Update README.md and mud

Required on BSD. Doesn't break anything elsewhere.

.build.sh

@@ -0,0 +1,15 @@
+#!/bin/sh
+
+export CC="gcc -static"
+
+git clone https://github.com/jedisct1/libsodium --depth=1 --branch stable
+cd libsodium || exit 1
+./autogen.sh && ./configure --enable-minimal --disable-shared --prefix=/usr && make install
+cd ..
+
+./autogen.sh && ./configure && make
+[ -x glorytun ] || exit 1
+
+mkdir -p deploy
+strip -s glorytun
+mv glorytun deploy/glorytun-$(cat VERSION)-$(uname -m).bin

.gitmodules

@@ -0,0 +1,3 @@
+[submodule "mud"]
+	path = mud
+	url = https://github.com/angt/mud.git

Makefile.am

@@ -20,6 +20,11 @@ glorytun_SOURCES = \
     src/state.c \
     src/state.h
 
+glorytun_CFLAGS  += -I$(srcdir)/mud
+glorytun_SOURCES += \
+    mud/mud.h \
+    mud/mud.c
+
 EXTRA_DIST = \
     LICENSE \
     README.md \

README.md

@@ -1,19 +1,14 @@
-# Glorytun
+# π₁(Glorytun)=0
 
-Small, Simple and Stupid TCP VPN.
-
-#### Work In Progress
-
-This code will probably format your harddisk!
+Small, Simple and Stupid VPN over [mud](https://github.com/angt/mud).
 
 #### Build and Install
 
-Glorytun depends on [libsodium](https://github.com/jedisct1/libsodium) version >= 1.0.4
-and needs an AES-NI capable CPU.
+Glorytun depends on [libsodium](https://github.com/jedisct1/libsodium) version >= 1.0.4.
 
 To build and install the latest version:
 
-    $ git clone https://github.com/angt/glorytun
+    $ git clone https://github.com/angt/glorytun --recursive --branch mud
     $ cd glorytun
     $ ./autogen.sh
     $ ./configure

configure.ac

@@ -14,8 +14,9 @@ AM_SILENT_RULES([yes])
 AM_PROG_CC_C_O
 AC_PROG_CC_C99
 AC_USE_SYSTEM_EXTENSIONS
-AC_SEARCH_LIBS([getaddrinfo], [resolv nsl])
 AC_SEARCH_LIBS([socket], [socket])
+AC_CHECK_LIB([rt], [clock_gettime])
+AC_CHECK_FUNCS([clock_gettime])
 PKG_CHECK_MODULES([libsodium], [libsodium >= 1.0.4])
 AC_CONFIG_FILES([Makefile])
 AC_OUTPUT

src/common.c

@@ -1,22 +1,24 @@
 #include "common.h"
 
-#include <stdio.h>
 #include <stdarg.h>
+#include <stdio.h>
 
-int gt_print (const char *fmt, ...)
+int
+gt_print(const char *fmt, ...)
 {
     va_list ap;
     va_start(ap, fmt);
     int ret = vfprintf(stdout, fmt, ap);
     va_end(ap);
 
-    if (ret<0)
+    if (ret < 0)
         return 0;
 
     return ret;
 }
 
-void gt_log (const char *fmt, ...)
+void
+gt_log(const char *fmt, ...)
 {
     va_list ap;
     va_start(ap, fmt);
@@ -24,7 +26,8 @@ void gt_log (const char *fmt, ...)
     va_end(ap);
 }
 
-void gt_fatal (const char *fmt, ...)
+void
+gt_fatal(const char *fmt, ...)
 {
     va_list ap;
     va_start(ap, fmt);
@@ -34,24 +37,26 @@ void gt_fatal (const char *fmt, ...)
     exit(EXIT_FAILURE);
 }
 
-void gt_na (const char *name)
+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)
+int
+gt_tohex(char *dst, size_t dst_size, const uint8_t *src, size_t src_size)
 {
-    if _0_(!dst_size)
+    if (_0_(!dst_size))
         return -1;
 
