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Run idnits with the --verbose option for more detailed information about the items above. -------------------------------------------------------------------------------- 2 ECRIT B. Rosen 3 Internet-Draft NeuStar, Inc. 4 Intended status: Standards Track H. Schulzrinne 5 Expires: August 18, 2014 Columbia U. 6 H. Tschofenig 7 Nokia Siemens Networks 8 February 14, 2014 10 Data-Only Emergency Calls 11 draft-ietf-ecrit-data-only-ea-07.txt 13 Abstract 15 RFC 6443 'Framework for Emergency Calling Using Internet Multimedia' 16 describes how devices use the Internet to place emergency calls and 17 how Public Safety Answering Points (PSAPs) can handle Internet 18 multimedia emergency calls natively. The exchange of multimedia 19 traffic typically involves a SIP session establishment starting with 20 a SIP INVITE that negotiates various parameters for that session. 22 In some cases, however, the transmission of application data is 23 everything that is needed. Examples of such environments include a 24 temperature sensors issuing alerts, or vehicles sending crash data. 25 Often these alerts are conveyed as one-shot data transmissions. 26 These type of interactions are called 'data-only emergency calls'. 27 This document describes a container for the data based on the Common 28 Alerting Protocol (CAP) and its transmission using the SIP MESSAGE 29 transaction. 31 Status of This Memo 33 This Internet-Draft is submitted in full conformance with the 34 provisions of BCP 78 and BCP 79. 36 Internet-Drafts are working documents of the Internet Engineering 37 Task Force (IETF). Note that other groups may also distribute 38 working documents as Internet-Drafts. The list of current Internet- 39 Drafts is at http://datatracker.ietf.org/drafts/current/. 41 Internet-Drafts are draft documents valid for a maximum of six months 42 and may be updated, replaced, or obsoleted by other documents at any 43 time. It is inappropriate to use Internet-Drafts as reference 44 material or to cite them other than as "work in progress." 46 This Internet-Draft will expire on August 18, 2014. 48 Copyright Notice 50 Copyright (c) 2014 IETF Trust and the persons identified as the 51 document authors. All rights reserved. 53 This document is subject to BCP 78 and the IETF Trust's Legal 54 Provisions Relating to IETF Documents 55 (http://trustee.ietf.org/license-info) in effect on the date of 56 publication of this document. Please review these documents 57 carefully, as they describe your rights and restrictions with respect 58 to this document. Code Components extracted from this document must 59 include Simplified BSD License text as described in Section 4.e of 60 the Trust Legal Provisions and are provided without warranty as 61 described in the Simplified BSD License. 63 Table of Contents 65 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 3 66 2. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 3 67 3. Architectural Overview . . . . . . . . . . . . . . . . . . . 4 68 4. Protocol Specification . . . . . . . . . . . . . . . . . . . 6 69 4.1. CAP Transport . . . . . . . . . . . . . . . . . . . . . . 6 70 4.2. Profiling of the CAP Document Content . . . . . . . . . . 7 71 4.3. Sending a Data-Only Emergency Call . . . . . . . . . . . 8 72 5. Error Handling . . . . . . . . . . . . . . . . . . . . . . . 8 73 5.1. 425 (Bad Alert Message) Response Code . . . . . . . . . . 9 74 5.2. The AlertMsg-Error Header Field . . . . . . . . . . . . . 9 75 6. Updates to the CAP Message . . . . . . . . . . . . . . . . . 11 76 7. Call Backs . . . . . . . . . . . . . . . . . . . . . . . . . 11 77 8. Handling Large Amounts of Data . . . . . . . . . . . . . . . 11 78 9. Example . . . . . . . . . . . . . . . . . . . . . . . . . . . 11 79 10. Security Considerations . . . . . . . . . . . . . . . . . . . 15 80 11. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 17 81 11.1. Registration of the 'application/emergencyCall.cap+xml' 82 MIME type . . . . . . . . . . . . . . . . . . . . . . . 17 83 11.2. IANA Registration of Additional Data Block . . . . . . . 18 84 11.3. IANA Registration for 425 Response Code . . . . . . . . 18 85 11.4. IANA Registration of New AlertMsg-Error Header Field . . 19 86 11.5. IANA Registration for the SIP AlertMsg-Error Codes . . . 19 87 12. Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . 