shared: Introduce new top-level dir and move 1st party lib code there.

This commit moves all first-party code developed for this project from lib/
to shared/, so that lib/ now only contains third-party code.

The following directories are moved as-is from lib to shared:

    lib/libc            -> shared/libc
    lib/memzip          -> shared/memzip
    lib/netutils        -> shared/netutils
    lib/timeutils       -> shared/timeutils
    lib/upytesthelper   -> shared/upytesthelper

All files in lib/embed/ have been moved to shared/libc/.

lib/mp-readline has been moved to shared/readline.

lib/utils has been moved to shared/runtime, with the exception of
lib/utils/printf.c which has been moved to shared/libc/printf.c.

Signed-off-by: Damien George <damien@micropython.org>

5 files changed, 673 insertions, 0 deletions

diff --git a/shared/netutils/dhcpserver.c b/shared/netutils/dhcpserver.c
new file mode 100644
index 0000000000..7f97ee6e46
--- /dev/null
+++ b/shared/netutils/dhcpserver.c
@@ -0,0 +1,304 @@
+/*
+ * This file is part of the MicroPython project, http://micropython.org/
+ *
+ * The MIT License (MIT)
+ *
+ * Copyright (c) 2018-2019 Damien P. George
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy
+ * of this software and associated documentation files (the "Software"), to deal
+ * in the Software without restriction, including without limitation the rights
+ * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+ * copies of the Software, and to permit persons to whom the Software is
+ * furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in
+ * all copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+ * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+ * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
+ * THE SOFTWARE.
+ */
+
+// For DHCP specs see:
+//  https://www.ietf.org/rfc/rfc2131.txt
+//  https://tools.ietf.org/html/rfc2132 -- DHCP Options and BOOTP Vendor Extensions
+
+#include <stdio.h>
+#include <string.h>
+#include "py/mperrno.h"
+#include "py/mphal.h"
+
+#if MICROPY_PY_LWIP
+
+#include "lib/netutils/dhcpserver.h"
+#include "lwip/udp.h"
+
+#define DHCPDISCOVER    (1)
+#define DHCPOFFER       (2)
+#define DHCPREQUEST     (3)
+#define DHCPDECLINE     (4)
+#define DHCPACK         (5)
+#define DHCPNACK        (6)
+#define DHCPRELEASE     (7)
+#define DHCPINFORM      (8)
+
+#define DHCP_OPT_PAD                (0)
+#define DHCP_OPT_SUBNET_MASK        (1)
+#define DHCP_OPT_ROUTER             (3)
+#define DHCP_OPT_DNS                (6)
+#define DHCP_OPT_HOST_NAME          (12)
+#define DHCP_OPT_REQUESTED_IP       (50)
+#define DHCP_OPT_IP_LEASE_TIME      (51)
+#define DHCP_OPT_MSG_TYPE           (53)
+#define DHCP_OPT_SERVER_ID          (54)
+#define DHCP_OPT_PARAM_REQUEST_LIST (55)
+#define DHCP_OPT_MAX_MSG_SIZE       (57)
+#define DHCP_OPT_VENDOR_CLASS_ID    (60)
+#define DHCP_OPT_CLIENT_ID          (61)
+#define DHCP_OPT_END                (255)
+
+#define PORT_DHCP_SERVER (67)
+#define PORT_DHCP_CLIENT (68)
+
+#define DEFAULT_DNS MAKE_IP4(8, 8, 8, 8)
+#define DEFAULT_LEASE_TIME_S (24 * 60 * 60) // in seconds
+
+#define MAC_LEN (6)
+#define MAKE_IP4(a, b, c, d) ((a) << 24 | (b) << 16 | (c) << 8 | (d))
+
+typedef struct {
+    uint8_t op; // message opcode
+    uint8_t htype; // hardware address type
+    uint8_t hlen; // hardware address length
+    uint8_t hops;
