Source code
Revision control
Copy as Markdown
Other Tools
(mozilla-projects-nss-reference-nspr-functions)=
# NSPR functions
:::{container}
a cross-platform API to common OS services. NSS uses NSPR internally as the porting layer.
However, a small number of NSPR functions are required for using the certificate verification and
SSL functions in NSS. These NSPR functions are listed in this section.
:::
(nspr-initialization-and-shutdown)=
## [NSPR initialization and shutdown](#nspr_initialization_and_shutdown)
:::{container}
NSPR is automatically initialized by the first NSPR function called by the application. Call
`` `PR_Cleanup `` \</en-US/PR_Cleanup>\`\_\_ to shut down NSPR and clean up its resources.
- [PR_Cleanup](/en-US/PR_Cleanup)
:::
(error-reporting)=
## [Error reporting](#error_reporting)
:::{container}
NSS uses NSPR's thread-specific error code to report errors. Call
`` `PR_GetError `` \</en-US/PR_GetError>\`\_\_ to get the error code of the last failed NSS or NSPR
function. Call `` `PR_SetError `` \</en-US/PR_SetError>\`\_\_ to set the error code, which can be
retrieved with `PR_GetError` later.
The NSS functions `PORT_GetError` and `PORT_SetError` are simply wrappers of `PR_GetError`
and `PR_SetError`.
- [PR_GetError](/en-US/PR_GetError)
- [PR_SetError](/en-US/PR_SetError)
:::
(calendar-time)=
## [Calendar time](#calendar_time)
:::{container}
NSS certificate verification functions take a `PRTime` parameter that specifies the time
instant at which the validity of the certificate should verified. The NSPR function
`` `PR_Now `` \</en-US/PR_Now>\`\_\_ returns the current time in `PRTime`.
- [PR_Now](/en-US/PR_Now)
:::
(interval-time)=
## [Interval time](#interval_time)
:::{container}
The NSPR socket I/O functions `` `PR_Recv `` \</en-US/PR_Recv>\`\_\_ and
`` `PR_Send `` \</en-US/PR_Send>\`\_\_ (used by the NSS SSL functions) take a `PRIntervalTime`
timeout parameter. `PRIntervalTime` has an abstract, platform-dependent time unit. Call
`` `PR_SecondsToInterval `` \</en-US/PR_SecondsToInterval>\`\_\_ or `PR_MillisecondsToInterval` to
convert a time interval in seconds or milliseconds to `PRIntervalTime`.
- [PR_SecondsToInterval](/en-US/PR_SecondsToInterval)
- [PR_MillisecondsToInterval](/en-US/PR_MillisecondsToInterval)
:::
(nspr-io-layering)=
## [NSPR I/O layering](#nspr_io_layering)
:::{container}
NSPR file descriptors can be layered, corresponding to the layers in the network stack. The SSL
library in NSS implements the SSL protocol as an NSPR I/O layer, which sits on top of another
NSPR I/O layer that represents TCP.
You can implement an NSPR I/O layer that wraps your own TCP socket code. The following NSPR
functions allow you to create your own NSPR I/O layer and manipulate it.
- [PR_GetUniqueIdentity](/en-US/PR_GetUniqueIdentity)
- [PR_CreateIOLayerStub](/en-US/PR_CreateIOLayerStub)
- [PR_GetDefaultIOMethods](/en-US/PR_GetDefaultIOMethods)
- [PR_GetIdentitiesLayer](/en-US/PR_GetIdentitiesLayer)
- [PR_GetLayersIdentity](/en-US/PR_GetLayersIdentity)
- [PR_PushIOLayer](/en-US/PR_PushIOLayer)
- [PR_PopIOLayer](/en-US/PR_PopIOLayer)
:::
(wrapping-a-native-file-descriptor)=
## [Wrapping a native file descriptor](#wrapping_a_native_file_descriptor)
:::{container}
If your current TCP socket code uses the standard BSD socket API, a lighter-weight method than
creating your own NSPR I/O layer is to simply import a native file descriptor into NSPR. This
method is convenient and works for most applications.
- [PR_ImportTCPSocket](/en-US/PR_ImportTCPSocket)
:::
(socket-io-functions)=
## [Socket I/O functions](#socket_io_functions)
:::{container}
As mentioned above, the SSL library in NSS implements the SSL protocol as an NSPR I/O layer.
Users call NSPR socket I/O functions to read from, write to, and shut down an SSL connection, and
to close an NSPR file descriptor.
- [PR_Read](/en-US/PR_Read)
- [PR_Write](/en-US/PR_Write)
- [PR_Recv](/en-US/PR_Recv)
- [PR_Send](/en-US/PR_Send)
- [PR_GetSocketOption](/en-US/PR_GetSocketOption)
- [PR_SetSocketOption](/en-US/PR_SetSocketOption)
- [PR_Shutdown](/en-US/PR_Shutdown)
- [PR_Close](/en-US/PR_Close)
:::