Refuse to start the client without keyfile

.travis.yml

@@ -29,3 +29,7 @@ deploy:
     on:
         tags: true
         repo: angt/glorytun
+        condition: "${TRAVIS_OS_NAME}-${CC} == linux-gcc"
+
+after_deploy:
+    - md5sum glorytun-*.tar.gz

README.md

@@ -1,8 +1,12 @@
 # Glorytun
 
-Small, Simple and Stupid **TCP** VPN.
+Small, Simple and Stupid TCP VPN.
 
-**Work In Progress:** Do not touch! This code will probably format your harddisk!
+#### Work In Progress
+
+This code will probably format your harddisk!
+
+#### Build and Install
 
 Glorytun depends on [libsodium](https://github.com/jedisct1/libsodium) version >= 1.0.4
 and needs an AES-NI capable CPU.
@@ -16,7 +20,4 @@ To build and install the latest version:
     $ make
     # make install
 
-To create and use a new secret key:
-
-    $ dd if=/dev/urandom of=glorytun.key bs=32 count=1
-    # glorytun keyfile glorytun.key [...]
+For feature requests and bug reports, please create an [issue](https://github.com/angt/glorytun/issues).

src/common-static.h

@@ -18,7 +18,7 @@ static inline void byte_set (void *dst, const char value, size_t size)
 
 static inline void byte_cpy (void *dst, const void *src, size_t size)
 {
-    if (!dst || !src)
+    if (!dst)
         return;
 
     char *restrict d = dst;
@@ -43,6 +43,13 @@ static inline size_t str_cpy (char *restrict dst, const char *restrict src, size
     return i;
 }
 
+_pure_
+static inline int str_empty (const char *restrict str)
+{
+    return !str || !str[0];
+}
+
+_pure_
 static inline int str_cmp (const char *restrict sa, const char *restrict sb)
 {
     if (!sa || !sb)
@@ -55,6 +62,7 @@ static inline int str_cmp (const char *restrict sa, const char *restrict sb)
     return 1;
 }
 
+_pure_
 static inline size_t str_len (const char *restrict str)
 {
     if (!str)
@@ -111,16 +119,19 @@ static inline void buffer_format (buffer_t *buffer)
     buffer->read  = buffer->data;
 }
 
+_pure_
 static inline size_t buffer_size (buffer_t *buffer)
 {
     return buffer->end-buffer->data;
 }
 
+_pure_
 static inline size_t buffer_write_size (buffer_t *buffer)
 {
     return buffer->end-buffer->write;
 }
 
+_pure_
 static inline size_t buffer_read_size (buffer_t *buffer)
 {
     return buffer->write-buffer->read;

src/common.c

@@ -38,3 +38,59 @@ void gt_na (const char *name)
 {
     gt_log("%s is not available on your platform!\n", name);
 }
+
+int gt_tohex (char *dst, size_t dst_size, const uint8_t *src, size_t src_size)
+{
+    if _0_(!dst_size)
+        return -1;
+
+    if _0_(((dst_size-1)/2)<src_size)
+        return -1;
+
+    static const char tbl[] = "0123456789ABCDEF";
+
+    for (size_t i=0; i<src_size; i++) {
+        *dst++ = tbl[0xF&(src[i]>>4)];
+        *dst++ = tbl[0xF&(src[i])];
+    }
+
+    *dst = 0;
+
+    return 0;
+}
+
+_const_
+static inline int fromhex (const char c)
+{
+    if (c>='0' && c<='9')
+        return c-'0';
+
+    if (c>='A' && c<='F')
+        return c-'A'+10;
+
+    if (c>='a' && c<='f')
+        return c-'a'+10;
+
+    return -1;
+}
+
+int gt_fromhex (uint8_t *dst, size_t dst_size, const char *src, size_t src_size)
+{
+    if _0_(src_size&1)
+        return -1;
+
+    if _0_(dst_size<(src_size/2))
+        return -1;
+
+    for (size_t i=0; i<src_size; i+=2) {
+        const int a = fromhex(src[i]);
+        const int b = fromhex(src[i+1]);
+
+        if _0_(a==-1 || b==-1)
+            return -1;
+
+        *dst++ = (a<<4)|b;
+    }
+
+    return 0;
+}

