Add unix socket listening mode

src/server.cpp

@@ -11,6 +11,7 @@
 #include <stdexcept>
 #include <sys/epoll.h>
 #include <sys/socket.h>
+#include <sys/un.h>
 #include <unistd.h>
 
 extern std::atomic<int> activeConnections;
@@ -145,9 +146,64 @@ void Server::setup_shutdown_pipe() {
 }
 
 int Server::create_listen_socket() {
+  int sfd;
+
+  // Check if unix socket path is specified
+  if (!config_.server.unix_socket_path.empty()) {
+    // Create unix socket
+    sfd = socket(AF_UNIX, SOCK_STREAM, 0);
+    if (sfd == -1) {
+      perror("socket");
+      throw std::runtime_error("Failed to create unix socket");
+    }
+
+    // Remove existing socket file if it exists
+    unlink(config_.server.unix_socket_path.c_str());
+
+    struct sockaddr_un addr;
+    memset(&addr, 0, sizeof(addr));
+    addr.sun_family = AF_UNIX;
+
+    if (config_.server.unix_socket_path.length() >= sizeof(addr.sun_path)) {
+      close(sfd);
+      throw std::runtime_error("Unix socket path too long");
+    }
+
+    strncpy(addr.sun_path, config_.server.unix_socket_path.c_str(),
+            sizeof(addr.sun_path) - 1);
+
+    // Set socket to non-blocking for graceful shutdown
+    int flags = fcntl(sfd, F_GETFL, 0);
+    if (flags == -1) {
+      perror("fcntl F_GETFL");
+      close(sfd);
+      throw std::runtime_error("Failed to get socket flags");
+    }
+    if (fcntl(sfd, F_SETFL, flags | O_NONBLOCK) == -1) {
+      perror("fcntl F_SETFL");
+      close(sfd);
+      throw std::runtime_error("Failed to set socket non-blocking");
+    }
+
+    if (bind(sfd, (struct sockaddr *)&addr, sizeof(addr)) == -1) {
+      perror("bind");
+      close(sfd);
+      throw std::runtime_error("Failed to bind unix socket");
+    }
+
+    if (listen(sfd, SOMAXCONN) == -1) {
+      perror("listen");
+      close(sfd);
+      throw std::runtime_error("Failed to listen on unix socket");
+    }
+
+    return sfd;
+  }
+
+  // TCP socket creation (original code)
   struct addrinfo hints;
   struct addrinfo *result, *rp;
-  int sfd, s;
+  int s;
 
   memset(&hints, 0, sizeof(hints));
   hints.ai_family = AF_UNSPEC;     /* Allow IPv4 or IPv6 */
@@ -178,11 +234,13 @@ int Server::create_listen_socket() {
       continue;
     }
 
-    // Enable TCP_NODELAY for low latency
-    if (setsockopt(sfd, IPPROTO_TCP, TCP_NODELAY, &val, sizeof(val)) == -1) {
-      perror("setsockopt TCP_NODELAY");
-      close(sfd);
-      continue;
+    // Enable TCP_NODELAY for low latency (only for TCP sockets)
+    if (rp->ai_family == AF_INET || rp->ai_family == AF_INET6) {
+      if (setsockopt(sfd, IPPROTO_TCP, TCP_NODELAY, &val, sizeof(val)) == -1) {
+        perror("setsockopt TCP_NODELAY");
+        close(sfd);
+        continue;
+      }
     }
 
     // Set socket to non-blocking for graceful shutdown
@@ -438,4 +496,9 @@ void Server::cleanup_resources() {
     close(listen_sockfd_);
     listen_sockfd_ = -1;
   }
+
+  // Clean up unix socket file if it exists
+  if (!config_.server.unix_socket_path.empty()) {
+    unlink(config_.server.unix_socket_path.c_str());
+  }
 }