[rkfshakti]

Summary

CreateSIPParticipant rejects valid Twilio X-Twilio-CallToken values over 1,024 bytes:

TwirpError: invalid header value for X-Twilio-CallToken:
header X-Twilio-CallToken: value too long (max 1024 characters)

HTTP status: 400
Twirp code: invalid_argument
at SipClient.createSipParticipant

Twilio's Immutable Call Forwarding flow requires this token to be forwarded unchanged on the outbound leg so the original caller ID can be presented. The token is opaque and may contain SHAKEN/STIR and DIV PASSporTs, so truncating it is not valid either.

Root cause

ValidateHeaderValueResult caps every header value at 1,024 characters. RFC 3261 does not bound individual header values — §7.1 bounds the whole message (8 KB datagram over UDP, larger over TCP). The 1 KB figure is this codebase's own policy and sits below the size real carrier tokens reach.

Fix

• Introduce maxHeaderValueLength = 4096 and reject values above it. 4 KB keeps a single header from dominating an 8 KB datagram while tolerating real-world carrier tokens. Character-set validation is unchanged.
• Update the valid/invalid test boundary cases (1024 & 4096 pass; 4097 fails) and add a changeset.

Fixes #789

[changeset-bot]

🦋 Changeset detected

Latest commit: 491e261

The changes in this PR will be included in the next version bump.

This PR includes changesets to release 2 packages

Name	Type
github.com/livekit/protocol	Patch
@livekit/protocol	Patch

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[rkfshakti]

Friendly ping for review — this raises the SIP header value cap so long X-Twilio-CallToken headers (large Twilio call SIDs) aren't rejected; pairs with livekit/sip #822 which depends on it. Test and CLA are green on the current head. Could someone take a look when convenient? Happy to make any adjustments needed.

[rkfshakti]

Hi @davidzhao — gentle nudge. This raises the SIP header value cap to 4 KB so large carrier tokens (e.g. Twilio call SIDs in X-Twilio-CallToken) aren't rejected — it unblocks livekit/sip #822, which is waiting on it. Tests and CI changes are in place; the only red check is notify-devs, which is the fork-triggered notify bot, not a code failure (same as the earlier runs here). Would appreciate a look when you get a chance. Thanks!

[rkfshakti]

Friendly maintainer ping (34+ days, last nudge Sep 27) — raises the SIP header value cap to 4 KB for carrier tokens like X-Twilio-CallToken (head 7dae06bb). This is the dependency for livekit/sip #822 (in-dialog REFER routing); merging it unblocks that test flow. CI green except the known notify-devs Slack-token infra gate. Would appreciate a look.