From 052c7d94d05c4ac6d654fc42584f8694fbeb430d Mon Sep 17 00:00:00 2001
From: XANTRONIX Development <dev@xantronix.com>
Date: Sun, 19 Jul 2020 01:44:16 -0400
Subject: [PATCH] Implement functions for setting params on sockets

Changes:

    * Implement patty_ax25_sock_upgrade() to upgrade a socket from the
      default AX.25 2.0 parameters to AX.25 2.2 parameters, meant to be
      used upon receipt of an XID frame

    * Implement patty_ax25_sock_params_set() to set lowest common
      denominator parameters to a socket, downgrading or adapting to the
      parameters advertised by a peer XID frame as necessary
---
 include/patty/ax25/sock.h |  5 +++
 src/sock.c                | 95 +++++++++++++++++++++++++++++++++++++++
 2 files changed, 100 insertions(+)

diff --git a/include/patty/ax25/sock.h b/include/patty/ax25/sock.h
index 0b83b37..5e24593 100644
--- a/include/patty/ax25/sock.h
+++ b/include/patty/ax25/sock.h
@@ -87,8 +87,13 @@ patty_ax25_sock *patty_ax25_sock_new(enum patty_ax25_proto proto,
 
 void patty_ax25_sock_reset(patty_ax25_sock *sock);
 
+void patty_ax25_sock_upgrade(patty_ax25_sock *sock);
+
 void patty_ax25_sock_destroy(patty_ax25_sock *sock);
 
+int patty_ax25_sock_params_set(patty_ax25_sock *sock,
+                               patty_ax25_params *params);
+
 int patty_ax25_sock_mode_set(patty_ax25_sock *sock,
                              enum patty_ax25_sock_mode mode);
 
diff --git a/src/sock.c b/src/sock.c
index 59b209e..99edcff 100644
--- a/src/sock.c
+++ b/src/sock.c
@@ -130,6 +130,15 @@ void patty_ax25_sock_reset(patty_ax25_sock *sock) {
     sock->seq_recv        = 0;
 }
 
+void patty_ax25_sock_upgrade(patty_ax25_sock *sock) {
+    sock->version     = PATTY_AX25_2_2;
+    sock->flags_hdlc  = PATTY_AX25_SOCK_2_2_DEFAULT_HDLC;
+    sock->n_maxlen_tx = PATTY_AX25_SOCK_2_2_DEFAULT_MAXLEN;
+    sock->n_maxlen_rx = PATTY_AX25_SOCK_2_2_DEFAULT_MAXLEN;
+    sock->n_window_tx = PATTY_AX25_SOCK_2_2_DEFAULT_WINDOW;
+    sock->n_window_rx = PATTY_AX25_SOCK_2_2_DEFAULT_WINDOW;
+}
+
 void patty_ax25_sock_destroy(patty_ax25_sock *sock) {
     if (sock->fd) {
         if (sock->iface) {
@@ -144,6 +153,92 @@ void patty_ax25_sock_destroy(patty_ax25_sock *sock) {
     free(sock);
 }
 
+int patty_ax25_sock_params_set(patty_ax25_sock *sock,
+                               patty_ax25_params *params) {
+    if (params->flags & PATTY_AX25_PARAM_CLASSES) {
+        if (!(params->classes & PATTY_AX25_PARAM_CLASSES_ABM)) {
+            goto error_invalid;
+        }
+
+        /*
+         * TODO: Eventually support full duplex
+         */
+        if (!(params->classes & PATTY_AX25_PARAM_CLASSES_HALF_DUPLEX)) {
+            goto error_invalid;
+        }
+
+        if (params->classes & PATTY_AX25_PARAM_CLASSES_FULL_DUPLEX) {
+            goto error_invalid;
+        }
+    }
+
+    if (params->flags & PATTY_AX25_PARAM_HDLC) {
+        if (!(params->hdlc & PATTY_AX25_PARAM_HDLC_REJ)) {
+            sock->flags_hdlc &= ~PATTY_AX25_PARAM_HDLC_REJ;
+        }
+
+        if (!(params->hdlc & PATTY_AX25_PARAM_HDLC_SREJ)) {
+            sock->flags_hdlc &= ~PATTY_AX25_PARAM_HDLC_SREJ;
+        }
+
+        if (!(params->hdlc & PATTY_AX25_PARAM_HDLC_XADDR)) {
+            goto error_invalid;
+        }
+
+        if (!(params->hdlc & PATTY_AX25_PARAM_HDLC_MODULO_8)) {
+            if (!(params->hdlc & PATTY_AX25_PARAM_HDLC_MODULO_128)) {
+                goto error_invalid;
+            }
+        } else {
+            if (!(params->hdlc & PATTY_AX25_PARAM_HDLC_MODULO_128)) {
+                goto error_invalid;
+            }
+
+            params->hdlc &= ~PATTY_AX25_PARAM_HDLC_MODULO_8;
+            params->hdlc |=  PATTY_AX25_PARAM_HDLC_MODULO_128;
+        }
+
+        if (!(params->hdlc & PATTY_AX25_PARAM_HDLC_TEST)) {
+            params->hdlc &= ~PATTY_AX25_PARAM_HDLC_TEST;
+        }
+
+        if (!(params->hdlc & PATTY_AX25_PARAM_HDLC_SYNC_TX)) {
+            goto error_invalid;
+        }
+    }
+
+    if (params->flags & PATTY_AX25_PARAM_INFO_RX) {
+        if (sock->n_maxlen_tx > params->info_rx) {
+            sock->n_maxlen_tx = params->info_rx;
+        }
+    }
+
+    if (params->flags & PATTY_AX25_PARAM_WINDOW_RX) {
+        if (sock->n_window_tx > params->window_rx) {
+            sock->n_window_tx = params->window_rx;
+        }
+    }
+
+    if (params->flags & PATTY_AX25_PARAM_ACK) {
+        if (sock->n_ack < params->ack) {
+            sock->n_ack = params->ack;
+        }
+    }
+
+    if (params->flags & PATTY_AX25_PARAM_RETRY) {
+        if (sock->n_retry < params->retry) {
+            sock->n_retry = params->retry;
+        }
+    }
+
+    return 0;
+
+error_invalid:
+    errno = EINVAL;
+
+    return -1;
+}
+
 int patty_ax25_sock_mode_set(patty_ax25_sock *sock,
                              enum patty_ax25_sock_mode mode) {
     if (sock->mode == mode) {