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Diffstat (limited to 'src/gsupclient/gsup_req.c')
| -rw-r--r-- | src/gsupclient/gsup_req.c | 410 |
1 files changed, 410 insertions, 0 deletions
diff --git a/src/gsupclient/gsup_req.c b/src/gsupclient/gsup_req.c new file mode 100644 index 0000000..4a2ff23 --- /dev/null +++ b/src/gsupclient/gsup_req.c @@ -0,0 +1,410 @@ +/* Copyright 2019 by sysmocom s.f.m.c. GmbH <info@sysmocom.de> + * + * 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 <http://www.gnu.org/licenses/>. + */ + +#include <errno.h> +#include <inttypes.h> + +#include <osmocom/core/logging.h> +#include <osmocom/gsm/gsm23003.h> + +#include <osmocom/gsupclient/gsup_req.h> + +/*! 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 = <empty> + * + * "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_ipa_name *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 (!msgb_l2(msg) || !msgb_l2len(msg)) { + LOGP(DLGSUP, LOGL_ERROR, "Rx GSUP from %s: missing or empty L2 data\n", + osmo_ipa_name_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; + if (from_peer) + 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_ipa_name_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_ipa_name_set(&req->source_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_ipa_name_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_ipa_name_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) +} |