+    uint32_t xid; // transaction id, chosen by client
+    uint16_t secs; // client seconds elapsed
+    uint16_t flags;
+    uint8_t ciaddr[4]; // client IP address
+    uint8_t yiaddr[4]; // your IP address
+    uint8_t siaddr[4]; // next server IP address
+    uint8_t giaddr[4]; // relay agent IP address
+    uint8_t chaddr[16]; // client hardware address
+    uint8_t sname[64]; // server host name
+    uint8_t file[128]; // boot file name
+    uint8_t options[312]; // optional parameters, variable, starts with magic
+} dhcp_msg_t;
+
+static int dhcp_socket_new_dgram(struct udp_pcb **udp, void *cb_data, udp_recv_fn cb_udp_recv) {
+    // family is AF_INET
+    // type is SOCK_DGRAM
+
+    *udp = udp_new();
+    if (*udp == NULL) {
+        return -MP_ENOMEM;
+    }
+
+    // Register callback
+    udp_recv(*udp, cb_udp_recv, (void *)cb_data);
+
+    return 0; // success
+}
+
+static void dhcp_socket_free(struct udp_pcb **udp) {
+    if (*udp != NULL) {
+        udp_remove(*udp);
+        *udp = NULL;
+    }
+}
+
+static int dhcp_socket_bind(struct udp_pcb **udp, uint32_t ip, uint16_t port) {
+    ip_addr_t addr;
+    IP4_ADDR(&addr, ip >> 24 & 0xff, ip >> 16 & 0xff, ip >> 8 & 0xff, ip & 0xff);
+    // TODO convert lwIP errors to errno
+    return udp_bind(*udp, &addr, port);
+}
+
+static int dhcp_socket_sendto(struct udp_pcb **udp, const void *buf, size_t len, uint32_t ip, uint16_t port) {
+    if (len > 0xffff) {
+        len = 0xffff;
+    }
+
+    struct pbuf *p = pbuf_alloc(PBUF_TRANSPORT, len, PBUF_RAM);
+    if (p == NULL) {
+        return -MP_ENOMEM;
+    }
+
+    memcpy(p->payload, buf, len);
+
+    ip_addr_t dest;
+    IP4_ADDR(&dest, ip >> 24 & 0xff, ip >> 16 & 0xff, ip >> 8 & 0xff, ip & 0xff);
+    err_t err = udp_sendto(*udp, p, &dest, port);
+
+    pbuf_free(p);
+
+    if (err != ERR_OK) {
+        return err;
+    }
+
+    return len;
+}
+
+static uint8_t *opt_find(uint8_t *opt, uint8_t cmd) {
+    for (int i = 0; i < 308 && opt[i] != DHCP_OPT_END;) {
+        if (opt[i] == cmd) {
+            return &opt[i];
+        }
+        i += 2 + opt[i + 1];
+    }
+    return NULL;
+}
+
+static void opt_write_n(uint8_t **opt, uint8_t cmd, size_t n, void *data) {
+    uint8_t *o = *opt;
+    *o++ = cmd;
+    *o++ = n;
+    memcpy(o, data, n);
+    *opt = o + n;
+}
+
+static void opt_write_u8(uint8_t **opt, uint8_t cmd, uint8_t val) {
+    uint8_t *o = *opt;
+    *o++ = cmd;
+    *o++ = 1;
+    *o++ = val;
+    *opt = o;
+}
+
+static void opt_write_u32(uint8_t **opt, uint8_t cmd, uint32_t val) {
+    uint8_t *o = *opt;
+    *o++ = cmd;
+    *o++ = 4;
+    *o++ = val >> 24;
+    *o++ = val >> 16;
+    *o++ = val >> 8;
+    *o++ = val;
+    *opt = o;
+}
+
+static void dhcp_server_process(void *arg, struct udp_pcb *upcb, struct pbuf *p, const ip_addr_t *src_addr, u16_t src_port) {
+    dhcp_server_t *d = arg;
+    (void)upcb;
+    (void)src_addr;
+    (void)src_port;
+
+    // This is around 548 bytes
+    dhcp_msg_t dhcp_msg;
+
+    #define DHCP_MIN_SIZE (240 + 3)
+    if (p->tot_len < DHCP_MIN_SIZE) {
+        goto ignore_request;
+    }
+
+    size_t len = pbuf_copy_partial(p, &dhcp_msg, sizeof(dhcp_msg), 0);
+    if (len < DHCP_MIN_SIZE) {
+        goto ignore_request;
+    }
+
+    dhcp_msg.op = DHCPOFFER;
+    memcpy(&dhcp_msg.yiaddr, &d->ip.addr, 4);
+
+    uint8_t *opt = (uint8_t *)&dhcp_msg.options;
