Poor man's virtualization of ntp

diff --git a/fd_myntp.c b/fd_myntp.c
new file mode 100644 (file)
index 0000000..5c29c98
--- /dev/null
+++ b/fd_myntp.c
@@ -0,0 +1,138 @@
+#include <sys/types.h>
+#include <sys/socket.h>
+#include <sys/mount.h>
+#include <stdlib.h>
+#include <stdio.h>
+#include <errno.h>
+#include <string.h>
+#include "fdpass.h"
+
+unsigned int rcvbuf = 16*1024*1024;
+unsigned int arg_length = 128;
+unsigned int mountflags = MS_NODEV | MS_NOSUID;
+
+FILE *logfd;
+
+void receive_argument(int control_channel_fd, char *source) {
+    int received;
+    received=recv(control_channel_fd, source, arg_length, 0);
+    if (received<arg_length) {
+        fprintf(logfd,"Error receiving arguments over the control buffer\n");
+        close(logfd);
+        exit(1);
+    }
+}
+
+int set_magic_fd (char *data, int new_fd) {
+    char *ptr;
+    int fd;
+
+    data[arg_length-1]='\0';
+    ptr = strstr(data,"fd=");
+    if (!ptr)
+        return -1;
+
+    // Found two fd= expressions
+    if (strstr(ptr+3,"fd="))
+        return -1;
+
+    if (*(ptr+3)!='\0') {
+        char *new_data = (char *) malloc(arg_length);
+        char *head = (char *) malloc(arg_length);
+        char *tail;
+        sscanf(ptr+3,"%d",&fd);
+        strncpy(head, data, ptr - data);
+        tail = strchr(ptr+3,',');
+        sprintf(new_data,"%sfd=%d%s",head,new_fd,tail);
+        strcpy(data,new_data);
+        free(head);
+        free(new_data);
+        return fd;
+    }
+    else
+        return -1;
+}
+
+void check_source(char *source) {
+    source[arg_length-1]='\0';
+    if (strchr(source,'/') || strstr(source,"..")) {
+        fprintf(logfd, "Tried mounting with source = %s\n", source);
+        close(logfd);
+        exit(1);
+    }
+}
+
+void check_target(char *target) {
+    target[arg_length-1]='\0';
+    if (strstr(target,"..")) {
+        fprintf(logfd,"Tried mounting with target = %s\n", target);
+        close(logfd);
+        exit(1);
+    }
+}
+
+void check_fstype(char *filesystemtype) {
+    if (strncmp(filesystemtype,"fuse",4)) {
+        fprintf(logfd,"Tried mounting filesystem type %s\n", filesystemtype);
+        close(logfd);
+        exit(1);
+    }
+}
+
+int main(int argc, char *argv[]) {
+    int control_channel_fd, magic_fd, mount_fd;
+    char source[128],target[128],filesystemtype[128],data[128],slice_target[1024];
+
+    int received;
+
+    if (argc < 3) {
+        printf("This script is called by vsys.\n");
+        exit(1);
+    }
+
+    char *slice_name = argv[1];
+
+    logfd=fopen("/tmp/fuselog","w");
+    if (!logfd) {logfd = stderr;}
+    
+    sscanf(argv[2],"%d", &control_channel_fd);
+
+    if (control_channel_fd <3 || control_channel_fd > 1023) {
+        printf ("Got control_channel_fd = %d\n", control_channel_fd);
+        exit(1);
+    }
+
+    receive_argument(control_channel_fd, source);
+    receive_argument(control_channel_fd, target);
+    receive_argument(control_channel_fd, filesystemtype);
+    receive_argument(control_channel_fd, data);
+
+    mount_fd = receive_fd (control_channel_fd);
+
+    if (mount_fd < 2) {
+        printf("mount_fd = %d\n", mount_fd);
+        exit(1);
+    }
+
+    set_magic_fd(data, mount_fd);
+
+
+    check_source(source);
+    check_target(target);
+    check_fstype(filesystemtype);
+
+    sprintf(slice_target,"/vservers/%s/%s", slice_name, target);
+
+    fprintf(logfd, "Mount fd: %d Source: %s slice_target: %s fstype: %s mountflags: %d data: %s\n", mount_fd, source, slice_target, filesystemtype, mountflags, data);
+
+    if (!mount(source, slice_target, filesystemtype, mountflags, data)) {
+        send_fd(control_channel_fd, mount_fd);
+    }
+    else {
+        printf ("Error executing mount\n");
+        exit(1);
+    }
+
+    close(logfd);
+    return 0;
+}