61c9c80275
I was unable to find a single use of this anywhere, and the networking folks point out https://tools.ietf.org/html/rfc6093: """ 5. Advice to New Applications Employing TCP As a result of the issues discussed in Section 3.2 and Section 3.4, new applications SHOULD NOT employ the TCP urgent mechanism. """ Applications that think they want to do these tricksy things should be referred to section 3.4, wherein it's noted that these semantics are effectively dead and it's middleboxes what killed 'em: """ 3.4. Interaction of Middleboxes with TCP Urgent Indications As a result of the publication of Network Intrusion Detection System (NIDS) evasion techniques based on TCP urgent indications [phrack], some middleboxes clear the urgent indications by clearing the URG flag and setting the Urgent Pointer to zero. This causes the "urgent data" to become "in line" (that is, accessible by the read(2) call or the recv(2) call without the MSG_OOB flag) in the case of those TCP implementations that interpret the TCP urgent mechanism as a facility for delivering "out-of-band" data (as described in Section 3.1). An example of such a middlebox is the Cisco PIX firewall [Cisco-PIX]. This should discourage applications from depending on urgent indications for their correct operation, as urgent indications may not be reliable in the current Internet. """ Bug: N/A Test: N/A Change-Id: I73280db1d803bb7bd93954c13c653fa0cd3daff9 |
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| 32-bit-abi.md | ||
| status.md | ||