Add IPv6 support (command-line and tuntap) (#16)

* tncattach

- Added `set_ipv6`, `ipv6_addr` and `netmask_v6` globals
- Added `--ipv6` option
- If `n` is specified (i.e. `--noipv6`) then bail out if the user specified IPv6 addressing with `--ipv6 <arg>`
- Added `6` parsing, this is for when we have an `--ipv6` and want to set the address

* tncattach

- Removed global `netmask_v6` which is never used

* TAP

- Added initial code that I have been working on

* TAP

- Removed old (bad) code `trySixSet2(...)`

* TAP

- Clean up

* TAP

- Clean up

* TAP

- Added device type checl

* TAP

- Randomize the remaining octets of the link-local address

* TAP

- Seed random number generatro based off of current time

* TAP

- Removed TODO

* TAP_

- Cleaned up a little bit
- The `mtu` (on Luinux) must be `1280` of greater, else IPv6 won't work (and the address will not be allowed to be added)

* TAP

- More clean up

* TAP

- Moved mtu check for Ipv6 to be earlier

* TAP

- Added missing `cleanup()` calls

* TAP

- Aded newline

* TAP

- Now link-local and normal v6 can be requested independently

tncattach

- Added `--ll` mode to add link-local

* TAP

- More cleanup

* TAP

- Removed code to generate a link-local address

* tncattach

- Added error handling for mtu with IPv6 support

* TAP

- Removed uneeded imports

* TAP

- Cleaned up

* Cleaned up

* TAP

- Removed duplicate import

* TAP

- Removed error checking code from there

* TAP

- Cleaned up
- Remove dneed for `link_local_v6`

tncattach

- Removed `link_local_v6`

* TAP

- Close control socket when done

* tncattach

- Removed debug print

* TAP

- Cleaned up

* TAP

- Cleaned up

* TAP

- Cleaned up

* TAP

- Added check for bad open

* TAP

- Added another check

* tncattach

- Now parse IPv6 address and prefix in opt-args

TAP

- Removed parsing from here

* Fixed mtu stuff

* tncattach

- Typo fix

* Work

* tncattach

- WHen parsing the `prefixPart_s` (the prefix length), only continue if
the text is a number, if not then bail out with an error

* tncattach

- Only allow prefix length of between 0 to 128

* TAP

- Cleaned up

* TAP

- Cleaned up

* tncattach

- Cleaned up

README.md

@@ -133,4 +133,11 @@ On some versions of Raspbian (and probably other operating systems), the DHCP cl
 # of /etc/dhcpcd.conf to prevent dhcpcd from changing MTU
 
 denyinterfaces tnc0
-```
+```
+
+## Support tncattach development
+You can help support the continued development of open, free and private communications systems by donating via one of the following channels:
+
+- Ethereum: 0x81F7B979fEa6134bA9FD5c701b3501A2e61E897a
+- Bitcoin: 3CPmacGm34qYvR6XWLVEJmi2aNe3PZqUuq
+- Ko-Fi: https://ko-fi.com/markqvist

TAP.c

@@ -5,15 +5,72 @@ char tap_name[IFNAMSIZ];
 extern bool verbose;
 extern bool noipv6;
 extern bool set_ipv4;
+extern bool set_ipv6;
+extern bool set_linklocal;
 extern bool set_netmask;
 extern bool noup;
 extern int mtu;
 extern int device_type;
 extern char if_name[IFNAMSIZ];
 extern char* ipv4_addr;
+extern char* ipv6_addr;
+extern long ipv6_prefixLen;
 extern char* netmask;
 extern void cleanup();
 
