@azure/functions/src/http/extractHttpUserFromHeaders.ts

Microsoft Azure Functions NodeJS Framework

// Copyright (c) .NET Foundation. All rights reserved.
// Licensed under the MIT License.

import { HttpRequestUser } from '@azure/functions';
import { nonNullValue } from '../utils/nonNull';
import { workerSystemLog } from '../utils/workerSystemLog';

/* grandfathered in. Should fix when possible */
/* eslint-disable @typescript-eslint/no-unsafe-assignment, @typescript-eslint/no-unsafe-argument, @typescript-eslint/no-unsafe-member-access */

export function extractHttpUserFromHeaders(headers: Headers): HttpRequestUser | null {
    let user: HttpRequestUser | null = null;

    const clientPrincipal = headers.get('x-ms-client-principal');
    if (clientPrincipal) {
        let claimsPrincipalData: any;
        try {
            claimsPrincipalData = JSON.parse(Buffer.from(clientPrincipal, 'base64').toString('utf-8'));
        } catch (err) {
            workerSystemLog(
                'warning',
                `Failed to parse x-ms-client-principal header: ${err instanceof Error ? err.message : String(err)}`
            );
            return null;
        }

        if (
            claimsPrincipalData === null ||
            typeof claimsPrincipalData !== 'object' ||
            Array.isArray(claimsPrincipalData)
        ) {
            workerSystemLog('warning', 'Parsed x-ms-client-principal header was not a JSON object.');
            return null;
        }

        if (claimsPrincipalData['identityProvider']) {
            user = {
                type: 'StaticWebApps',
                id: claimsPrincipalData['userId'],
                username: claimsPrincipalData['userDetails'],
                identityProvider: claimsPrincipalData['identityProvider'],
                claimsPrincipalData,
            };
        } else {
            user = {
                type: 'AppService',
                id: nonNullValue(headers.get('x-ms-client-principal-id'), 'user-id'),
                username: nonNullValue(headers.get('x-ms-client-principal-name'), 'user-name'),
                identityProvider: nonNullValue(headers.get('x-ms-client-principal-idp'), 'user-idp'),
                claimsPrincipalData,
            };
        }
    }

    return user;
}