src/common.h

@@ -20,6 +20,8 @@
 #define _printf_(A,B)  __attribute__((format(printf,A,B)))
 #define _noreturn_     __attribute__((noreturn))
 #define _unused_       __attribute__((unused))
+#define _pure_         __attribute__((pure))
+#define _const_        __attribute__((const))
 #define _align_(...)   __attribute__((aligned(__VA_ARGS__)))
 
 typedef struct buffer buffer_t;
@@ -35,3 +37,6 @@ int  gt_print (const char *, ...) _printf_(1,2);
 void gt_log   (const char *, ...) _printf_(1,2);
 void gt_fatal (const char *, ...) _printf_(1,2) _noreturn_;
 void gt_na    (const char *);
+
+int gt_tohex   (char *, size_t, const uint8_t *, size_t);
+int gt_fromhex (uint8_t *, size_t, const char *, size_t);

src/ip-static.h

@@ -2,6 +2,7 @@
 
 #include <stdint.h>
 
+_pure_
 static inline int ip_get_version (const uint8_t *data, size_t size)
 {
     if (size<20)   // XXX
@@ -10,17 +11,14 @@ static inline int ip_get_version (const uint8_t *data, size_t size)
     return data[0]>>4;
 }
 
-static inline void ip_set_size (uint8_t *data, size_t size)
+_pure_
+static inline ssize_t ip_get_size (const int ip_version, const 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)) {
+    switch (ip_version) {
     case 4:
-        return (data[2]<<8)|data[3];
+        return ((data[2]<<8)|data[3]);
+    case 6:
+        return ((data[4]<<8)|data[5])+40;
     case -1:
         return -1;
     }
@@ -28,11 +26,31 @@ static inline ssize_t ip_get_size (const uint8_t *data, size_t size)
     return 0;
 }
 
-static inline int ip_get_dscp (const uint8_t *data, size_t size)
+_pure_
+static inline ssize_t ip_get_proto (const int ip_version, const uint8_t *data, size_t size)
 {
-    switch (ip_get_version(data, size)) {
+    switch (ip_version) {
     case 4:
-        return data[1]>>2;
+        return data[9];
+    case 6:
+        return data[6];
+    case -1:
+        return -1;
+    }
+
+    return 0;
+}
+
+_pure_
+static inline ssize_t ip_get_hdr_size (const int ip_version, const uint8_t *data, size_t size)
+{
+    switch (ip_version) {
+    case 4:
+        return (data[0]&0xF)<<2;
+    case 6:
+        return 40;
+    case -1:
+        return -1;
     }
 
     return 0;

src/main.c

@@ -5,8 +5,21 @@
 #include <poll.h>
 #include <sys/time.h>
 #include <sys/fcntl.h>
-#include <sys/socket.h>
+
+#ifndef __FAVOR_BSD
+#define __FAVOR_BSD
+#define GT_FAKE_BSD
+#endif
+
+#include <netinet/in.h>
 #include <netinet/tcp.h>
+#include <netinet/udp.h>
+
+#ifdef GT_FAKE_BSD
+#undef GT_FAKE_BSD
+#undef __FAVOR_BSD
+#endif
+
 #include <arpa/inet.h>
 #include <netdb.h>
 
@@ -50,6 +63,7 @@ struct crypto_ctx {
 volatile sig_atomic_t gt_close = 0;
 volatile sig_atomic_t gt_info = 0;
 
+_pure_
 static int64_t dt_ms (struct timeval *ta, struct timeval *tb)
 {
     const int64_t s = ta->tv_sec-tb->tv_sec;
@@ -84,6 +98,7 @@ enum sk_opt {
     sk_keepintvl,
     sk_congestion,
     sk_defer_accept,
+    sk_acceptfilter,
     sk_quickack,
 };
 
@@ -129,6 +144,11 @@ static void sk_set (int fd, enum sk_opt opt, const void *val, socklen_t len)
         [sk_quickack] = { "TCP_QUICKACK",
 #ifdef TCP_QUICKACK
             1, IPPROTO_TCP, TCP_QUICKACK,
+#endif
+        },
+        [sk_acceptfilter] = { "SO_ACCEPTFILTER",
+#ifdef SO_ACCEPTFILTER
+            1, SOL_SOCKET, SO_ACCEPTFILTER,
 #endif
         },
     };
@@ -151,21 +171,23 @@ static int sk_listen (int fd, struct addrinfo *ai)
 {
     sk_set_int(fd, sk_reuseaddr, 1);
 
