| // Header-value sanitizer for the diagnostics headers built out of provider and | |
| // model names (#619). | |
| // | |
| // Node validates every outgoing header value against RFC 7230's field-value | |
| // grammar and throws ERR_INVALID_CHAR ("Invalid character in header content") | |
| // on anything outside it. Relay catalogs happily hand out ids like | |
| // `我的模型[test] v2`, and splicing one into `X-Routed-Via` killed the response | |
| // AFTER the upstream call had already succeeded. Worse, the throw surfaced | |
| // inside the failover loop, so the router booked it as a provider failure and | |
| // cooled the model down — every request to that relay failed, forever. | |
| // | |
| // Encoding rules, deliberately narrow so the output is safe on every surface: | |
| // - SP and VCHAR (0x21-0x7E) pass through, so ordinary ids like | |
| // `groq/llama-3.3-70b-versatile` are byte-identical to before; | |
| // - everything else — control characters (header injection), DEL, and every | |
| // non-ASCII code point — becomes its percent-encoded UTF-8 bytes, so the | |
| // value stays decodable with decodeURIComponent instead of being lost; | |
| // - a literal '%' becomes '%25', which is what makes that decode unambiguous. | |
| // The result is capped so a pathological id cannot push a response past a | |
| // proxy's header budget. | |
| const MAX_HEADER_VALUE_LENGTH = 256; | |
| function percentEncode(char: string): string { | |
| try { | |
| return encodeURIComponent(char); | |
| } catch { | |
| // Lone surrogate — encodeURIComponent refuses it. Stand in the UTF-8 | |
| // replacement character rather than dropping the position silently. | |
| return '%EF%BF%BD'; | |
| } | |
| } | |
| /** | |
| * Coerce an arbitrary string into a valid HTTP header field value. Never | |
| * throws, and never returns a value Node will reject. | |
| */ | |
| export function safeHeaderValue(value: string, maxLength = MAX_HEADER_VALUE_LENGTH): string { | |
| if (value == null) return ''; | |
| let out = ''; | |
| // Iterate by code point so astral characters (emoji in a display name) encode | |
| // as one UTF-8 sequence instead of two broken surrogate halves. | |
| for (const char of String(value)) { | |
| const code = char.codePointAt(0)!; | |
| const piece = code >= 0x20 && code <= 0x7e && char !== '%' ? char : percentEncode(char); | |
| if (out.length + piece.length > maxLength) break; | |
| out += piece; | |
| } | |
| return out; | |
| } | |
| /** `<platform>/<model>` for X-Routed-Via, sanitized. */ | |
| export function routedViaValue(platform: string, modelId: string): string { | |
| return safeHeaderValue(`${platform}/${modelId}`); | |
| } | |