+
+void trySixSet
+(
+    int interfaceIndex,
+    struct in6_addr address,
+    int prefixLen
+)
+{
+    char ip_str[INET6_ADDRSTRLEN+1];
+    inet_ntop(AF_INET6, &address, ip_str, INET6_ADDRSTRLEN+1);
+
+    printf
+    (
+        "Adding IPv6 address of '%s/%d' to interface at if_index %d\n",
+        ip_str,
+        prefixLen,
+        interfaceIndex
+    );
+
+    int inet6 = socket(AF_INET6, SOCK_DGRAM, 0);
+    if(inet6 < 0)
+    {
+        printf("Error opening control socket for adding IPv6 address to interface\n");
+        cleanup();
+        exit(1);
+    }
+
+    struct in6_ifreq paramReq;
+    memset(&paramReq, 0, sizeof(struct in6_ifreq));
+    paramReq.ifr6_ifindex = interfaceIndex;
+    paramReq.ifr6_prefixlen = prefixLen;
+    paramReq.ifr6_addr = address;
+
+
+    // Try add the address
+    if(ioctl(inet6, SIOCSIFADDR, &paramReq) < 0)
+    {
+        printf
+        (
+            "There was an errror assigning address '%s/%d' to if_index %d\n",
+            ip_str,
+            prefixLen,
+            interfaceIndex
+        );
+        cleanup();
+        close(inet6);
+        exit(1);
+    }
+
+    printf("Address '%s/%d' added\n", ip_str, prefixLen);
+    close(inet6);
+}
+
 int open_tap(void) {
     struct ifreq ifr;
     int fd = open("/dev/net/tun", O_RDWR);
@@ -43,10 +100,11 @@ int open_tap(void) {
             exit(1);
         } else {
             strcpy(if_name, ifr.ifr_name);
+
             
             int inet = socket(AF_INET, SOCK_DGRAM, 0);
             if (inet == -1) {
-                perror("Could not open AF_INET socket");
+                perror("Could not open control socket");
                 cleanup();
                 exit(1);
             } else {
@@ -182,6 +240,54 @@ int open_tap(void) {
                                         }
                                     }
                                 }
+
+                                if(set_ipv6 || set_linklocal)
+                                {
+                                    // Firstly, obtain the interface index by `ifr_name`
+                                    int inet6 = socket(AF_INET6, SOCK_DGRAM, 0);
+                                    if(inet6 < 0)
+                                    {
+                                        printf("Error opening control socket for adding IPv6 address to interface\n");
+                                        cleanup();
+                                        exit(1);
+                                    }
+
+                                    if(ioctl(inet6, SIOCGIFINDEX, &ifr) < 0)
+                                    {
+                                        printf("Could not get interface index for interface '%s'\n", ifr.ifr_name);
+                                        close(inet6);
+                                        cleanup();
+                                        exit(1);
+                                    }
+
+                                    // if link-local was NOT requested and interface
+                                    // has been up'd -> then kernel would have added
+                                    // a link-local already, this removes it
+                                    if(!set_linklocal & !noup)
+                                    {
+                                    		// TODO: Get all addresses that start with fe80
+                                    }
+                                    // Else it could have been no-up; hence you will have to remove
+                                    // the link-local yourself
+                                    // Other else is link-local was requested, then we don't care (whether
+                                    // up'd or not as it will inevitably be added by the kernel)
+
+                                    // Convert ASCII IPv6 address to ABI structure
+                                    struct in6_addr six_addr_itself;
+                                    memset(&six_addr_itself, 0, sizeof(struct in6_addr));
+                                    if(inet_pton(AF_INET6, ipv6_addr, &six_addr_itself) < 0)
+                                    {
+                                        printf("Error parsing IPv6 address '%s'\n", ipv6_addr);
+                                        close(inet6);
+                                        cleanup();
+                                        exit(1);
+                                    }
+
+                                    // Add user's requested address
+                                    trySixSet(ifr.ifr_ifindex, six_addr_itself, ipv6_prefixLen);
+
+                                    close(inet6);
+                                }
                             }
                         }
                     }
@@ -195,4 +301,4 @@ int open_tap(void) {
 
 int close_tap(int tap_fd) {
     return close(tap_fd);
-}
+}

TAP.h

@@ -9,6 +9,7 @@
 #include <linux/if_tun.h>
 #include <sys/socket.h>
 #include <arpa/inet.h>
+#include <linux/ipv6.h>
 #include "Constants.h"
 
 int open_tap(void);

makefile

@@ -1,26 +1,35 @@
 .DEFAULT_GOAL := all
 .PHONY: all clean install uninstall tncattach
 