-    if _0_(((dst_size-1)/2)<src_size)
+    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])];
+    for (size_t i = 0; i < src_size; i++) {
+        *dst++ = tbl[0xF & (src[i] >> 4)];
+        *dst++ = tbl[0xF & (src[i])];
     }
 
     *dst = 0;
@@ -59,37 +64,38 @@ int gt_tohex (char *dst, size_t dst_size, const uint8_t *src, size_t src_size)
     return 0;
 }
 
-_const_
-static inline int fromhex (const char c)
+_const_ static inline int
+fromhex(const char c)
 {
-    if (c>='0' && c<='9')
-        return c-'0';
+    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;
 
-    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)
+int
+gt_fromhex(uint8_t *dst, size_t dst_size, const char *src, size_t src_size)
 {
-    if _0_(src_size&1)
+    if (_0_(src_size & 1))
         return -1;
 
-    if _0_(dst_size<(src_size/2))
+    if (_0_(dst_size < (src_size / 2)))
         return -1;
 
-    for (size_t i=0; i<src_size; i+=2) {
+    for (size_t i = 0; i < src_size; i += 2) {
         const int a = fromhex(src[i]);
-        const int b = fromhex(src[i+1]);
+        const int b = fromhex(src[i + 1]);
 
-        if _0_(a==-1 || b==-1)
+        if (_0_(a == -1 || b == -1))
             return -1;
 
-        *dst++ = (a<<4)|b;
+        *dst++ = (a << 4) | b;
     }
 
     return 0;

src/db.c

@@ -3,56 +3,57 @@
 #include "db.h"
 #include "str.h"
 
-#define CBIT(X)      (1&(intptr_t)(X))
-#define CBIT_PTR(X)  (uint8_t *)(1|(intptr_t)(X))
-#define CBIT_NODE(X) (struct node *)(1^(intptr_t)(X))
+#define CBIT(X) (1 & (intptr_t)(X))
+#define CBIT_PTR(X) (uint8_t *)(1 | (intptr_t)(X))
+#define CBIT_NODE(X) (struct node *)(1 ^ (intptr_t)(X))
 
 struct node {
     uint8_t *child[2];
     uint32_t point;
 };
 
-_pure_
-static inline size_t db_size (const uint8_t *a)
+_pure_ static inline size_t
+db_size(const uint8_t *a)
 {
-    return (a[0]?:str_len((char *)a+1))+1;
+    return (a[0] ?: str_len((char *)a + 1)) + 1;
 }
 
-_pure_
-static inline size_t db_cmp (const uint8_t *a, const uint8_t *b)
+_pure_ static inline size_t
+db_cmp(const uint8_t *a, const uint8_t *b)
 {
     const size_t size = a[0];
 
-    if (size!=b[0])
+    if (size != b[0])
         return 1;
 
     if (!size) {
-        size_t i = str_cmp((char *)a+1, (char *)b+1);
-        return i?i+1:0;
+        size_t i = str_cmp((char *)a + 1, (char *)b + 1);
+        return i ? i + 1 : 0;
     }
 
-    for (size_t i=1; i<=size; i++) {
-        if (a[i]!=b[i])
-            return i+1;
+    for (size_t i = 1; i <= size; i++) {
+        if (a[i] != b[i])
+            return i + 1;
     }
 
     return 0;
 }
 
-_pure_
-static inline int db_dir (const uint32_t point, uint8_t *data, const size_t size)
+_pure_ static inline int
+db_dir(const uint32_t point, uint8_t *data, const size_t size)
 {
-    const size_t pos = point>>8;
+    const size_t pos = point >> 8;
 
-    if (pos>=size)
+    if (pos >= size)
         return 0;
 
-    return ((point|data[pos])&255)==255;
+    return ((point | data[pos]) & 255) == 255;
 }
 
