Network Error Logging (NEL) provides out-of-band reporting of network errors via the Reporting API (see//net/reporting). Site operators can specify a NEL policy that defines the Reporting endpoint(s) on which they wish to receive reports about client-side errors encountered while connecting to the site. The draft spec can be foundhere.
This directory contains the core implementation of NEL.
Most of the action takes place inNetworkErrorLoggingService, which handles receiving/processingNEL: response headers and generating/queueing reports about network requests. TheNetworkErrorLoggingService is owned by theURLRequestContext.
Information about network requests comes directly fromHttpNetworkTransaction, which informsNetworkErrorLoggingService of the details of the request such as the remote IP address and outcome (anet::Error code).
TheNetworkErrorLoggingService finds a NEL policy applicable to the request (previously set by aNEL header), and if one exists, potentially queues a NEL report to be uploaded out-of-band to the policy's specified Reporting endpoint via theReportingService.
Received NEL policies are persisted to disk by aPersistentNelStore, whose main implementation is theSqlitePersistentReportingAndNelStore.
