feat(otlp): support vsock gRPC endpoints

CHANGELOG.md

@@ -15,6 +15,9 @@ Increment the:
 
 ## [Unreleased]
 
+* [OTLP/gRPC] Support VSOCK endpoints on Linux
+  [#4706](https://github.com/open-telemetry/opentelemetry-cpp/issues/4706)
+
 * [SDK] `BatchLogRecordProcessor` now exports at most one batch on normal
   wakeups instead of continuously draining the buffer, matching
   `BatchSpanProcessor`

exporters/otlp/README.md

@@ -75,6 +75,11 @@ auto exporter = std::make_unique<otlp::OtlpFileExporter>(options);
 |`metadata`                        |`OTEL_EXPORTER_OTLP_HEADERS`                  |                       | Custom metadata for GRPC             |
 |                                  |`OTEL_EXPORTER_OTLP_TRACES_HEADERS`           |                       |                                      |
 
+On Linux, the OTLP gRPC exporter supports VSOCK endpoints with gRPC 1.57.0 or
+later. Set `vsock://<cid>:<port>` as the endpoint; the exporter converts it
+to the `vsock:<cid>:<port>` target format expected by gRPC. A raw
+`vsock:<cid>:<port>` target is also accepted.
+
 ### Configuration options ( OTLP HTTP Exporter )
 
 | Option             | Env Variable                       | Default                         | Description                                                       |

exporters/otlp/src/otlp_grpc_client.cc

@@ -310,6 +310,12 @@ OtlpGrpcClient::~OtlpGrpcClient()
 
 std::string OtlpGrpcClient::GetGrpcTarget(const std::string &endpoint)
 {
+  // A raw VSOCK target is already in the format expected by gRPC.
+  if (endpoint.rfind("vsock:", 0) == 0 && endpoint.rfind("vsock://", 0) != 0)
+  {
+    return endpoint;
+  }
+
   //
   // Scheme is allowed in OTLP endpoint definition, but is not allowed for creating gRPC
   // channel. Passing URI with scheme to grpc::CreateChannel could resolve the endpoint to some
@@ -327,6 +333,10 @@ std::string OtlpGrpcClient::GetGrpcTarget(const std::string &endpoint)
   {
     grpc_target = "unix:" + url.path_;
   }
+  else if (url.scheme_ == "vsock")
+  {
+    grpc_target = "vsock:" + url.host_ + ":" + std::to_string(url.port_);
+  }
   else
   {
     grpc_target = url.host_ + ":" + std::to_string(static_cast<int>(url.port_));

exporters/otlp/test/otlp_grpc_target_test.cc

@@ -68,6 +68,13 @@ TEST(OtlpGrpcClientEndpointTest, GrpcClientTest)
   EXPECT_EQ(target3, "localhost:4317");
 }
 
+TEST(OtlpGrpcClientEndpointTest, VsockEndpoints)
+{
+  EXPECT_EQ(OtlpGrpcClient::GetGrpcTarget("vsock:3:1234"), "vsock:3:1234");
+  EXPECT_EQ(OtlpGrpcClient::GetGrpcTarget("vsock://3:1234"), "vsock:3:1234");
+  EXPECT_EQ(OtlpGrpcClient::GetGrpcTarget("vsock://3:100000"), "vsock:3:100000");
+}
+
 TEST_F(OtlpGrpcClientTestPeer, ChannelArgumentsOptionTest)
 {
   OtlpGrpcClientOptions options;

ext/include/opentelemetry/ext/http/common/url_parser.h

@@ -6,6 +6,7 @@
 #include <cerrno>
 #include <cstdint>
 #include <cstdlib>
+#include <limits>
 #include <string>
 #include <utility>
 
@@ -32,7 +33,7 @@ class UrlParser
   std::string host_;
   std::string scheme_;
   std::string path_;
-  uint16_t port_{};
+  std::uint32_t port_{};
   std::string query_;
   bool success_{true};
 
@@ -171,18 +172,21 @@ class UrlParser
     return std::string::npos;
   }
 
-  std::uint16_t GetPort(const std::string &s)
+  std::uint32_t GetPort(const std::string &s)
   {
-    char *e   = nullptr;
-    errno     = 0;
-    auto port = std::strtol(s.c_str(), &e, 10);
-    if (e == s.c_str() || e != s.c_str() + s.size() || errno == ERANGE || port < 0 || port > 65535)
+    char *e = nullptr;
+    errno   = 0;
+    auto port = std::strtoull(s.c_str(), &e, 10);
+    auto max_port = scheme_ == "vsock" ? std::numeric_limits<std::uint32_t>::max()
+                                        : std::numeric_limits<std::uint16_t>::max();
+    if (e == s.c_str() || e != s.c_str() + s.size() || errno == ERANGE || s[0] == '-' ||
+        port > max_port)
     {
       success_ = false;
       return 0;
     }
 
-    return static_cast<uint16_t>(port);
+    return static_cast<std::uint32_t>(port);
   }
 };
 

ext/test/http/url_parser_test.cc

@@ -23,7 +23,7 @@ struct ParsedUrl
 {
   std::string scheme;
   std::string host;
-  std::uint16_t port{};
+  std::uint32_t port{};
   std::string path;
   std::string query;
   bool success{};
@@ -104,7 +104,11 @@ INSTANTIATE_TEST_SUITE_P(
         std::make_tuple("https://example.com:80a/some/path",
                         ParsedUrl{"https", "example.com", 0, "/some/path", "", false}),
         std::make_tuple("https://example.com:18446744073709551616/some/path",
-                        ParsedUrl{"https", "example.com", 0, "/some/path", "", false})));
+                        ParsedUrl{"https", "example.com", 0, "/some/path", "", false}),
+        std::make_tuple("vsock://3:100000",
+                        ParsedUrl{"vsock", "3", 100000, "/", "", true}),
+        std::make_tuple("vsock://3:4294967296",
+                        ParsedUrl{"vsock", "3", 0, "/", "", false})));
 
 TEST_P(UrlParserTests, BasicTests)
 {