# SSLGetDatagramWriteSize(_:_:) Provides the largest packet that the OS guarantees it can send without fragmentation. ``` func SSLGetDatagramWriteSize(_ dtlsContext: SSLContext, _ bufSize: UnsafeMutablePointer) -> OSStatus ``` ## Parameters `dtlsContext` The SSL context associated with the connection. `bufSize` The address of a `size_t` integer for storing the length. ## Return Value A result code. See [Secure Transport Result Codes](/documentation/Security/secure-transport-result-codes). ## Discussion Although any packet below this threshold size will not be fragmented by the OS when sent using [`SSLWrite(_:_:_:_:)`](/documentation/Security/SSLWrite(_:_:_:_:)), this function provides no guarantees about whether the packet will be fragmented by routers en route. This size value is equal to the maximum Datagram Record size (set by calling [`SSLSetMaxDatagramRecordSize(_:_:)`](/documentation/Security/SSLSetMaxDatagramRecordSize(_:_:))) minus the DTLS Record header size. --- Copyright © 2026 Apple Inc. All rights reserved. | [Terms of Use](https://www.apple.com/legal/internet-services/terms/site.html) | [Privacy Policy](https://www.apple.com/privacy/privacy-policy)