Sockets (#3)

* Socket methods to be used by an event loop

* Git ignore build files

* File renames

* Some fixes

* Fixes

* Fixes

* Memory leakage fix

.gitignore

@@ -33,3 +33,6 @@
 # Debug files
 *.dSYM/
 *.su
+
+# Build files
+build/*

Makefile

@@ -9,6 +9,9 @@ CFLAGS += -Wmissing-declarations
 $(BUILD)/db_tests: hiredis test/db_tests.c thirdparty/greatest.h event_loop.c state/redis.c common.c
 	$(CC) -o $@ test/db_tests.c event_loop.c state/redis.c common.c thirdparty/hiredis/libhiredis.a $(CFLAGS) -I. -Ithirdparty
 
+$(BUILD)/socket_tests: test/socket_tests.c thirdparty/greatest.h sockets.c
+	$(CC) -o $@ test/socket_tests.c sockets.c $(CFLAGS) -I. -Ithirdparty
+
 clean:
 	rm -r $(BUILD)/*
 
@@ -18,7 +21,8 @@ redis:
 hiredis:
 	git submodule update --init --recursive -- "thirdparty/hiredis" ; cd thirdparty/hiredis ; make
 
-test: hiredis redis $(BUILD)/db_tests FORCE
-	./thirdparty/redis-3.2.3/src/redis-server & sleep 1s ; ./build/db_tests
+test: hiredis redis $(BUILD)/db_tests $(BUILD)/socket_tests FORCE
+	./thirdparty/redis-3.2.3/src/redis-server &
+	sleep 1s ; ./build/db_tests ; ./build/socket_tests
 
 FORCE:

event_loop.c

@@ -1,7 +1,6 @@
 #include "event_loop.h"
 
 #include <assert.h>
-#include <unistd.h>
 
 UT_icd item_icd = {sizeof(event_loop_item), NULL, NULL, NULL};
 UT_icd poll_icd = {sizeof(struct pollfd), NULL, NULL, NULL};