+    opt += 4; // assume magic cookie: 99, 130, 83, 99
+
+    switch (opt[2]) {
+        case DHCPDISCOVER: {
+            int yi = DHCPS_MAX_IP;
+            for (int i = 0; i < DHCPS_MAX_IP; ++i) {
+                if (memcmp(d->lease[i].mac, dhcp_msg.chaddr, MAC_LEN) == 0) {
+                    // MAC match, use this IP address
+                    yi = i;
+                    break;
+                }
+                if (yi == DHCPS_MAX_IP) {
+                    // Look for a free IP address
+                    if (memcmp(d->lease[i].mac, "\x00\x00\x00\x00\x00\x00", MAC_LEN) == 0) {
+                        // IP available
+                        yi = i;
+                    }
+                    uint32_t expiry = d->lease[i].expiry << 16 | 0xffff;
+                    if ((int32_t)(expiry - mp_hal_ticks_ms()) < 0) {
+                        // IP expired, reuse it
+                        memset(d->lease[i].mac, 0, MAC_LEN);
+                        yi = i;
+                    }
+                }
+            }
+            if (yi == DHCPS_MAX_IP) {
+                // No more IP addresses left
+                goto ignore_request;
+            }
+            dhcp_msg.yiaddr[3] = DHCPS_BASE_IP + yi;
+            opt_write_u8(&opt, DHCP_OPT_MSG_TYPE, DHCPOFFER);
+            break;
+        }
+
+        case DHCPREQUEST: {
+            uint8_t *o = opt_find(opt, DHCP_OPT_REQUESTED_IP);
+            if (o == NULL) {
+                // Should be NACK
+                goto ignore_request;
+            }
+            if (memcmp(o + 2, &d->ip.addr, 3) != 0) {
+                // Should be NACK
+                goto ignore_request;
+            }
+            uint8_t yi = o[5] - DHCPS_BASE_IP;
+            if (yi >= DHCPS_MAX_IP) {
+                // Should be NACK
+                goto ignore_request;
+            }
+            if (memcmp(d->lease[yi].mac, dhcp_msg.chaddr, MAC_LEN) == 0) {
+                // MAC match, ok to use this IP address
+            } else if (memcmp(d->lease[yi].mac, "\x00\x00\x00\x00\x00\x00", MAC_LEN) == 0) {
+                // IP unused, ok to use this IP address
+                memcpy(d->lease[yi].mac, dhcp_msg.chaddr, MAC_LEN);
+            } else {
+                // IP already in use
+                // Should be NACK
+                goto ignore_request;
+            }
+            d->lease[yi].expiry = (mp_hal_ticks_ms() + DEFAULT_LEASE_TIME_S * 1000) >> 16;
+            dhcp_msg.yiaddr[3] = DHCPS_BASE_IP + yi;
+            opt_write_u8(&opt, DHCP_OPT_MSG_TYPE, DHCPACK);
+            printf("DHCPS: client connected: MAC=%02x:%02x:%02x:%02x:%02x:%02x IP=%u.%u.%u.%u\n",
+                dhcp_msg.chaddr[0], dhcp_msg.chaddr[1], dhcp_msg.chaddr[2], dhcp_msg.chaddr[3], dhcp_msg.chaddr[4], dhcp_msg.chaddr[5],
+                dhcp_msg.yiaddr[0], dhcp_msg.yiaddr[1], dhcp_msg.yiaddr[2], dhcp_msg.yiaddr[3]);
+            break;
+        }
+
+        default:
+            goto ignore_request;
+    }
+
+    opt_write_n(&opt, DHCP_OPT_SERVER_ID, 4, &d->ip.addr);
+    opt_write_n(&opt, DHCP_OPT_SUBNET_MASK, 4, &d->nm.addr);
+    opt_write_n(&opt, DHCP_OPT_ROUTER, 4, &d->ip.addr); // aka gateway; can have mulitple addresses
+    opt_write_u32(&opt, DHCP_OPT_DNS, DEFAULT_DNS); // can have mulitple addresses
+    opt_write_u32(&opt, DHCP_OPT_IP_LEASE_TIME, DEFAULT_LEASE_TIME_S);
+    *opt++ = DHCP_OPT_END;
