Relay messages between client and server, but without fds

Makefile

@@ -5,8 +5,8 @@ way_cflags := $(shell pkg-config --cflags wayland-client wayland-server)
 
 all: waypipe
 
-waypipe: waypipe.c server.c client.c Makefile
-	gcc -ggdb3 $(way_libs) $(way_cflags) -o waypipe waypipe.c server.c client.c
+waypipe: waypipe.c server.c client.c util.c util.h Makefile
+	gcc -std=c11 -ggdb3 $(way_libs) $(way_cflags) -o waypipe waypipe.c server.c client.c util.h util.c
 
 clean:
 	rm -f waypipe

client.c

@@ -23,12 +23,18 @@
  * SOFTWARE.
  */
 
+#define _XOPEN_SOURCE 700
+
+#include "util.h"
+
 #include <errno.h>
 #include <stdio.h>
 #include <stdlib.h>
 #include <string.h>
+#include <sys/select.h>
 #include <sys/socket.h>
 #include <sys/un.h>
+#include <time.h>
 #include <unistd.h>
 #include <wayland-client-core.h>
 
@@ -39,6 +45,7 @@ int run_client(const char *socket_path)
 		fprintf(stderr, "Failed to connect to a wayland server.\n");
 		return EXIT_FAILURE;
 	}
+	int displayfd = wl_display_get_fd(display);
 
 	struct sockaddr_un saddr;
 	int fd;
@@ -70,9 +77,13 @@ int run_client(const char *socket_path)
 		return EXIT_FAILURE;
 	}
 
+	int maxmsg = 4096;
+	char *buffer = calloc(1, maxmsg + 1);
+
 	fprintf(stderr, "I'm a client on %s!\n", socket_path);
 	for (int i = 0; i < 1; i++) {
-		// Q: multiple parallel client support?
+		// Q: multiple parallel remote client support? then multiplex
+		// over all accepted clients?
 
 		int client = accept(fd, NULL, NULL);
 		if (client == -1) {
@@ -83,18 +94,86 @@ int run_client(const char *socket_path)
 		int bufsize = 4096;
 		char *buf = calloc(bufsize + 1, 1);
 		while (1) {
-			int nb = read(client, buf, bufsize);
-			if (nb <= 0) {
-				fprintf(stderr, "Read failed, stopping\n");
+			// pselect multiple.
+			fd_set readfds;
+			FD_ZERO(&readfds);
+			FD_SET(client, &readfds);
+			FD_SET(displayfd, &readfds);
+			struct timespec timeout = {
+					.tv_sec = 0, .tv_nsec = 700000000L};
+			int maxfd = client > displayfd ? client : displayfd;
+			int r = pselect(maxfd + 1, &readfds, NULL, NULL,
+					&timeout, NULL);
+			if (r == -1) {
+				fprintf(stderr, "Select failed, stopping\n");
 				break;
-			} else {
-				fprintf(stderr, "Read with %d bytes of data |%s|\n",
-						nb, buf);
+			}
+			fprintf(stderr, "Post select %d %d %d\n", r,
+					FD_ISSET(client, &readfds),
+					FD_ISSET(displayfd, &readfds));
+			if (r == 0) {
+				const char *msg = "magic";
+				ssize_t nb = write(
+						client, msg, strlen(msg) + 1);
+				if (nb == -1) {
+					fprintf(stderr, "Write failed, retrying anyway\n");
+				}
+
+				continue;
+			}
+			if (FD_ISSET(client, &readfds)) {
+				fprintf(stderr, "client isset\n");
+				int rc = iovec_read(client, buffer, maxmsg,
+						NULL, NULL);
+				if (rc == -1) {
+					fprintf(stderr, "FD Read failure %ld: %s\n",
+							rc, strerror(errno));
+					break;
+				}
+				fprintf(stderr, "read bytes: %d\n", rc);
+				if (rc > 0) {
+					int wc = iovec_write(displayfd, buffer,
+							rc, NULL, NULL);
+					if (wc == -1) {
+						fprintf(stderr, "FD Write  failure %ld: %s\n",
+								wc,
+								strerror(errno));
+						break;
+					}
+				} else {
+					fprintf(stderr, "the other side shut down\n");
+					break;
+				}
+			}
+			if (FD_ISSET(displayfd, &readfds)) {
+				fprintf(stderr, "displayfd isset\n");
+				int rc = iovec_read(displayfd, buffer, maxmsg,
+						NULL, NULL);
+				if (rc == -1) {
+					fprintf(stderr, "CS Read failure %ld: %s\n",
+							rc, strerror(errno));
+					break;
+				}
+				if (rc > 0) {
+					int wc = iovec_write(client, buffer, rc,
+							NULL, NULL);
+					if (wc == -1) {
+						fprintf(stderr, "CS Write  failure %ld: %s\n",
+								wc,
+								strerror(errno));
+						break;
+					}
+				} else {
+					fprintf(stderr, "the display shut down\n");
+					break;
+				}
 			}
 		}
 		fprintf(stderr, "...\n");
 	}
 
