Dedup netlink utility functions in tests.

PiperOrigin-RevId: 305749697

test/syscalls/linux/BUILD

@@ -138,7 +138,6 @@ cc_library(
     hdrs = ["socket_netlink_route_util.h"],
     deps = [
         ":socket_netlink_util",
-        "@com_google_absl//absl/types:optional",
     ],
 )
 
@@ -2804,13 +2803,13 @@ cc_binary(
     srcs = ["socket_netlink_route.cc"],
     linkstatic = 1,
     deps = [
+        ":socket_netlink_route_util",
         ":socket_netlink_util",
         ":socket_test_util",
         "//test/util:capability_util",
         "//test/util:cleanup",
         "//test/util:file_descriptor",
         "@com_google_absl//absl/strings:str_format",
-        "@com_google_absl//absl/types:optional",
         gtest,
         "//test/util:test_main",
         "//test/util:test_util",

test/syscalls/linux/socket_netlink_route.cc

@@ -26,7 +26,7 @@
 
 #include "gtest/gtest.h"
 #include "absl/strings/str_format.h"
-#include "absl/types/optional.h"
+#include "test/syscalls/linux/socket_netlink_route_util.h"
 #include "test/syscalls/linux/socket_netlink_util.h"
 #include "test/syscalls/linux/socket_test_util.h"
 #include "test/util/capability_util.h"
@@ -118,24 +118,6 @@ void CheckGetLinkResponse(const struct nlmsghdr* hdr, int seq, int port) {
   // TODO(mpratt): Check ifinfomsg contents and following attrs.
 }
 
-PosixError DumpLinks(
-    const FileDescriptor& fd, uint32_t seq,
-    const std::function<void(const struct nlmsghdr* hdr)>& fn) {
-  struct request {
-    struct nlmsghdr hdr;
-    struct ifinfomsg ifm;
-  };
-
-  struct request req = {};
-  req.hdr.nlmsg_len = sizeof(req);
-  req.hdr.nlmsg_type = RTM_GETLINK;
-  req.hdr.nlmsg_flags = NLM_F_REQUEST | NLM_F_DUMP;
-  req.hdr.nlmsg_seq = seq;
-  req.ifm.ifi_family = AF_UNSPEC;
-
-  return NetlinkRequestResponse(fd, &req, sizeof(req), fn, false);
-}
-
 TEST(NetlinkRouteTest, GetLinkDump) {
   FileDescriptor fd =
       ASSERT_NO_ERRNO_AND_VALUE(NetlinkBoundSocket(NETLINK_ROUTE));
@@ -161,37 +143,6 @@ TEST(NetlinkRouteTest, GetLinkDump) {
   EXPECT_TRUE(loopbackFound);
 }
 
-struct Link {
-  int index;
-  std::string name;
-};
-
-PosixErrorOr<absl::optional<Link>> FindLoopbackLink() {
-  ASSIGN_OR_RETURN_ERRNO(FileDescriptor fd, NetlinkBoundSocket(NETLINK_ROUTE));
-
-  absl::optional<Link> link;
-  RETURN_IF_ERRNO(DumpLinks(fd, kSeq, [&](const struct nlmsghdr* hdr) {
-    if (hdr->nlmsg_type != RTM_NEWLINK ||
-        hdr->nlmsg_len < NLMSG_SPACE(sizeof(struct ifinfomsg))) {
-      return;
-    }
-    const struct ifinfomsg* msg =
-        reinterpret_cast<const struct ifinfomsg*>(NLMSG_DATA(hdr));
-    if (msg->ifi_type == ARPHRD_LOOPBACK) {
-      const auto* rta = FindRtAttr(hdr, msg, IFLA_IFNAME);
-      if (rta == nullptr) {
-        // Ignore links that do not have a name.
-        return;
-      }
-
-      link = Link();
-      link->index = msg->ifi_index;
-      link->name = std::string(reinterpret_cast<const char*>(RTA_DATA(rta)));
-    }
-  }));
-  return link;
-}
-
 // CheckLinkMsg checks a netlink message against an expected link.
 void CheckLinkMsg(const struct nlmsghdr* hdr, const Link& link) {
   ASSERT_THAT(hdr->nlmsg_type, Eq(RTM_NEWLINK));
@@ -209,9 +160,7 @@ void CheckLinkMsg(const struct nlmsghdr* hdr, const Link& link) {
 }
 