-compiler = gcc
+RM ?= rm
-flags = -Wall -std=gnu11 -static-libgcc
+INSTALL ?= install
+CC ?= gcc
+CFLAGS ?= -Wall -std=gnu11 -static-libgcc
+LDFLAGS ?= 
+PREFIX ?= /usr/local
 
 all: tncattach
 rebuild: clean all
 
 clean:
 	@echo "Cleaning tncattach build..."
-	@rm -f tncattach
+	$(RM) -f tncattach
 
 tncattach:
 	@echo "Making tncattach..."
-	@echo "Compiling with: ${compiler}"
+	@echo "Compiling with: $(CC)"
-	${compiler} ${flags} tncattach.c Serial.c TCP.c KISS.c TAP.c -o tncattach -Wall
+	$(CC) $(CFLAGS) $(LDFLAGS) tncattach.c Serial.c TCP.c KISS.c TAP.c -o tncattach
 
 install:
 	@echo "Installing tncattach..."
-	chmod a+x tncattach
+	$(INSTALL) -d $(DESTDIR)/$(PREFIX)/bin
-	cp ./tncattach /usr/local/sbin/
+	$(INSTALL) -Dm755 tncattach $(DESTDIR)/$(PREFIX)/bin/tncattach
+	@echo "Installing man page..."
+	gzip -9 tncattach.8
+	$(INSTALL) -d $(DESTDIR)/$(PREFIX)/share/man/man8
+	$(INSTALL) -Dm644 tncattach.8.gz $(DESTDIR)/$(PREFIX)/share/man/man8/tncattach.8.gz
 
 uninstall:
 	@echo "Uninstalling tncattach"
-	rm /usr/local/sbin/tncattach
+	$(RM) $(DESTDIR)/$(PREFIX)/bin/tncattach
+	$(RM) $(DESTDIR)/$(PREFIX)/share/man/man8/tncattach.8.gz

