add tunctl

CMakeLists.txt

@@ -31,8 +31,10 @@ build_switch(TUN2SOCKS 1)
 build_switch(UDPGW 1)
 if (CMAKE_SYSTEM_NAME STREQUAL "Linux")
     build_switch(NCD 1)
+    build_switch(TUNCTL 1)
 else ()
     build_switch(NCD 0)
+    build_switch(TUNCTL 0)
 endif ()
 
 if (BUILD_NCD AND NOT (CMAKE_SYSTEM_NAME STREQUAL "Linux"))
@@ -229,6 +231,9 @@ if (BUILD_TUN2SOCKS)
     add_subdirectory(udpgw_client)
     add_subdirectory(lwip)
 endif ()
+if (BUILD_TUNCTL)
+    add_subdirectory(tunctl)
+endif ()
 
 # example programs
 if (BUILD_EXAMPLES)

tunctl/CMakeLists.txt

@@ -0,0 +1,6 @@
+add_executable(badvpn-tunctl tunctl.c)
+
+install(
+    TARGETS badvpn-tunctl
+    RUNTIME DESTINATION bin
+)

tunctl/tunctl.c

@@ -0,0 +1,352 @@
+#include <stdio.h>
+#include <string.h>
+#include <stdlib.h>
+#include <unistd.h>
+#include <fcntl.h>
+#include <sys/ioctl.h>
+#include <net/if.h>
+#include <linux/if_tun.h>
+#include <pwd.h>
+#include <grp.h>
+
+#include <misc/version.h>
+#include <misc/open_standard_streams.h>
+
+#define PROGRAM_NAME "tunctl"
+
+#define TUN_DEVNODE "/dev/net/tun"
+
+struct {
+    int help;
+    int version;
+    int op;
+    char *device_name;
+    char *user;
+    char *group;
+} options;
+
+#define OP_MKTUN 1
+#define OP_MKTAP 2
+#define OP_RMTUN 3
+#define OP_RMTAP 4
+
+static void print_help (const char *name);
+static void print_version (void);
+static int parse_arguments (int argc, char *argv[]);
+static int make_tuntap (const char *ifname, int is_tun, const char *user, const char *group);
+static int remove_tuntap (const char *ifname, int is_tun);
+
+int main (int argc, char *argv[])
+{
+    int res = 1;
+    
+    // open standard streams
+    open_standard_streams();
+    
+    // parse command-line arguments
+    if (!parse_arguments(argc, argv)) {
+        fprintf(stderr, "Error: Failed to parse arguments\n");
+        print_help(argv[0]);
+        goto fail0;
+    }
+    
+    // handle --help and --version
+    if (options.help) {
+        print_version();
+        print_help(argv[0]);
+        return 0;
+    }
+    if (options.version) {
+        print_version();
+        return 0;
+    }
+    
+    if (options.op == OP_MKTUN || options.op == OP_MKTAP) {
+        if (!options.user && !options.group) {
+            fprintf(stderr, "WARNING: with neither --user nor --group, anyone will be able to use the device!\n");
+        }
+        res = !make_tuntap(options.device_name, options.op == OP_MKTUN, options.user, options.group);
+    } else {
+        res = !remove_tuntap(options.device_name, options.op == OP_RMTUN);
+    }
+    
+fail0:
+    return res;
+}
+
+void print_help (const char *name)
+{
+    printf(
+        "Usage:\n"
+        "    %s [--help] [--version]\n"
+        "    %s --mktun <device_name> [--user <username>] [--group <groupname>]\n"
+        "    %s --mktap <device_name> [--user <username>] [--group <groupname>]\n"
+        "    %s --rmtun <device_name>\n"
+        "    %s --rmtap <device_name>\n",
+        name, name, name, name, name
+    );
+}
+
+void print_version (void)
+{
+    printf(GLOBAL_PRODUCT_NAME" "PROGRAM_NAME" "GLOBAL_VERSION"\n"GLOBAL_COPYRIGHT_NOTICE"\n");
+}
+
+int parse_arguments (int argc, char *argv[])
+{
+    if (argc <= 0) {
+        return 0;
+    }
+    
+    options.help = 0;
+    options.version = 0;
+    options.op = -1;
+    options.device_name = NULL;
+    options.user = NULL;
+    options.group = NULL;