20 88 13. References . . . . . . . . . . . . . . . . . . . . . . . . . 20 89 13.1. Normative References . . . . . . . . . . . . . . . . . . 20 90 13.2. Informative References . . . . . . . . . . . . . . . . . 21 91 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 22 93 1. Introduction 95 RFC 6443 [RFC6443] describes how devices use the Internet to place 96 emergency calls and how Public Safety Answering Points (PSAPs) can 97 handle Internet multimedia emergency calls natively. The exchange of 98 multimedia traffic typically involves a SIP session establishment 99 starting with a SIP INVITE that negotiates various parameters for 100 that session. 102 In some cases, however, there is only application data to be conveyed 103 from the end devices to a PSAP or some other intermediary. Examples 104 of such environments includes sensors issuing alerts, or vehicles 105 sending crash data. These messages may be one-shot alerts to 106 emergency authorities and do not require establishment of a session. 107 These type of interactions are called 'data-only emergency calls'. 108 In this document, we use the term "call" so that similarities between 109 full sessions with interactive media can be exploited. 111 Data-only emergency calls are similar to regular emergency calls in 112 the sense that they require the emergency indications, emergency call 113 routing functionality and may even have the same location 114 requirements. However, the communication interaction will not lead 115 to the exchange of interactive media, that is, Real-Time Protocol 116 packets, such as voice, video data or real-time text. 118 The Common Alerting Protocol (CAP) [cap] is a document format for 119 exchanging emergency alerts and public warnings. CAP is mainly used 120 for conveying alerts and warnings between authorities and from 121 authorities to citizen/individuals. This document is concerned with 122 citizen to authority "alerts", where the alert is sent without any 123 interactive media. 125 This document describes a method of including a CAP message in a SIP 126 transaction, either by value (CAP message is in the body of the 127 message, using a CID) or by reference (A URI is included in the 128 message, which when dereferenced returns the CAP message) by defining 129 it as a block of "additional data" as defined in 130 [I-D.ietf-ecrit-additional-data]. The additional data mechanism is 131 also used to send alert specific data beyond that available in the 132 CAP message. 134 2. Terminology 136 The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", 137 "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this 138 document are to be interpreted as described in RFC 2119 [RFC2119]. 140 3. Architectural Overview 142 This section illustrates two envisioned usage modes; targeted and 143 location-based emergency alert routing. 145 1. Emergency alerts containing only data are targeted to a 146 intermediary recipient responsible for evaluating the next steps. 147 These steps could include: 149 1. Sending an alert containing only data toward a Public Safety 150 Answering Point (PSAP); 152 2. Establishing a third-party initiated emergency call towards a 153 PSAP that could include audio, video, and data. 155 2. Emergency alerts targeted to a Service URN used for IP-based 156 emergency calls where the recipient is not known to the 157 originator. In this scenario, the alert may contain only data 158 (e.g., a CAP, Geolocation header and one or more Call-Info 159 headers containing Additional Data 160 [I-D.ietf-ecrit-additional-data] in a SIP MESSAGE). 162 Figure 1 shows a deployment variant where a sensor, is pre-configured 163 (using techniques outside the scope of this document) to issue an 164 alert to an aggregator that processes these messages and performs 165 whatever steps are necessary to appropriately react on the alert. 