Added ICMP sockets, DNS PTR. Refactored posix support

.github/workflows/linux.yml

@@ -44,6 +44,10 @@ jobs:
         run: |
           ./build/test-ttl-expired
 
+      - name: Testing ICMP socket by stealing system calls in ping
+        run: |
+          sudo LD_PRELOAD=$PWD/libwolfip.so ping -c 5 10.10.10.1
+
       - name: Install check
         run: |
           sudo apt-get install -y check
@@ -55,4 +59,3 @@ jobs:
       - name: Run unit tests
         run: |
           build/test/unit
-

README.md

@@ -27,8 +27,35 @@ A single network interface can be associated with the device.
   - Pre-allocated buffers for packet processing in static memory
 
 
+## Functional tests with `LD_PRELOAD`
+
+The POSIX shim builds `libwolfip.so`, which can be injected in front of
+host tools so that calls to `socket(2)` and friends are redirected to the
+wolfIP stack and the TAP device (`wtcp0`).  After running `make`:
+
+```sh
+sudo LD_PRELOAD=$PWD/libwolfip.so nc 10.10.10.2 80
+```
+
+The example above mirrors the existing `nc`-driven demos: any TCP sockets
+opened by the intercepted process are serviced by wolfIP instead of the host
+kernel.
+
+### Ping over the TAP device
+
+ICMP datagram sockets can be validated the same way.  With the TAP interface
+created automatically by the shim and the host endpoint configured in
+`config.h` (`HOST_STACK_IP` defaults to `10.10.10.1`), run:
+
+```sh
+sudo LD_PRELOAD=$PWD/libwolfip.so ping -I wtcp0 -c5 10.10.10.1
+```
+
+The `-I wtcp0` flag pins the test to the injected interface and `-c5`
+generates five echo requests.  Successful replies confirm the ICMP
+datagram socket support end-to-end through the tap device.
+
 ## Copyright and License
 
 wolfIP is licensed under the GPLv3 license. See the LICENSE file for details.
 Copyright (c) 2025 wolfSSL Inc.
-

config.h

@@ -10,9 +10,14 @@
 
 #define MAX_TCPSOCKETS 4
 #define MAX_UDPSOCKETS 2
+#define MAX_ICMPSOCKETS 2
 #define RXBUF_SIZE LINK_MTU * 16
 #define TXBUF_SIZE LINK_MTU * 16
 
+#ifndef WOLFIP_POSIX_TCPDUMP
+#define WOLFIP_POSIX_TCPDUMP 0
+#endif
+
 #define MAX_NEIGHBORS 16
 
 #ifndef WOLFIP_MAX_INTERFACES
@@ -34,5 +39,6 @@
 /* Linux test configuration */
 #define WOLFIP_IP "10.10.10.2"
 #define HOST_STACK_IP "10.10.10.1"
+#define WOLFIP_STATIC_DNS_IP "9.9.9.9"
 
 #endif