-uint8_t *db_search (uint8_t **p, uint8_t *data)
+uint8_t *
+db_search(uint8_t **p, uint8_t *data)
 {
-    if _0_(!*p)
+    if (_0_(!*p))
         return NULL;
 
     uint8_t *r = *p;
@@ -69,12 +70,13 @@ uint8_t *db_search (uint8_t **p, uint8_t *data)
     return NULL;
 }
 
-uint8_t *db_insert (uint8_t **p, uint8_t *data)
+uint8_t *
+db_insert(uint8_t **p, uint8_t *data)
 {
-    if _0_(CBIT(data))
+    if (_0_(CBIT(data)))
         return NULL;
 
-    if _0_(!*p) {
+    if (_0_(!*p)) {
         *p = data;
         return data;
     }
@@ -89,31 +91,31 @@ uint8_t *db_insert (uint8_t **p, uint8_t *data)
 
     const size_t diff = db_cmp(r, data);
 
-    if _0_(!diff)
+    if (_0_(!diff))
         return r;
 
-    const size_t pos = diff-1;
-    const uint8_t mask = ~((1u<<31)>>CLZ(r[pos]^data[pos]));
-    const size_t point = (pos<<8)|mask;
+    const size_t pos = diff - 1;
+    const uint8_t mask = ~((1u << 31) >> CLZ(r[pos] ^ data[pos]));
+    const size_t point = (pos << 8) | mask;
 
     while (CBIT(*p)) {
         struct node *node = CBIT_NODE(*p);
 
-        if (node->point>point)
+        if (node->point > point)
             break;
 
-        p = node->child+db_dir(node->point, data, size);
+        p = node->child + db_dir(node->point, data, size);
     }
 
     struct node *node = malloc(sizeof(struct node));
 
-    if _0_(!node)
+    if (_0_(!node))
         return NULL;
 
-    const int dir = (mask|r[pos])==255;
+    const int dir = (mask | r[pos]) == 255;
 
     node->child[dir] = *p;
-    node->child[1-dir] = data;
+    node->child[1 - dir] = data;
     node->point = point;
 
     *p = CBIT_PTR(node);
@@ -121,9 +123,10 @@ uint8_t *db_insert (uint8_t **p, uint8_t *data)
     return data;
 }
 
-uint8_t *db_remove (uint8_t **p, uint8_t *data)
+uint8_t *
+db_remove(uint8_t **p, uint8_t *data)
 {
-    if _0_(!*p)
+    if (_0_(!*p))
         return NULL;
 
     const size_t size = db_size(data);
@@ -136,16 +139,16 @@ uint8_t *db_remove (uint8_t **p, uint8_t *data)
         p_old = p;
         node = CBIT_NODE(*p);
         dir = db_dir(node->point, data, size);
-        p = node->child+dir;
+        p = node->child + dir;
     }
 
-    if _0_(db_cmp(data, *p))
+    if (_0_(db_cmp(data, *p)))
         return NULL;
 
     uint8_t *r = *p;
 
     if (p_old) {
-        *p_old = node->child[1-dir];
+        *p_old = node->child[1 - dir];
         free(node);
     } else {
         *p = NULL;

src/ip.h

@@ -4,6 +4,7 @@
 
 struct ip_common {
     uint8_t version;
+    uint8_t tc;
     uint8_t proto;
     uint8_t hdr_size;
     uint16_t size;
@@ -24,11 +25,13 @@ static inline int ip_get_common (struct ip_common *ic, const uint8_t *data, size
 
     switch (ic->version) {
     case 4:
+        ic->tc = data[1];
         ic->proto = data[9];
         ic->hdr_size = (data[0]&0xF)<<2;
         ic->size = ((data[2]<<8)|data[3]);
         return 0;
     case 6:
+        ic->tc = ((data[0]&0xF)<<4)|(data[1]>>4);
         ic->proto = data[6];
         ic->hdr_size = 40;
         ic->size = ((data[4]<<8)|data[5])+40;

src/option.c

@@ -3,9 +3,10 @@
 #include "option.h"
 #include "str.h"
 