+    dhcp_socket_sendto(&d->udp, &dhcp_msg, opt - (uint8_t *)&dhcp_msg, 0xffffffff, PORT_DHCP_CLIENT);
+
+ignore_request:
+    pbuf_free(p);
+}
+
+void dhcp_server_init(dhcp_server_t *d, ip_addr_t *ip, ip_addr_t *nm) {
+    ip_addr_copy(d->ip, *ip);
+    ip_addr_copy(d->nm, *nm);
+    memset(d->lease, 0, sizeof(d->lease));
+    if (dhcp_socket_new_dgram(&d->udp, d, dhcp_server_process) != 0) {
+        return;
+    }
+    dhcp_socket_bind(&d->udp, 0, PORT_DHCP_SERVER);
+}
+
+void dhcp_server_deinit(dhcp_server_t *d) {
+    dhcp_socket_free(&d->udp);
+}
+
+#endif // MICROPY_PY_LWIP
diff --git a/shared/netutils/dhcpserver.h b/shared/netutils/dhcpserver.h
new file mode 100644
index 0000000000..2349d2ea42
--- /dev/null
+++ b/shared/netutils/dhcpserver.h
@@ -0,0 +1,49 @@
+/*
+ * This file is part of the MicroPython project, http://micropython.org/
+ *
+ * The MIT License (MIT)
+ *
+ * Copyright (c) 2018-2019 Damien P. George
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy
+ * of this software and associated documentation files (the "Software"), to deal
+ * in the Software without restriction, including without limitation the rights
+ * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+ * copies of the Software, and to permit persons to whom the Software is
+ * furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in
+ * all copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+ * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+ * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
+ * THE SOFTWARE.
+ */
+#ifndef MICROPY_INCLUDED_LIB_NETUTILS_DHCPSERVER_H
+#define MICROPY_INCLUDED_LIB_NETUTILS_DHCPSERVER_H
+
+#include "lwip/ip_addr.h"
+
+#define DHCPS_BASE_IP (16)
+#define DHCPS_MAX_IP (8)
+
+typedef struct _dhcp_server_lease_t {
+    uint8_t mac[6];
+    uint16_t expiry;
+} dhcp_server_lease_t;
+
+typedef struct _dhcp_server_t {
+    ip_addr_t ip;
+    ip_addr_t nm;
+    dhcp_server_lease_t lease[DHCPS_MAX_IP];
+    struct udp_pcb *udp;
+} dhcp_server_t;
+
+void dhcp_server_init(dhcp_server_t *d, ip_addr_t *ip, ip_addr_t *nm);
+void dhcp_server_deinit(dhcp_server_t *d);
+
+#endif // MICROPY_INCLUDED_LIB_NETUTILS_DHCPSERVER_H
diff --git a/shared/netutils/netutils.c b/shared/netutils/netutils.c
new file mode 100644
index 0000000000..40fbd5bca3
--- /dev/null
+++ b/shared/netutils/netutils.c
@@ -0,0 +1,94 @@
+/*
+ * This file is part of the MicroPython project, http://micropython.org/
+ *
+ * The MIT License (MIT)
+ *
+ * Copyright (c) 2013, 2014 Damien P. George
+ * Copyright (c) 2015 Daniel Campora
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy
+ * of this software and associated documentation files (the "Software"), to deal
+ * in the Software without restriction, including without limitation the rights
+ * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+ * copies of the Software, and to permit persons to whom the Software is
+ * furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in
+ * all copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+ * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+ * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
+ * THE SOFTWARE.
+ */
+
+#include <stdint.h>
+#include <stdio.h>
+#include <string.h>
+
+#include "py/runtime.h"
+#include "lib/netutils/netutils.h"
+
+// Takes an array with a raw IPv4 address and returns something like '192.168.0.1'.
