Implemented BGP community parsers logic (#895)

src/CMakeLists.txt

@@ -212,7 +212,7 @@ target_link_libraries(unified_parser fastnetmon_packet_parser)
 # Our ipfix database library
 add_library(ipfix_rfc STATIC ipfix_rfc.cpp)
 
-add_library(bgp_protocol bgp_flow_spec.cpp)
+add_library(bgp_protocol bgp_protocol.cpp)
 
 # Our packet parser
 add_library(fastnetmon_packet_parser STATIC fastnetmon_packet_parser.c)

src/bgp_protocol.cpp

@@ -1,4 +1,4 @@
-#include "bgp_flow_spec.h"
+#include "bgp_protocol.hpp"
 
 #include "log4cpp/Appender.hh"
 #include "log4cpp/BasicLayout.hh"
@@ -9,6 +9,11 @@
 #include "log4cpp/PatternLayout.hh"
 #include "log4cpp/Priority.hh"
 
+#include "all_logcpp_libraries.h"
+
+// Get log4cpp logger from main programm
+extern log4cpp::Category& logger;
+
 // Enable custom casts from our own types
 std::ostream& operator<<(std::ostream& os, bgp_flow_spec_protocol_t const& protocol) {
     if (protocol == FLOW_SPEC_PROTOCOL_UDP) {
@@ -63,3 +68,55 @@ std::ostream& operator<<(std::ostream& os, flow_spec_fragmentation_types_t const
     }
 }
 
+bool read_bgp_community_from_string(std::string community_as_string, bgp_community_attribute_element_t& bgp_community_attribute_element) {
+    std::vector<std::string> community_as_vector;
+
+    split(community_as_vector, community_as_string, boost::is_any_of(":"), boost::token_compress_on);
+
+    if (community_as_vector.size() != 2) {
+        logger << log4cpp::Priority::WARN << "Could not parse community: " << community_as_string;
+        return false;
+    }
+
+    int asn_as_integer = 0;
+
+    if (!convert_string_to_positive_integer_safe(community_as_vector[0], asn_as_integer)) {
+        logger << log4cpp::Priority::WARN << "Could not parse ASN from raw format: " << community_as_vector[0];
+        return false;
+    }
+
+    int community_number_as_integer = 0;
+
+    if (!convert_string_to_positive_integer_safe(community_as_vector[1], community_number_as_integer)) {
+        logger << log4cpp::Priority::WARN << "Could not parse community from raw format: " << community_as_vector[0];
+        return false;
+    }
+
+    if (asn_as_integer < 0 or community_number_as_integer < 0) {
+        logger << log4cpp::Priority::WARN << "For some strange reasons we've got negative ASN or community numbers";
+        return false;
+    }
+
+    if (asn_as_integer > UINT16_MAX) {
+        logger << log4cpp::Priority::ERROR << "Your ASN value exceeds maximum allowed value " << UINT16_MAX;
+        return false;
+    }
+
+    if (community_number_as_integer > UINT16_MAX) {
+        logger << log4cpp::Priority::ERROR << "Your community value exceeds maximum allowed value " << UINT16_MAX;
+        return false;
+    }
+
+    bgp_community_attribute_element.asn_number       = asn_as_integer;
+    bgp_community_attribute_element.community_number = community_number_as_integer;
+
+    return true;
+}
+
+// Wrapper function which just checks correctness of bgp community
+bool is_bgp_community_valid(std::string community_as_string) {
+    bgp_community_attribute_element_t bgp_community_attribute_element;
+
+    return read_bgp_community_from_string(community_as_string, bgp_community_attribute_element);
+}
+

src/bgp_protocol.hpp

@@ -1,5 +1,4 @@
-#ifndef BGP_FLOW_SPEC_H
-#define BGP_FLOW_SPEC_H
+#pragma once
 
 #include <stdint.h>
 #include <string>
@@ -64,6 +63,23 @@ enum bgp_flow_spec_protocol_t {
     FLOW_SPEC_PROTOCOL_ICMP,
 };
 