-    int ret = bind(fd, ai->ai_addr, ai->ai_addrlen);
-
-    if (ret==-1) {
+    if (bind(fd, ai->ai_addr, ai->ai_addrlen)==-1) {
         perror("bind");
         return -1;
     }
 
-    ret = listen(fd, 8);
-
-    if (ret==-1) {
+    if (listen(fd, 8)==-1) {
         perror("listen");
         return -1;
     }
 
+#ifdef __linux__
     sk_set_int(fd, sk_defer_accept, GT_TIMEOUT/1000);
+#else
+    char data[256] = {0};
+    str_cpy(data, "dataready", sizeof(data)-1);
+    sk_set(fd, sk_acceptfilter, &data, sizeof(data));
+#endif
 
     return 0;
 }
@@ -245,38 +267,6 @@ static char *sk_get_name (int fd)
     return str_cat(strs, COUNT(strs));
 }
 
-#ifdef TCP_INFO
-static socklen_t sk_get_info (int fd, struct tcp_info *ti)
-{
-    socklen_t len = sizeof(struct tcp_info);
-
-    if (getsockopt(fd, SOL_TCP, TCP_INFO, ti, &len)==-1) {
-        perror("getsockopt TCP_INFO");
-        return 0;
-    }
-
-    return len;
-}
-
-static void print_tcp_info (const char *name, struct tcp_info *ti)
-{
-    gt_log("%s: tcpinfo"
-            " rto:%"     PRIu32 " ato:%"          PRIu32 " snd_mss:%"  PRIu32
-            " rcv_mss:%" PRIu32 " unacked:%"      PRIu32 " sacked:%"   PRIu32
-            " lost:%"    PRIu32 " retrans:%"      PRIu32 " fackets:%"  PRIu32
-            " pmtu:%"    PRIu32 " rcv_ssthresh:%" PRIu32 " rtt:%"      PRIu32
-            " rttvar:%"  PRIu32 " snd_ssthresh:%" PRIu32 " snd_cwnd:%" PRIu32
-            " advmss:%"  PRIu32 " reordering:%"   PRIu32 "\n",
-            name,
-            ti->tcpi_rto,       ti->tcpi_ato,            ti->tcpi_snd_mss,
-            ti->tcpi_rcv_mss,   ti->tcpi_unacked,        ti->tcpi_sacked,
-            ti->tcpi_lost,      ti->tcpi_retrans,        ti->tcpi_fackets,
-            ti->tcpi_pmtu,      ti->tcpi_rcv_ssthresh,   ti->tcpi_rtt,
-            ti->tcpi_rttvar,    ti->tcpi_snd_ssthresh,   ti->tcpi_snd_cwnd,
-            ti->tcpi_advmss,    ti->tcpi_reordering);
-}
-#endif
-
 static struct addrinfo *ai_create (const char *host, const char *port, int listener)
 {
     if (!port || !port[0]) {
@@ -380,6 +370,9 @@ static ssize_t fd_write (int fd, const void *data, size_t size)
         if (errno==EAGAIN || errno==EINTR)
             return -1;
 
+        if (errno==EPIPE || errno==ECONNRESET)
+            return 0;
+
         if (errno)
             perror("write");
 
@@ -389,15 +382,10 @@ static ssize_t fd_write (int fd, const void *data, size_t size)
     return ret;
 }
 
-static ssize_t fd_read_all (int fd, void *data, size_t size)
+static size_t fd_read_all (int fd, void *data, size_t size)
 {
     size_t done = 0;
 
-    struct pollfd pollfd = {
-        .fd = fd,
-        .events = POLLIN,
-    };
-
     while (done<size) {
         ssize_t ret = fd_read(fd, (uint8_t *)data+done, size-done);
 
@@ -405,8 +393,14 @@ static ssize_t fd_read_all (int fd, void *data, size_t size)
             break;
 
         if (ret<0) {
+            struct pollfd pollfd = {
+                .fd = fd,
+                .events = POLLIN,
+            };
+
             if (!poll(&pollfd, 1, GT_TIMEOUT))
                 break;
+
             continue;
         }
 
@@ -416,15 +410,10 @@ static ssize_t fd_read_all (int fd, void *data, size_t size)
     return done;
 }
 
-static ssize_t fd_write_all (int fd, const void *data, size_t size)
+static size_t fd_write_all (int fd, const void *data, size_t size)
 {
     size_t done = 0;
 
