/* Copyright 2019 by sysmocom s.f.m.c. GmbH * * All Rights Reserved * * This program is free software; you can redistribute it and/or modify * it under the terms of the GNU General Public License as published by * the Free Software Foundation; either version 2 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 General Public License for more details. * * You should have received a copy of the GNU General Public License along * with this program. If not, see . */ #include #include #include #include #include /*! Create a new osmo_gsup_req record, decode GSUP and add to a provided list of requests. * * Rationales: * * - osmo_gsup_req makes it easy to handle GSUP requests asynchronously. Before this, a GSUP message struct would be * valid only within a read callback function, and would not survive asynchronous handling, because the struct often * points directly into the received msgb. An osmo_gsup_req takes ownership of the msgb and ensures that the data * remains valid, so that it can easily be queued for later handling. * - osmo_gsup_req unifies the composition of response messages to ensure that all IEs that identify it to belong to * the initial request are preserved / derived, like the source_name, destination_name, session_id, etc (see * osmo_gsup_make_response() for details). * - Deallocation of an osmo_gsup_req is implicit upon sending a response. The idea is that msgb memory leaks are a * recurring source of bugs. By enforcing a request-response relation with implicit deallocation, osmo_gsup_req aims * to help avoid most such memory leaks implicitly. * * The typical GSUP message sequence is: * -> rx request, * <- tx response. * * With osmo_gsup_req we can easily expand to: * -> rx request, * ... wait asynchronously, * <- tx response. * * Only few GSUP conversations go beyond a 1:1 request-response match. But some have a session (e.g. USSD) or more * negotiation may happen before the initial request is completed (e.g. Update Location with interleaved Insert * Subscriber Data), so osmo_gsup_req also allows passing non-final responses. * The final_response flag allows for: * -> rx request, * ... wait async, * <- tx intermediate message to same peer (final_response = false, req remains open), * ... wait async, * -> rx intermediate response, * ... wait async, * <- tx final response (final_response = true, req is deallocated). * * This function takes ownership of the msgb, which will, on success, be owned by the returned osmo_gsup_req instance * until osmo_gsup_req_free(). If a decoding error occurs, send an error response immediately, and return NULL. * * The original CNI entity that sent the message is found in req->source_name. If the message was passed on by an * intermediate CNI peer, then req->via_proxy is set to the immediate peer, and it is the responsibility of the caller * to add req->source_name to the GSUP routes that are serviced by req->via_proxy (usually not relevant for clients with * a single GSUP conn). * Examples: * * "msc" ---> here * source_name = "msc" * via_proxy = * * "msc" ---> "proxy-HLR" ---> here (e.g. home HLR) * source_name = "msc" * via_proxy = "proxy-HLR" * * "msc" ---> "proxy-HLR" ---> "home-HLR" ---> here (e.g. EUSE) * source_name = "msc" * via_proxy = "home-HLR" * * An osmo_gsup_req must be concluded (and deallocated) by calling one of the osmo_gsup_req_respond* functions. * * Note: osmo_gsup_req API makes use of OTC_SELECT to allocate volatile buffers for logging. Use of * osmo_select_main_ctx() is mandatory when using osmo_gsup_req. * * \param[in] ctx Talloc context for allocation of the new request. * \param[in] from_peer The IPA unit name of the immediate GSUP peer from which this msgb was received. * \param[in] msg The message buffer containing the received GSUP message, where msgb_l2() shall point to the GSUP * message start. The caller no longer owns the msgb when it is passed to this function: on error, the * msgb is freed immediately, and on success, the msgb is owned by the returned osmo_gsup_req. * \param[in] send_response_cb User specific method to send a GSUP response message, invoked upon * osmo_gsup_req_respond*() functions. Typically this invokes encoding