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Create and free a nftables ctx per invokation #5

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26 changes: 12 additions & 14 deletions src/nftables.cr
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Original file line number Diff line number Diff line change
Expand Up @@ -2,12 +2,12 @@
# Class to interact with nftables
# Not linked to libnftables, but calls out to the `nft` binary
class Nftables
def run_cmd(cmd : String) : Nil
def self.run_cmd(cmd : String) : Nil
status = Process.run("nft", {cmd}, output: Process::Redirect::Inherit, error: Process::Redirect::Inherit)
status.success? || raise Error.new("nftables command '#{cmd}' failed")
end

def run_file(file : String) : Nil
def self.run_file(file : String) : Nil
status = Process.run("nft", {"-f", file}, output: Process::Redirect::Inherit, error: Process::Redirect::Inherit)
status.success? || raise Error.new("nftables file '#{file}' failed")
end
Expand All @@ -18,28 +18,26 @@
# Class to interact with nftables
# All output is printed to stdout/stderr
class Nftables
def initialize
@nft = LibNftables.nft_ctx_new(LibNftables::NFT_CTX_DEFAULT)
end

def finalize
LibNftables.nft_ctx_free(@nft)
end

# Execute a nft command, eg. 'list ruleset'
def run_cmd(cmd : String) : Nil
def self.run_cmd(cmd : String) : Nil
nft = LibNftables.nft_ctx_new(LibNftables::NFT_CTX_DEFAULT)
buf = Bytes.new(cmd.bytesize + 1) # null terminated string
buf.copy_from(cmd.to_slice)
LibNftables.nft_run_cmd_from_buffer(@nft, buf).zero? ||
LibNftables.nft_run_cmd_from_buffer(nft, buf).zero? ||
raise Error.new("nftables command '#{cmd}' failed")
ensure
LibNftables.nft_ctx_free(nft) if nft
end

# Execute a nft script in a file
def run_file(file : String) : Nil
def self.run_file(file : String) : Nil
nft = LibNftables.nft_ctx_new(LibNftables::NFT_CTX_DEFAULT)
buf = Bytes.new(file.bytesize + 1) # null terminated string
buf.copy_from(file.to_slice)
LibNftables.nft_run_cmd_from_filename(@nft, buf).zero? ||
LibNftables.nft_run_cmd_from_filename(nft, buf).zero? ||
raise Error.new("nftables file '#{file}' failed")
ensure
LibNftables.nft_ctx_free(nft) if nft
end

class Error < Exception; end
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5 changes: 2 additions & 3 deletions src/server-cli.cr
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Original file line number Diff line number Diff line change
Expand Up @@ -9,9 +9,8 @@ begin
puts "HMAC keys: #{c.hmac_keys.size}"
if c.nftables_cmd.bytesize > 0
puts "nftables command: #{c.nftables_cmd}"
nft = Nftables.new
on_accept = ->(ip_str : String) {
nft.run_cmd sprintf(c.nftables_cmd, ip_str)
on_accept = ->(ip_str : String) : Nil {
Nftables.run_cmd sprintf(c.nftables_cmd, ip_str)
}
else
puts "Open command: #{c.open_cmd}"
Expand Down