+mp_obj_t netutils_format_ipv4_addr(uint8_t *ip, netutils_endian_t endian) {
+    char ip_str[16];
+    mp_uint_t ip_len;
+    if (endian == NETUTILS_LITTLE) {
+        ip_len = snprintf(ip_str, 16, "%u.%u.%u.%u", ip[3], ip[2], ip[1], ip[0]);
+    } else {
+        ip_len = snprintf(ip_str, 16, "%u.%u.%u.%u", ip[0], ip[1], ip[2], ip[3]);
+    }
+    return mp_obj_new_str(ip_str, ip_len);
+}
+
+// Takes an array with a raw IP address, and a port, and returns a net-address
+// tuple such as ('192.168.0.1', 8080).
+mp_obj_t netutils_format_inet_addr(uint8_t *ip, mp_uint_t port, netutils_endian_t endian) {
+    mp_obj_t tuple[2] = {
+        tuple[0] = netutils_format_ipv4_addr(ip, endian),
+        tuple[1] = mp_obj_new_int(port),
+    };
+    return mp_obj_new_tuple(2, tuple);
+}
+
+void netutils_parse_ipv4_addr(mp_obj_t addr_in, uint8_t *out_ip, netutils_endian_t endian) {
+    size_t addr_len;
+    const char *addr_str = mp_obj_str_get_data(addr_in, &addr_len);
+    if (addr_len == 0) {
+        // special case of no address given
+        memset(out_ip, 0, NETUTILS_IPV4ADDR_BUFSIZE);
+        return;
+    }
+    const char *s = addr_str;
+    const char *s_top = addr_str + addr_len;
+    for (mp_uint_t i = 3; ; i--) {
+        mp_uint_t val = 0;
+        for (; s < s_top && *s != '.'; s++) {
+            val = val * 10 + *s - '0';
+        }
+        if (endian == NETUTILS_LITTLE) {
+            out_ip[i] = val;
+        } else {
+            out_ip[NETUTILS_IPV4ADDR_BUFSIZE - 1 - i] = val;
+        }
+        if (i == 0 && s == s_top) {
+            return;
+        } else if (i > 0 && s < s_top && *s == '.') {
+            s++;
+        } else {
+            mp_raise_ValueError(MP_ERROR_TEXT("invalid arguments"));
+        }
+    }
+}
+
+// Takes an address of the form ('192.168.0.1', 8080), returns the port and
+// puts IP in out_ip (which must take at least IPADDR_BUF_SIZE bytes).
+mp_uint_t netutils_parse_inet_addr(mp_obj_t addr_in, uint8_t *out_ip, netutils_endian_t endian) {
+    mp_obj_t *addr_items;
+    mp_obj_get_array_fixed_n(addr_in, 2, &addr_items);
+    netutils_parse_ipv4_addr(addr_items[0], out_ip, endian);
+    return mp_obj_get_int(addr_items[1]);
+}
diff --git a/shared/netutils/netutils.h b/shared/netutils/netutils.h
new file mode 100644
index 0000000000..9261337858
--- /dev/null
+++ b/shared/netutils/netutils.h
@@ -0,0 +1,56 @@
+/*
+ * This file is part of the MicroPython project, http://micropython.org/
+ *
+ * The MIT License (MIT)
+ *
+ * Copyright (c) 2013, 2014 Damien P. George
+ * Copyright (c) 2015 Daniel Campora
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy
+ * of this software and associated documentation files (the "Software"), to deal
+ * in the Software without restriction, including without limitation the rights
+ * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+ * copies of the Software, and to permit persons to whom the Software is
+ * furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in
+ * all copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+ * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+ * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
+ * THE SOFTWARE.
+ */
+#ifndef MICROPY_INCLUDED_LIB_NETUTILS_NETUTILS_H
+#define MICROPY_INCLUDED_LIB_NETUTILS_NETUTILS_H
+
+#define NETUTILS_IPV4ADDR_BUFSIZE    4
+
+#define NETUTILS_TRACE_IS_TX        (0x0001)
+#define NETUTILS_TRACE_PAYLOAD      (0x0002)
+#define NETUTILS_TRACE_NEWLINE      (0x0004)
+
+typedef enum _netutils_endian_t {
+    NETUTILS_LITTLE,
+    NETUTILS_BIG,
+} netutils_endian_t;
+
+// Takes an array with a raw IPv4 address and returns something like '192.168.0.1'.
