Merge pull request #1 from kalinon/master

Add SNMP::Client (#1)

Author: stakach

.gitignore

@@ -1,8 +1,9 @@
-doc
-lib
-bin
-.crystal
-.shards
+/docs/
+/lib/
+/bin/
+/.shards/
+*.dwarf
 app
 *.dwarf
 *.DS_Store
+shard.lock

spec/client_spec.cr

@@ -0,0 +1,12 @@
+require "./helper"
+
+describe SNMP::Client do
+  it "should perform a walk" do
+    client = SNMP::Client.new("demo.snmplabs.com")
+    client.should_not be_nil
+    messages = client.walk("1.3.6.1.2.1.1.9.1.3")
+    messages.should be_a(Array(SNMP::Message))
+    messages.empty?.should be_false
+    messages.size.should eq 8
+  end
+end

spec/snmp_spec.cr

@@ -272,6 +272,7 @@ describe SNMP do
     socket = UDPSocket.new
     socket.connect("demo.snmplabs.com", 161)
     socket.sync = false
+    socket.read_timeout = 3
 
     # Setup session
     session = SNMP::V3::Session.new("usr-md5-none", "authkey1")
@@ -296,6 +297,7 @@ describe SNMP do
     socket = UDPSocket.new
     socket.connect("demo.snmplabs.com", 161)
     socket.sync = false
+    socket.read_timeout = 3
 
     # Setup session
     session = SNMP::V3::Session.new("usr-md5-aes", "authkey1", "privkey1", priv_protocol: SNMP::V3::Security::PrivacyProtocol::AES)
@@ -320,6 +322,7 @@ describe SNMP do
     socket = UDPSocket.new
     socket.connect("demo.snmplabs.com", 161)
     socket.sync = false
+    socket.read_timeout = 3
 
     # Setup session
     session = SNMP::V3::Session.new("usr-md5-des", "authkey1", "privkey1")
@@ -344,6 +347,7 @@ describe SNMP do
     socket = UDPSocket.new
     socket.connect("demo.snmplabs.com", 161)
     socket.sync = false
+    socket.read_timeout = 3
 
     # Make request
     session = SNMP::Session.new
@@ -361,6 +365,7 @@ describe SNMP do
     # socket.connect("localhost", 32771)
     socket.connect("demo.snmplabs.com", 161)
     socket.sync = false
+    socket.read_timeout = 3
 
     # Make request
     session = SNMP::Session.new("public")

src/snmp.cr

@@ -117,3 +117,4 @@ require "./snmp/message"
 require "./snmp/session"
 require "./snmp/v3/message"
 require "./snmp/v3/session"
+require "./snmp/client"

src/snmp/client.cr

@@ -0,0 +1,79 @@
+require "socket"
+require "../snmp"
+
+class SNMP::Client
+  class Error < Exception
+  end
+
+  getter socket : UDPSocket
+  getter session : SNMP::Session
+  getter host, timeout, port
+
+  def initialize(@host : String, community = "public", @timeout = 3, @port = 161)
+    @socket = UDPSocket.new
+    socket.sync = false
+    socket.read_timeout = timeout
+    @session = SNMP::Session.new(community: community)
+  end
+
+  private def with_socket
+    if socket.closed?
+      @socket = UDPSocket.new
+      socket.sync = false
+      socket.read_timeout = timeout
+    end
+    socket.connect(host, port)
+    yield socket
+    socket.close
+  end
+
+  def get(oid : String) : SNMP::Message
+    msg : SNMP::Message? = nil
+    with_socket do |sock|
+      msg = get(oid, sock)
+    end
+
+    raise Error.new("Failed to read message") if msg.nil?
+    msg
+  end
+
+  private def get(oid : String, sock : UDPSocket) : SNMP::Message
+    sock.write_bytes session.get(oid)
+    sock.flush
+    session.parse(sock.read_bytes(ASN1::BER))
+  end
+
+  def get_next(oid : String) : SNMP::Message
+    msg : SNMP::Message? = nil
+
+    with_socket do |sock|
+      msg = get_next(oid, sock)
+    end
+
+    raise Error.new("Failed to read message") if msg.nil?
+    msg
+  end
+
+  private def get_next(oid : String, sock : UDPSocket) : SNMP::Message
+    sock.write_bytes session.get_next(oid)
+    sock.flush
+    session.parse(sock.read_bytes(ASN1::BER))
+  end
+
+  def walk(oid : String) : Array(SNMP::Message)
+    messages = [] of SNMP::Message
+    with_socket do |sock|
+      msg = get_next(oid, sock)
+
+      # While the message is not nil and the returned oid is a child of the request
+      while (!msg.nil? && msg.oid.includes?(oid))
+        # Break at END OF MIB
+        break if msg.value.payload.empty?
+
+        messages << msg
+        msg = get_next(msg.oid, sock)
+      end
+    end
+    messages
+  end
+end