1*6236dae4SAndroid Build Coastguard Worker--- 2*6236dae4SAndroid Build Coastguard Workerc: Copyright (C) Daniel Stenberg, <[email protected]>, et al. 3*6236dae4SAndroid Build Coastguard WorkerSPDX-License-Identifier: curl 4*6236dae4SAndroid Build Coastguard WorkerLong: http3 5*6236dae4SAndroid Build Coastguard WorkerTags: Versions 6*6236dae4SAndroid Build Coastguard WorkerProtocols: HTTP 7*6236dae4SAndroid Build Coastguard WorkerAdded: 7.66.0 8*6236dae4SAndroid Build Coastguard WorkerMutexed: http1.1 http1.0 http2 http2-prior-knowledge http3-only 9*6236dae4SAndroid Build Coastguard WorkerRequires: HTTP/3 10*6236dae4SAndroid Build Coastguard WorkerHelp: Use HTTP v3 11*6236dae4SAndroid Build Coastguard WorkerCategory: http 12*6236dae4SAndroid Build Coastguard WorkerMulti: mutex 13*6236dae4SAndroid Build Coastguard WorkerSee-also: 14*6236dae4SAndroid Build Coastguard Worker - http1.1 15*6236dae4SAndroid Build Coastguard Worker - http2 16*6236dae4SAndroid Build Coastguard WorkerExample: 17*6236dae4SAndroid Build Coastguard Worker - --http3 $URL 18*6236dae4SAndroid Build Coastguard Worker--- 19*6236dae4SAndroid Build Coastguard Worker 20*6236dae4SAndroid Build Coastguard Worker# `--http3` 21*6236dae4SAndroid Build Coastguard Worker 22*6236dae4SAndroid Build Coastguard WorkerAttempt HTTP/3 to the host in the URL, but fallback to earlier HTTP versions 23*6236dae4SAndroid Build Coastguard Workerif the HTTP/3 connection establishment fails or is slow. HTTP/3 is only 24*6236dae4SAndroid Build Coastguard Workeravailable for HTTPS and not for HTTP URLs. 25*6236dae4SAndroid Build Coastguard Worker 26*6236dae4SAndroid Build Coastguard WorkerThis option allows a user to avoid using the Alt-Svc method of upgrading to 27*6236dae4SAndroid Build Coastguard WorkerHTTP/3 when you know or suspect that the target speaks HTTP/3 on the given 28*6236dae4SAndroid Build Coastguard Workerhost and port. 29*6236dae4SAndroid Build Coastguard Worker 30*6236dae4SAndroid Build Coastguard WorkerWhen asked to use HTTP/3, curl issues a separate attempt to use older HTTP 31*6236dae4SAndroid Build Coastguard Workerversions with a slight delay, so if the HTTP/3 transfer fails or is slow, curl 32*6236dae4SAndroid Build Coastguard Workerstill tries to proceed with an older HTTP version. The fallback performs the 33*6236dae4SAndroid Build Coastguard Workerregular negotiation between HTTP/1 and HTTP/2. 34*6236dae4SAndroid Build Coastguard Worker 35*6236dae4SAndroid Build Coastguard WorkerUse --http3-only for similar functionality *without* a fallback. 36