tncattach.8

@@ -0,0 +1,165 @@
+.TH tncattach 8 "September 12, 2020"
+
+.SH NAME
+.
+.
+tncattach \- Attach TNC devices as system network interfaces
+
+.SH SYNOPSIS
+.
+.
+\f[B]tncattach\f[R] [OPTION...] port baudrate
+
+.SH DESCRIPTION
+Attach KISS TNC devices as network interfaces in Linux. This program allows you to attach TNCs or any KISS-compatible device as a network interface. This program does not need any kernel modules, and has no external dependencies outside the standard Linux and GNU C libraries.
+
+.SH OPTIONS
+.
+.
+.TP
+.BI \-m, \-\-mtu=MTU
+.
+Specify interface MTU
+.
+.
+.TP
+.BI \-e, \-\-ethernet
+Create a full ethernet device
+.
+.
+.TP
+.BI \-i, \-\-ipv4=IP_ADDRESS
+Configure an IPv4 address on interface
+.
+.
+.TP
+.BI \-n, \-\-noipv6
+Filter IPv6 traffic from reaching TNC
+.
+.
+.TP
+.BI \-\-noup
+Only create interface, don't bring it up
+.
+.
+.TP
+.BI \-T, \-\-kisstcp
+Use KISS over TCP instead of serial port
+.
+.
+.TP
+.BI \-H, \-\-tcphost=TCP_HOST
+Host to connect to when using KISS over TCP
+.
+.
+.TP
+.BI \-P, \-\-tcpport=TCP_PORT
+TCP port when using KISS over TCP
+.
+.
+.TP
+.BI \-t, \-\-interval=SECONDS
+Maximum interval between station identifications
+.
+.
+.TP
+.B \-s, \-\-id=CALLSIGN
+Station identification data
+.
+.
+.TP
+.BI \-d, \-\-daemon
+Run tncattach as a daemon
+.
+.
+.TP
+.BI \-v, \-\-verbose
+Enable verbose output
+.
+.
+.TP
+.BI \-?, \-\-help
+Show help
+.
+.
+.TP
+.BI \-\-usage
+Give a short usage message
+.
+.
+.TP
+.BI \-V, \-\-version
+Print program version
+.
+.
+
+.SH USAGE
+The program supports attaching TNCs as point-to-point tunnel devices, or generic ethernet devices. The ethernet mode is suitable for point-to-multipoint setups, and can be enabled with the corresponding command line switch. If you only need point-to-point links, it is advisable to just use the standard point-to-point mode, since it doesn't incur the ethernet header overhead on each packet.
+.P
+If you want to connect to a virtual KISS TNC over a TCP connection, you can use the -T option, along with the -H and -P options to specify the host and port.
+.P
+Additionally, it is worth noting that tncattach can filter out IPv6 packets from reaching the TNC. Most operating systems attempts to autoconfigure IPv6 when an interface is brought up, which results in a substantial amount of IPv6 traffic generated by router solicitations and similar, which is usually unwanted for packet radio links and similar.
+.P
+If you intend to use tncattach on a system with mDNS services enabled (avahi-daemon, for example), you may want to consider modifying your mDNS setup to exclude TNC interfaces, or turning it off entirely, since it will generate a lot of traffic that might be unwanted.
+
+.SH STATION IDENTIFICATION
+
+You can configure tncattach to automatically transmit station identification beacons according to a given interval, by using the --id and --interval options. Identification will be transmitted as raw data frames with whatever content has been specified in the --id option. Useful for amateur radio use, or other areas where station identification is necessary.
+.P
+Identification beacons will be transmitted when:
+.P
+.IP
+There is outgoing data to send, and the specified interval has elapsed.
+.IP
+The specified interval elapses, and data has been sent since the last ID beacon.
+.IP
+The program exits, if any data frames have been transmitted since the last ID beacon.
+.P
+The above methodology should comply with station identification rules for amateur radio in most parts of the world, and complies with US Part 97 rules.
+
+.SH EXAMPLES
+.
+Create an ethernet device with a USB-connected TNC, set the MTU, filter IPv6 traffic, and set an IPv4 address:
+.IP
+sudo tncattach /dev/ttyUSB0 115200 --ethernet --mtu 576 --noipv6 --ipv4 10.92.0.10/24
+.P
+Create an ethernet device with a TCP-connected TNC, set the MTU, filter IPv6 traffic, and set an IPv4 address:
+.IP
+sudo tncattach -T -H localhost -P 8001 --ethernet --mtu 576 --noipv6 --ipv4 10.92.0.10/24
+.P
+You can interact with the interface like any other using the ip or ifconfig utilities.
+.p
+Check interface is running:
+.P
+# ifconfig
+.br
+tnc0: flags=4305<UP,POINTOPOINT,RUNNING,NOARP,MULTICAST>  mtu 400
+.br
+        inet 10.93.0.1  netmask 255.255.255.255  destination 10.93.0.2
+.br
+        unspec 00-00-00-00-00-00-00-00-00-00-00-00-00-00-00-00  txqueuelen 500  (UNSPEC)
+.br
+        RX packets 0  bytes 0 (0.0 B)
+.br
+        RX errors 0  dropped 0  overruns 0  frame 0
+.br
+        TX packets 0  bytes 0 (0.0 B)
+.br
+        TX errors 0  dropped 0 overruns 0  carrier 0  collisions 0
+.P
+.SH WORTH KNOWING ON RASPBIAN
+On some versions of Raspbian (and probably other operating systems), the DHCP client daemon dhcpcd interferes with TNC interfaces, by overriding their MTU and trying to auto-configure link-local addresses. You probably don't want this, and it can be disabled by editing the /etc/dhcpcd.conf file, adding a statement telling dhcpcd to ignore your TNC interface:
+.P
+# Add the following statement somewhere at the beginning
+.br
+# of /etc/dhcpcd.conf to prevent dhcpcd from changing MTU
+.br
+denyinterfaces tnc0
+
+.SH SEE ALSO
+
+rnodeconfigutil(8)
+
+.SH AUTHOR
+
+Mark Qvist

tncattach.c

@@ -34,11 +34,16 @@ bool noipv6 = false;
 bool noup = false;
 bool daemonize = false;
 bool set_ipv4 = false;
+bool set_ipv6 = false;
+bool set_linklocal = false;
 bool set_netmask = false;
 bool kiss_over_tcp = false;
 char* ipv4_addr;
 char* netmask;
 