-    struct pollfd pollfd = {
-        .fd = fd,
-        .events = POLLOUT,
-    };
-
     while (done<size) {
         ssize_t ret = fd_write(fd, (const uint8_t *)data+done, size-done);
 
@@ -432,8 +421,14 @@ static ssize_t fd_write_all (int fd, const void *data, size_t size)
             break;
 
         if (ret<0) {
+            struct pollfd pollfd = {
+                .fd = fd,
+                .events = POLLOUT,
+            };
+
             if (!poll(&pollfd, 1, GT_TIMEOUT))
                 break;
+
             continue;
         }
 
@@ -510,32 +505,79 @@ static int gt_decrypt (struct crypto_ctx *ctx, buffer_t *dst, buffer_t *src)
     return 0;
 }
 
-static void dump_ip_header (uint8_t *data, size_t size)
+static void gt_print_hdr (const int ip_version, uint8_t *data, size_t ip_size, const char *sockname)
 {
-    if (size<20)
-        return;
+    const ssize_t ip_proto = ip_get_proto(ip_version, data, ip_size);
+    const ssize_t ip_hdr_size = ip_get_hdr_size(ip_version, data, ip_size);
 
-    const char tbl[] = "0123456789ABCDEF";
-    char hex[41];
+    char ip_src[INET6_ADDRSTRLEN];
+    char ip_dst[INET6_ADDRSTRLEN];
 
-    for (size_t i=0; i<20; i++) {
-        hex[(i<<1)+0] = tbl[0xF&(data[i]>>4)];
-        hex[(i<<1)+1] = tbl[0xF&(data[i])];
+    switch (ip_version) {
+    case 4:
+        inet_ntop(AF_INET, &data[12], ip_src, sizeof(ip_src));
+        inet_ntop(AF_INET, &data[16], ip_dst, sizeof(ip_dst));
+        break;
+    case 6:
+        inet_ntop(AF_INET6, &data[9],  ip_src, sizeof(ip_src));
+        inet_ntop(AF_INET6, &data[25], ip_dst, sizeof(ip_dst));
+        break;
     }
 
-    hex[40] = 0;
+    gt_log("%s: version=%i size=%zi proto=%zi src=%s dst=%s\n", sockname, ip_version, ip_size, ip_proto, ip_src, ip_dst);
 
-    gt_log("DUMP(%zu): %s\n", size, hex);
+    if (ip_hdr_size<=0)
+        return;
+
+    if (ip_proto==6) {
+        struct tcphdr tcp;
+
+        byte_cpy(&tcp, &data[ip_hdr_size], sizeof(tcp));
+
+        tcp.th_sport = ntohs(tcp.th_sport);
+        tcp.th_dport = ntohs(tcp.th_dport);
+        tcp.th_seq = ntohl(tcp.th_seq);
+        tcp.th_ack = ntohl(tcp.th_ack);
+        tcp.th_win = ntohs(tcp.th_win);
+
+        gt_log("%s: tcp src=%u dst=%u seq=%u ack=%u win=%u %c%c%c%c%c%c\n",
+                sockname, tcp.th_sport, tcp.th_dport, tcp.th_seq, tcp.th_ack, tcp.th_win,
+                (tcp.th_flags&TH_FIN) ?'F':'.',
+                (tcp.th_flags&TH_SYN) ?'S':'.',
+                (tcp.th_flags&TH_RST) ?'R':'.',
+                (tcp.th_flags&TH_PUSH)?'P':'.',
+                (tcp.th_flags&TH_ACK) ?'A':'.',
+                (tcp.th_flags&TH_URG) ?'U':'.');
+    }
+
+    if (ip_proto==17) {
+        struct udphdr udp;
+
+        byte_cpy(&udp, &data[ip_hdr_size], sizeof(udp));
+
+        udp.uh_sport = ntohs(udp.uh_sport);
+        udp.uh_dport = ntohs(udp.uh_dport);
+        udp.uh_ulen = ntohs(udp.uh_ulen);
+
+        gt_log("%s: udp src=%u dst=%u len=%u\n",
+                sockname, udp.uh_sport, udp.uh_dport, udp.uh_ulen);
+    }
 }
 
 static int gt_setup_secretkey (struct crypto_ctx *ctx, char *keyfile)
 {
     const size_t size = sizeof(ctx->skey);
 