and transmitting the * GSUP message over a network socket. See for example gsup_server_send_req_response(). * \param[inout] cb_data Context data to be used freely by the caller. * \param[inout] add_to_list List to which to append this request, or NULL for no list. * \return a newly allocated osmo_gsup_req, or NULL on error. If NULL is returned, an error response has already been * dispatched to the send_response_cb. */ struct osmo_gsup_req *osmo_gsup_req_new(void *ctx, const struct osmo_cni_peer_id *from_peer, struct msgb *msg, osmo_gsup_req_send_response_t send_response_cb, void *cb_data, struct llist_head *add_to_list) { static unsigned int next_req_nr = 1; struct osmo_gsup_req *req; int rc; if (!from_peer) { LOGP(DLGSUP, LOGL_ERROR, "Rx GSUP from NULL peer is not allowed\n"); msgb_free(msg); return NULL; } if (!msgb_l2(msg) || !msgb_l2len(msg)) { LOGP(DLGSUP, LOGL_ERROR, "Rx GSUP from %s: missing or empty L2 data\n", osmo_cni_peer_id_to_str(from_peer)); msgb_free(msg); return NULL; } req = talloc_zero(ctx, struct osmo_gsup_req); OSMO_ASSERT(req); /* Note: req->gsup is declared const, so that the incoming message cannot be modified by handlers. */ req->nr = next_req_nr++; req->msg = msg; req->send_response_cb = send_response_cb; req->cb_data = cb_data; req->source_name = *from_peer; rc = osmo_gsup_decode(msgb_l2(req->msg), msgb_l2len(req->msg), (struct osmo_gsup_message*)&req->gsup); if (rc < 0) { LOGP(DLGSUP, LOGL_ERROR, "Rx GSUP from %s: cannot decode (rc=%d)\n", osmo_cni_peer_id_to_str(from_peer), rc); osmo_gsup_req_free(req); return NULL; } LOG_GSUP_REQ(req, LOGL_DEBUG, "new request: {%s}\n", osmo_gsup_message_to_str_c(OTC_SELECT, &req->gsup)); if (req->gsup.source_name_len) { if (osmo_cni_peer_id_set(&req->source_name, OSMO_CNI_PEER_ID_IPA_NAME, req->gsup.source_name, req->gsup.source_name_len)) { LOGP(DLGSUP, LOGL_ERROR, "Rx GSUP from %s: failed to decode source_name, message is not routable\n", osmo_cni_peer_id_to_str(from_peer)); osmo_gsup_req_respond_msgt(req, OSMO_GSUP_MSGT_ROUTING_ERROR, true); return NULL; } /* The source of the GSUP message is not the immediate GSUP peer; the peer is our proxy for that source. */ if (osmo_cni_peer_id_cmp(&req->source_name, from_peer)) req->via_proxy = *from_peer; } if (!osmo_imsi_str_valid(req->gsup.imsi)) { osmo_gsup_req_respond_err(req, GMM_CAUSE_INV_MAND_INFO, "invalid IMSI: %s", osmo_quote_str(req->gsup.imsi, -1)); return NULL; } if (add_to_list) llist_add_tail(&req->entry, add_to_list); return req; } /*! Free an osmo_gsup_req and its msgb -- this is usually implicit in osmo_gsup_req_resond_*(), it should not be * necessary to call this directly. */ void osmo_gsup_req_free(struct osmo_gsup_req *req) { LOG_GSUP_REQ(req, LOGL_DEBUG, "free\n"); if (req->msg) msgb_free(req->msg); if (req->entry.prev) llist_del(&req->entry); talloc_free(req); } /*! Send a response to a GSUP request. * * Ensure that the response message contains all GSUP IEs that identify it as a response for the request req, by calling * osmo_gsup_make_response(). * * The final complete response message is passed to req->send_response_cb() to take care of the transmission. * * \param req Request as previously initialized by osmo_gsup_req_new(). * \param response Buffer to compose the response, possibly with some pre-configured IEs. * Any missing IEs are added via osmo_gsup_make_response(). * Must not be NULL. Does not need to remain valid memory beyond the function call, * i.e. this can just be a local variable in the calling function. * \param error True when the response message indicates an error response (error message type). * \param final_response True when the request is concluded by this response, which deallocates the req. * False when the request should remain open after this response. * For most plain request->response GSUP messages, this should be True. * \param file Source file for logging as in __FILE__, added by osmo_gsup_req_respond() macro. * \param line Source line for logging as in __LINE__, added by osmo_gsup_req_respond() macro. */ int _osmo_gsup_req_respond(struct osmo_gsup_req *req, struct osmo_gsup_message *response, bool error, bool final_response, const char *file, int