+    
+    for (int i = 1; i < argc; i++) {
+        char *arg = argv[i];
+        if (!strcmp(arg, "--help")) {
+            options.help = 1;
+        }
+        else if (!strcmp(arg, "--version")) {
+            options.version = 1;
+        }
+        else if (!strcmp(arg, "--mktun")) {
+            if (1 >= argc - i) {
+                fprintf(stderr, "%s: requires an argument\n", arg);
+                return 0;
+            }
+            if (options.op >= 0) {
+                fprintf(stderr, "%s: can only do one operation\n", arg);
+                return 0;
+            }
+            options.op = OP_MKTUN;
+            options.device_name = argv[i + 1];
+            i++;
+        }
+        else if (!strcmp(arg, "--mktap")) {
+            if (1 >= argc - i) {
+                fprintf(stderr, "%s: requires an argument\n", arg);
+                return 0;
+            }
+            if (options.op >= 0) {
+                fprintf(stderr, "%s: can only do one operation\n", arg);
+                return 0;
+            }
+            options.op = OP_MKTAP;
+            options.device_name = argv[i + 1];
+            i++;
+        }
+        else if (!strcmp(arg, "--rmtun")) {
+            if (1 >= argc - i) {
+                fprintf(stderr, "%s: requires an argument\n", arg);
+                return 0;
+            }
+            if (options.op >= 0) {
+                fprintf(stderr, "%s: can only do one operation\n", arg);
+                return 0;
+            }
+            options.op = OP_RMTUN;
+            options.device_name = argv[i + 1];
+            i++;
+        }
+        else if (!strcmp(arg, "--rmtap")) {
+            if (1 >= argc - i) {
+                fprintf(stderr, "%s: requires an argument\n", arg);
+                return 0;
+            }
+            if (options.op >= 0) {
+                fprintf(stderr, "%s: can only do one operation\n", arg);
+                return 0;
+            }
+            options.op = OP_RMTAP;
+            options.device_name = argv[i + 1];
+            i++;
+        }
+        else if (!strcmp(arg, "--user")) {
+            if (1 >= argc - i) {
+                fprintf(stderr, "%s: requires an argument\n", arg);
+                return 0;
+            }
+            options.user = argv[i + 1];
+            i++;
+        }
+        else if (!strcmp(arg, "--group")) {
+            if (1 >= argc - i) {
+                fprintf(stderr, "%s: requires an argument\n", arg);
+                return 0;
+            }
+            options.group = argv[i + 1];
+            i++;
+        }
+        else {
+            fprintf(stderr, "unknown option: %s\n", arg);
+            return 0;
+        }
+    }
+    
+    if (options.help || options.version) {
+        return 1;
+    }
+    
+    if (options.op < 0) {
+        fprintf(stderr, "--mktun, --mktap --rmtun or --rmtap is required\n");
+        return 0;
+    }
+    
+    if ((options.user || options.group) && options.op != OP_MKTUN && options.op != OP_MKTAP) {
+        fprintf(stderr, "--user and --group only make sense for --mktun and --mktap\n");
+        return 0;
+    }
+    
+    return 1;
+}
+
+static int make_tuntap (const char *ifname, int is_tun, const char *user, const char *group)
+{
+    int res = 0;
+    
+    if (strlen(ifname) >= IFNAMSIZ) {
+        fprintf(stderr, "Error: ifname too long\n");
+        goto fail0;
+    }
+    