+mp_obj_t netutils_format_ipv4_addr(uint8_t *ip, netutils_endian_t endian);
+
+// Takes an array with a raw IP address, and a port, and returns a net-address
+// tuple such as ('192.168.0.1', 8080).
+mp_obj_t netutils_format_inet_addr(uint8_t *ip, mp_uint_t port, netutils_endian_t endian);
+
+void netutils_parse_ipv4_addr(mp_obj_t addr_in, uint8_t *out_ip, netutils_endian_t endian);
+
+// Takes an address of the form ('192.168.0.1', 8080), returns the port and
+// puts IP in out_ip (which must take at least IPADDR_BUF_SIZE bytes).
+mp_uint_t netutils_parse_inet_addr(mp_obj_t addr_in, uint8_t *out_ip, netutils_endian_t endian);
+
+void netutils_ethernet_trace(const mp_print_t *print, size_t len, const uint8_t *buf, unsigned int flags);
+
+#endif // MICROPY_INCLUDED_LIB_NETUTILS_NETUTILS_H
diff --git a/shared/netutils/trace.c b/shared/netutils/trace.c
new file mode 100644
index 0000000000..1610966c2d
--- /dev/null
+++ b/shared/netutils/trace.c
@@ -0,0 +1,170 @@
+/*
+ * This file is part of the MicroPython project, http://micropython.org/
+ *
+ * The MIT License (MIT)
+ *
+ * Copyright (c) 2019 Damien P. George
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy
+ * of this software and associated documentation files (the "Software"), to deal
+ * in the Software without restriction, including without limitation the rights
+ * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+ * copies of the Software, and to permit persons to whom the Software is
+ * furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in
+ * all copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+ * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+ * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
+ * THE SOFTWARE.
+ */
+
+#include "py/mphal.h"
+#include "lib/netutils/netutils.h"
+
+static uint32_t get_be16(const uint8_t *buf) {
+    return buf[0] << 8 | buf[1];
+}
+
+static uint32_t get_be32(const uint8_t *buf) {
+    return buf[0] << 24 | buf[1] << 16 | buf[2] << 8 | buf[3];
+}
+
+static void dump_hex_bytes(const mp_print_t *print, size_t len, const uint8_t *buf) {
+    for (size_t i = 0; i < len; ++i) {
+        mp_printf(print, " %02x", buf[i]);
+    }
+}
+
+static const char *ethertype_str(uint16_t type) {
+    // A value between 0x0000 - 0x05dc (inclusive) indicates a length, not type
+    switch (type) {
+        case 0x0800:
+            return "IPv4";
+        case 0x0806:
+            return "ARP";
+        case 0x86dd:
+            return "IPv6";
+        default:
+            return NULL;
+    }
+}
+
+void netutils_ethernet_trace(const mp_print_t *print, size_t len, const uint8_t *buf, unsigned int flags) {
+    mp_printf(print, "[% 8d] ETH%cX len=%u", mp_hal_ticks_ms(), flags & NETUTILS_TRACE_IS_TX ? 'T' : 'R', len);
+    mp_printf(print, " dst=%02x:%02x:%02x:%02x:%02x:%02x", buf[0], buf[1], buf[2], buf[3], buf[4], buf[5]);
+    mp_printf(print, " src=%02x:%02x:%02x:%02x:%02x:%02x", buf[6], buf[7], buf[8], buf[9], buf[10], buf[11]);
+
+    const char *ethertype = ethertype_str(buf[12] << 8 | buf[13]);
+    if (ethertype) {
+        mp_printf(print, " type=%s", ethertype);
+    } else {
+        mp_printf(print, " type=0x%04x", buf[12] << 8 | buf[13]);
+    }
+    if (len > 14) {
+        len -= 14;
+        buf += 14;
+        if (buf[-2] == 0x08 && buf[-1] == 0x00 && buf[0] == 0x45) {
+            // IPv4 packet
+            len = get_be16(buf + 2);
+            mp_printf(print, " srcip=%u.%u.%u.%u dstip=%u.%u.%u.%u",
+                buf[12], buf[13], buf[14], buf[15],
+                buf[16], buf[17], buf[18], buf[19]);
+            uint8_t prot = buf[9];
+            buf += 20;
+            len -= 20;
+            if (prot == 6) {
+                // TCP packet
+                uint16_t srcport = get_be16(buf);