166 For example, a security firm may use different sensor inputs to 167 dispatch their security staff to a building they protect or to 168 initiate a third-party emergency call. 170 +------------+ +------------+ 171 | Sensor | | Aggregator | 172 | | | | 173 +---+--------+ +------+-----+ 174 | | 175 Sensors | 176 trigger | 177 emergency | 178 alert | 179 | MESSAGE with CAP | 180 |----------------------------->| 181 | | 182 | Aggregator 183 | processes 184 | emergency 185 | alert 186 | 200 (OK) | 187 |<-----------------------------| 188 | | 189 | | 191 Figure 1: Targeted Emergency Alert Routing 193 In Figure 2 a scenario is shown whereby the alert is routed using 194 location information and the Service URN. An emergency services 195 routing proxy (ESRP) may use LoST to determine the next hop proxy to 196 route the alert message to. A possible receiver is a PSAP and the 197 recipient of the alert may be call taker. In the generic case, there 198 is very likely no prior relationship between the originator and the 199 receiver, e.g. PSAP. A PSAP, for example, is likely to receive and 200 accept alerts from entities it cannot authorize. This scenario 201 corresponds more to the classical emergency services use case and the 202 description in [RFC6881] is applicable. In this use case, the only 203 difference between an emergency call, and an emergency data-only call 204 is that the former uses INVITE and creates a session and negotiates 205 one or more media streams, and the latter uses MESSAGE, does not 206 create a session and does not have media. 208 +-----------+ +----------+ 209 +--------+ | ESRP | | PSAP | 210 | Sensor | | | | | 211 +---+----+ +---+-------+ +---+------+ 212 | | | 213 Sensors | | 214 trigger | | 215 emergency | | 216 alert | | 217 | | | 218 | | | 219 | MESSAGE with CAP | | 220 | (including Service URN, | 221 | such as urn:service:sos) | 222 |------------------->| | 223 | | | 224 | ESRP performs | 225 | emergency alert | 226 | routing | 227 | | MESSAGE with CAP | 228 | | (including identity info) | 229 | |----------------------------->| 230 | | | 231 | | PSAP 232 | | processes 233 | | emergency 234 | | alert 235 | | 200 (OK) | 236 | |<-----------------------------| 237 | | | 238 | 200 (OK) | | 239 |<-------------------| | 240 | | | 241 | | | 243 Figure 2: Location-Based Emergency Alert Routing 245 4. Protocol Specification 247 4.1. CAP Transport 249 A CAP message may be sent on the initial message of any SIP 250 transaction. However, this document only describes specific behavior 251 when used with a SIP MESSAGE transaction for a one-shot, data-only 252 emergency call. Behavior with other transactions is not defined. 254 The CAP message included in a SIP message as an additional-data block 255 [I-D.ietf-ecrit-additional-data]. Accordingly, it is introduced to 256 the SIP message with a Call-Info header with a purpose of 257 "emergencyCall.cap". The header may contain a URI that is used by 258 the recipient (or in some cases, an intermediary) to obtain the CAP 259 message. Alternative, the Call-Info header may contain a Content 260 Indirect url [RFC2392] and the CAP message included in the body of 261 the message. In either case, the CAP message is located in a MIME 262 block. The MIME type is set to 'application/emergencyCall.cap+xml'. 264 If the server does not support the functionality required to fulfill 265 the request then a 501 Not Implemented MUST be returned as specified 266 in RFC 3261 [RFC3261]. This is the appropriate response when a UAS 267 does not recognize the request method and is not capable of 268 supporting it for any user. 270 The 415 Unsupported Media Type error MUST be returned as specified in 271 RFC 3261 [RFC3261] if the server is refusing to service the request 272 because the message body of the request is in a format not supported 273 by the server for the requested method. The server MUST return a 274 list of acceptable formats using the Accept, Accept-Encoding, or 275 Accept-Language header field, depending on the specific problem with 276 the content. 278 4.2. Profiling of the CAP Document Content 280 The usage of CAP MUST conform to the specification provided with 281 [cap]. For the usage with SIP the following additional requirements 282 are imposed: 284 sender: A few sub-categories for putting a value in the 285 element have to be considered: 287 Originator is a SIP entity, Author indication irrelevant: When 288 the alert was created by a SIP-based originator and it is not 289 useful to be explicit about the author of the alert then the 290 element MUST be populated with the SIP URI of the user 291 agent. 293 Originator is a non-SIP entity, Author indication irrelevant: In 294 case that the alert was created by a non-SIP based entity and 295 the identity of this original sender wants to be preserved then 296 this identity MUST be placed into the element. In 297 this category the it is not useful to be explicit about the 298 author of the alert. The specific type of identity being used 299 will depends on the technology being used by the original 300 originator. 