+    int fd = open(TUN_DEVNODE, O_RDWR);
+    if (fd < 0) {
+        perror("open");
+        fprintf(stderr, "Error: open tun failed\n");
+        goto fail0;
+    }
+    
+    struct ifreq ifr;
+    memset(&ifr, 0, sizeof(ifr));
+    ifr.ifr_flags = (is_tun ? IFF_TUN : IFF_TAP);
+    snprintf(ifr.ifr_name, IFNAMSIZ, "%s", ifname);
+    
+    if (ioctl(fd, TUNSETIFF, (void *)&ifr) < 0) {
+        perror("ioctl(TUNSETIFF)");
+        fprintf(stderr, "Error: TUNSETIFF failed\n");
+        goto fail1;
+    }
+    
+    uid_t uid = -1;
+    gid_t gid = -1;
+    
+    if (user) {
+        long bufsize = sysconf(_SC_GETPW_R_SIZE_MAX);
+        if (bufsize < 0) {
+            bufsize = 16384;
+        }
+        
+        char *buf = malloc(bufsize);
+        if (!buf) {
+            fprintf(stderr, "Error: malloc failed\n");
+            goto fail1;
+        }
+        
+        struct passwd pwd;
+        struct passwd *res;
+        getpwnam_r(user, &pwd, buf, bufsize, &res);
+        if (!res) {
+            fprintf(stderr, "Error: getpwnam_r failed\n");
+            free(buf);
+            goto fail1;
+        }
+        
+        uid = pwd.pw_uid;
+        free(buf);
+    }
+    
+    if (group) {
+        long bufsize = sysconf(_SC_GETGR_R_SIZE_MAX);
+        if (bufsize < 0) {
+            bufsize = 16384;
+        }
+        
+        char *buf = malloc(bufsize);
+        if (!buf) {
+            fprintf(stderr, "Error: malloc failed\n");
+            goto fail1;
+        }
+        
+        struct group grp;
+        struct group *res;
+        getgrnam_r(group, &grp, buf, bufsize, &res);
+        if (!res) {
+            fprintf(stderr, "Error: getgrnam_r failed\n");
+            free(buf);
+            goto fail1;
+        }
+        
+        gid = grp.gr_gid;
+        free(buf);
+    }
+    
+    if (ioctl(fd, TUNSETOWNER, uid) < 0) {
+        perror("ioctl(TUNSETOWNER)");
+        fprintf(stderr, "Error: TUNSETOWNER failed\n");
+        goto fail1;
+    }
+    
+    if (ioctl(fd, TUNSETGROUP, gid) < 0) {
+        perror("ioctl(TUNSETGROUP)");
+        fprintf(stderr, "Error: TUNSETGROUP failed\n");
+        goto fail1;
+    }
+    
+    if (ioctl(fd, TUNSETPERSIST, (void *)1) < 0) {
+        perror("ioctl(TUNSETPERSIST)");
+        fprintf(stderr, "Error: TUNSETPERSIST failed\n");
+        goto fail1;
+    }
+    
+    res = 1;
+    
+fail1:
+    close(fd);
+fail0:
+    return res;
+}
+
+static int remove_tuntap (const char *ifname, int is_tun)
+{
+    int res = 0;
+    
+    if (strlen(ifname) >= IFNAMSIZ) {
+        fprintf(stderr, "Error: ifname too long\n");
+        goto fail0;
+    }
+    
+    int fd = open(TUN_DEVNODE, O_RDWR);
+    if (fd < 0) {
+        perror("open");
+        fprintf(stderr, "Error: open tun failed\n");
+        goto fail0;
+    }
+    
+    struct ifreq ifr;
+    memset(&ifr, 0, sizeof(ifr));
+    ifr.ifr_flags = (is_tun ? IFF_TUN : IFF_TAP);
+    snprintf(ifr.ifr_name, IFNAMSIZ, "%s", ifname);
+    
+    if (ioctl(fd, TUNSETIFF, (void *)&ifr) < 0) {
+        perror("ioctl(TUNSETIFF)");
+        fprintf(stderr, "Error: TUNSETIFF failed\n");
+        goto fail1;
+    }
+    
+    if (ioctl(fd, TUNSETPERSIST, (void *)0) < 0) {
+        perror("ioctl(TUNSETPERSIST)");
+        fprintf(stderr, "Error: TUNSETPERSIST failed\n");
+        goto fail1;
+    }
+    
+    res = 1;
+    
+fail1:
+    close(fd);
+fail0:
+    return res;
+}