line) { int rc; rc = osmo_gsup_make_response(response, &req->gsup, error, final_response); if (rc) { LOG_GSUP_REQ_SRC(req, LOGL_ERROR, file, line, "Invalid response (rc=%d): {%s}\n", rc, osmo_gsup_message_to_str_c(OTC_SELECT, response)); rc = -EINVAL; goto exit_cleanup; } if (!req->send_response_cb) { LOG_GSUP_REQ_SRC(req, LOGL_ERROR, file, line, "No send_response_cb set, cannot send: {%s}\n", osmo_gsup_message_to_str_c(OTC_SELECT, response)); rc = -EINVAL; goto exit_cleanup; } LOG_GSUP_REQ_SRC(req, LOGL_DEBUG, file, line, "Tx response: {%s}\n", osmo_gsup_message_to_str_c(OTC_SELECT, response)); req->send_response_cb(req, response); exit_cleanup: if (final_response) osmo_gsup_req_free(req); return rc; } /*! Shorthand for _osmo_gsup_req_respond() with no additional IEs and a fixed message type. * Set the message type in a local osmo_gsup_message and feed it to _osmo_gsup_req_respond(). * That will ensure to add all IEs that identify it as a response to req. * * \param req Request as previously initialized by osmo_gsup_req_new(). * \param message_type The GSUP message type discriminator to respond with. * \param final_response True when the request is concluded by this response, which deallocates the req. * False when the request should remain open after this response. * For most plain request->response GSUP messages, this should be True. * \param file Source file for logging as in __FILE__, added by osmo_gsup_req_respond_msgt() macro. * \param line Source line for logging as in __LINE__, added by osmo_gsup_req_respond_msgt() macro. */ int _osmo_gsup_req_respond_msgt(struct osmo_gsup_req *req, enum osmo_gsup_message_type message_type, bool final_response, const char *file, int line) { struct osmo_gsup_message response = { .message_type = message_type, }; return _osmo_gsup_req_respond(req, &response, OSMO_GSUP_IS_MSGT_ERROR(message_type), final_response, file, line); } /*! Shorthand for _osmo_gsup_req_respond() with an error cause IEs and using the req's matched error message type. * Set the error cause in a local osmo_gsup_message and feed it to _osmo_gsup_req_respond(). * That will ensure to add all IEs that identify it as a response to req. * * Responding with an error always implies a final response: req is implicitly deallocated. * * \param req Request as previously initialized by osmo_gsup_req_new(). * \param cause The error cause to include in a OSMO_GSUP_CAUSE_IE. * \param file Source file for logging as in __FILE__, added by osmo_gsup_req_respond_err() macro. * \param line Source line for logging as in __LINE__, added by osmo_gsup_req_respond_err() macro. */ void _osmo_gsup_req_respond_err(struct osmo_gsup_req *req, enum gsm48_gmm_cause cause, const char *file, int line) { struct osmo_gsup_message response = { .cause = cause, }; /* No need to answer if we couldn't parse an ERROR message type, only REQUESTs need an error reply. */ if (!OSMO_GSUP_IS_MSGT_REQUEST(req->gsup.message_type)) { osmo_gsup_req_free(req); return; } osmo_gsup_req_respond(req, &response, true, true); } /*! This function is implicitly called by the osmo_gsup_req API, if at all possible rather use osmo_gsup_req_respond(). * This function is non-static mostly to allow unit testing. * * Set fields, if still unset, that need to be copied from a received message over to its response message, to ensure * the response can be routed back to the requesting peer even via GSUP proxies. * * Note: after calling this function, fields in the reply may reference the same memory as rx and are not deep-copied, * as is the usual way we are handling decoded GSUP messages. * * These fields are set in the reply message, iff they are still unset: * - Set reply->message_type to the rx's matching RESULT code (or ERROR code if error == true). * - IMSI, * - Set reply->destination_name to rx->source_name (for proxy routing), * - sm_rp_mr (for SMS), * - session_id (for SS/USSD), * - if rx->session_state is not NONE, set tx->session_state depending on the final_response argument: * If false, set to OSMO_GSUP_SESSION_STATE_CONTINUE, else OSMO_GSUP_SESSION_STATE_END. * * If values in reply are already set, they will not be overwritten. The return code is an