302 Author indication relevant: In case the author is different from 303 the actual originator of the message and this distinction 304 should be preserved then the element MUST NOT contain 305 the SIP URI of the user agent. 307 incidents: The element MUST be present. This incident 308 identifier MUST be chosen in such a way that it is unique for a 309 given combination. Note that the 310 element is optional and may not be present. 312 scope: The value of the element MAY be set to "Private" if 313 the alert is not meant for public consumption. The 314 element is, however, not used by this specification since the 315 message routing is performed by SIP and the respective address 316 information is already available in other SIP headers. Populating 317 information twice into different parts of the message may lead to 318 inconsistency. 320 parameter: The element MAY contain additional 321 information specific to the sendor. 323 area: It is RECOMMENDED to omit this element when constructing a 324 message. In case that the CAP message already contained an 325 element then the specified location information SHOULD be copied 326 into the PIDF-LO structure of the 'geolocation' header. 328 4.3. Sending a Data-Only Emergency Call 330 A data-only emergency call is sent using a SIP MESSAGE transaction 331 with a CAP URI or body as described above in a manner similar to how 332 an emergency call with interactive media is sent, as described in 333 [RFC6881]. The MESSAGE transaction does not create a session or send 334 media, but otherwise, the header content of the transaction, routing, 335 and processing of data-only calls are the same as those of other 336 emergency calls. 338 5. Error Handling 340 This section defines a new error response code and a header field for 341 additional information. 343 5.1. 425 (Bad Alert Message) Response Code 345 This SIP extension creates a new location-specific response code, 346 defined as follows, 348 425 (Bad Alert Message) 350 The 425 response code is a rejection of the request due to its 351 included alert content, indicating that it was malformed or not 352 satisfactory for the recipient's purpose. 354 A SIP intermediary can also reject an alert it receives from a UA 355 when it understands that the provided alert is malformed. 357 Section 5.2 describes an AlertMsg-Error header field with more 358 details about what was wrong with the alert message in the request. 359 This header field MUST be included in the 425 response. 361 It is only appropriate to generate a 425 response when the responding 362 entity has no other information in the request that are usable by the 363 responder. 365 A 425 response code MUST NOT be sent in response to a request that 366 lacks an alert message entirely, as the user agent in that case may 367 not support this extension at all. 369 A 425 response is a final response within a transaction, and MUST NOT 370 terminate an existing dialog. 372 5.2. The AlertMsg-Error Header Field 374 The AlertMsg-Error header provides additional information about what 375 was wrong with the original request. In some cases the provided 376 information will be used for debugging purposes. 378 The AlertMsg-Error header field has the following ABNF [RFC5234]: 380 message-header /= AlertMsg-Error 381 ; (message-header from 3261) 382 AlertMsg-Error = "AlertMsg-Error" HCOLON 383 ErrorValue 384 ErrorValue = error-code 385 *(SEMI error-params) 386 error-code = 1*3DIGIT 387 error-params = error-code-text 388 / generic-param ; from RFC3261 389 error-code-text = "code" EQUAL quoted-string ; from RFC3261 391 HCOLON, SEMI, and EQUAL are defined in RFC3261 [RFC3261]. DIGIT is 392 defined in RFC5234 [RFC5234]. 394 The AlertMsg-Error header field MUST contain only one ErrorValue to 395 indicate what was wrong with the alert payload the recipient 396 determined was bad. 398 The ErrorValue contains a 3-digit error code indicating what was 399 wrong with the alert in the request. This error code has a 400 corresponding quoted error text string that is human understandable. 