Try to close nicely, waiting for a real proto

Avoid pointer arithmetic on void *

Makefile.am

@@ -1,4 +1,13 @@
 bin_PROGRAMS = glorytun
-glorytun_SOURCES = src/common.h src/common-static.h src/main.c src/option.c src/option.h
 glorytun_CFLAGS = $(libsodium_CFLAGS)
 glorytun_LDADD = $(libsodium_LIBS)
+glorytun_SOURCES = \
+    src/common.h \
+    src/common-static.h \
+    src/common.c \
+    src/ip-static.h \
+    src/main.c \
+    src/option.c \
+    src/option.h \
+    src/tun.c \
+    src/tun.h

README.md

@@ -16,5 +16,5 @@ To build and install the latest version:
 
 To create and use a new secret key:
 
-    $ dd if=/dev/random iflag=fullblock of=glorytun.key bs=32 count=1
+    $ dd if=/dev/urandom of=glorytun.key bs=32 count=1
     # glorytun keyfile glorytun.key [...]

configure.ac

@@ -1,5 +1,5 @@
 AC_PREREQ([2.65])
-AC_INIT([glorytun], [0.0.1], [https://github.com/angt/glorytun/issues],
+AC_INIT([glorytun], [0.0.2], [https://github.com/angt/glorytun/issues],
         [glorytun], [https://github.com/angt/glorytun])
 AC_CONFIG_SRCDIR([src/common.h])
 AC_CONFIG_AUX_DIR([build-aux])

src/common.c

@@ -0,0 +1,27 @@
+#include "common.h"
+
+#include <stdio.h>
+#include <stdarg.h>
+
+void gt_log (const char *fmt, ...)
+{
+    va_list ap;
+    va_start(ap, fmt);
+    vfprintf(stderr, fmt, ap);
+    va_end(ap);
+}
+
+void gt_fatal (const char *fmt, ...)
+{
+    va_list ap;
+    va_start(ap, fmt);
+    vfprintf(stderr, fmt, ap);
+    va_end(ap);
+
+    exit(EXIT_FAILURE);
+}
+
+void gt_na (const char *name)
+{
+    gt_log("%s is not available on your platform!\n", name);
+}

src/common.h

@@ -14,6 +14,8 @@
 #define PALIGN(x)      ((void *)ALIGN((size_t)(x)))
 #define PALIGN_DOWN(x) ((void *)ALIGN_DOWN((size_t)(x)))
 
+#define _printf_(A,B)  __attribute__((format(printf,A,B)))
+#define _noreturn_     __attribute__((noreturn))
 #define _unused_       __attribute__((unused))
 
 typedef struct buffer buffer_t;
@@ -24,3 +26,7 @@ struct buffer {
     uint8_t *write;
     uint8_t *end;
 };
+
+void gt_log   (const char *, ...) _printf_(1,2);
+void gt_fatal (const char *, ...) _printf_(1,2) _noreturn_;
+void gt_na    (const char *);

src/ip-static.h

@@ -0,0 +1,30 @@
+#pragma once
+
+#include <stdint.h>
+
+static inline int ip_get_version (const uint8_t *data, size_t size)
+{
+    if (size<20)   // XXX
+        return -1; // XXX
+
+    return data[0]>>4;
+}
+
+static inline void ip_set_size (uint8_t *data, size_t size)
+{
+    data[2] = 0xFF&(size>>8);
+    data[3] = 0xFF&(size);
+}
+
+static inline ssize_t ip_get_size (const uint8_t *data, size_t size)
+{
+    switch (ip_get_version(data, size)) {
+    case 4:
+        return (data[2]<<8)|data[3];
+    case -1:
+        return -1;
+    }
+
+    return 0;
+}
+

src/main.c

@@ -1,27 +1,23 @@
-#include "common-static.h"
-#include "option.h"
-
 #include <inttypes.h>
 #include <stdio.h>
-#include <stdint.h>
 #include <signal.h>
 #include <poll.h>
 
 #include <sys/time.h>
-#include <sys/ioctl.h>
 #include <sys/fcntl.h>
 #include <sys/socket.h>
 #include <netinet/tcp.h>
 #include <arpa/inet.h>
 #include <netdb.h>
 