 TEST(NetlinkRouteTest, GetLinkByIndex) {
-  absl::optional<Link> loopback_link =
-      ASSERT_NO_ERRNO_AND_VALUE(FindLoopbackLink());
-  ASSERT_TRUE(loopback_link.has_value());
+  Link loopback_link = ASSERT_NO_ERRNO_AND_VALUE(LoopbackLink());
 
   FileDescriptor fd =
       ASSERT_NO_ERRNO_AND_VALUE(NetlinkBoundSocket(NETLINK_ROUTE));
@@ -227,13 +176,13 @@ TEST(NetlinkRouteTest, GetLinkByIndex) {
   req.hdr.nlmsg_flags = NLM_F_REQUEST;
   req.hdr.nlmsg_seq = kSeq;
   req.ifm.ifi_family = AF_UNSPEC;
-  req.ifm.ifi_index = loopback_link->index;
+  req.ifm.ifi_index = loopback_link.index;
 
   bool found = false;
   ASSERT_NO_ERRNO(NetlinkRequestResponse(
       fd, &req, sizeof(req),
       [&](const struct nlmsghdr* hdr) {
-        CheckLinkMsg(hdr, *loopback_link);
+        CheckLinkMsg(hdr, loopback_link);
         found = true;
       },
       false));
@@ -241,9 +190,7 @@ TEST(NetlinkRouteTest, GetLinkByIndex) {
 }
 
 TEST(NetlinkRouteTest, GetLinkByName) {
-  absl::optional<Link> loopback_link =
-      ASSERT_NO_ERRNO_AND_VALUE(FindLoopbackLink());
-  ASSERT_TRUE(loopback_link.has_value());
+  Link loopback_link = ASSERT_NO_ERRNO_AND_VALUE(LoopbackLink());
 
   FileDescriptor fd =
       ASSERT_NO_ERRNO_AND_VALUE(NetlinkBoundSocket(NETLINK_ROUTE));
@@ -262,8 +209,8 @@ TEST(NetlinkRouteTest, GetLinkByName) {
   req.hdr.nlmsg_seq = kSeq;
   req.ifm.ifi_family = AF_UNSPEC;
   req.rtattr.rta_type = IFLA_IFNAME;
-  req.rtattr.rta_len = RTA_LENGTH(loopback_link->name.size() + 1);
-  strncpy(req.ifname, loopback_link->name.c_str(), sizeof(req.ifname));
+  req.rtattr.rta_len = RTA_LENGTH(loopback_link.name.size() + 1);
+  strncpy(req.ifname, loopback_link.name.c_str(), sizeof(req.ifname));
   req.hdr.nlmsg_len =
       NLMSG_LENGTH(sizeof(req.ifm)) + NLMSG_ALIGN(req.rtattr.rta_len);
 
@@ -271,7 +218,7 @@ TEST(NetlinkRouteTest, GetLinkByName) {
   ASSERT_NO_ERRNO(NetlinkRequestResponse(
       fd, &req, sizeof(req),
       [&](const struct nlmsghdr* hdr) {
-        CheckLinkMsg(hdr, *loopback_link);
+        CheckLinkMsg(hdr, loopback_link);
         found = true;
       },
       false));
@@ -523,9 +470,7 @@ TEST(NetlinkRouteTest, LookupAll) {
 TEST(NetlinkRouteTest, AddAddr) {
   SKIP_IF(!ASSERT_NO_ERRNO_AND_VALUE(HaveCapability(CAP_NET_ADMIN)));
 
-  absl::optional<Link> loopback_link =
-      ASSERT_NO_ERRNO_AND_VALUE(FindLoopbackLink());
-  ASSERT_TRUE(loopback_link.has_value());
+  Link loopback_link = ASSERT_NO_ERRNO_AND_VALUE(LoopbackLink());
 