401 The text string are OPTIONAL, but RECOMMENDED for human readability, 402 similar to the string phrase used for SIP response codes. That said, 403 the strings are complete enough for rendering to the user, if so 404 desired. The strings in this document are recommendations, and are 405 not standardized - meaning an operator can change the strings - but 406 MUST NOT change the meaning of the error code. Similar to how RFC 407 3261 specifies, there MUST NOT be more than one string per error 408 code. 410 The AlertMsg-Error header field MAY be included in any response as an 411 alert message was in the request part of the same transaction. For 412 example, a UA includes an alert in an MESSAGE to a PSAP. The PSAP 413 can accept this MESSAGE, thus creating a dialog, even though his UA 414 determined the alert message contained in the MESSAGE was bad. The 415 PSAP merely includes an AlertMsg-Error header value in the 200 OK to 416 the MESSAGE informing the UA that the MESSAGE was accepted but the 417 alert provided was bad. 419 If, on the other hand, the PSAP cannot accept the transaction without 420 a suitable alert message, a 425 response is sent. 422 A SIP intermediary that requires the UA's alert message in order to 423 properly process the transaction may also sends a 425 with a 424 AlertMsg-Error code. 426 This document defines an initial list of error code ranges for any 427 SIP response, including provisional responses (other than 100 Trying) 428 and the new 425 response. There MUST be no more than one AlertMsg- 429 Error code in a SIP response. 431 AlertMsg-Error: 100 ; code="Cannot Process the Alert Payload" 433 AlertMsg-Error: 101 ; code="Alert Payload was not present or could 434 not be found" 436 AlertMsg-Error: 102 ; code="Not enough information to determine the 437 purpose of the alert" 438 AlertMsg-Error: 103 ; code="Alert Payload was corrupted" 440 Additionally, if an entity cannot or chooses not to process the alert 441 message from a SIP request, a 500 (Server Internal Error) SHOULD be 442 used with or without a configurable Retry-After header field. 444 6. Updates to the CAP Message 446 If the sender anticipates that the content of the CAP message may 447 need to be updated during the lifecycle of the event referred to in 448 the message, it may include an update block as defined in 449 [I-D.rosen-ecrit-addldata-subnot]. 451 7. Call Backs 453 This document does not describe any method for the recipient to call 454 back the sender of the data-only call. Usually, these alerts are 455 sent by automata, and do not have any mechanism to receive calls of 456 any kind. The identifier in the From header may be useful to obtain 457 more information, but any such mechanism is not defined in this 458 document. The CAP message may contain related contact information 459 for the sender. 461 8. Handling Large Amounts of Data 463 It is not atypical for sensor to have large quantities of data that 464 they may wish to send. Including large amounts of data in a MESSAGE 465 is not advisable, because SIP entities are usually not equipped to 466 handle very large messages. In such cases, the sender SHOULD make 467 use of the by-reference mechanisms defined for Additional Data which 468 involve sending a URI in the Call-Info header and using HTTPS to 469 retrieve the data. The CAP message itself can be sent by-reference 470 using this mechanism as well as any or all of the Additional Data 471 blocks that may contain sensor-specific data. 473 9. Example 475 Figure 3 shows a CAP document indicating a BURGLARY alert issued by a 476 sensor called 'sensor1@domain.com'. The location of the sensor can 477 be obtained from the attached location information provided via the 478 'geolocation' header contained in the SIP MESSAGE structure. 479 Additionally, the sensor provided some data long with the alert 480 message using proprietary information elements only to be processed 481 by the receiver, a SIP entity acting as an aggregator. This example 482 reflects the description in Figure 1. 484 MESSAGE sip:aggregator@domain.com SIP/2.0 485 Via: SIP/2.0/TCP sensor1.domain.com;branch=z9hG4bK776sgdkse 486 Max-Forwards: 70 487 From: sip:sensor1@domain.com;tag=49583 488 To: sip:aggregator@domain.com 489 Call-ID: asd88asd77a@1.2.3.4 490 Geolocation: 491 ;routing-allowed=yes 492 Supported: geolocation 493 Accept: application/pidf+xml, application/emergencyCall.cap+xml 494 CSeq: 1 MESSAGE 495 Call-Info: cid:abcdef2@domain.com;purpose=emergencyCall.cap 496 Content-Type: multipart/mixed; boundary=boundary1 497 Content-Length: ... 