-#ifdef __linux__
-# include <linux/if.h>
-# include <linux/if_tun.h>
-#endif
-
 #include <sodium.h>
 
+#include "common-static.h"
+#include "ip-static.h"
+
+#include "option.h"
+#include "tun.h"
+
 #ifndef O_CLOEXEC
 #define O_CLOEXEC 0
 #endif
@@ -33,24 +29,18 @@ struct netio {
     int fd;
     struct {
         buffer_t buf;
-        ssize_t ret;
     } write, read;
 };
 
 struct crypto_ctx {
-    crypto_aead_aes256gcm_state state_r;
-    crypto_aead_aes256gcm_state state_w;
-    uint8_t nonce_r[crypto_aead_aes256gcm_NPUBBYTES];
-    uint8_t nonce_w[crypto_aead_aes256gcm_NPUBBYTES];
+    struct {
+        crypto_aead_aes256gcm_state state;
+        uint8_t nonce[crypto_aead_aes256gcm_NPUBBYTES];
+    } write, read;
     uint8_t skey[crypto_generichash_KEYBYTES];
 };
 
-volatile sig_atomic_t running;
-
-static void gt_not_available (const char *name)
-{
-    fprintf(stderr, "%s is not available on your platform!\n", name);
-}
+volatile sig_atomic_t gt_close = 0;
 
 static int64_t dt_ms (struct timeval *ta, struct timeval *tb)
 {
@@ -93,6 +83,14 @@ static void sk_set_reuseaddr (int fd)
         perror("setsockopt SO_REUSEADDR");
 }
 
+static void sk_set_keepalive (int fd)
+{
+    int val = 1;
+
+    if (setsockopt(fd, SOL_SOCKET, SO_KEEPALIVE, &val, sizeof(val))==-1)
+        perror("setsockopt SO_KEEPALIVE");
+}
+
 #ifdef TCP_CONGESTION
 static void sk_set_congestion (int fd, const char *name)
 {
@@ -107,7 +105,7 @@ static void sk_set_congestion (int fd, const char *name)
 #else
 static void sk_set_congestion (_unused_ int fd, _unused_ const char *name)
 {
-    gt_not_available("TCP_CONGESTION");
+    gt_na("TCP_CONGESTION");
 }
 #endif
 
@@ -222,8 +220,7 @@ static socklen_t sk_get_info (int fd, struct tcp_info *ti)
 
 static void print_tcp_info (const char *name, struct tcp_info *ti)
 {
-    fprintf(stderr,
-            "%s: tcpinfo"
+    gt_log("%s: tcpinfo"
             " rto:%"     PRIu32 " ato:%"          PRIu32 " snd_mss:%"  PRIu32
             " rcv_mss:%" PRIu32 " unacked:%"      PRIu32 " sacked:%"   PRIu32
             " lost:%"    PRIu32 " retrans:%"      PRIu32 " fackets:%"  PRIu32
@@ -243,7 +240,7 @@ static void print_tcp_info (const char *name, struct tcp_info *ti)
 static struct addrinfo *ai_create (const char *host, const char *port, int listener)
 {
     if (!port || !port[0]) {
-        fprintf(stderr, "port is not valid\n");
+        gt_log("port is not valid\n");
         return NULL;
     }
 
@@ -270,74 +267,21 @@ static struct addrinfo *ai_create (const char *host, const char *port, int liste
         break;
     case EAI_FAIL:
     case EAI_AGAIN:
-        fprintf(stderr, "the name server returned a failure\n");
+        gt_log("the name server returned a failure\n");
         break;
     default:
-        fprintf(stderr, "%s.%s is not valid\n", host?:"", port);
+        gt_log("%s.%s is not valid\n", host?:"", port);
     }
 
