282 lines
10 KiB
C#
282 lines
10 KiB
C#
using System;
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using System.Collections.Generic;
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using System.Net.Http;
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using System.Net.Http.Headers;
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using System.Text;
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using System.Text.Json;
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using System.Threading;
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using System.Threading.Tasks;
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using DouyinApi.Common.Option;
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using DouyinApi.IServices;
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using DouyinApi.Model.Security;
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using Microsoft.Extensions.Caching.Memory;
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using Microsoft.Extensions.Logging;
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using Microsoft.Extensions.Options;
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namespace DouyinApi.Services.Security;
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public class ContentSecurityService : IContentSecurityService
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{
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private const string TokenCacheKey = "douyin:content-security:token";
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private static readonly JsonSerializerOptions SerializerOptions = new(JsonSerializerDefaults.Web);
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private readonly IHttpClientFactory _httpClientFactory;
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private readonly IMemoryCache _memoryCache;
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private readonly ContentSecurityOptions _options;
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private readonly ILogger<ContentSecurityService> _logger;
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public ContentSecurityService(
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IHttpClientFactory httpClientFactory,
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IMemoryCache memoryCache,
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IOptions<ContentSecurityOptions> options,
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ILogger<ContentSecurityService> logger)
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{
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_httpClientFactory = httpClientFactory ?? throw new ArgumentNullException(nameof(httpClientFactory));
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_memoryCache = memoryCache ?? throw new ArgumentNullException(nameof(memoryCache));
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_options = options?.Value ?? new ContentSecurityOptions();
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_logger = logger ?? throw new ArgumentNullException(nameof(logger));
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}
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public async Task<ContentSecurityResult> CheckTextAsync(string text, CancellationToken cancellationToken = default)
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{
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if (string.IsNullOrWhiteSpace(text))
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{
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return ContentSecurityResult.Safe();
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}
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if (!_options.Enable)
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{
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return ContentSecurityResult.Safe();
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}
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if (string.IsNullOrWhiteSpace(_options.ClientKey))
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{
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_logger.LogWarning("Content security skipped: client_key missing.");
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return ContentSecurityResult.Safe();
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}
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var accessToken = await GetAccessTokenAsync(cancellationToken).ConfigureAwait(false);
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if (string.IsNullOrEmpty(accessToken))
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{
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return ContentSecurityResult.Failure("content_security_token_unavailable");
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}
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try
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{
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var requestUri = ResolveTextCheckUrl();
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var httpClient = _httpClientFactory.CreateClient();
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var payload = new Dictionary<string, object?>
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{
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["tasks"] = new[]
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{
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new Dictionary<string, object?>
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{
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["content"] = text
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}
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}
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};
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using var request = new HttpRequestMessage(HttpMethod.Post, requestUri)
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{
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Content = new StringContent(JsonSerializer.Serialize(payload, SerializerOptions), Encoding.UTF8, "application/json")
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};
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request.Headers.TryAddWithoutValidation("X-Token", accessToken);
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using var response = await httpClient.SendAsync(request, cancellationToken).ConfigureAwait(false);
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var body = await response.Content.ReadAsStringAsync(cancellationToken).ConfigureAwait(false);
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if (!response.IsSuccessStatusCode)
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{
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_logger.LogWarning("Content security request failed: {StatusCode} - {Body}", response.StatusCode, body);
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return ContentSecurityResult.Failure("content_security_request_failed");
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}
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return ParseResult(body);
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}
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catch (Exception ex)
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{
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_logger.LogError(ex, "Content security check failed.");
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return ContentSecurityResult.Failure("content_security_exception");
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}
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}
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private async Task<string?> GetAccessTokenAsync(CancellationToken cancellationToken)
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{
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if (_memoryCache.TryGetValue(TokenCacheKey, out string cachedToken) && !string.IsNullOrEmpty(cachedToken))
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{
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return cachedToken;
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}
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var httpClient = _httpClientFactory.CreateClient();
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var tokenUrl = string.IsNullOrWhiteSpace(_options.TokenUrl)
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? "https://developer.toutiao.com/api/apps/token"
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: _options.TokenUrl;
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var appId = string.IsNullOrWhiteSpace(_options.AppId) ? _options.ClientKey : _options.AppId;
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if (string.IsNullOrWhiteSpace(appId))
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{
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_logger.LogWarning("Content security token request skipped: appId missing.");
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return null;
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}
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if (string.IsNullOrWhiteSpace(_options.ClientSecret))
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{
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_logger.LogWarning("Content security token request skipped: secret missing.");
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return null;
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}
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var payload = new Dictionary<string, string>
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{
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["appid"] = appId,
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["secret"] = _options.ClientSecret,
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["grant_type"] = "client_credential"
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};
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using var request = new HttpRequestMessage(HttpMethod.Post, tokenUrl)
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{
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Content = new StringContent(JsonSerializer.Serialize(payload, SerializerOptions), Encoding.UTF8, "application/json")
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};