499 --boundary1 501 Content-Type: application/emergencyCall.cap 502 Content-ID: 503 Content-Disposition: by-reference;handling=optional 504 506 507 S-1 508 sip:sensor1@domain.com 509 2008-11-19T14:57:00-07:00 510 Actual 511 Alert 512 Private 513 abc1234 514 515 Security 516 BURGLARY 517 Expected 518 Likely 519 Moderate 520 SENSOR 1 521 522 SENSOR-DATA-NAMESPACE1 523 123 524 525 526 SENSOR-DATA-NAMESPACE2 527 TRUE 528 529 530 532 --boundary1 533 Content-Type: application/pidf+xml 534 Content-ID: 535 Content-Disposition: by-reference;handling=optional 536 537 546 547 548 549 550 551 32.86726 -97.16054 552 553 554 555 556 false 557 558 2010-11-14T20:00:00Z 559 560 561 802.11 562 563 2010-11-04T20:57:29Z 564 565 566 --boundary1-- 568 Figure 3: Example Message conveying an Alert to an Aggregator 570 Figure 4 shows the same CAP document sent as a data-only emergency 571 call towards a PSAP. 573 MESSAGE urn:service:sos SIP/2.0 574 Via: SIP/2.0/TCP sip:aggreg.1.example.com;branch=z9hG4bK776abssa 575 Max-Forwards: 70 576 From: sip:aggregator@example.com;tag=32336 577 To: 112 578 Call-ID: asdf33443a@example.com 579 Route: sip:psap1.example.gov 580 Geolocation: 581 ;routing-allowed=yes 582 Supported: geolocation 583 Accept: application/pidf+xml, application/emergencyCall.cap+xml 584 Call-info: cid:abcdef2@domain.com;purpose=emergencyCall.cap 585 CSeq: 1 MESSAGE 586 Content-Type: multipart/mixed; boundary=boundary1 587 Content-Length: ... 589 --boundary1 591 Content-Type: application/emergencyCall.cap+xml 592 Content-ID: 593 595 596 S-1 597 sip:sensor1@domain.com 598 2008-11-19T14:57:00-07:00 599 Actual 600 Alert 601 Private 602 abc1234 603 604 Security 605 BURGLARY 606 Expected 607 Likely 608 Moderate 609 SENSOR 1 610 611 SENSOR-DATA-NAMESPACE1 612 123 613 614 615 SENSOR-DATA-NAMESPACE2 616 TRUE 617 618 619 621 --boundary1 623 Content-Type: application/pidf+xml 624 Content-ID: 625 626 635 636 637 638 639 640 32.86726 -97.16054 641 642 643 644 645 false 646 647 2010-11-14T20:00:00Z 648 649 650 802.11 651 652 2010-11-04T20:57:29Z 653 654 655 --boundary1-- 657 Figure 4: Example Message conveying an Alert to a PSAP 659 10. Security Considerations 661 This section discusses security considerations when SIP user agents 662 issue emergency alerts utilizing MESSAGE and CAP. Location specific 663 threats are not unique to this document and are discussed in 664 [I-D.ietf-ecrit-trustworthy-location] and [RFC6442]. 666 The ECRIT emergency services architecture [RFC6443] considers 667 classical individual-to-authority emergency calling and the identity 668 of the emergency caller does not play a role at the time of the call 669 establishment itself, i.e., a response to the emergency call will not 670 depend on the identity of the caller. In case of emergency alerts 671 generated by devices, like sensors, the processing may be different 672 in order to reduce the number of falsely generated emergency alerts. 673 Alerts may get triggered based on certain sensor input that may have 674 been caused by other factors than the actual occurrence of an alert 675 relevant event. For example, a sensor may simply be malfunctioning. 677 For this purpose not all alert messages are directly sent to a PSAP 678 but rather may be pre-processed by a separate entity, potentially 679 under supervision by a human, to filter alerts and potentially 680 correlate received alerts with others to obtain a larger picture of 681 the ongoing situation. 683 In any case, for alerts that are initiated by sensors the identity 684 may play an important role in deciding whether to accept or ignore an 685 incoming alert message. With the scenario shown in Figure 1 it is 686 very likely that only authorized sensor input will be processed. For 687 this purpose it needs to be ensured that no alert messages from an 688 unknown origin are accepted. Two types of information elements can 689 be used for this purpose: 691 1. SIP itself provides security mechanisms that allow the 692 verification of the originator's identity. These mechanisms can 693 be re-used, such as P-Asserted-Identity [RFC3325] or SIP Identity 694 [RFC4474]. The latter provides a cryptographic assurance while 695 the former relies on a chain of trust model. 697 2. CAP provides additional security mechanisms and the ability to 698 carry additional information about the sender's identity. 699 Section 3.3.2.1 of [cap] specifies the signing algorithms of CAP 700 documents. 