     return NULL;
 }
 
-#ifdef __linux__
-static int tun_create (char *name, int multiqueue)
-{
-    int fd = open("/dev/net/tun", O_RDWR);
-
-    if (fd<0) {
-        perror("open /dev/net/tun");
-        return -1;
-    }
-
-    struct ifreq ifr = {
-        .ifr_flags = IFF_TUN|IFF_NO_PI,
-    };
-
-    if (multiqueue) {
-#ifdef IFF_MULTI_QUEUE
-        ifr.ifr_flags |= IFF_MULTI_QUEUE;
-#else
-        gt_not_available("IFF_MULTI_QUEUE");
-#endif
-    }
-
-    str_cpy(ifr.ifr_name, name, IFNAMSIZ-1);
-
-    int ret = ioctl(fd, TUNSETIFF, &ifr);
-
-    if (ret<0) {
-        perror("ioctl TUNSETIFF");
-        return -1;
-    }
-
-    printf("tun name: %s\n", ifr.ifr_name);
-
-    return fd;
-}
-#else
-static int tun_create (_unused_ char *name, _unused_ int mq)
-{
-    for (unsigned dev_id = 0U; dev_id < 32U; dev_id++) {
-        char dev_path[11U];
-
-        snprintf(dev_path, sizeof(dev_path), "/dev/tun%u", dev_id);
-
-        int fd = open(dev_path, O_RDWR);
-
-        if (fd!=-1)
-            return fd;
-    }
-
-    return -1;
-}
-#endif
-
 static void gt_sa_stop (int sig)
 {
     switch (sig) {
     case SIGINT:
     case SIGTERM:
-        running = 0;
+        gt_close = 1;
     }
 }
 
@@ -346,7 +290,6 @@ static void gt_set_signal (void)
     struct sigaction sa;
 
     byte_set(&sa, 0, sizeof(sa));
-    running = 1;
 
     sa.sa_handler = gt_sa_stop;
     sigaction(SIGINT,  &sa, NULL);
@@ -407,7 +350,7 @@ static ssize_t fd_read_all (int fd, void *data, size_t size)
     };
 
     while (done<size) {
-        ssize_t ret = fd_read(fd, data+done, size-done);
+        ssize_t ret = fd_read(fd, (uint8_t *)data+done, size-done);
 
         if (!ret)
             break;
@@ -434,7 +377,7 @@ static ssize_t fd_write_all (int fd, const void *data, size_t size)
     };
 
     while (done<size) {
-        ssize_t ret = fd_write(fd, data+done, size-done);
+        ssize_t ret = fd_write(fd, (const uint8_t *)data+done, size-done);
 
         if (!ret)
             break;
@@ -466,10 +409,10 @@ static int encrypt_packet (struct crypto_ctx *ctx, uint8_t *packet, size_t size,
             buffer->write + hs, NULL,
             packet + hs, size - hs,
             packet, hs,
-            NULL, ctx->nonce_w,
-            (const crypto_aead_aes256gcm_state *)&ctx->state_w);
+            NULL, ctx->write.nonce,
+            (const crypto_aead_aes256gcm_state *)&ctx->write.state);
 
-    sodium_increment(ctx->nonce_w, crypto_aead_aes256gcm_NPUBBYTES);
+    sodium_increment(ctx->write.nonce, crypto_aead_aes256gcm_NPUBBYTES);
     buffer->write += ws;
 
     return 0;
@@ -491,11 +434,11 @@ static int decrypt_packet (struct crypto_ctx *ctx, uint8_t *packet, size_t size,
                 NULL,
                 buffer->read + hs, rs - hs,
                 packet, hs,
-                ctx->nonce_r,
-                (const crypto_aead_aes256gcm_state *)&ctx->state_r))
+                ctx->read.nonce,
+                (const crypto_aead_aes256gcm_state *)&ctx->read.state))
         return -1;
 
-    sodium_increment(ctx->nonce_r, crypto_aead_aes256gcm_NPUBBYTES);
+    sodium_increment(ctx->read.nonce, crypto_aead_aes256gcm_NPUBBYTES);
     buffer->read += rs;
 
     return 0;
@@ -516,24 +459,7 @@ static void dump_ip_header (uint8_t *data, size_t size)
 
     hex[40] = 0;
 