-int option_str (void *data, int argc, char **argv)
+int
+option_str(void *data, int argc, char **argv)
 {
-    if (argc<2 || str_empty(argv[1])) {
+    if (argc < 2 || str_empty(argv[1])) {
         gt_print("option `%s' need a string argument\n", argv[0]);
         return -1;
     }
@@ -15,9 +16,10 @@ int option_str (void *data, int argc, char **argv)
     return 1;
 }
 
-int option_long (void *data, int argc, char **argv)
+int
+option_long(void *data, int argc, char **argv)
 {
-    if (argc<2 || str_empty(argv[1])) {
+    if (argc < 2 || str_empty(argv[1])) {
         gt_print("option `%s' need an integer argument\n", argv[0]);
         return -1;
     }
@@ -26,7 +28,7 @@ int option_long (void *data, int argc, char **argv)
     char *end;
     long val = strtol(argv[1], &end, 0);
 
-    if (errno || argv[1]==end) {
+    if (errno || argv[1] == end) {
         gt_print("argument `%s' is not a valid integer\n", argv[1]);
         return -1;
     }
@@ -36,9 +38,10 @@ int option_long (void *data, int argc, char **argv)
     return 1;
 }
 
-int option_is_set (struct option *opts, const char *name)
+int
+option_is_set(struct option *opts, const char *name)
 {
-    for (int k=0; opts[k].name; k++) {
+    for (int k = 0; opts[k].name; k++) {
         if (!str_cmp(opts[k].name, name))
             return opts[k].set;
     }
@@ -46,20 +49,21 @@ int option_is_set (struct option *opts, const char *name)
     return 0;
 }
 
-int option_option (void *data, int argc, char **argv)
+int
+option_option(void *data, int argc, char **argv)
 {
     if (!data)
         return 0;
 
     struct option *opts = (struct option *)data;
 
-    for (int k=0; opts[k].name; k++)
+    for (int k = 0; opts[k].name; k++)
         opts[k].set = 0;
 
-    for (int i=1; i<argc; i++) {
+    for (int i = 1; i < argc; i++) {
         int found = 0;
 
-        for (int k=0; opts[k].name; k++) {
+        for (int k = 0; opts[k].name; k++) {
             if (str_cmp(opts[k].name, argv[i]))
                 continue;
 
@@ -68,9 +72,9 @@ int option_option (void *data, int argc, char **argv)
                 return -1;
             }
 
-            int ret = opts[k].call(opts[k].data, argc-i, &argv[i]);
+            int ret = opts[k].call(opts[k].data, argc - i, &argv[i]);
 
-            if (ret<0)
+            if (ret < 0)
                 return -1;
 
             opts[k].set = 1;
@@ -81,29 +85,30 @@ int option_option (void *data, int argc, char **argv)
         }
 
         if (!found)
-            return i-1;
+            return i - 1;
     }
 
     return argc;
 }
 
-static int option_usage (struct option *opts, int slen)
+static int
+option_usage(struct option *opts, int slen)
 {
     if (!opts)
         return 0;
 
     int len = 0;
 
-    for (int k=0; opts[k].name; k++) {
-        if (len>40) {
+    for (int k = 0; opts[k].name; k++) {
+        if (len > 40) {
             gt_print("\n%*s", slen, "");
             len = 0;
         }
 
         len += gt_print(" [%s", opts[k].name);
 
-        if (opts[k].call==option_option) {
-            len += option_usage((struct option *)opts[k].data, slen+len);
+        if (opts[k].call == option_option) {
+            len += option_usage((struct option *)opts[k].data, slen + len);
         } else {
             len += gt_print(" ARG");
         }
@@ -114,21 +119,22 @@ static int option_usage (struct option *opts, int slen)
     return len;
 }
 
