
+ if (out->len != ARRAY_SIZE(cc_setup_national_patched)) {
+ fprintf(stderr, "FAIL: Length is wrong.\n");
+ abort();
+ }
+
+ if (memcmp(cc_setup_national_patched, out->data, out->len) != 0) {
+ fprintf(stderr, "FAIL: Data is wrong.\n");
+ fprintf(stderr, "Data was: %s\n", hexdump(out->data, out->len));
+ abort();
+ }
+
+ msgb_free(out);
+}
+
int main(int argc, char **argv)
{
struct log_target *stderr_target;
@@ -818,6 +899,7 @@
test_mgcp_parse();
test_cr_filter();
test_dt_filter();
+ test_setup_rewrite();
return 0;
}