-    fprintf(stderr, "DUMP(%zu): %s\n", size, hex);
-}
-
-static void set_ip_size (uint8_t *data, size_t size)
-{
-    data[2] = 0xFF&(size>>8);
-    data[3] = 0xFF&(size);
-}
-
-static ssize_t get_ip_size (const uint8_t *data, size_t size)
-{
-    if (size<20)
-        return -1;
-
-    if ((data[0]>>4)==4)
-        return (data[2]<<8)|data[3];
-
-    return 0;
+    gt_log("DUMP(%zu): %s\n", size, hex);
 }
 
 static int gt_setup_secretkey (struct crypto_ctx *ctx, char *keyfile)
@@ -553,13 +479,11 @@ static int gt_setup_secretkey (struct crypto_ctx *ctx, char *keyfile)
     }
 
     if (fd_read_all(fd, ctx->skey, size)!=size) {
-        fprintf(stderr, "unable to read secret key in `%s'\n", keyfile);
+        gt_log("unable to read secret key in `%s'\n", keyfile);
         close(fd);
         return -1;
     }
 
-    // TODO: check key
-
     close(fd);
 
     return 0;
@@ -569,22 +493,25 @@ static int gt_setup_crypto (struct crypto_ctx *ctx, int fd, int listener)
 {
     const size_t nonce_size = crypto_aead_aes256gcm_NPUBBYTES;
     const size_t public_size = crypto_scalarmult_SCALARBYTES;
-    const size_t hkey_size = crypto_generichash_BYTES;
-    const size_t size = nonce_size + public_size + hkey_size;
+    const size_t hash_size = crypto_generichash_BYTES;
+    const size_t size = nonce_size + public_size + hash_size;
 
     uint8_t secret[crypto_scalarmult_SCALARBYTES];
     uint8_t shared[crypto_scalarmult_BYTES];
     uint8_t key[crypto_aead_aes256gcm_KEYBYTES];
 
     uint8_t data_r[size], data_w[size];
-    uint8_t hkey_c[hkey_size];
+    uint8_t auth_r[hash_size], auth_w[hash_size];
+    uint8_t hash[hash_size];
+
+    crypto_generichash_state state;
 
     randombytes_buf(data_w, nonce_size);
     randombytes_buf(secret, sizeof(secret));
     crypto_scalarmult_base(&data_w[nonce_size], secret);
 
-    crypto_generichash(&data_w[size-hkey_size], hkey_size,
-            data_w, size-hkey_size, ctx->skey, sizeof(ctx->skey));
+    crypto_generichash(&data_w[size-hash_size], hash_size,
+            data_w, size-hash_size, ctx->skey, sizeof(ctx->skey));
 
     if (!listener && fd_write_all(fd, data_w, size)!=size)
         return -1;
@@ -592,38 +519,53 @@ static int gt_setup_crypto (struct crypto_ctx *ctx, int fd, int listener)
     if (fd_read_all(fd, data_r, size)!=size)
         return -1;
 
-    crypto_generichash(hkey_c, hkey_size,
-            data_r, size-hkey_size, ctx->skey, sizeof(ctx->skey));
+    crypto_generichash(hash, hash_size,
+            data_r, size-hash_size, ctx->skey, sizeof(ctx->skey));
 
-    if (sodium_memcmp(&data_r[size-hkey_size], hkey_c, hkey_size))
+    if (sodium_memcmp(&data_r[size-hash_size], hash, hash_size))
         return -2;
 
     if (listener && fd_write_all(fd, data_w, size)!=size)
         return -1;
 
-    crypto_scalarmult(shared, secret, &data_r[nonce_size]);
+    crypto_generichash(auth_w, hash_size,
+            data_r, size, ctx->skey, sizeof(ctx->skey));
+
+    if (fd_write_all(fd, auth_w, hash_size)!=hash_size)
+        return -1;
+
+    if (fd_read_all(fd, auth_r, hash_size)!=hash_size)
+        return -1;
+
+    crypto_generichash(hash, hash_size,
+            data_w, size, ctx->skey, sizeof(ctx->skey));
+
+    if (sodium_memcmp(auth_r, hash, hash_size))
+        return -2;
+
+    if (crypto_scalarmult(shared, secret, &data_r[nonce_size]))
+        return -2;
 