-    byte_set(ctx->skey, 1, size);
+    if (!keyfile) {
+        char buf[2*size+1];
+
+        randombytes_buf(ctx->skey, size);
+        gt_tohex(buf, sizeof(buf), ctx->skey, size);
+
+        gt_print("new secret key: %s\n", buf);
 
-    if (!keyfile)
         return 0;
+    }
 
     int fd;
 
@@ -548,13 +590,20 @@ static int gt_setup_secretkey (struct crypto_ctx *ctx, char *keyfile)
         return -1;
     }
 
-    if (fd_read_all(fd, ctx->skey, size)!=size) {
-        gt_log("unable to read secret key in `%s'\n", keyfile);
+    char key[2*size];
+    size_t r = fd_read_all(fd, key, sizeof(key));
+
     close(fd);
+
+    if (r!=sizeof(key)) {
+        gt_log("unable to read secret key\n");
         return -1;
     }
 
-    close(fd);
+    if (gt_fromhex(ctx->skey, size, key, sizeof(key))) {
+        gt_log("secret key is not valid\n");
+        return -1;
+    }
 
     return 0;
 }
@@ -646,7 +695,7 @@ int main (int argc, char **argv)
 
     char *host = NULL;
     char *port = "5000";
-    char *dev = PACKAGE_NAME;
+    char *dev = NULL;
     char *keyfile = NULL;
     char *congestion = NULL;
 
@@ -656,8 +705,8 @@ int main (int argc, char **argv)
     long ka_idle = -1;
     long ka_interval = -1;
 
-    long retry_count = 0;
-    long retry_slope = 1000;
+    long retry_count = -1;
+    long retry_slope = 0;
     long retry_const = 0;
     long retry_limit = 1000000;
 
@@ -690,6 +739,7 @@ int main (int argc, char **argv)
         { "noquickack",  NULL,         option_option },
         { "retry",       &retry_opts,  option_option },
         { "daemon",      NULL,         option_option },
+        { "debug",       NULL,         option_option },
         { "version",     NULL,         option_option },
         { NULL },
     };
@@ -706,12 +756,23 @@ int main (int argc, char **argv)
     const int delay = option_is_set(opts, "delay");
     const int keepalive = option_is_set(opts, "keepalive");
     const int noquickack = option_is_set(opts, "noquickack");
+    const int debug = option_is_set(opts, "debug");
 
     if (buffer_size < 2048) {
         buffer_size = 2048;
         gt_log("buffer size must be greater than 2048!\n");
     }
 
+    if (!listener) {
+        if (!option_is_set(opts, "keyfile")) {
+            gt_log("keyfile option must be set\n");
+            return 1;
+        }
+
+        if (!option_is_set(opts, "retry"))
+            retry_count = 0;
+    }
+
     if (sodium_init()==-1) {
         gt_log("libsodium initialization has failed!\n");
         return 1;
@@ -722,11 +783,6 @@ int main (int argc, char **argv)
         return 1;
     }
 
-    struct crypto_ctx ctx;
-
-    if (gt_setup_secretkey(&ctx, keyfile))
-        return 1;
-
     struct addrinfo *ai = ai_create(host, port, listener);
 
     if (!ai)
@@ -737,8 +793,10 @@ int main (int argc, char **argv)
 
     tun.fd = tun_create(dev, option_is_set(opts, "multiqueue"));
 
-    if (tun.fd==-1)
+    if (tun.fd==-1) {
+        gt_log("couldn't create tun device\n");
         return 1;
+    }
 
     struct blk *blks = calloc(256, sizeof(struct blk));
     size_t blk_count = 0;
@@ -765,6 +823,11 @@ int main (int argc, char **argv)
             return 1;
     }
 
+    struct crypto_ctx ctx;
+
+    if (gt_setup_secretkey(&ctx, keyfile))
+        return 1;
+
     if (option_is_set(opts, "daemon")) {
         switch (fork()) {
         case -1:
@@ -784,33 +847,30 @@ int main (int argc, char **argv)
     long retry = 0;
 
     while (!gt_close) {
-        sock.fd = listener?sk_accept(fd):sk_create(ai, sk_connect);
-
-        if (sock.fd==-1) {
-            if (retry<LONG_MAX)
-                retry++;
-
-            long usec = retry*retry_slope+retry_const;
-
-            if (retry_count>=0 && retry>=retry_count) {
-                gt_log("couldn't %s (%d attempt%s)\n",
-                        listener?"listen":"connect",
+        if (retry_count>=0 && retry>=retry_count+1) {
+            gt_log("couldn't %s (%d attempt%s)\n", listener?"listen":"connect",
                    (int)retry, (retry>1)?"s":"");
             break;
         }
 