+char* ipv6_addr;
+long ipv6_prefixLen;
+
 char* tcp_host;
 int tcp_port;
 
@@ -261,7 +266,7 @@ void read_loop(void) {
     exit(1);
 }
 
-const char *argp_program_version = "tncattach 0.1.8";
+const char *argp_program_version = "tncattach 0.1.9";
 const char *argp_program_bug_address = "<mark@unsigned.io>";
 static char doc[] = "\r\nAttach TNC devices as system network interfaces\vTo attach the TNC connected to /dev/ttyUSB0 as an ethernet device with an MTU of 512 bytes and assign an IPv4 address, while filtering IPv6 traffic, use:\r\n\r\n\ttncattach /dev/ttyUSB0 115200 -m 512 -e --noipv6 --ipv4 10.0.0.1/24\r\n\r\nStation identification can be performed automatically to comply with Part 97 rules. See the README for a complete description. Use the --id and --interval options, which should commonly be set to your callsign, and 600 seconds.";
 static char args_doc[] = "port baudrate";
@@ -269,15 +274,17 @@ static struct argp_option options[] = {
     { "mtu", 'm', "MTU", 0, "Specify interface MTU", 1},
     { "ethernet", 'e', 0, 0, "Create a full ethernet device", 2},
     { "ipv4", 'i', "IP_ADDRESS", 0, "Configure an IPv4 address on interface", 3},
-    { "noipv6", 'n', 0, 0, "Filter IPv6 traffic from reaching TNC", 4},
+    { "ipv6", '6', "IP6_ADDRESS", 0, "Configure an IPv6 address on interface", 4},
-    { "noup", 1, 0, 0, "Only create interface, don't bring it up", 5},
+    { "ll", 'l', 0, 0, "Add a link-local Ipv6 address", 5},
-    { "kisstcp", 'T', 0, 0, "Use KISS over TCP instead of serial port", 6},
+    { "noipv6", 'n', 0, 0, "Filter IPv6 traffic from reaching TNC", 6},
-    { "tcphost", 'H', "TCP_HOST", 0, "Host to connect to when using KISS over TCP", 7},
+    { "noup", 1, 0, 0, "Only create interface, don't bring it up", 7},
-    { "tcpport", 'P', "TCP_PORT", 0, "TCP port when using KISS over TCP", 8},
+    { "kisstcp", 'T', 0, 0, "Use KISS over TCP instead of serial port", 8},
-    { "interval", 't', "SECONDS", 0, "Maximum interval between station identifications", 9},
+    { "tcphost", 'H', "TCP_HOST", 0, "Host to connect to when using KISS over TCP", 9},
-    { "id", 's', "CALLSIGN", 0, "Station identification data", 10},
+    { "tcpport", 'P', "TCP_PORT", 0, "TCP port when using KISS over TCP", 10},
-    { "daemon", 'd', 0, 0, "Run tncattach as a daemon", 11},
+    { "interval", 't', "SECONDS", 0, "Maximum interval between station identifications", 11},
-    { "verbose", 'v', 0, 0, "Enable verbose output", 12},
+    { "id", 's', "CALLSIGN", 0, "Station identification data", 12},
+    { "daemon", 'd', 0, 0, "Run tncattach as a daemon", 13},
+    { "verbose", 'v', 0, 0, "Enable verbose output", 14},
     { 0 }
 };
 