-    crypto_generichash_state state;
     crypto_generichash_init(&state, ctx->skey, sizeof(ctx->skey), sizeof(key));
     crypto_generichash_update(&state, shared, sizeof(shared));
     crypto_generichash_update(&state, data_r, size);
     crypto_generichash_update(&state, data_w, size);
     crypto_generichash_final(&state, key, sizeof(key));
-    crypto_aead_aes256gcm_beforenm(&ctx->state_r, key);
+    crypto_aead_aes256gcm_beforenm(&ctx->read.state, key);
 
     crypto_generichash_init(&state, ctx->skey, sizeof(ctx->skey), sizeof(key));
     crypto_generichash_update(&state, shared, sizeof(shared));
     crypto_generichash_update(&state, data_w, size);
     crypto_generichash_update(&state, data_r, size);
     crypto_generichash_final(&state, key, sizeof(key));
-    crypto_aead_aes256gcm_beforenm(&ctx->state_w, key);
+    crypto_aead_aes256gcm_beforenm(&ctx->write.state, key);
 
     sodium_memzero(secret, sizeof(secret));
     sodium_memzero(shared, sizeof(shared));
     sodium_memzero(key, sizeof(key));
 
-    byte_cpy(ctx->nonce_r, data_r, nonce_size);
-    byte_cpy(ctx->nonce_w, data_w, nonce_size);
+    byte_cpy(ctx->read.nonce, data_r, nonce_size);
+    byte_cpy(ctx->write.nonce, data_w, nonce_size);
 
     return 0;
 }
@@ -640,6 +582,7 @@ int main (int argc, char **argv)
     char *congestion = NULL;
     int delay = 0;
     int multiqueue = 0;
+    int keepalive = 0;
     int version = 0;
     int debug = 0;
 
@@ -659,6 +602,7 @@ int main (int argc, char **argv)
         { "congestion", &congestion, option_str  },
         { "delay",      &delay,      option_flag },
         { "multiqueue", &multiqueue, option_flag },
+        { "keepalive",  &keepalive,  option_flag },
         { "debug",      &debug,      option_flag },
         { "version",    &version,    option_flag },
         { NULL },
@@ -673,12 +617,12 @@ int main (int argc, char **argv)
     }
 
     if (sodium_init()==-1) {
-        fprintf(stderr, "libsodium initialization has failed!\n");
+        gt_log("libsodium initialization has failed!\n");
         return 1;
     }
 
     if (!crypto_aead_aes256gcm_is_available()) {
-        gt_not_available("AES-256-GCM");
+        gt_na("AES-256-GCM");
         return 1;
     }
 
@@ -714,12 +658,12 @@ int main (int argc, char **argv)
             return 1;
     }
 
-    while (running) {
+    while (1) {
         sock.fd = listener?sk_accept(fd):sk_create(ai, sk_connect);
 
         if (sock.fd==-1) {
             usleep(100000);
-            continue;
+            goto restart;
         }
 
         char *sockname = sk_get_name(sock.fd);
@@ -727,25 +671,24 @@ int main (int argc, char **argv)
         if (!sockname)
             goto restart;
 
-        fprintf(stderr, "%s: connected\n", sockname);
+        gt_log("%s: connected\n", sockname);
 
         if (!delay)
             sk_set_nodelay(sock.fd);
 
         fd_set_nonblock(sock.fd);
+
+        if (keepalive)
+            sk_set_keepalive(sock.fd);
+
         sk_set_congestion(sock.fd, congestion);
 
         switch (gt_setup_crypto(&ctx, sock.fd, listener)) {
-            case -2: fprintf(stderr, "%s: key exchange could not be verified!\n", sockname);
+            case -2: gt_log("%s: key exchange could not be verified!\n", sockname);
             case -1: goto restart;
             default: break;
         }
 
-        struct pollfd fds[] = {
-            { .fd = tun.fd,  .events = POLLIN },
-            { .fd = sock.fd, .events = POLLIN },
-        };
-
         struct {
             uint8_t buf[2048];
             size_t size;
@@ -754,9 +697,30 @@ int main (int argc, char **argv)
         tunr.size = 0;
         tunw.size = 0;
 
