From bec778de7bed2388c071c50651360c8b93337203 Mon Sep 17 00:00:00 2001
From: XANTRONIX Development <dev@xantronix.com>
Date: Tue, 22 Sep 2020 18:47:20 -0400
Subject: [PATCH] Implement bin/tncd.c

Implement bin/tncd.c to expose a network interface as a KISS TNC device
over a PTY
---
 bin/Makefile |   7 ++-
 bin/tncd.c   | 170 +++++++++++++++++++++++++++++++++++++++++++++++++++
 2 files changed, 175 insertions(+), 2 deletions(-)
 create mode 100644 bin/tncd.c

diff --git a/bin/Makefile b/bin/Makefile
index ec6eefe..c90b8bf 100644
--- a/bin/Makefile
+++ b/bin/Makefile
@@ -8,14 +8,14 @@ HEADERS_SUBDIR	= patty/bin
 CFLAGS		+= -I$(INCLUDE_PATH)
 LDFLAGS		= -L../src -lpatty
 
-PROGRAMS	= pattyd ax25dump
+PROGRAMS	= pattyd ax25dump tncd
 MAN8PAGES	= pattyd.8 ax25dump.8
 MANPAGES	= $(MAN8PAGES)
 
 HEADERS		= kiss.h if.h
 HEADERS_BUILD	= $(addprefix $(INCLUDE_PATH)/$(HEADERS_SUBDIR)/, $(HEADERS))
 
-OBJS		= pattyd.o ax25dump.o kiss.o if.o
+OBJS		= pattyd.o ax25dump.o kiss.o if.o tncd.o
 
 all: $(PROGRAMS)
 
@@ -30,6 +30,9 @@ pattyd: pattyd.o kiss.o if.o
 ax25dump: ax25dump.o kiss.o
 	$(CC) $(CFLAGS) $^ -o $@ $(LDFLAGS)
 
+tncd: tncd.o
+	$(CC) $(CFLAGS) $^ -o $@ $(LDFLAGS)
+
 $(OBJS): %.o: %.c $(HEADERS_BUILD)
 	$(CC) $(CFLAGS) -c $<
 
diff --git a/bin/tncd.c b/bin/tncd.c
new file mode 100644
index 0000000..61deb77
--- /dev/null
+++ b/bin/tncd.c
@@ -0,0 +1,170 @@
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <stdarg.h>
+#include <getopt.h>
+#include <unistd.h>
+#include <sys/types.h>
+#include <sys/stat.h>
+#include <sys/socket.h>
+#include <sys/un.h>
+#include <fcntl.h>
+#include <errno.h>
+#include <sysexits.h>
+
+#include <patty/ax25.h>
+#include <patty/print.h>
+
+#include <patty/bin/kiss.h>
+
+static void usage(int argc, char **argv, const char *message, ...) {
+    if (message != NULL) {
+        va_list args;
+
+        va_start(args, message);
+        vfprintf(stderr, message, args);
+         fprintf(stderr, "\n");
+        va_end(args);
+    }
+
+    fprintf(stderr, "usage: %s /var/run/patty.sock ifname\n", argv[0]);
+
+    exit(EX_USAGE);
+}
+
+static int pty_promisc(patty_client *client,
+                       const char *ifname,
+                       char *pty,
+                       size_t len) {
+    enum patty_client_call call;
+
+    patty_client_socket_request socket_request = {
+        .proto = PATTY_AX25_PROTO_NONE,
+        .type  = PATTY_AX25_SOCK_RAW
+    };
+
+    patty_client_socket_response socket_response;
+    patty_client_setsockopt_request setsockopt_request;
+    patty_client_setsockopt_response setsockopt_response;
+
+    patty_client_setsockopt_if ifreq;
+
+    call = PATTY_CLIENT_SOCKET;
+
+    if (patty_client_write(client, &call, sizeof(call)) < 0) {
+        goto error_client_write_socket_request;
+    }
+
+    if (patty_client_write(client,
+                           &socket_request,
+                           sizeof(socket_request)) < 0) {
+        goto error_client_write_socket_request;
+    }
+
+    if (patty_client_read(client,
+                          &socket_response,
+                          sizeof(socket_response)) < 0) {
+        goto error_client_read_socket_response;
+    }
+
+    if (socket_response.fd < 0) {
+        errno = socket_response.eno;
+
+        goto error_client_socket;
+    }
+
+    setsockopt_request.fd  = socket_response.fd;
+    setsockopt_request.opt = PATTY_AX25_SOCK_IF;
+    setsockopt_request.len = sizeof(ifreq);
+
+    strncpy(ifreq.name, ifname, sizeof(ifreq.name));
+    ifreq.state = PATTY_AX25_SOCK_PROMISC;
+
+    call = PATTY_CLIENT_SETSOCKOPT;
+
+    if (patty_client_write(client, &call, sizeof(call)) < 0) {
+        goto error_client_write_socket_request;
+    }
+
+    if (patty_client_write(client,
+                           &setsockopt_request,
+                           sizeof(setsockopt_request)) < 0) {
+        goto error_client_write_setsockopt_request;
+    }
+
+    if (patty_client_write(client,
+                           &ifreq,
+                           sizeof(ifreq)) < 0) {
+        goto error_client_write_ifreq;
+    }
+
+    if (patty_client_read(client,
+                          &setsockopt_response,
+                          sizeof(setsockopt_response)) < 0) {
+        goto error_client_read_setsockopt_response;
+    }
+
+    if (setsockopt_response.ret < 0) {
+        errno = setsockopt_response.eno;
+
+        goto error_client_setsockopt;
+    }
+
+    strncpy(pty, socket_response.path, len);
+
+    return 0;
+
+error_client_setsockopt:
+error_client_read_setsockopt_response:
+error_client_write_ifreq:
+error_client_write_setsockopt_request:
+    /* TODO: Close socket on error */
+
+error_client_socket:
+error_client_read_socket_response:
+error_client_write_socket_request:
+    return -1;
+}
+
+int main(int argc, char **argv) {
+    struct option opts[] = {
+        { NULL, 0, NULL, 0 }
+    };
+
+    patty_client *client;
+    char pty[256];
+
+    if (getopt_long(argc, argv, "", opts, NULL) >= 0) {
+        usage(argc, argv, NULL);
+    }
+
+    if (argc < 3) {
+        usage(argc, argv, "Not enough arguments provided");
+    }
+
+    if ((client = patty_client_new(argv[1])) == NULL) {
+        fprintf(stderr, "%s: %s: %s\n",
+            argv[0], "patty_client_new()", strerror(errno));
+
+        goto error_client_new;
+    }
+
+    if (pty_promisc(client, argv[2], pty, sizeof(pty)) < 0) {
+        fprintf(stderr, "%s: %s: %s: %s\n",
+            argv[0], "pty_promisc()", argv[2], strerror(errno));
+
+        goto error_pty_promisc;
+    }
+
+    printf("%s\n", pty);
+
+    while (1) {
+        sleep(86400);
+    }
+
+    patty_client_destroy(client);
+
+error_pty_promisc:
+error_client_new:
+    return 1;
+}