@@ -285,6 +292,7 @@ static struct argp_option options[] = {
 struct arguments {
     char *args[N_ARGS];
     char *ipv4;
+    char *ipv6;
     char *id;
     bool valid_id;
     int id_interval;
@@ -296,6 +304,9 @@ struct arguments {
     bool verbose;
     bool set_ipv4;
     bool set_netmask;
+    bool set_ipv6;
+    bool link_local_v6;
+    bool set_netmask_v6;
     bool noipv6;
     bool noup;
     bool kiss_over_tcp;
@@ -321,6 +332,13 @@ static error_t parse_opt(int key, char *arg, struct argp_state *state) {
                 printf("Error: Invalid MTU specified\r\n\r\n");
                 argp_usage(state);
             }
+
+            if((arguments->set_ipv6 || arguments->link_local_v6) && arguments->mtu < 1280)
+            {
+                printf("IPv6 and/or link-local IPv6 was requested, but the MTU provided is lower than 1280\n");
+                exit(EXIT_FAILURE);
+            }
+
             break;
 
         case 't':
@@ -466,9 +484,70 @@ static error_t parse_opt(int key, char *arg, struct argp_state *state) {
             }
 
             break;
+        case '6':
+            if(arguments->noipv6)
+            {
+                perror("Sorry, but you had noipv6 set yet want to use ipv6?\n");
+                exit(EXIT_FAILURE);
+            }
+
+            char* ipPart_s = strtok(arg, "/");
+            char* prefixPart_s = strtok(NULL, "/");
+            printf("ipPart_s: %s\n", ipPart_s);
+
+            if(!prefixPart_s)
+            {
+                printf("No prefix length was provided\n");
+                exit(1);
+            }
+            printf("prefixPart_s: %s\n", prefixPart_s);
+
+            long prefixLen_l = strtol(prefixPart_s, NULL, 10); // TODO: Add handling here for errors (using errno)
+
+            if(prefixLen_l == 0) {
+                printf("Prefix length '%s' is not numeric\n", prefixPart_s);
+                exit(EXIT_FAILURE);
+            }
+            else if(!(prefixLen_l >= 0 && prefixLen_l <= 128))
+            {
+                printf("Prefix length '%s' is not within valid range of 0-128\n", prefixPart_s);
+                exit(EXIT_FAILURE);
+            }
+
+            arguments->ipv6 = ipPart_s;
+            
+            arguments->set_ipv6 = true;
+
+            // Copy across global IPv6 address
+            ipv6_addr = malloc(strlen(arguments->ipv6)+1);
+            strcpy(ipv6_addr, arguments->ipv6);
+
+            // Set global IPv6 prefix length
+            ipv6_prefixLen = prefixLen_l;
+
+            printf("MTU was %d, setting to minimum of %d as is required for IPv6\n", arguments->mtu, 1280);
+            arguments->mtu = 1280;
+            break;
+
+        case 'l':
+            if(arguments->noipv6)
+            {
+                perror("Sorry, but you had noipv6 set yet want to use ipv6 link-local?\n");
+                exit(EXIT_FAILURE);
+            }
+            arguments->link_local_v6 = true;
+
+            printf("MTU was %d, setting to minimum of %d as is required for IPv6\n", arguments->mtu, 1280);
+            arguments->mtu = 1280;
+            break;
 
         case 'n':
             arguments->noipv6 = true;
+            if(arguments->set_ipv6)
+            {
+                printf("Requested no IPv6 yet you have set the IPv6 to '%s'\n", arguments->ipv6);
+                exit(1);
+            }
             break;
 
         case 'd':
@@ -559,11 +638,15 @@ int main(int argc, char **argv) {
     arguments.verbose = false;
     arguments.set_ipv4 = false;
     arguments.set_netmask = false;
+    arguments.set_ipv6 = false;
+    arguments.link_local_v6 = false;
+    arguments.set_netmask_v6 = false;
     arguments.noipv6 = false;
     arguments.daemon = false;
     arguments.noup = false;
     arguments.id_interval = -1;
     arguments.valid_id = false;
+    arguments.kiss_over_tcp = false;
 
     argp_parse(&argp, argc, argv, 0, 0, &arguments);
 
@@ -585,6 +668,7 @@ int main(int argc, char **argv) {
     if (arguments.noipv6) noipv6 = true;
     if (arguments.set_ipv4) set_ipv4 = true;
     if (arguments.set_netmask) set_netmask = true;
+    if (arguments.set_ipv6) set_ipv6 = true;
     if (arguments.noup) noup = true;
     mtu = arguments.mtu;
 
@@ -631,4 +715,4 @@ int main(int argc, char **argv) {
     read_loop();
 
     return 0;
-}
+}