Demonstrates use of the Domain Name System (DNS) resolution system in KasperskyOS, and the integration of several virtual file systems (hereinafter VFS) in one solution. For more information about using multiple VFS programs, please refer to the File systems and network section.
Example directory in the SDK
The code of the example and build scripts are available at the following path:
/opt/KasperskyOS-Community-Edition-<platform>-<version>/examples/multi_vfs_dns_client
List of programs
Client – application that uses the functions of the libc library to access a DNS server.Dhcpcd – system program that implements the DHCP client.DCM – system program that lets you dynamically create IPC channels.VfsSdCardFs – system program that supports the file system of SD cards.VfsNet – system program that supports network protocols.EntropyEntity – system program that implements random number generation.DNetSrv – network card driver.SDCard – SD card driver.When you build an example for the target hardware platform, platform-specific drivers are automatically included in the solution:
BSP is a hardware platform support package (Board Support Package). Provides cross-platform configuration of peripherals for the Radxa ROCK 3A and Raspberry Pi 4 B.Bcm2711MboxArmToVc – driver for working with the VideoCore (VC6) coprocessor via mailbox technology for Raspberry Pi 4 B.GPIO – GPIO support driver for the Radxa ROCK 3A.PinCtrl – low-level pin multiplexing (pinmux) configuration driver for the Radxa ROCK 3A.Initialization description
The solution initialization description file named init.yaml is generated during the solution build process based on the ./einit/src/init.yaml.in template. Macros in @INIT_*@ format contained in the template are automatically expanded in the resulting init.yaml file. For more details, refer to init.yaml.in template.
Security policy description
The security.psl file contains a description of a security policy for a KasperskyOS-based solution and is located in the ./einit/src directory. The declarations in the PSL file are provided with comments that explain the purpose of these declarations.
Resources
The ./resources/xdl/multi_vfs_dns_client directory contains the Client.edl file, which is the EDL description for the Client program.
The directory ./resources/hdd/etc contains the configuration files for the VfsNet and Dhcpcd programs: hosts and dhcpcd.conf, respectively.
The ./resources/hdd/var/db/dhcpcd directory is used by the Dhcpcd program to store network connection data.
Operating scenario
The Client program uses standard libc library functions for contacting an external DNS service. These functions are converted into queries to the VfsNet program via IPC.
After checking the network connection, the Client program receives information about the DNS server by using its fully qualified domain name and port. Then it resolves the domain name to an IP address and verifies that the IP address matches the previously predefined values.
Building and running the example
The CMake system, which is included with KasperskyOS Community Edition, is used to build and run the example.
See Building and running examples section.
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