optional way of finding out * whether all values that were already set in 'reply' are indeed matching the 'rx' values that would have been set. * * \param[in] rx Received GSUP message that is being replied to. * \param[inout] reply The message that should be the response to rx, either empty or with some values already set up. * \return 0 if the resulting message is a valid response for rx, nonzero otherwise. A nonzero rc has no effect on the * values set in the reply message: all unset fields are first updated, and then the rc is determined. * The rc is intended to merely warn if the reply message already contained data that is incompatible with rx, * e.g. a mismatching IMSI. */ int osmo_gsup_make_response(struct osmo_gsup_message *reply, const struct osmo_gsup_message *rx, bool error, bool final_response) { int rc = 0; if (!reply->message_type) { if (error) reply->message_type = OSMO_GSUP_TO_MSGT_ERROR(rx->message_type); else reply->message_type = OSMO_GSUP_TO_MSGT_RESULT(rx->message_type); } if (*reply->imsi == '\0') OSMO_STRLCPY_ARRAY(reply->imsi, rx->imsi); if (reply->message_class == OSMO_GSUP_MESSAGE_CLASS_UNSET) reply->message_class = rx->message_class; if (!reply->destination_name || !reply->destination_name_len) { reply->destination_name = rx->source_name; reply->destination_name_len = rx->source_name_len; } /* RP-Message-Reference is mandatory for SM Service */ if (!reply->sm_rp_mr) reply->sm_rp_mr = rx->sm_rp_mr; /* For SS/USSD, it's important to keep both session state and ID IEs */ if (!reply->session_id) reply->session_id = rx->session_id; if (rx->session_state != OSMO_GSUP_SESSION_STATE_NONE && reply->session_state == OSMO_GSUP_SESSION_STATE_NONE) { if (final_response || rx->session_state == OSMO_GSUP_SESSION_STATE_END) reply->session_state = OSMO_GSUP_SESSION_STATE_END; else reply->session_state = OSMO_GSUP_SESSION_STATE_CONTINUE; } if (strcmp(reply->imsi, rx->imsi)) rc |= 1 << 0; if (reply->message_class != rx->message_class) rc |= 1 << 1; if (rx->sm_rp_mr && (!reply->sm_rp_mr || *rx->sm_rp_mr != *reply->sm_rp_mr)) rc |= 1 << 2; if (reply->session_id != rx->session_id) rc |= 1 << 3; return rc; } /*! Print the most important value of a GSUP message to a string buffer in human readable form. * \param[out] buf The buffer to write to. * \param[out] buflen sizeof(buf). * \param[in] msg GSUP message to print. */ size_t osmo_gsup_message_to_str_buf(char *buf, size_t buflen, const struct osmo_gsup_message *msg) { struct osmo_strbuf sb = { .buf = buf, .len = buflen }; if (!msg) { OSMO_STRBUF_PRINTF(sb, "NULL"); return sb.chars_needed; } if (msg->message_class) OSMO_STRBUF_PRINTF(sb, "%s ", osmo_gsup_message_class_name(msg->message_class)); OSMO_STRBUF_PRINTF(sb, "%s:", osmo_gsup_message_type_name(msg->message_type)); OSMO_STRBUF_PRINTF(sb, " imsi="); OSMO_STRBUF_APPEND(sb, osmo_quote_cstr_buf, msg->imsi, strnlen(msg->imsi, sizeof(msg->imsi))); if (msg->cause) OSMO_STRBUF_PRINTF(sb, " cause=%s", get_value_string(gsm48_gmm_cause_names, msg->cause)); switch (msg->cn_domain) { case OSMO_GSUP_CN_DOMAIN_CS: OSMO_STRBUF_PRINTF(sb, " cn_domain=CS"); break; case OSMO_GSUP_CN_DOMAIN_PS: OSMO_STRBUF_PRINTF(sb, " cn_domain=PS"); break; default: if (msg->cn_domain) OSMO_STRBUF_PRINTF(sb, " cn_domain=?(%d)", msg->cn_domain); break; } if (msg->source_name_len) { OSMO_STRBUF_PRINTF(sb, " source_name="); OSMO_STRBUF_APPEND(sb, osmo_quote_cstr_buf, (char*)msg->source_name, msg->source_name_len); } if (msg->destination_name_len) { OSMO_STRBUF_PRINTF(sb, " destination_name="); OSMO_STRBUF_APPEND(sb, osmo_quote_cstr_buf, (char*)msg->destination_name, msg->destination_name_len); } if (msg->session_id) OSMO_STRBUF_PRINTF(sb, " session_id=%" PRIu32, msg->session_id); if (msg->session_state) OSMO_STRBUF_PRINTF(sb, " session_state=%s", osmo_gsup_session_state_name(msg->session_state)); if (msg->sm_rp_mr) OSMO_STRBUF_PRINTF(sb, " sm_rp_mr=%" PRIu8, *msg->sm_rp_mr); return sb.chars_needed; } /*! Same as osmo_gsup_message_to_str_buf() but returns a talloc allocated string. */ char *osmo_gsup_message_to_str_c(void *ctx, const struct osmo_gsup_message *msg) { OSMO_NAME_C_IMPL(ctx, 64, "ERROR", osmo_gsup_message_to_str_buf, msg) }