+	fprintf(stderr, "Closing\n");
+	close(displayfd);
 	close(fd);
 	unlink(socket_path);
 

server.c

@@ -23,14 +23,22 @@
  * SOFTWARE.
  */
 
-#define _POSIX_C_SOURCE 200112L
+#define _XOPEN_SOURCE 700
+
+#include "util.h"
+
 #include <errno.h>
+#include <fcntl.h>
 #include <stdio.h>
 #include <stdlib.h>
 #include <string.h>
+#include <sys/select.h>
 #include <sys/socket.h>
+#include <sys/time.h>
+#include <sys/types.h>
 #include <sys/un.h>
 #include <sys/wait.h>
+#include <time.h>
 #include <unistd.h>
 #include <wayland-server-core.h>
 
@@ -43,20 +51,15 @@ int run_server(const char *socket_path, int app_argc, char *const app_argv[])
 	}
 	fprintf(stderr, "\n");
 
-	struct wl_display *display = wl_display_create();
 	// create another socketpair; one goes to display; one goes to child
 	int csockpair[2];
 	socketpair(AF_UNIX, SOCK_STREAM, 0, csockpair);
-	if (wl_display_add_socket_fd(display, csockpair[0]) == -1) {
-		fprintf(stderr, "Failed to add socket to display object\n");
-		wl_display_destroy(display);
-		return EXIT_FAILURE;
-	}
+	int flags = fcntl(csockpair[0], F_GETFD);
+	fcntl(csockpair[0], F_SETFD, flags | FD_CLOEXEC);
 
 	pid_t pid = fork();
 	if (pid == -1) {
 		fprintf(stderr, "Fork failed\n");
-		wl_display_destroy(display);
 		return EXIT_FAILURE;
 	} else if (pid == 0) {
 		char bufs2[16];
@@ -70,6 +73,14 @@ int run_server(const char *socket_path, int app_argc, char *const app_argv[])
 		fprintf(stderr, "Failed to execv: %s\n", strerror(errno));
 		return EXIT_FAILURE;
 	}
+
+	struct wl_display *display = wl_display_create();
+	if (wl_display_add_socket_fd(display, csockpair[0]) == -1) {
+		fprintf(stderr, "Failed to add socket to display object\n");
+		wl_display_destroy(display);
+		return EXIT_FAILURE;
+	}
+
 	int status;
 
 	struct sockaddr_un saddr;
@@ -95,11 +106,90 @@ int run_server(const char *socket_path, int app_argc, char *const app_argv[])
 		return EXIT_FAILURE;
 	}
 
-	for (int i = 0; i < 10; i++) {
-		sleep(1);
-		char msg[256];
-		sprintf(msg, "Message #%d", i);
-		write(fd, msg, strlen(msg) + 1);
+	// A connection has already been established
+	int client_socket = csockpair[0];
+
+	/** Main select loop:
+	 * fd -> csockpair[0]
+	 * csockpair[0] -> fd
+	 * 1 second timer (poll waitpid) */
+	struct timespec timeout = {.tv_sec = 0, .tv_nsec = 500000000L};
+	fd_set readfds;
+	int iter = 0;
+
+	int maxmsg = 4096;
+	char *buffer = calloc(1, maxmsg + 1);
+
+	while (true) {
+		iter++;
+		if (iter > 10) {
+			break;
+		}
+		FD_ZERO(&readfds);
+		FD_SET(fd, &readfds);
+		FD_SET(client_socket, &readfds);
+		int maxfd = fd > client_socket ? fd : client_socket;
+		int r = pselect(maxfd + 1, &readfds, NULL, NULL, &timeout,
+				NULL);
+		if (r < 0) {
+			fprintf(stderr, "Error selecting fds: %s\n",
+					strerror(errno));
+			return EXIT_FAILURE;
+		}
+		if (r == 0) {
+			// timeout!
+			fprintf(stderr, "timeout,?? \n");
+		} else {
+			fprintf(stderr, "%d are set\n", r);
+		}
+		if (FD_ISSET(fd, &readfds)) {
+			fprintf(stderr, "Readfd isset\n");
+			int rc = iovec_read(fd, buffer, maxmsg, NULL, NULL);
+			if (rc == -1) {
+				fprintf(stderr, "FD Read failure %ld: %s\n", rc,
+						strerror(errno));
+				break;
+			}
+			fprintf(stderr, "Read from conn %d bytes\n", rc);
+			if (rc > 0) {
+				int wc = iovec_write(client_socket, buffer, rc,
+						NULL, NULL);
+				if (wc == -1) {
+					fprintf(stderr, "FD Write  failure %ld: %s\n",
+							wc, strerror(errno));
+					break;
+				}
+			} else {
+				fprintf(stderr, "the other side shut down\n");
+				break;
+			}
+		}
+		if (FD_ISSET(client_socket, &readfds)) {
+			fprintf(stderr, "client socket isset\n");
+			int rc = iovec_read(client_socket, buffer, maxmsg, NULL,
+					NULL);
+			if (rc == -1) {
+				fprintf(stderr, "CS Read failure %ld: %s\n", rc,
+						strerror(errno));
+				break;
+			}
+			if (rc > 0) {
+				int wc = iovec_write(
+						fd, buffer, rc, NULL, NULL);
+				if (wc == -1) {
+					fprintf(stderr, "CS Write  failure %ld: %s\n",
+							wc, strerror(errno));
+					break;
+				}
+			} else {
+				fprintf(stderr, "the client shut down\n");
+				break;
+			}
+		}
+
+		if (waitpid(pid, &status, WNOHANG) > 0) {
+			break;
+		}
 	}
 	close(fd);
 