702 In addition to the desire to perform identity-based access control 703 the classical communication security threats need to be considered, 704 including integrity protection to prevent forgery and replay of alert 705 messages in transit. To deal with replay of alerts a CAP document 706 contains the mandatory , , elements and an 707 optional element. These attributes make the CAP document 708 unique for a specific sender and provide time restrictions. An 709 entity that has received a CAP message already within the indicated 710 timeframe is able to detect a replayed message and, if the content of 711 that message is unchanged, then no additional security vulnerability 712 is created. Additionally, it is RECOMMENDED to make use of SIP 713 security mechanisms, such as SIP Identity [RFC4474], to tie the CAP 714 message to the SIP message. To provide protection of the entire SIP 715 message exchange between neighboring SIP entities the usage of TLS is 716 mandatory. 718 Note that none of the security mechanism in this document protect 719 against a compromised sensor sending crafted alerts. 721 11. IANA Considerations 723 11.1. Registration of the 'application/emergencyCall.cap+xml' MIME type 725 To: ietf-types@iana.org 727 Subject: Registration of MIME media type application/ 728 emergencyCall.cap+xml 730 MIME media type name: application 732 MIME subtype name: cap+xml 734 Required parameters: (none) 736 Optional parameters: charset; Indicates the character encoding of 737 enclosed XML. Default is UTF-8 [RFC3629]. 739 Encoding considerations: Uses XML, which can employ 8-bit 740 characters, depending on the character encoding used. See RFC 741 3023 [RFC3023], Section 3.2. 743 Security considerations: This content type is designed to carry 744 payloads of the Common Alerting Protocol (CAP). 746 Interoperability considerations: This content type provides a way to 747 convey CAP payloads. 749 Published specification: RFC XXX [Replace by the RFC number of this 750 specification]. 752 Applications which use this media type: Applications that convey 753 alerts and warnings according to the CAP standard. 755 Additional information: OASIS has published the Common Alerting 756 Protocol at http://www.oasis-open.org/committees/ 757 documents.php&wg_abbrev=emergency 759 Person and email address to contact for further information: Hannes 760 Tschofenig, Hannes.Tschofenig@nsn.com 762 Intended usage: Limited use 764 Author/Change controller: IETF ECRIT working group 766 Other information: This media type is a specialization of 767 application/xml RFC 3023 [RFC3023], and many of the considerations 768 described there also apply to application/cap+xml. 770 11.2. IANA Registration of Additional Data Block 772 This document registers a new block type in the sub-registry called 773 'Additional Data Blocks' defined in [I-D.ietf-ecrit-additional-data]. 774 The token is "cap" and the reference is this document. 776 11.3. IANA Registration for 425 Response Code 778 In the SIP Response Codes registry, the following is added 780 Reference: RFC-XXXX (i.e., this document) 782 Response code: 425 (recommended number to assign) 784 Default reason phrase: Bad Alert Message 786 Registry: 787 Response Code Reference 788 ------------------------------------------ --------- 789 Request Failure 4xx 790 425 Bad Alert Message [this doc] 792 This SIP Response code is defined in Section 5. 794 11.4. IANA Registration of New AlertMsg-Error Header Field 796 The SIP AlertMsg-error header field is created by this document, with 797 its definition and rules in Section 5, to be added to the IANA sip- 798 parameters registry with two actions: 800 1. Update the Header Fields registry with 802 Registry: 803 Header Name compact Reference 804 ----------------- ------- --------- 805 AlertMsg-Error [this doc] 807 2. In the portion titled "Header Field Parameters and Parameter 808 Values", add 810 Predefined 811 Header Field Parameter Name Values Reference 812 ----------------- ------------------- ---------- --------- 813 AlertMsg-Error code yes [this doc] 815 11.5. IANA Registration for the SIP AlertMsg-Error Codes 817 This document creates a new registry for SIP, called "AlertMsg-Error 818 Codes". AlertMsg-Error codes provide reason for the error discovered 819 by recipients, categorized by action to be taken by error recipient. 