-int option (struct option *opts, int argc, char **argv)
+int
+option(struct option *opts, int argc, char **argv)
 {
     int ret = option_option(opts, argc, argv);
 
-    if (ret==argc)
+    if (ret == argc)
         return 0;
 
-    if (ret<0 || ret+1>=argc)
+    if (ret < 0 || ret + 1 >= argc)
         return 1;
 
-    gt_print("option `%s' is unknown\n", argv[ret+1]);
+    gt_print("option `%s' is unknown\n", argv[ret + 1]);
 
     int slen = gt_print("usage: %s", argv[0]);
 
-    if (slen>40) {
+    if (slen > 40) {
         slen = 12;
         gt_print("\n%*s", slen, "");
     }

src/state.c

@@ -3,59 +3,62 @@
 #include "state.h"
 #include "str.h"
 
-#include <stdio.h>
 #include <fcntl.h>
+#include <stdio.h>
 #include <sys/stat.h>
 
-static int state_fd = -1;
-
-int state_init (const char *filename)
+int
+state_create(const char *filename)
 {
     if (str_empty(filename))
-        return 0;
+        return -1;
 
-    state_fd = open(filename, O_WRONLY);
+    int fd = open(filename, O_WRONLY);
 
-    if (state_fd==-1) {
-        if (errno!=EINTR)
+    if (fd == -1) {
+        if (errno != EINTR)
             perror("open");
         return -1;
     }
 
     struct stat st = {0};
 
-    if (fstat(state_fd, &st)==-1) {
+    if (fstat(fd, &st) == -1) {
         perror("fstat");
-        close(state_fd);
-        state_fd = -1;
+        close(fd);
         return -1;
     }
 
     if (!S_ISFIFO(st.st_mode)) {
         gt_log("`%s' is not a fifo\n", filename);
-        close(state_fd);
-        state_fd = -1;
+        close(fd);
         return -1;
     }
 
-    return 0;
+    return fd;
 }
 
-void state (const char *state, const char *info)
+void
+state_send(int fd, const char *state, const char *info)
 {
     if (str_empty(state))
         return;
 
-    const char *strs[] = { state, " ", info, "\n" };
+    if (fd == -1) {
+        gt_print("%s %s\n", state, info);
+        return;
+    }
+
+    const char *strs[] = {state, " ", info, "\n"};
     char *str = str_cat(strs, COUNT(strs));
 
-    if (!str)
+    if (!str) {
+        perror("str_cat");
         return;
-
-    if (state_fd==-1) {
-        gt_print("%s", str);
-    } else {
-        if (write(state_fd, str, str_len(str))==-1 && errno!=EINTR)
-            perror("write");
     }
+
+    if (write(fd, str, str_len(str)) == -1 && errno != EINTR)
+        perror("write");
+
+    free(str);
 }

src/state.h

@@ -1,4 +1,4 @@
 #pragma once
 
-int  state_init (const char *);
-void state      (const char *, const char *);
+int  state_create (const char *);
+void state_send   (int, const char *, const char *);

src/tun.c

@@ -1,25 +1,26 @@
 #include "common.h"
 
-#include "tun.h"
-#include "str.h"
 #include "ip.h"
+#include "str.h"
+#include "tun.h"
 
-#include <stdio.h>
 #include <fcntl.h>
+#include <stdio.h>
 
 #include <sys/ioctl.h>
 #include <sys/socket.h>
 #include <sys/uio.h>
 
+#include <net/if.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>
+#include <sys/kern_control.h>
+#include <sys/sys_domain.h>
 #endif
 
 #if defined(__APPLE__) || defined(__OpenBSD__)
@@ -28,17 +29,18 @@
 
 #ifdef __APPLE__
 
-static int tun_create_by_id (char *name, size_t size, unsigned id, _unused_ int mq)
+static int
+tun_create_by_id(char *name, size_t size, unsigned id)
 {
     int fd = socket(PF_SYSTEM, SOCK_DGRAM, SYSPROTO_CONTROL);
 