test.sh

@@ -2,8 +2,9 @@
 
 root=`pwd`
 
-# program=`which bash`
-program=`which weston-flower`
+#program=`which bash`
+# program=`which weston-flower`
+program=`which demo.py`
 
 ($root/waypipe client /tmp/socket-client 2>&1 | sed 's/.*/\x1b[33m&\x1b[0m/') &
 # ssh-to-self; should have a local keypair set up

util.c

+/*
+ * Copyright © 2019 Manuel Stoeckl
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining
+ * a copy of this software and associated documentation files (the
+ * "Software"), to deal in the Software without restriction, including
+ * without limitation the rights to use, copy, modify, merge, publish,
+ * distribute, sublicense, and/or sell copies of the Software, and to
+ * permit persons to whom the Software is furnished to do so, subject to
+ * the following conditions:
+ *
+ * The above copyright notice and this permission notice (including the
+ * next paragraph) shall be included in all copies or substantial
+ * portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
+ * EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
+ * MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
+ * NONINFRINGEMENT.  IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS
+ * BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN
+ * ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN
+ * CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+ * SOFTWARE.
+ */
+
+#include <sys/socket.h>
+#include <sys/time.h>
+#include <sys/un.h>
+#include <unistd.h>
+
+
+int iovec_read(int conn, char* buf, size_t buflen, int* fds, int* numfds) {
+	char cmsgdata[ (CMSG_LEN(28 * sizeof(int32_t))) ];
+	struct iovec the_iovec;
+	the_iovec.iov_len = buflen;
+	the_iovec.iov_base = buf;
+	struct msghdr msg;
+	msg.msg_name = NULL;
+	msg.msg_namelen = 0;
+	msg.msg_iov = &the_iovec;
+	msg.msg_iovlen = 1;
+	msg.msg_control = &cmsgdata;
+	msg.msg_controllen = sizeof(cmsgdata);
+	msg.msg_flags = 0;
+	ssize_t ret = recvmsg(conn, &msg, MSG_DONTWAIT);
+
+	// parse FDS
+
+	return ret;
+}
+int iovec_write(int conn, char* buf, size_t buflen, int* fds, int* numfds) {
+//	char cmsgdata[ (CMSG_LEN(28 * sizeof(int32_t))) ];
+	struct iovec the_iovec;
+	the_iovec.iov_len = buflen;
+	the_iovec.iov_base = buf;
+	struct msghdr msg;
+	msg.msg_name = NULL;
+	msg.msg_namelen = 0;
+	msg.msg_iov = &the_iovec;
+	msg.msg_iovlen = 1;
+	msg.msg_control = NULL;
+	msg.msg_controllen = 0;
+	msg.msg_flags = 0;
+	ssize_t ret = sendmsg(conn, &msg, 0);
+
+	// parse FDS
+
+	return ret;
+}

util.h

+/*
+ * Copyright © 2019 Manuel Stoeckl
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining
+ * a copy of this software and associated documentation files (the
+ * "Software"), to deal in the Software without restriction, including
+ * without limitation the rights to use, copy, modify, merge, publish,
+ * distribute, sublicense, and/or sell copies of the Software, and to
+ * permit persons to whom the Software is furnished to do so, subject to
+ * the following conditions:
+ *
+ * The above copyright notice and this permission notice (including the
+ * next paragraph) shall be included in all copies or substantial
+ * portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
+ * EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
+ * MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
+ * NONINFRINGEMENT.  IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS
+ * BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN
+ * ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN
+ * CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+ * SOFTWARE.
+ */
+#ifndef WAYPIPE_UTIL_H
+#define WAYPIPE_UTIL_H
+
+#include <stdint.h>
+#include <stddef.h>
+
+int iovec_read(int socket, char* buf, size_t buflen, int* fds, int* numfds);
+int iovec_write(int conn, char* buf, size_t buflen, int* fds, int* numfds);
+
+#endif // WAYPIPE_UTIL_H