+                uint16_t dstport = get_be16(buf + 2);
+                uint32_t seqnum = get_be32(buf + 4);
+                uint32_t acknum = get_be32(buf + 8);
+                uint16_t dataoff_flags = get_be16(buf + 12);
+                uint16_t winsz = get_be16(buf + 14);
+                mp_printf(print, " TCP srcport=%u dstport=%u seqnum=%u acknum=%u dataoff=%u flags=%x winsz=%u",
+                    srcport, dstport, (unsigned)seqnum, (unsigned)acknum, dataoff_flags >> 12, dataoff_flags & 0x1ff, winsz);
+                buf += 20;
+                len -= 20;
+                if (dataoff_flags >> 12 > 5) {
+                    mp_printf(print, " opts=");
+                    size_t opts_len = ((dataoff_flags >> 12) - 5) * 4;
+                    dump_hex_bytes(print, opts_len, buf);
+                    buf += opts_len;
+                    len -= opts_len;
+                }
+            } else if (prot == 17) {
+                // UDP packet
+                uint16_t srcport = get_be16(buf);
+                uint16_t dstport = get_be16(buf + 2);
+                mp_printf(print, " UDP srcport=%u dstport=%u", srcport, dstport);
+                len = get_be16(buf + 4);
+                buf += 8;
+                if ((srcport == 67 && dstport == 68) || (srcport == 68 && dstport == 67)) {
+                    // DHCP
+                    if (srcport == 67) {
+                        mp_printf(print, " DHCPS");
+                    } else {
+                        mp_printf(print, " DHCPC");
+                    }
+                    dump_hex_bytes(print, 12 + 16 + 16 + 64, buf);
+                    size_t n = 12 + 16 + 16 + 64 + 128;
+                    len -= n;
+                    buf += n;
+                    mp_printf(print, " opts:");
+                    switch (buf[6]) {
+                        case 1:
+                            mp_printf(print, " DISCOVER");
+                            break;
+                        case 2:
+                            mp_printf(print, " OFFER");
+                            break;
+                        case 3:
+                            mp_printf(print, " REQUEST");
+                            break;
+                        case 4:
+                            mp_printf(print, " DECLINE");
+                            break;
+                        case 5:
+                            mp_printf(print, " ACK");
+                            break;
+                        case 6:
+                            mp_printf(print, " NACK");
+                            break;
+                        case 7:
+                            mp_printf(print, " RELEASE");
+                            break;
+                        case 8:
+                            mp_printf(print, " INFORM");
+                            break;
+                    }
+                }
+            } else {
+                // Non-UDP packet
+                mp_printf(print, " prot=%u", prot);
+            }
+        } else if (buf[-2] == 0x86 && buf[-1] == 0xdd && (buf[0] >> 4) == 6) {
+            // IPv6 packet
+            uint32_t h = get_be32(buf);
+            uint16_t l = get_be16(buf + 4);
+            mp_printf(print, " tclass=%u flow=%u len=%u nexthdr=%u hoplimit=%u", (unsigned)((h >> 20) & 0xff), (unsigned)(h & 0xfffff), l, buf[6], buf[7]);
+            mp_printf(print, " srcip=");
+            dump_hex_bytes(print, 16, buf + 8);
+            mp_printf(print, " dstip=");
+            dump_hex_bytes(print, 16, buf + 24);
+            buf += 40;
+            len -= 40;
+        }
+        if (flags & NETUTILS_TRACE_PAYLOAD) {
+            mp_printf(print, " data=");
+            dump_hex_bytes(print, len, buf);
+        }
+    }
+    if (flags & NETUTILS_TRACE_NEWLINE) {
+        mp_printf(print, "\n");
+    }
+}