-    if (fd==-1)
+    if (fd == -1)
         return -1;
 
     struct ctl_info ci;
 
     memset(&ci, 0, sizeof(ci));
-    str_cpy(ci.ctl_name, UTUN_CONTROL_NAME, sizeof(ci.ctl_name)-1);
+    str_cpy(ci.ctl_name, UTUN_CONTROL_NAME, sizeof(ci.ctl_name) - 1);
 
     if (ioctl(fd, CTLIOCGINFO, &ci)) {
         close(fd);
@@ -50,7 +52,7 @@ static int tun_create_by_id (char *name, size_t size, unsigned id, _unused_ int
         .sc_len = sizeof(sc),
         .sc_family = AF_SYSTEM,
         .ss_sysaddr = AF_SYS_CONTROL,
-        .sc_unit = id+1,
+        .sc_unit = id + 1,
     };
 
     if (connect(fd, (struct sockaddr *)&sc, sizeof(sc))) {
@@ -63,98 +65,93 @@ static int tun_create_by_id (char *name, size_t size, unsigned id, _unused_ int
     return fd;
 }
 
-static int tun_create_by_name (char *name, size_t size, char *dev_name, int mq)
+static int
+tun_create_by_name(char *name, size_t size, char *dev_name)
 {
     unsigned id = 0;
 
-    if (sscanf(dev_name, "utun%u", &id)!=1)
+    if (sscanf(dev_name, "utun%u", &id) != 1)
         return -1;
 
-    return tun_create_by_id(name, size, id, mq);
+    return tun_create_by_id(name, size, id);
 }
 
 #else /* not __APPLE__ */
 
 #ifdef __linux__
 
-static int tun_create_by_name (char *name, size_t size, char *dev_name, int mq)
+static int
+tun_create_by_name(char *name, size_t size, char *dev_name)
 {
     int fd = open("/dev/net/tun", O_RDWR);
 
-    if (fd==-1)
+    if (fd == -1)
         return -1;
 
     struct ifreq ifr = {
-        .ifr_flags = IFF_TUN|IFF_NO_PI,
+        .ifr_flags = IFF_TUN | IFF_NO_PI,
     };
 
-    if (mq) {
-#ifdef IFF_MULTI_QUEUE
-        ifr.ifr_flags |= IFF_MULTI_QUEUE;
-#endif
-    }
-
-    str_cpy(ifr.ifr_name, dev_name, IFNAMSIZ-1);
+    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);
+    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)
+static int
+tun_create_by_name(char *name, size_t size, char *dev_name)
 {
     char path[64];
 
     snprintf(path, sizeof(path), "/dev/%s", dev_name);
-    str_cpy(name, dev_name, size-1);
+    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)
+static int
+tun_create_by_id(char *name, size_t size, unsigned id)
 {
     char dev_name[64];
 
     snprintf(dev_name, sizeof(dev_name), "tun%u", id);
 
-    return tun_create_by_name(name, size, dev_name, mq);
+    return tun_create_by_name(name, size, dev_name);
 }
 
 #endif
 
-int tun_create (char *dev_name, char **ret_name, int mq)
+int
+tun_create(char *dev_name, char **ret_name)
 {
     char name[64] = {0};
     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);
+        for (unsigned id = 0; id < 32 && fd == -1; id++)
+            fd = tun_create_by_id(name, sizeof(name), id);
     } else {
-        fd = tun_create_by_name(name, sizeof(name), dev_name, mq);
+        fd = tun_create_by_name(name, sizeof(name), dev_name);
     }
 
