Fix messy extern "C" related issues.

Author: gfr10598

src/connection_cache.cc

@@ -21,7 +21,7 @@
 
 extern "C" {
 #include <linux/inet_diag.h>
-#include <sys/socket.h>
+#include <sys/socket.h>  // For AF_INET
 }
 
 namespace mlab {

src/tcpinfo.proto

@@ -82,10 +82,12 @@ enum TCPState {  //  from tcp_states.h
 
 message InetDiagMsgProto {
   enum AddressFamily {
+    // NOTE: these are equivalent to AF_... in socket.h, but cannot have the
+    // same names since those are macros and will cause collisions.
     // There are many other families, but for now we only care about these.
-    AF_UNSPEC = 0;
-    AF_INET = 2;
-    AF_INET6 = 10;
+    UNSPEC = 0;
+    INET = 2;
+    INET6 = 10;
   }
   // These are 8 bit unsigned.
   optional AddressFamily family = 1;

src/tcpinfo_c_adapter.c

@@ -18,6 +18,7 @@
 #include "tcpinfo_c_adapter.h"
 
 #include <arpa/inet.h>
+#include <linux/inet_diag.h>  // for INET_DIAG_...
 #include <linux/sock_diag.h>
 #include <unistd.h>
 

src/tcpinfo_c_adapter.h

@@ -1,3 +1,6 @@
+#ifndef TCPINFO_C_ADAPTER_H_
+#define TCPINFO_C_ADAPTER_H_
+
 // Copyright 2016 measurement-lab
 //
 // Licensed under the Apache License, Version 2.0 (the "License");
@@ -13,24 +16,14 @@
 // limitations under the License.
 
 /****************************************************************************
-*  This file contains declarations that are used by both .c files and .cc
-*  files.  When included in .cc files, it must be enclosed in an extern "C"
-*  block.
-*
-*  fetch_tcpinfo(...) is implemented in the tcpinfo_c_adapter.c for easy
-*  access to C libraries.
-*  update_record(...) is implemented in tcpinfo_lib.cc, because it requires
-*  access to C++ functions.
+*  fetch_tcpinfo() is called from C++, but implemented in C to provide clear
+*  linkage to C library functions.
 ****************************************************************************/
 
-#ifndef TCPINFO_C_ADAPTER_H_
-#define TCPINFO_C_ADAPTER_H_
-
-#include <linux/inet_diag.h>
-#include <linux/netlink.h>
-#include <sys/socket.h>
-
-#include "libnetlink.h"
+#ifdef __cplusplus
+extern "C" {
+#endif
+#include "libnetlink.h"  // For rtnl_filter_t
 
 struct inet_diag_arg {
   int protocol;
@@ -40,9 +33,7 @@ struct inet_diag_arg {
 // `callback` has rtnl_filter_t signature, and is passed to rtnl_dump_filter.
 int fetch_tcpinfo(rtnl_filter_t callback);
 
-// rtnl_filter_t function to handle each result, passed into fetch_tcpinfo()
-// function. Implementation in tcpinfo_lib.cc
-int update_record(const struct sockaddr_nl *addr,
-                  struct nlmsghdr *nlh, void *arg);
-
+#ifdef __cplusplus
+}
+#endif
 #endif  // TCPINFO_C_ADAPTER_H_

src/tcpinfo_lib.cc

@@ -18,14 +18,14 @@
 #include <string>
 
 #include "connection_cache.h"  // For ConnectionTracker
+#include "tcpinfo_c_adapter.h"  // For update_record, inet_diag_arg
 
 extern "C" {
 #include <arpa/inet.h>
 #include <linux/sock_diag.h>
 #include <linux/tcp.h>
 
 #include "libnetlink.h"
-#include "tcpinfo_c_adapter.h"  // declaration of update_record.
 }
 
 namespace mlab {
@@ -56,7 +56,7 @@ InetDiagMsgProto::AddressFamily GetFamily(struct inet_diag_msg* r) {
   auto family = r->idiag_family;
   if (!InetDiagMsgProto_AddressFamily_IsValid(family)) {
     fprintf(stderr, "Invalid family: %d\n", family);
-    return InetDiagMsgProto_AddressFamily_AF_UNSPEC;
+    return InetDiagMsgProto_AddressFamily_UNSPEC;
   } else {
     return InetDiagMsgProto::AddressFamily(family);
   }
@@ -81,15 +81,15 @@ void ParseInetDiagMsg(struct inet_diag_msg* r, InetDiagMsgProto* proto) {
   dest->set_port(ntohs(r->id.idiag_dport));
 
   switch (proto->family()) {
-  case InetDiagMsgProto_AddressFamily_AF_INET:
+  case InetDiagMsgProto_AddressFamily_INET:
     src->set_ip(r->id.idiag_src, 4);
     dest->set_ip(r->id.idiag_dst, 4);
     break;
-  case InetDiagMsgProto_AddressFamily_AF_INET6:
+  case InetDiagMsgProto_AddressFamily_INET6:
     src->set_ip(r->id.idiag_src, 16);
     dest->set_ip(r->id.idiag_dst, 16);
     break;
-  case InetDiagMsgProto_AddressFamily_AF_UNSPEC:
+  case InetDiagMsgProto_AddressFamily_UNSPEC:
     // We don't know how to interpret the addresses, so leave them unset.
     // TODO(gfr) Log a warning here.
     break;

src/tcpinfo_lib.h

@@ -36,6 +36,12 @@ extern "C" {
 namespace mlab {
 namespace netlink {
 
+extern "C"
+// rtnl_filter_t function to handle each result, passed into fetch_tcpinfo()
+// function.
+int update_record(const struct sockaddr_nl *addr,
+                  struct nlmsghdr *nlh, void *arg);
+
 class TCPInfoPoller;
 namespace test {
 // Test support function that required friend status.

src/tcpinfo_lib_test.cc

@@ -12,20 +12,12 @@
 // See the License for the specific language governing permissions and
 // limitations under the License.
 
-#include <string>
-
-#include "gtest/gtest.h"
-#include "connection_cache.h"
-// TODO(gfr) The include order matters.  If tcpinfo_lib.h is included later,
-// we get obscure compiler errors processing tcpinfo.pb.h.
 #include "tcpinfo_lib.h"
 
-extern "C" {
-#include <netinet/in.h>  // IPPROTO_TCP
-#include <sys/socket.h>  // AF_INET*
+#include <string>
 
+#include "gtest/gtest.h"
 #include "tcpinfo_c_adapter.h"
-}
 
 extern mlab::netlink::TCPInfoPoller g_poller_;
 

src/tcpinfo_proto_test.cc

@@ -403,15 +403,15 @@ std::string raw19(
 
 TEST(Parser, IPToString) {
   InetDiagMsgProto p4;
-  p4.set_family(InetDiagMsgProto_AddressFamily_AF_INET);
+  p4.set_family(InetDiagMsgProto_AddressFamily_INET);
   auto* sock_id = p4.mutable_sock_id();
   auto* src = sock_id->mutable_source();
   src->set_port(1234);
   src->set_ip("abcd", 4);
   EXPECT_EQ(ToString(p4.sock_id().source()), "97.98.99.100:1234");
 
   InetDiagMsgProto p6;
-  p6.set_family(InetDiagMsgProto_AddressFamily_AF_INET6);
+  p6.set_family(InetDiagMsgProto_AddressFamily_INET6);
   auto* sock_id6 = p6.mutable_sock_id();
   auto* src6 = sock_id6->mutable_source();
   src6->set_port(5678);