-        while (running) {
-            if (poll(fds, COUNT(fds), -1)==-1 && errno!=EINTR) {
-                perror("poll");
+        fd_set rfds, wfds;
+        FD_ZERO(&rfds);
+        FD_ZERO(&wfds);
+
+        int stop_loop = 0;
+
+        while (1) {
+            if (gt_close)
+                stop_loop = 1;
+
+            if (stop_loop) {
+                if (((stop_loop>>1)==3) &&
+                    (buffer_read_size(&sock.write.buf)==0) &&
+                    (buffer_read_size(&sock.read.buf)==0))
+                    goto restart;
+                FD_CLR(tun.fd, &rfds);
+            } else {
+                FD_SET(tun.fd, &rfds);
+            }
+
+            FD_SET(sock.fd, &rfds);
+
+            if (select(sock.fd+1, &rfds, &wfds, NULL, NULL)==-1 && errno!=EINTR) {
+                perror("select");
                 return 1;
             }
 
@@ -773,12 +737,12 @@ int main (int argc, char **argv)
 
             buffer_shift(&sock.write.buf);
 
-            if (fds[0].revents & POLLIN) {
+            if (FD_ISSET(tun.fd, &rfds)) {
                 while (1) {
                     if (buffer_write_size(&sock.write.buf)<sizeof(tunr.buf)+16)
                         break;
 
-                    ssize_t r = fd_read(fds[0].fd, tunr.buf, sizeof(tunr.buf));
+                    ssize_t r = tun_read(tun.fd, tunr.buf, sizeof(tunr.buf));
 
                     if (!r)
                         return 2;
@@ -786,7 +750,7 @@ int main (int argc, char **argv)
                     if (r<0)
                         break;
 
-                    ssize_t ip_size = get_ip_size(tunr.buf, sizeof(tunr.buf));
+                    ssize_t ip_size = ip_get_size(tunr.buf, sizeof(tunr.buf));
 
                     if (ip_size<=0)
                         continue;
@@ -795,7 +759,7 @@ int main (int argc, char **argv)
                         dump_ip_header(tunr.buf, r);
 
                         if (r<ip_size) {
-                            set_ip_size(tunr.buf, r);
+                            ip_set_size(tunr.buf, r);
                         } else {
                             continue;
                         }
@@ -805,63 +769,73 @@ int main (int argc, char **argv)
                 }
             }
 
-            if (fds[1].revents & POLLOUT)
-                fds[1].events = POLLIN;
+            if (FD_ISSET(sock.fd, &wfds))
+                FD_CLR(sock.fd, &wfds);
 
             if (buffer_read_size(&sock.write.buf)) {
-                sock.write.ret = fd_write(fds[1].fd, sock.write.buf.read, buffer_read_size(&sock.write.buf));
+                ssize_t r = fd_write(sock.fd, sock.write.buf.read, buffer_read_size(&sock.write.buf));
 
-                if (!sock.write.ret)
-                    goto restart;
+                if (r==-1)
+                    FD_SET(sock.fd, &wfds);
 
-                if (sock.write.ret==-1)
-                    fds[1].events = POLLIN|POLLOUT;
+                if (!r) {
+                    stop_loop |= (1<<2);
+                    buffer_format(&sock.write.buf);
+                }
 
-                if (sock.write.ret>0)
-                    sock.write.buf.read += sock.write.ret;
+                if (r>0)
+                    sock.write.buf.read += r;
+            } else {
+                if (stop_loop) {
+                    stop_loop |= (1<<2);
+                    shutdown(sock.fd, SHUT_WR);
+                }
             }
 
             buffer_shift(&sock.read.buf);
 
-            if (fds[1].revents & POLLIN) {
-                sock.read.ret = fd_read(fds[1].fd, sock.read.buf.write, buffer_write_size(&sock.read.buf));
+            if (FD_ISSET(sock.fd, &rfds)) {
+                ssize_t r = fd_read(sock.fd, sock.read.buf.write, buffer_write_size(&sock.read.buf));
 
