examples: add POSIX socket example

examples/posix_sockets/Makefile

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+# name of your application
+APPLICATION = posix_sockets
+
+# If no BOARD is found in the environment, use this default:
+BOARD ?= native
+
+# This has to be the absolute path to the RIOT base directory:
+RIOTBASE ?= $(CURDIR)/../..
+
+# TODO: select stack according to size of available memory (or by user?)
+
+BOARD_INSUFFICIENT_MEMORY := airfy-beacon chronos msb-430 msb-430h nrf51dongle \
+                          nrf6310 nucleo-f334 pca10000 pca10005 \
+                          stm32f0discovery telosb wsn430-v1_3b wsn430-v1_4 \
+                          yunjia-nrf51822 z1
+
+BOARD_BLACKLIST        := arduino-mega2560 spark-core
+# arduino-mega2560: unknown error types (e.g. -EBADMSG)
+
+# Include packages that pull up and auto-init the link layer.
+# NOTE: 6LoWPAN will be included if IEEE802.15.4 devices are present
+USEMODULE += gnrc_netif_default
+USEMODULE += auto_init_gnrc_netif
+# Specify the mandatory networking modules for socket communication via UDP
+USEMODULE += gnrc_ipv6_default
+USEMODULE += gnrc_udp
+USEMODULE += gnrc_conn_udp
+USEMODULE += posix_sockets
+# Add also the shell, some shell commands
+USEMODULE += shell
+USEMODULE += shell_commands
+USEMODULE += ps
+
+# Comment this out to disable code in RIOT that does safety checking
+# which is not needed in a production environment but helps in the
+# development process:
+CFLAGS += -DDEVELHELP
+
+# Change this to 0 show compiler invocation lines by default:
+QUIET ?= 1
+
+include $(RIOTBASE)/Makefile.include

examples/posix_sockets/README.md

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+examples/posix_sockets
+======================
+This application is a showcase for RIOT's POSIX socket support. To
+keep things simple this application has only one-hop support and
+no routing capabilities.
+
+Usage
+=====
+
+Build, flash and start the application:
+```
+export BOARD=your_board
+make
+make flash
+make term
+```
+
+The `term` make target starts a terminal emulator for your board. It
+connects to a default port so you can interact with the shell, usually
+that is `/dev/ttyUSB0`. If your port is named differently, the
+`PORT=/dev/yourport` variable can be used to override this.
+
+
+Example output
+==============
+
+The shell commands come with online help. Call `help` to see which commands
+exist and what they do.
+
+Running the `help` command on an iotlab-m3:
+```
+2014-05-06 13:14:38,508 - INFO # > help
+```
+
+Running the `ps` command on an iotlab-m3:
+
+```
+2014-05-09 17:38:33,388 - INFO # > ps
+```
+
+Start a UDP server:
+
+```
+> udp server start <port>
+```
+
+Stop a UDP server:
+
+```
+> udp server start <port>
+```
+
+
+Send a UDP package:
+
+```
+> udp send <ip_addr> <port> <content>
+```

examples/posix_sockets/udp.c

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+/*
+ * Copyright (C) 2015 Martine Lenders <mlenders@inf.fu-berlin.de>
+ *
+ * This file is subject to the terms and conditions of the GNU Lesser
+ * General Public License v2.1. See the file LICENSE in the top level
+ * directory for more details.
+ */
+
+/**
+ * @ingroup     examples
+ * @{
+ *
+ * @file
+ * @brief       Demonstrating the sending and receiving of UDP data over POSIX sockets.
+ *
+ * @author      Martine Lenders <mlenders@inf.fu-berlin.de>
+ *
+ * @}
+ */
+
+#include <inttypes.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+
+#include <arpa/inet.h>
+#include <netinet/in.h>
+#include <sys/socket.h>
+#include <unistd.h>
+
+static int server_socket = 0;
+
+static void udp_send(char *addr_str, char *port_str, char *data, unsigned int num,
+                     unsigned int delay)
+{
+    struct sockaddr_in6 dst;
+    size_t data_len = strlen(data);
+    uint16_t port;
+    int s;
+    /* parse destination address */
+    if (inet_pton(AF_INET6, addr_str, &dst.sin6_addr) != 1) {
+        puts("Error: unable to parse destination address");
+        return;
+    }
+    /* parse port */
+    port = (uint16_t)atoi(port_str);
+    dst.sin6_port = htons(port);
+    s = socket(AF_INET6, SOCK_DGRAM, IPPROTO_UDP);
+    for (unsigned int i = 0; i < num; i++) {
+        sendto(s, data, data_len, 0, (struct sockaddr *)&dst, sizeof(dst));
+        printf("Success: send %u byte to %s:%u\n", (unsigned)data_len, addr_str, port);
+        usleep(delay);
+    }
+    close(s);
+}
+
+static void udp_start_server(char *port_str)
+{
+    struct sockaddr_in6 dst;
+    size_t data_len = strlen(data);
+    uint16_t port;
+
+    /* check if server is already running */
+    if (server_socket != 0) {
+        puts("Error: server already running");
+        return;
+    }
+    /* parse port */
+    port = (uint16_t)atoi(port_str);
+    if (port == 0) {
+        puts("Error: invalid port specified");
+        return;
+    }
+    memset(&dst.sin6_addr, 0, sizeof(dst.sin6_addr));
+    dst.sin6_port = htons(port);
+    /* start server (which means registering pktdump for the chosen port) */
+    server_socket = socket(AF_INET6, SOCK_DGRAM, IPPROTO_UDP);
+    /* TODO: start server thread, if not running */
+    printf("Success: started UDP server on port %" PRIu16 "\n", port);
+}
+
+static void udp_stop_server(void)
+{
+    /* check if server is running at all */
+    if (server_socket == 0) {
+        printf("Error: server was not running\n");
+        return;
+    }
+    /* stop server */
+    /* TODO: send stop command to server thread */
+    close(server_socket);
+    server_socket = 0;
+    puts("Success: stopped UDP server");
+}
+
+int udp_cmd(int argc, char **argv)
+{
+    if (argc < 2) {
+        printf("usage: %s [send|server]\n", argv[0]);
+        return 1;
+    }
+
+    if (strcmp(argv[1], "send") == 0) {
+        uint32_t num = 1;
+        uint32_t delay = 1000000;
+        if (argc < 5) {
+            printf("usage: %s send <addr> <port> <data> [<num> [<delay in us>]]\n",
+                   argv[0]);
+            return 1;
+        }
+        if (argc > 5) {
+            num = (uint32_t)atoi(argv[5]);
+        }
+        if (argc > 6) {
+            delay = (uint32_t)atoi(argv[6]);
+        }
+        udp_send(argv[2], argv[3], argv[4], num, delay);
+    }
+    else if (strcmp(argv[1], "server") == 0) {
+        if (argc < 3) {
+            printf("usage: %s server [start|stop]\n", argv[0]);
+            return 1;
+        }
+        if (strcmp(argv[2], "start") == 0) {
+            if (argc < 4) {
+                printf("usage %s server start <port>\n", argv[0]);
+                return 1;
+            }
+            udp_start_server(argv[3]);
+        }
+        else if (strcmp(argv[2], "stop") == 0) {
+            udp_stop_server();
+        }
+        else {
+            puts("error: invalid command");
+        }
+    }
+    else {
+        puts("error: invalid command");
+    }
+    return 0;
+}
+
+/** @} */