-    if (fd!=-1 && ret_name)
+    if (fd != -1 && ret_name)
         *ret_name = strdup(name);
 
     return fd;
 }
 
-ssize_t tun_read (int fd, void *data, size_t size)
+ssize_t
+tun_read(int fd, void *data, size_t size)
 {
     if (!size)
         return -1;
@@ -163,8 +160,14 @@ ssize_t tun_read (int fd, void *data, size_t size)
     uint32_t family;
 
     struct iovec iov[2] = {
-        { .iov_base = &family, .iov_len = sizeof(family) },
-        { .iov_base = data, .iov_len = size }
+        {
+            .iov_base = &family,
+            .iov_len = sizeof(family),
+        },
+        {
+            .iov_base = data,
+            .iov_len = size,
+        },
     };
 
     ssize_t ret = readv(fd, iov, 2);
@@ -172,8 +175,8 @@ ssize_t tun_read (int fd, void *data, size_t size)
     ssize_t ret = read(fd, data, size);
 #endif
 
-    if (ret==-1) {
-        if (errno==EAGAIN || errno==EINTR)
+    if (ret == -1) {
+        if (errno == EAGAIN || errno == EINTR)
             return -1;
 
         if (errno)
@@ -183,16 +186,17 @@ ssize_t tun_read (int fd, void *data, size_t size)
     }
 
 #ifdef GT_BSD_TUN
-    if (ret<(ssize_t) sizeof(family))
+    if (ret < (ssize_t)sizeof(family))
         return 0;
 
-    return ret-sizeof(family);
+    return ret - sizeof(family);
 #else
     return ret;
 #endif
 }
 
-ssize_t tun_write (int fd, const void *data, size_t size)
+ssize_t
+tun_write(int fd, const void *data, size_t size)
 {
     if (!size)
         return -1;
@@ -212,8 +216,14 @@ ssize_t tun_write (int fd, const void *data, size_t size)
     }
 
     struct iovec iov[2] = {
-        { .iov_base = &family, .iov_len = sizeof(family) },
-        { .iov_base = (void *) data, .iov_len = size },
+        {
+            .iov_base = &family,
+            .iov_len = sizeof(family),
+        },
+        {
+            .iov_base = (void *)data,
+            .iov_len = size,
+        },
     };
 
     ssize_t ret = writev(fd, iov, 2);
@@ -221,8 +231,8 @@ ssize_t tun_write (int fd, const void *data, size_t size)
     ssize_t ret = write(fd, data, size);
 #endif
 
-    if (ret==-1) {
-        if (errno==EAGAIN || errno==EINTR)
+    if (ret == -1) {
+        if (errno == EAGAIN || errno == EINTR)
             return -1;
 
         if (errno)
@@ -232,11 +242,34 @@ ssize_t tun_write (int fd, const void *data, size_t size)
     }
 
 #ifdef GT_BSD_TUN
-    if (ret<(ssize_t) sizeof(family))
+    if (ret < (ssize_t)sizeof(family))
         return 0;
 
-    return ret-sizeof(family);
+    return ret - sizeof(family);
 #else
     return ret;
 #endif
 }
+
+int
+tun_set_mtu(char *dev_name, int mtu)
+{
+    struct ifreq ifr = {
+        .ifr_mtu = mtu,
+    };
+
+    str_cpy(ifr.ifr_name, dev_name, IFNAMSIZ - 1);
+
+    int fd = socket(AF_INET, SOCK_DGRAM, 0);
+
+    if (fd == -1)
+        return -1;
+
+    int ret = ioctl(fd, SIOCSIFMTU, &ifr);
+
+    int err = errno;
+    close(fd);
+    errno = err;
+
+    return ret;
+}

src/tun.h

@@ -2,6 +2,7 @@
 
 #include <unistd.h>
 
-int     tun_create (char *, char **, int);
-ssize_t tun_read   (int, void *, size_t);
-ssize_t tun_write  (int, const void *, size_t);
+int     tun_create  (char *, char **);
+ssize_t tun_read    (int, void *, size_t);
+ssize_t tun_write   (int, const void *, size_t);
+int     tun_set_mtu (char *, int);