   FileDescriptor fd =
       ASSERT_NO_ERRNO_AND_VALUE(NetlinkBoundSocket(NETLINK_ROUTE));
@@ -545,7 +490,7 @@ TEST(NetlinkRouteTest, AddAddr) {
   req.ifa.ifa_prefixlen = 24;
   req.ifa.ifa_flags = 0;
   req.ifa.ifa_scope = 0;
-  req.ifa.ifa_index = loopback_link->index;
+  req.ifa.ifa_index = loopback_link.index;
   req.rtattr.rta_type = IFA_LOCAL;
   req.rtattr.rta_len = RTA_LENGTH(sizeof(req.addr));
   inet_pton(AF_INET, "10.0.0.1", &req.addr);

test/syscalls/linux/socket_netlink_route_util.cc

@@ -18,7 +18,6 @@
 #include <linux/netlink.h>
 #include <linux/rtnetlink.h>
 
-#include "absl/types/optional.h"
 #include "test/syscalls/linux/socket_netlink_util.h"
 
 namespace gvisor {
@@ -73,14 +72,14 @@ PosixErrorOr<std::vector<Link>> DumpLinks() {
   return links;
 }
 
-PosixErrorOr<absl::optional<Link>> FindLoopbackLink() {
+PosixErrorOr<Link> LoopbackLink() {
   ASSIGN_OR_RETURN_ERRNO(auto links, DumpLinks());
   for (const auto& link : links) {
     if (link.type == ARPHRD_LOOPBACK) {
-      return absl::optional<Link>(link);
+      return link;
     }
   }
-  return absl::optional<Link>();
+  return PosixError(ENOENT, "loopback link not found");
 }
 
 PosixError LinkAddLocalAddr(int index, int family, int prefixlen,

test/syscalls/linux/socket_netlink_route_util.h

@@ -20,7 +20,6 @@
 
 #include <vector>
 
-#include "absl/types/optional.h"
 #include "test/syscalls/linux/socket_netlink_util.h"
 
 namespace gvisor {
@@ -37,7 +36,8 @@ PosixError DumpLinks(const FileDescriptor& fd, uint32_t seq,
 
 PosixErrorOr<std::vector<Link>> DumpLinks();
 
-PosixErrorOr<absl::optional<Link>> FindLoopbackLink();
+// Returns the loopback link on the system. ENOENT if not found.
+PosixErrorOr<Link> LoopbackLink();
 
 // LinkAddLocalAddr sets IFA_LOCAL attribute on the interface.
 PosixError LinkAddLocalAddr(int index, int family, int prefixlen,

test/syscalls/linux/tuntap.cc

@@ -56,14 +56,14 @@ PosixErrorOr<std::set<std::string>> DumpLinkNames() {
   return names;
 }
 
-PosixErrorOr<absl::optional<Link>> GetLinkByName(const std::string& name) {
+PosixErrorOr<Link> GetLinkByName(const std::string& name) {
   ASSIGN_OR_RETURN_ERRNO(auto links, DumpLinks());
   for (const auto& link : links) {
     if (link.name == name) {
-      return absl::optional<Link>(link);
+      return link;
     }
   }
-  return absl::optional<Link>();
+  return PosixError(ENOENT, "interface not found");
 }
 
 struct pihdr {
@@ -268,24 +268,21 @@ PosixErrorOr<FileDescriptor> OpenAndAttachTap(
     return PosixError(errno);
   }
 
-  ASSIGN_OR_RETURN_ERRNO(absl::optional<Link> link, GetLinkByName(dev_name));
-  if (!link.has_value()) {
-    return PosixError(ENOENT, "no link");
-  }
+  ASSIGN_OR_RETURN_ERRNO(auto link, GetLinkByName(dev_name));
 
   // Interface setup.
   struct in_addr addr;
   inet_pton(AF_INET, dev_ipv4_addr.c_str(), &addr);
-  EXPECT_NO_ERRNO(LinkAddLocalAddr(link->index, AF_INET, /*prefixlen=*/24,
-                                   &addr, sizeof(addr)));
+  EXPECT_NO_ERRNO(LinkAddLocalAddr(link.index, AF_INET, /*prefixlen=*/24, &addr,
+                                   sizeof(addr)));
 
   if (!IsRunningOnGvisor()) {
     // FIXME(b/110961832): gVisor doesn't support setting MAC address on
     // interfaces yet.
-    RETURN_IF_ERRNO(LinkSetMacAddr(link->index, kMacA, sizeof(kMacA)));
+    RETURN_IF_ERRNO(LinkSetMacAddr(link.index, kMacA, sizeof(kMacA)));
 
     // FIXME(b/110961832): gVisor always creates enabled/up'd interfaces.
-    RETURN_IF_ERRNO(LinkChangeFlags(link->index, IFF_UP, IFF_UP));
+    RETURN_IF_ERRNO(LinkChangeFlags(link.index, IFF_UP, IFF_UP));
   }
 
   return fd;