sockets.c

@@ -0,0 +1,111 @@
+#include "sockets.h"
+
+#include <stdlib.h>
+#include <unistd.h>
+#include <sys/socket.h>
+#include <sys/un.h>
+#include <string.h>
+#include <stdio.h>
+
+#include "common.h"
+
+/* Binds to a Unix domain datagram socket at the given
+ * pathname. Removes any existing file at the pathname. Returns
+ * a file descriptor for the socket, or -1 if an error
+ * occurred. */
+int bind_ipc_sock(const char *socket_pathname) {
+  struct sockaddr_un socket_address;
+  int socket_fd;
+
+  socket_fd = socket(AF_UNIX, SOCK_DGRAM, 0);
+  if (socket_fd < 0) {
+    LOG_ERR("socket() failed for pathname %s.", socket_pathname);
+    return -1;
+  }
+
+  unlink(socket_pathname);
+  memset(&socket_address, 0, sizeof(struct sockaddr_un));
+  socket_address.sun_family = AF_UNIX;
+  if (strlen(socket_pathname) + 1 > sizeof(socket_address.sun_path)) {
+    LOG_ERR("Socket pathname is too long.");
+    return -1;
+  }
+  strncpy(socket_address.sun_path, socket_pathname,
+          strlen(socket_pathname) + 1);
+
+  if (bind(socket_fd, (struct sockaddr *) &socket_address,
+           sizeof(struct sockaddr_un)) != 0) {
+    LOG_ERR("Bind failed for pathname %s.", socket_pathname);
+    return -1;
+  }
+
+  return socket_fd;
+}
+
+/* Connects to a Unix domain datagram socket at the given
+ * pathname. Returns a file descriptor for the socket, or -1 if
+ * an error occurred. */
+int connect_ipc_sock(const char *socket_pathname) {
+  struct sockaddr_un socket_address;
+  int socket_fd;
+
+  socket_fd = socket(AF_UNIX, SOCK_DGRAM, 0);
+  if (socket_fd < 0) {
+    LOG_ERR("socket() failed for pathname %s.", socket_pathname);
+    return -1;
+  }
+
+  memset(&socket_address, 0, sizeof(struct sockaddr_un));
+  socket_address.sun_family = AF_UNIX;
+  if (strlen(socket_pathname) + 1 > sizeof(socket_address.sun_path)) {
+    LOG_ERR("Socket pathname is too long.");
+    return -1;
+  }
+  strncpy(socket_address.sun_path, socket_pathname,
+          strlen(socket_pathname) + 1);
+
+  if (connect(socket_fd, (struct sockaddr *) &socket_address,
+              sizeof(struct sockaddr_un)) != 0) {
+    LOG_ERR("Connection to socket failed for pathname %s.", socket_pathname);
+    return -1;
+  }
+
+  return socket_fd;
+}
+
+/* Sends a message on the given socket file descriptor. */
+void send_ipc_sock(int socket_fd, char *message) {
+  int length = strlen(message);
+  int nbytes;
+  nbytes = send(socket_fd, (char *) &length, sizeof(length), 0);
+  if (nbytes == -1) {
+    fprintf(stderr, "Error sending to socket.\n");
+    return;
+  }
+  nbytes = send(socket_fd, (char *) message, length * sizeof(char), 0);
+  if (nbytes == -1) {
+    fprintf(stderr, "Error sending to socket.\n");
+    return;
+  }
+}
+
+/* Receives a message on the given socket file descriptor. Allocates and
+ * returns a pointer to the message.
+ * NOTE: Caller must free the message! */
+char *recv_ipc_sock(int socket_fd) {
+  int length;
+  int nbytes;
+  nbytes = recv(socket_fd, &length, sizeof(length), 0);
+  if (nbytes == -1) {
+    fprintf(stderr, "Error receiving from socket.\n");
+    return NULL;
+  }
+  char *message = malloc((length + 1) * sizeof(char));
+  nbytes = recv(socket_fd, message, length * sizeof(char), 0);
+  if (nbytes == -1) {
+    fprintf(stderr, "Error receiving from socket.\n");
+    return NULL;
+  }
+  message[length] = '\0';
+  return message;
+}

sockets.h

@@ -0,0 +1,10 @@
+#ifndef SOCKETS_H
+#define SOCKETS_H
+
+/* Helper functions for socket communication. */
+int bind_ipc_sock(const char* socket_pathname);
+int connect_ipc_sock(const char* socket_pathname);
+void send_ipc_sock(int socket_fd, char* message);
+char* recv_ipc_sock(int socket_fd);
+
+#endif

test/socket_tests.c

@@ -0,0 +1,45 @@
+#include "greatest.h"
+
+#include <assert.h>
+#include <unistd.h>
+
+#include "sockets.h"
+
+SUITE(event_loop_tests);
+
+TEST ipc_socket_test(void) {
+  const char* socket_pathname = "test-socket";
+  int socket_fd = bind_ipc_sock(socket_pathname);
+  ASSERT(socket_fd >= 0);
+
+  char* test_string = "hello world";
+  pid_t pid = fork();
+  if (pid == 0) {
+    close(socket_fd);
+    socket_fd = connect_ipc_sock(socket_pathname);
+    ASSERT(socket_fd >= 0);
+    send_ipc_sock(socket_fd, test_string);
+    close(socket_fd);
+  } else {
+    char* message = recv_ipc_sock(socket_fd);
+    ASSERT(message != NULL);
+    ASSERT_STR_EQ(test_string, message);
+    free(message);
+    close(socket_fd);
+    unlink(socket_pathname);
+  }
+
+  PASS();
+}
+
+SUITE(event_loop_tests) {
+  RUN_TEST(ipc_socket_test);
+}
+
+GREATEST_MAIN_DEFS();
+
+int main(int argc, char** argv) {
+  GREATEST_MAIN_BEGIN();
+  RUN_SUITE(event_loop_tests);
+  GREATEST_MAIN_END();
+}