Add RE2 example.

Signed-off-by: Martijn Stevenson <[email protected]>

Author: martijneken

bazel/repositories.bzl

@@ -31,3 +31,19 @@ def proxy_wasm_cpp_sdk_repositories():
         strip_prefix = "protobuf-3.17.3",
         url = "https://github.com/protocolbuffers/protobuf/releases/download/v3.17.3/protobuf-all-3.17.3.tar.gz",
     )
+
+    maybe(
+        http_archive,
+        name = "com_google_absl",
+        sha256 = "95e90be7c3643e658670e0dd3c1b27092349c34b632c6e795686355f67eca89f",
+        strip_prefix = "abseil-cpp-20240722.0",
+        urls = ["https://github.com/abseil/abseil-cpp/archive/20240722.0.zip"],
+    )
+
+    maybe(
+        http_archive,
+        name = "com_google_re2",
+        sha256 = "18cf85922e27fad3ed9c96a27733037da445f35eb1a2744c306a37c6d11e95c4",
+        strip_prefix = "re2-2023-07-01",
+        url = "https://github.com/google/re2/archive/2023-07-01.tar.gz",
+    )

example/BUILD

@@ -6,18 +6,21 @@ proxy_wasm_cc_binary(
     name = "http_wasm_example.wasm",
     srcs = ["http_wasm_example.cc"],
     copts = ["-std=c++17"],
+    deps = ["@com_google_re2//:re2"],
 )
 
 proxy_wasm_cc_binary(
     name = "http_wasm_example_with_protobuf_lite.wasm",
     srcs = ["http_wasm_example.cc"],
     copts = ["-std=c++17"],
     protobuf = "lite",
+    deps = ["@com_google_re2//:re2"],
 )
 
 proxy_wasm_cc_binary(
     name = "http_wasm_example_with_protobuf_full.wasm",
     srcs = ["http_wasm_example.cc"],
     copts = ["-std=c++17"],
     protobuf = "full",
+    deps = ["@com_google_re2//:re2"],
 )

example/http_wasm_example.cc

@@ -15,7 +15,7 @@
 
 #include <string>
 #include <string_view>
-#include <unordered_map>
+#include "re2/re2.h"
 
 #include "proxy_wasm_intrinsics.h"
 
@@ -26,11 +26,14 @@ class ExampleRootContext : public RootContext {
   bool onStart(size_t) override;
   bool onConfigure(size_t) override;
   void onTick() override;
+
+  std::optional<re2::RE2> path_match;
 };
 
 class ExampleContext : public Context {
 public:
-  explicit ExampleContext(uint32_t id, RootContext *root) : Context(id, root) {}
+  explicit ExampleContext(uint32_t id, RootContext *root)
+      : Context(id, root), root_(static_cast<ExampleRootContext *>(root)) {}
 
   void onCreate() override;
   FilterHeadersStatus onRequestHeaders(uint32_t headers, bool end_of_stream) override;
@@ -40,6 +43,9 @@ class ExampleContext : public Context {
   void onDone() override;
   void onLog() override;
   void onDelete() override;
+
+private:
+  const ExampleRootContext *root_;
 };
 static RegisterContextFactory register_ExampleContext(CONTEXT_FACTORY(ExampleContext),
                                                       ROOT_FACTORY(ExampleRootContext),
@@ -62,8 +68,12 @@ bool ExampleRootContext::onStart(size_t) {
 
 bool ExampleRootContext::onConfigure(size_t) {
   LOG_TRACE("onConfigure");
+  // Start a timer.
   proxy_set_tick_period_milliseconds(1000); // 1 sec
-  return true;
+
+  // Compile a regular expression.
+  path_match.emplace("/foo-([^/]+)/");
+  return path_match->ok();
 }
 
 void ExampleRootContext::onTick() { LOG_TRACE("onTick"); }
@@ -78,6 +88,11 @@ FilterHeadersStatus ExampleContext::onRequestHeaders(uint32_t, bool) {
   for (auto &p : pairs) {
     LOG_INFO(std::string(p.first) + std::string(" -> ") + std::string(p.second));
   }
+  // Regex.
+  auto path = getRequestHeader(":path");
+  if (path && re2::RE2::FullMatch(path->view(), *root_->path_match)) {
+    sendLocalResponse(403, "", "Access forbidden.", {});
+  }
   return FilterHeadersStatus::Continue;
 }