-                if (!sock.read.ret)
-                    goto restart;
+                if (!r)
+                    stop_loop |= (1<<1);
 
-                if (sock.read.ret>0)
-                    sock.read.buf.write += sock.read.ret;
+                if (r>0)
+                    sock.read.buf.write += r;
             }
 
-            if (fds[0].revents & POLLOUT)
-                fds[0].events = POLLIN;
+            if (FD_ISSET(tun.fd, &wfds))
+                FD_CLR(tun.fd, &wfds);
 
             while (1) {
                 if (!tunw.size) {
                     size_t size = buffer_read_size(&sock.read.buf);
-                    ssize_t ip_size = get_ip_size(sock.read.buf.read, size);
+                    ssize_t ip_size = ip_get_size(sock.read.buf.read, size);
 
                     if (!ip_size)
                         goto restart;
 
-                    if (ip_size<0 || (size_t)ip_size+16>size)
+                    if (ip_size<0 || (size_t)ip_size+16>size) {
+                        if (stop_loop&(1<<1))
+                            buffer_format(&sock.read.buf);
                         break;
+                    }
 
                     if (decrypt_packet(&ctx, tunw.buf, ip_size, &sock.read.buf)) {
-                        fprintf(stderr, "%s: message could not be verified!\n", sockname);
+                        gt_log("%s: message could not be verified!\n", sockname);
                         goto restart;
                     }
 
                     tunw.size = ip_size;
                 }
                 if (tunw.size) {
-                    ssize_t r = fd_write(fds[0].fd, tunw.buf, tunw.size);
+                    ssize_t r = tun_write(tun.fd, tunw.buf, tunw.size);
 
                     if (!r)
                         return 2;
 
                     if (r==-1)
-                        fds[0].events = POLLIN|POLLOUT;
+                        FD_SET(tun.fd, &wfds);
 
                     if (r<0)
                         break;
@@ -877,8 +851,13 @@ int main (int argc, char **argv)
             sockname = NULL;
         }
 
-        close(sock.fd);
-        sock.fd = -1;
+        if (sock.fd!=-1) {
+            close(sock.fd);
+            sock.fd = -1;
+        }
+
+        if (gt_close)
+            break;
     }
 
     freeaddrinfo(ai);