+        if (retry_slope || retry_const) {
+            long usec = retry*retry_slope+retry_const;
+
             if (usec>retry_limit)
                 usec = retry_limit;
 
-            if (usec<=0)
-                usec = 0;
-
-            if (usleep(usec)==-1 && errno==EINVAL)
+            if (usec>0 && usleep(usec)==-1 && errno==EINVAL)
                 sleep(usec/1000000);
-
-            continue;
         }
 
+        if (retry<LONG_MAX)
+            retry++;
+
+        sock.fd = listener?sk_accept(fd):sk_create(ai, sk_connect);
+
+        if (sock.fd==-1)
+            continue;
+
         char *sockname = sk_get_name(sock.fd);
 
         if (!sockname) {
@@ -901,17 +961,6 @@ int main (int argc, char **argv)
          // struct timeval now;
          // gettimeofday(&now, NULL);
 
-#ifdef TCP_INFO
-            if _0_(gt_info) {
-                struct tcp_info ti;
-
-                if (sk_get_info(sock.fd, &ti))
-                    print_tcp_info(sockname, &ti);
-
-                gt_info = 0;
-            }
-#endif
-
             if (FD_ISSET(tun.fd, &rfds)) {
                 while (!blks[blk_write].size) {
                     uint8_t *data = blks[blk_write].data;
@@ -922,20 +971,22 @@ int main (int argc, char **argv)
                         break;
                     }
 
-                    const ssize_t ip_size = ip_get_size(data, GT_MTU_MAX);
+                    const int ip_version = ip_get_version(data, GT_MTU_MAX);
+                    const ssize_t ip_size = ip_get_size(ip_version, data, GT_MTU_MAX);
 
                     if _0_(ip_size<=0)
                         continue;
 
                     if _0_(ip_size!=r) {
-                        dump_ip_header(data, r);
-
-                        if (r>ip_size)
+                        char tmp[2*GT_MTU_MAX+1];
+                        gt_tohex(tmp, sizeof(tmp), data, r);
+                        gt_log("%s: DUMP %zi %s\n", sockname, r, tmp);
                         continue;
-
-                        ip_set_size(data, r);
                     }
 
+                    if _0_(debug)
+                        gt_print_hdr(ip_version, data, ip_size, sockname);
+
                     blks[blk_write++].size = r;
                     blk_count++;
                 }
@@ -1009,7 +1060,9 @@ int main (int argc, char **argv)
                 }
 
                 size_t size = buffer_read_size(&tun.write);
-                ssize_t ip_size = ip_get_size(tun.write.read, size);
+
+                const int ip_version = ip_get_version(tun.write.read, size);
+                ssize_t ip_size = ip_get_size(ip_version, tun.write.read, size);
 
                 if _0_(!ip_size) {
                     gt_log("%s: bad packet!\n", sockname);

src/tun.c

@@ -11,72 +11,37 @@
 #include <sys/uio.h>
 
 #ifdef __linux__
-# include <linux/if.h>
-# include <linux/if_tun.h>
+#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>
+#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
+#define GT_BSD_TUN
 #endif
 
-#ifdef __linux__
-int tun_create (char *name, int multiqueue)
+#ifdef __APPLE__
+
+static int tun_create_by_id (char *name, size_t size, unsigned id, _unused_ int mq)
 {
-    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;
-    }
-
-    gt_log("tun name: %s\n", ifr.ifr_name);
-
-    return fd;
-}
-#elif defined(__APPLE__)
-int tun_create (_unused_ char *name, _unused_ int mq)
-{
-    for (unsigned dev_id = 0; dev_id < 32; dev_id++) {
-        struct ctl_info ci;
-
-        byte_set(&ci, 0, sizeof(ci));
-        str_cpy(ci.ctl_name, UTUN_CONTROL_NAME, sizeof(ci.ctl_name)-1);
-
     int fd = socket(PF_SYSTEM, SOCK_DGRAM, SYSPROTO_CONTROL);
 
     if (fd==-1)
         return -1;
 