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request.Content.Headers.ContentType = new System.Net.Http.Headers.MediaTypeHeaderValue("application/json");
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using var response = await httpClient.SendAsync(request, cancellationToken).ConfigureAwait(false);
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var body = await response.Content.ReadAsStringAsync(cancellationToken).ConfigureAwait(false);
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if (!response.IsSuccessStatusCode)
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{
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_logger.LogWarning("Content security token request failed: {StatusCode} - {Body}", response.StatusCode, body);
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return null;
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}
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using var document = JsonDocument.Parse(body);
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var root = document.RootElement;
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if (TryGetTopError(root, out var errorMessage))
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{
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_logger.LogWarning("Content security token response error: {Message}", errorMessage);
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return null;
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}
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if (!root.TryGetProperty("data", out var dataElement))
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{
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_logger.LogWarning("Content security token response missing access_token. Body: {Body}", body);
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return null;
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}
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if (!dataElement.TryGetProperty("access_token", out var tokenElement))
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{
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_logger.LogWarning("Content security token response missing access_token. Body: {Body}", body);
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return null;
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}
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var token = tokenElement.GetString();
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if (string.IsNullOrWhiteSpace(token))
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{
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return null;
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}
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var expires = root.TryGetProperty("expires_in", out var expiresElement)
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? expiresElement.GetInt32()
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: _options.TokenCacheSeconds;
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if (expires <= 0)
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{
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expires = _options.TokenCacheSeconds;
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}
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var cacheEntryOptions = new MemoryCacheEntryOptions
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{
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AbsoluteExpirationRelativeToNow = TimeSpan.FromSeconds(Math.Max(60, expires - 120))
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};
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_memoryCache.Set(TokenCacheKey, token, cacheEntryOptions);
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return token;
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}
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private string ResolveTextCheckUrl()
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{
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return string.IsNullOrWhiteSpace(_options.TextCheckUrl)
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? "https://developer.toutiao.com/api/v2/tags/text/antidirt"
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: _options.TextCheckUrl;
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}
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private ContentSecurityResult ParseResult(string body)
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{
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using var document = JsonDocument.Parse(body);
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var root = document.RootElement;
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if (TryGetTopError(root, out var error))
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{
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return ContentSecurityResult.Failure(error);
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}
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if (!root.TryGetProperty("data", out var dataElement) || dataElement.ValueKind != JsonValueKind.Array)
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{
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return ContentSecurityResult.Safe();
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}
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foreach (var item in dataElement.EnumerateArray())
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{
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var code = item.TryGetProperty("code", out var codeElement) && codeElement.ValueKind == JsonValueKind.Number
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? codeElement.GetInt32()
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: 0;
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var msg = item.TryGetProperty("msg", out var msgElement) ? msgElement.GetString() : string.Empty;
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if (code != 0)
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{
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var message = string.IsNullOrWhiteSpace(msg)
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? $"内容安全检测失败，code={code}"
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: msg!;
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return ContentSecurityResult.Failure(message);
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}
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if (!item.TryGetProperty("predicts", out var predictsElement) || predictsElement.ValueKind != JsonValueKind.Array)
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{
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continue;
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}
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foreach (var predict in predictsElement.EnumerateArray())
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{
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if (predict.TryGetProperty("hit", out var hitElement) && JsonBooleanEqualsTrue(hitElement))
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{
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var reason = string.IsNullOrWhiteSpace(msg) ? "内容包含风险信息" : msg!;
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return ContentSecurityResult.Unsafe("content_security_blocked", reason);
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}
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}
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}
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return ContentSecurityResult.Safe();
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}
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private static bool JsonBooleanEqualsTrue(JsonElement element)
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{
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return element.ValueKind switch
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{
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JsonValueKind.True => true,
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JsonValueKind.False => false,
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JsonValueKind.Number => element.GetDouble() != 0,
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JsonValueKind.String => bool.TryParse(element.GetString(), out var result) && result,
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_ => false
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};
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}
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private static bool TryGetTopError(JsonElement root, out string message)
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{
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if (root.TryGetProperty("err_no", out var errNoElement) && errNoElement.ValueKind == JsonValueKind.Number && errNoElement.GetInt32() != 0)
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{
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message = root.TryGetProperty("message", out var msgElement) ? msgElement.GetString() ?? "content_security_error" : "content_security_error";
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return true;
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}
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if (root.TryGetProperty("code", out var codeElement) && codeElement.ValueKind == JsonValueKind.Number && codeElement.GetInt32() != 0)
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{
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var code = codeElement.GetInt32();
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var baseMessage = $"content_security_error_{code}";
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message = root.TryGetProperty("message", out var msgElement) ? (msgElement.GetString() ?? baseMessage) : baseMessage;
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return true;
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}
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message = string.Empty;
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return false;
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}
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}
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