src/tun.c

@@ -0,0 +1,205 @@
+#include "common-static.h"
+#include "ip-static.h"
+
+#include "tun.h"
+
+#include <stdio.h>
+#include <fcntl.h>
+
+#include <sys/ioctl.h>
+#include <sys/socket.h>
+#include <sys/uio.h>
+
+#ifdef __linux__
+# include <linux/if.h>
+# include <linux/if_tun.h>
+#endif
+
+#ifdef __APPLE__
+# include <sys/sys_domain.h>
+# include <sys/kern_control.h>
+# include <net/if_utun.h>
+#endif
+
+#if defined(__APPLE__) || defined(__OpenBSD__)
+# define GT_BSD_TUN 1
+#endif
+
+#ifdef __linux__
+int tun_create (char *name, int multiqueue)
+{
+    int fd = open("/dev/net/tun", O_RDWR);
+
+    if (fd<0) {
+        perror("open /dev/net/tun");
+        return -1;
+    }
+
+    struct ifreq ifr = {
+        .ifr_flags = IFF_TUN|IFF_NO_PI,
+    };
+
+    if (multiqueue) {
+#ifdef IFF_MULTI_QUEUE
+        ifr.ifr_flags |= IFF_MULTI_QUEUE;
+#else
+        gt_na("IFF_MULTI_QUEUE");
+#endif
+    }
+
+    str_cpy(ifr.ifr_name, name, IFNAMSIZ-1);
+
+    int ret = ioctl(fd, TUNSETIFF, &ifr);
+
+    if (ret<0) {
+        perror("ioctl TUNSETIFF");
+        return -1;
+    }
+
+    printf("tun name: %s\n", ifr.ifr_name);
+
+    return fd;
+}
+#elif defined(__APPLE__)
+int tun_create (_unused_ char *name, _unused_ int mq)
+{
+    struct ctl_info ctlInfo;
+    struct sockaddr_ctl sc;
+    int fd;
+
+    for (unsigned dev_id = 0U; dev_id<32U; dev_id++) {
+        byte_set(&ctlInfo, 0, sizeof(ctlInfo));
+        str_cpy(ctlInfo.ctl_name, UTUN_CONTROL_NAME, sizeof(ctlInfo.ctl_name));
+        fd = socket(PF_SYSTEM, SOCK_DGRAM, SYSPROTO_CONTROL);
+
+        if (fd==-1)
+            return -1;
+
+        if (ioctl(fd, CTLIOCGINFO, &ctlInfo)==-1) {
+            close(fd);
+            continue;
+        }
+
+        sc.sc_id = ctlInfo.ctl_id;
+        sc.sc_len = sizeof(sc);
+        sc.sc_family = AF_SYSTEM;
+        sc.ss_sysaddr = AF_SYS_CONTROL;
+        sc.sc_unit = dev_id+1;
+
+        if (connect(fd, (struct sockaddr *) &sc, sizeof(sc))==-1) {
+            close(fd);
+            continue;
+        }
+
+        printf("tun name: /dev/utun%u\n", dev_id);
+
+        return fd;
+    }
+
+    return -1;
+}
+#else
+int tun_create (_unused_ char *name, _unused_ int mq)
+{
+    for (unsigned dev_id = 0U; dev_id<32U; dev_id++) {
+        char dev_path[11U];
+
+        snprintf(dev_path, sizeof(dev_path), "/dev/tun%u", dev_id);
+
+        int fd = open(dev_path, O_RDWR);
+
+        if (fd!=-1) {
+            printf("tun name: /dev/tun%u\n", dev_id);
+            return fd;
+        }
+    }
+
+    return -1;
+}
+#endif
+
+ssize_t tun_read (int fd, void *data, size_t size)
+{
+    if (!size)
+        return -2;
+
+#ifdef GT_BSD_TUN
+    uint32_t family;
+    struct iovec iov[2] = {
+        { .iov_base = &family, .iov_len = sizeof(family) },
+        { .iov_base = data, .iov_len = size }
+    };
+
+    ssize_t ret = readv(fd, iov, 2);
+#else
+    ssize_t ret = read(fd, data, size);
+#endif
+
+    if (ret==-1) {
+        if (errno==EAGAIN || errno==EINTR)
+            return -1;
+
+        if (errno)
+            perror("readv");
+
+        return 0;
+    }
+
+#ifdef GT_BSD_TUN
+    if (ret<(ssize_t) sizeof(family))
+        return 0;
+
+    return ret-sizeof(family);
+#else
+    return ret;
+#endif
+}
+
+ssize_t tun_write (int fd, const void *data, size_t size)
+{
+    if (!size)
+        return -2;
+
+#ifdef GT_BSD_TUN
+    uint32_t family;
+
+    switch (ip_get_version(data, size)) {
+    case 4:
+        family = htonl(AF_INET);
+        break;
+    case 6:
+        family = htonl(AF_INET6);
+        break;
+    default:
+        return -1;
+    }
+
+    struct iovec iov[2] = {
+        { .iov_base = &family, .iov_len = sizeof(family) },
+        { .iov_base = (void *) data, .iov_len = size },
+    };
+
+    ssize_t ret = writev(fd, iov, 2);
+#else
+    ssize_t ret = write(fd, data, size);
+#endif
+
+    if (ret==-1) {
+        if (errno==EAGAIN || errno==EINTR)
+            return -1;
+
+        if (errno)
+            perror("write");
+
+        return 0;
+    }
+
+#ifdef GT_BSD_TUN
+    if (ret<(ssize_t) sizeof(family))
+        return 0;
+
+    return ret-sizeof(family);
+#else
+    return ret;
+#endif
+}

src/tun.h

@@ -0,0 +1,7 @@
+#pragma once
+
+#include <unistd.h>
+
+int     tun_create (char *, int);
+ssize_t tun_read   (int, void *, size_t);
+ssize_t tun_write  (int, const void *, size_t);