+// Class for storing old style BGP communities which support only 16 bit ASN numbers
+class __attribute__((__packed__)) bgp_community_attribute_element_t {
+    public:
+    uint16_t asn_number       = 0;
+    uint16_t community_number = 0;
+
+    void host_byte_order_to_network_byte_order() {
+        asn_number       = htons(asn_number);
+        community_number = htons(community_number);
+    }
+};
+
+bool read_bgp_community_from_string(std::string community_as_string, bgp_community_attribute_element_t& bgp_community_attribute_element);
+
+static_assert(sizeof(bgp_community_attribute_element_t) == 4, "Broken size of bgp_community_attribute_element_t");
+
+
 // Enable custom casts from our own types
 std::ostream& operator<<(std::ostream& os, bgp_flow_spec_protocol_t const& protocol);
 
@@ -524,4 +540,5 @@ class exabgp_flow_spec_rule_t : public flow_spec_rule_t {
 
 void exabgp_flow_spec_rule_ban_manage(std::string action, flow_spec_rule_t flow_spec_rule);
 
-#endif
+bool read_bgp_community_from_string(std::string community_as_string, bgp_community_attribute_element_t& bgp_community_attribute_element);
+bool is_bgp_community_valid(std::string community_as_string);

src/fast_library.cpp

@@ -1439,3 +1439,26 @@ bool ip_belongs_to_patricia_tree_ipv6(patricia_tree_t* patricia_tree, struct in6
     return patricia_search_best2(patricia_tree, &prefix_for_check_address, 1) != NULL;
 }
 
+// Safe way to convert string to positive integer.
+// We accept only positive numbers here
+bool convert_string_to_positive_integer_safe(std::string line, int& value) {
+    int temp_value = 0;
+
+    try {
+        temp_value = std::stoi(line);
+    } catch (...) {
+        // Could not parse number correctly
+        return false;
+    }
+
+    if (temp_value >= 0) {
+        value = temp_value;
+        return true;
+    } else {
+        // We do not expect negative values here
+        return false;
+    }
+
+    return true;
+}
+

src/fast_library.h

@@ -1,5 +1,4 @@
-#ifndef FAST_LIBRARY_H
-#define FAST_LIBRARY_H
+#pragma once
 
 #include "fastnetmon_types.h"
 
@@ -121,4 +120,4 @@ bool set_boost_process_name(boost::thread* thread, std::string process_name);
 
  std::string print_ipv6_cidr_subnet(subnet_ipv6_cidr_mask_t subnet);
  std::string convert_any_ip_to_string(subnet_ipv6_cidr_mask_t subnet);
-#endif
+bool convert_string_to_positive_integer_safe(std::string line, int& value);

src/fastnetmon.conf

@@ -229,6 +229,7 @@ gobgp = off
 gobgp_next_hop = 0.0.0.0
 gobgp_announce_host = on
 gobgp_announce_whole_subnet = off
+gobgp_community = 65001:666
 
 # Graphite monitoring
 # InfluxDB is also supported, please check our reference:

src/fastnetmon.cpp

@@ -23,7 +23,7 @@
 #include <sys/resource.h>
 #include <sys/stat.h>
 
-#include "bgp_flow_spec.h"
+#include "bgp_protocol.hpp"
 #include "fast_library.h"
 #include "fastnetmon_packet_parser.h"
 #include "fastnetmon_types.h"

src/fastnetmon_logic.cpp

@@ -6,7 +6,7 @@
 #include <vector>
 
 #include "all_logcpp_libraries.h"
-#include "bgp_flow_spec.h"
+#include "bgp_protocol.hpp"
 #include "fast_library.h"
 #include "fast_platform.h"
 #include "fastnetmon_packet_parser.h"

src/fastnetmon_logic.hpp

@@ -1,5 +1,5 @@
 #include "fastnetmon_types.h"
-#include "bgp_flow_spec.h"
+#include "bgp_protocol.hpp"
 
 #ifdef ENABLE_DPI
 #include "fast_dpi.h"