-        if (ioctl(fd, CTLIOCGINFO, &ci)==-1) {
+    struct ctl_info ci;
+
+    byte_set(&ci, 0, sizeof(ci));
+    str_cpy(ci.ctl_name, UTUN_CONTROL_NAME, sizeof(ci.ctl_name)-1);
+
+    if (ioctl(fd, CTLIOCGINFO, &ci)) {
         close(fd);
-            continue;
+        return -1;
     }
 
     struct sockaddr_ctl sc = {
@@ -84,43 +49,110 @@ int tun_create (_unused_ char *name, _unused_ int mq)
         .sc_len = sizeof(sc),
         .sc_family = AF_SYSTEM,
         .ss_sysaddr = AF_SYS_CONTROL,
-            .sc_unit = dev_id+1,
+        .sc_unit = id+1,
     };
 
-        if (connect(fd, (struct sockaddr *)&sc, sizeof(sc))==-1) {
+    if (connect(fd, (struct sockaddr *)&sc, sizeof(sc))) {
         close(fd);
-            continue;
+        return -1;
     }
 
-        gt_log("tun name: /dev/utun%u\n", dev_id);
+    snprintf(name, size, "utun%u", id);
 
     return fd;
-    }
-
-    return -1;
 }
-#else
-int tun_create (_unused_ char *name, _unused_ int mq)
+
+static int tun_create_by_name (char *name, size_t size, char *dev_name, int mq)
 {
-    for (unsigned dev_id = 0; dev_id < 32; dev_id++) {
-        char dev_path[11];
+    unsigned id = 0;
 
-        snprintf(dev_path, sizeof(dev_path), "/dev/tun%u", dev_id);
+    if (sscanf(dev_name, "utun%u", &id)!=1)
+        return -1;
 
-        int fd = open(dev_path, O_RDWR);
+    return tun_create_by_id(name, size, id, mq);
+}
+
+#else /* not __APPLE__ */
+
+#ifdef __linux__
+
+static int tun_create_by_name (char *name, size_t size, char *dev_name, int mq)
+{
+    int fd = open("/dev/net/tun", O_RDWR);
 
     if (fd==-1)
-            continue;
+        return -1;
 
-        gt_log("tun name: %s\n", dev_path);
+    struct ifreq ifr = {
+        .ifr_flags = IFF_TUN|IFF_NO_PI,
+    };
 
-        return fd;
+    if (mq) {
+#ifdef IFF_MULTI_QUEUE
+        ifr.ifr_flags |= IFF_MULTI_QUEUE;
+#endif
     }
 
+    str_cpy(ifr.ifr_name, dev_name, IFNAMSIZ-1);
+
+    if (ioctl(fd, TUNSETIFF, &ifr)) {
+        close(fd);
         return -1;
+    }
+
+    str_cpy(name, ifr.ifr_name, size-1);
+
+    return fd;
 }
+
+#else /* not __linux__ not __APPLE__ */
+
+static int tun_create_by_name (char *name, size_t size, char *dev_name, _unused_ int mq)
+{
+    char path[64];
+
+    snprintf(path, sizeof(path), "/dev/%s", dev_name);
+    str_cpy(name, dev_name, size-1);
+
+    return open(path, O_RDWR);
+}
+
+#endif /* not __APPLE__ */
+
+static int tun_create_by_id (char *name, size_t size, unsigned id, int mq)
+{
+    char dev_name[64];
+
+    snprintf(dev_name, sizeof(dev_name), "tun%u", id);
+
+    return tun_create_by_name(name, size, dev_name, mq);
+}
+
 #endif
 
+int tun_create (char *dev_name, int mq)
+{
+    char name[64];
+    int fd = -1;
+
+#ifndef IFF_MULTI_QUEUE
+    if (mq)
+        gt_na("IFF_MULTI_QUEUE");
+#endif
+
+    if (str_empty(dev_name)) {
+        for (unsigned id=0; id<32 && fd==-1; id++)
+            fd = tun_create_by_id(name, sizeof(name), id, mq);
+    } else {
+        fd = tun_create_by_name(name, sizeof(name), dev_name, mq);
+    }
+
+    if (fd!=-1)
+        gt_print("tun name: %s\n", name);
+
+    return fd;
+}
+
 ssize_t tun_read (int fd, void *data, size_t size)
 {
     if (!size)