820 The initial values for this registry are shown below. 822 Registry Name: AlertMsg-Error Codes 824 Reference: [this doc] 826 Registration Procedures: Specification Required 827 Code Default Reason Phrase Reference 828 ---- --------------------------------------------------- --------- 829 100 "Cannot Process the Alert Payload" [this doc] 831 101 "Alert Payload was not present or could not be found" [this doc] 833 102 "Not enough information to determine 834 the purpose of the alert" [this doc] 836 103 "Alert Payload was corrupted" [this doc] 838 Details of these error codes are in Section 5. 840 12. Acknowledgments 842 The authors would like to thank the participants of the Early Warning 843 adhoc meeting at IETF#69 for their feedback. Additionally, we would 844 like to thank the members of the NENA Long Term Direction Working 845 Group for their feedback. 847 Additionally, we would like to thank Martin Thomson, James 848 Winterbottom, Shida Schubert, Bernard Aboba, and Marc Linsner for 849 their review comments. 851 13. References 853 13.1. Normative References 855 [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate 856 Requirement Levels", March 1997. 858 [cap] Jones, E. and A. Botterell, "Common Alerting Protocol v. 859 1.1", October 2005. 861 [RFC2392] Levinson, E., "Content-ID and Message-ID Uniform Resource 862 Locators", RFC 2392, August 1998. 864 [RFC3261] Rosenberg, J., Schulzrinne, H., Camarillo, G., Johnston, 865 A., Peterson, J., Sparks, R., Handley, M., and E. 866 Schooler, "SIP: Session Initiation Protocol", RFC 3261, 867 June 2002. 869 [RFC3428] Campbell, B., Rosenberg, J., Schulzrinne, H., Huitema, C., 870 and D. Gurle, "Session Initiation Protocol (SIP) Extension 871 for Instant Messaging", RFC 3428, December 2002. 873 [RFC5234] Crocker, D. and P. Overell, "Augmented BNF for Syntax 874 Specifications: ABNF", STD 68, RFC 5234, January 2008. 876 [RFC3903] Niemi, A., "Session Initiation Protocol (SIP) Extension 877 for Event State Publication", RFC 3903, October 2004. 879 [RFC3023] Murata, M., St. Laurent, S., and D. Kohn, "XML Media 880 Types", RFC 3023, January 2001. 882 [RFC3629] Yergeau, F., "UTF-8, a transformation format of ISO 883 10646", STD 63, RFC 3629, November 2003. 885 [RFC6442] Polk, J., Rosen, B., and J. Peterson, "Location Conveyance 886 for the Session Initiation Protocol", RFC 6442, December 887 2011. 889 [RFC6665] Roach, A., "SIP-Specific Event Notification", RFC 6665, 890 July 2012. 892 [RFC6881] Rosen, B. and J. Polk, "Best Current Practice for 893 Communications Services in Support of Emergency Calling", 894 BCP 181, RFC 6881, March 2013. 896 [I-D.ietf-ecrit-additional-data] 897 Rosen, B., Tschofenig, H., Marshall, R., Randy, R., and J. 898 Winterbottom, "Additional Data related to an Emergency 899 Call", draft-ietf-ecrit-additional-data-20 (work in 900 progress), February 2014. 902 [I-D.rosen-ecrit-addldata-subnot] 903 Rosen, B., "Updating Additional Data related to an 904 Emergency Call using Subscribe/ Notify", draft-rosen- 905 ecrit-addldata-subnot-01 (work in progress), November 906 2013. 908 13.2. Informative References 910 [I-D.ietf-ecrit-trustworthy-location] 911 Tschofenig, H., Schulzrinne, H., and B. Aboba, 912 "Trustworthy Location", draft-ietf-ecrit-trustworthy- 913 location-08 (work in progress), January 2014. 915 [RFC4474] Peterson, J. and C. Jennings, "Enhancements for 916 Authenticated Identity Management in the Session 917 Initiation Protocol (SIP)", RFC 4474, August 2006. 919 [RFC3325] Jennings, C., Peterson, J., and M. Watson, "Private 920 Extensions to the Session Initiation Protocol (SIP) for 921 Asserted Identity within Trusted Networks", RFC 3325, 922 November 2002. 924 [RFC6443] Rosen, B., Schulzrinne, H., Polk, J., and A. Newton, 925 "Framework for Emergency Calling Using Internet 926 Multimedia", RFC 6443, December 2011. 928 Authors' Addresses 930 Brian Rosen 931 NeuStar, Inc. 932 470 Conrad Dr 933 Mars, PA 16046 934 US 936 Email: br@brianrosen.net 938 Henning Schulzrinne 939 Columbia University 940 Department of Computer Science 941 450 Computer Science Building 942 New York, NY 10027 943 US 945 Phone: +1 212 939 7004 946 Email: hgs+ecrit@cs.columbia.edu 947 URI: http://www.cs.columbia.edu 949 Hannes Tschofenig 950 Nokia Siemens Networks 951 Linnoitustie 6 952 Espoo 02600 953 Finland 955 Phone: +358 (50) 4871445 956 Email: Hannes.Tschofenig@gmx.net 957 URI: http://www.tschofenig.priv.at