Practicing with interposition

.gitignore

@@ -144,7 +144,6 @@ test/models
 ratemon/runtime/new/.output
 ratemon/runtime/new/ratemon_test
 
-ratemon/runtime/new/client_server/*.o
-ratemon/runtime/new/client_server/*.so
+ratemon/runtime/new/client_server/.output/
 ratemon/runtime/new/client_server/client
 ratemon/runtime/new/client_server/server

ratemon/runtime/new/client_server/Makefile

@@ -1,23 +1,41 @@
+OUTPUT = .output
 CC = gcc
-CFLAGS = -I. -g
+CXX = g++
+CFLAGS = -g -std=c17 -Wall -Wextra
+CXXFLAGS = -g -std=c++17 -Wall -Wextra
 DEPS = common.h
-CLIENT_OBJ = client.o
-SERVER_OBJ = server.o
+APPS = client server
+INTERPS = libinterptest libinterptest_cpp
 
-%.o: %.c $(DEPS)
-	$(CC) -c -o $@ $< $(CFLAGS)
+.PHONY: all
+all: $(APPS) $(INTERPS)
 
-client: $(CLIENT_OBJ)
-	$(CC) -o $@ $^ $(CFLAGS)
+$(OUTPUT):
+	mkdir -p $(@)
 
-server: $(SERVER_OBJ)
-	$(CC) -o $@ $^ $(CFLAGS)
+$(OUTPUT)/%.o: %.c $(DEPS) | $(OUTPUT)
+	$(CC) $(CFLAGS) -c -o $@ $<
 
-libinterptest: interptest.c
-	$(CC) -shared -ldl -fPIC interptest.c -o libinterptest.so
+$(APPS): %: $(OUTPUT)/%.o | $(OUTPUT)
+	$(CC) $(CFLAGS) -o $@ $^
 
+$(OUTPUT)/%.so: %.c | $(OUTPUT)
+	$(CC) $(CFLAGS) -shared -ldl -fPIC $^ -o $@
 
-all: client server libinterptest
+$(OUTPUT)/%_cpp.so: %_cpp.cpp | $(OUTPUT)
+	$(CXX) $(CXXFLAGS) -shared -ldl -fPIC $^ -o $@
 
+$(INTERPS): %: $(OUTPUT)/%.so ;
+
+interp_server : server $(OUTPUT)/libinterptest.so
+	LD_PRELOAD=$(OUTPUT)/libinterptest.so ./server
+
+interp_server_cpp : server $(OUTPUT)/libinterptest_cpp.so
+	LD_PRELOAD=$(OUTPUT)/libinterptest_cpp.so ./server
+
+run_client: client
+	./client
+
+.PHONY: clean
 clean:
-	rm -f *.o *.so client server
+	rm -rfv $(OUTPUT) $(APPS)

ratemon/runtime/new/client_server/libinterptest.c

@@ -0,0 +1,53 @@
+#define _GNU_SOURCE
+#include <dlfcn.h>
+#include <netinet/in.h>  // structure for storing address information
+#include <netinet/tcp.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <sys/socket.h>  // for socket APIs
+
+int storedSockFd = 0;
+
+int accept(int sockfd, struct sockaddr *addr, socklen_t *addrlen) {
+  printf("Intercepted call to 'accept'\n");
+
+  static int (*real_accept)(int, struct sockaddr *, socklen_t *) = NULL;
+  real_accept =
+      (int (*)(int, struct sockaddr *, socklen_t *))dlsym(RTLD_NEXT, "accept");
+  if (real_accept == NULL) {
+    fprintf(stderr, "Error in dlsym when querying for 'accept': %s\n",
+            dlerror());
+    return -1;
+  }
+
+  int ret = real_accept(sockfd, addr, addrlen);
+  printf("accept for FD=%d got FD=%d\n", sockfd, ret);
+
+  if (ret != -1) {
+    struct tcp_info info;
+    socklen_t tcp_info_length = (socklen_t)sizeof(info);
+    if (getsockopt(ret, SOL_TCP, TCP_INFO, (void *)&info, &tcp_info_length) ==
+        0) {
+      printf("TCP_INFO rtt=%u, rto=%u\n", info.tcpi_rtt, info.tcpi_rto);
+    } else {
+      printf("Error in getsockopt TCP_INFO\n");
+    }
+  }
+
+  return ret;
+}
+
+int close(int sockfd) {
+  printf("Intercepted call to 'close' for FD=%d\n", sockfd);
+
+  static int (*real_close)(int) = NULL;
+  real_close = (int (*)(int))dlsym(RTLD_NEXT, "close");
+  if (real_close == NULL) {
+    fprintf(stderr, "Error in dlsym when querying for 'close': %s\n",
+            dlerror());
+    return -1;
+  }
+
+  return real_close(sockfd);
+  ;
+}

ratemon/runtime/new/client_server/libinterptest_cpp.cpp

@@ -0,0 +1,64 @@
+#ifndef _GNU_SOURCE
+#define _GNU_SOURCE
+#endif
+
+#include <dlfcn.h>
+#include <netinet/in.h>  // structure for storing address information
+#include <netinet/tcp.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <sys/socket.h>  // for socket APIs
+
+#include <unordered_set>
+
+std::unordered_set<int> sockfds;
+
+int accept(int sockfd, struct sockaddr *addr, socklen_t *addrlen) {
+  printf("Intercepted call to 'accept'\n");
+
+  static int (*real_accept)(int, struct sockaddr *, socklen_t *) =
+      (int (*)(int, struct sockaddr *, socklen_t *))dlsym(RTLD_NEXT, "accept");
+  if (real_accept == NULL) {
+    fprintf(stderr, "Error in dlsym when querying for 'accept': %s\n",
+            dlerror());
+    return -1;
+  }
+
+  int ret = real_accept(sockfd, addr, addrlen);
+  printf("accept for FD=%d got FD=%d\n", sockfd, ret);
+
+  if (ret != -1) {
+    sockfds.insert(ret);
+
+    struct tcp_info info;
+    socklen_t tcp_info_length = (socklen_t)sizeof(info);
+    if (getsockopt(ret, SOL_TCP, TCP_INFO, (void *)&info, &tcp_info_length) ==
+        0) {
+      printf("TCP_INFO rtt=%u, rto=%u\n", info.tcpi_rtt, info.tcpi_rto);
+    } else {
+      printf("Error in getsockopt TCP_INFO\n");
+    }
+  }
+
+  return ret;
+}
+
+int close(int sockfd) {
+  printf("Intercepted call to 'close' for FD=%d\n", sockfd);
+
+  static int (*real_close)(int) = (int (*)(int))dlsym(RTLD_NEXT, "close");
+  if (real_close == NULL) {
+    fprintf(stderr, "Error in dlsym when querying for 'close': %s\n",
+            dlerror());
+    return -1;
+  }
+
+  int ret = real_close(sockfd);
+  if (ret != -1) {
+    if (sockfds.find(sockfd) != sockfds.end()) {
+      sockfds.erase(sockfd);
+    }
+  }
+
+  return ret;
+}

ratemon/runtime/new/client_server/server.c

@@ -54,6 +54,10 @@ int main(int argc, char const* argv[]) {
 
   printf("Server done sending. Exiting...\n");
 
+  if (close(clientSocket) == -1) {
+    printf("Error in closing client socket\n");
+    return 1;
+  }
   // close server listen socket
   if (close(servSockD) == -1) {
     printf("Error in closing server socket\n");