survive to width.precision screw ups in %s

mongoose.c

@@ -2968,7 +2968,12 @@ size_t mg_vxprintf(void (*out)(char, void *), void *param, const char *fmt,
         n++;
       } else if (c == 's') {
         char *p = va_arg(*ap, char *);
-        if (pr == ~0U) pr = p == NULL ? 0 : strlen(p);
+        if (p != NULL && pr != ~0U) {
+          for (j = 0; j < pr && p[j] != '\0'; j++) ;  // portable strnlen()
+          pr = j;
+        } else {
+          pr = p == NULL ? 0 : strlen(p);
+        }
         for (j = 0; !minus && pr < w && j + pr < w; j++)
           n += scpy(out, param, &pad, 1);
         n += scpy(out, param, p, pr);
@@ -9399,7 +9404,6 @@ static void rx_dhcp_client(struct mg_tcpip_if *ifp, struct pkt *pkt) {
                         : pkt->dhcp->siaddr ? pkt->dhcp->siaddr
                                             : pkt->ip->src);
     ifp->state = MG_TCPIP_STATE_REQ;  // REQUESTING state
-    ifp->lease_expire = ifp->now + 5000;  // No ACK by then: start over
   } else if (msgtype == 5) {          // DHCPACK
     if (ifp->state == MG_TCPIP_STATE_REQ && ip && gw && lease) {  // got an IP
       uint64_t rand;
@@ -10707,9 +10711,6 @@ static void mg_ip_poll(struct mg_tcpip_if *ifp, bool s1) {
   if (ifp->enable_dhcp_client && s1) {
     if (ifp->state == MG_TCPIP_STATE_UP) {
       tx_dhcp_discover(ifp);  // INIT (4.4.1)
-    } else if (ifp->state == MG_TCPIP_STATE_REQ &&
-               ifp->now >= ifp->lease_expire) {
-      ifp->state = MG_TCPIP_STATE_UP;  // REQUEST or ACK lost: DISCOVER again
     } else if (ifp->state == MG_TCPIP_STATE_READY &&
                ifp->lease_expire > 0) {  // BOUND / RENEWING / REBINDING
       if (ifp->now >= ifp->lease_expire) {

src/fmt.c

@@ -214,7 +214,12 @@ size_t mg_vxprintf(void (*out)(char, void *), void *param, const char *fmt,
         n++;
       } else if (c == 's') {
         char *p = va_arg(*ap, char *);
-        if (pr == ~0U) pr = p == NULL ? 0 : strlen(p);
+        if (p != NULL && pr != ~0U) {
+          for (j = 0; j < pr && p[j] != '\0'; j++) ;  // portable strnlen()
+          pr = j;
+        } else {
+          pr = p == NULL ? 0 : strlen(p);
+        }
         for (j = 0; !minus && pr < w && j + pr < w; j++)
           n += scpy(out, param, &pad, 1);
         n += scpy(out, param, p, pr);

src/net_builtin.c

@@ -734,7 +734,6 @@ static void rx_dhcp_client(struct mg_tcpip_if *ifp, struct pkt *pkt) {
                         : pkt->dhcp->siaddr ? pkt->dhcp->siaddr
                                             : pkt->ip->src);
     ifp->state = MG_TCPIP_STATE_REQ;  // REQUESTING state
-    ifp->lease_expire = ifp->now + 5000;  // No ACK by then: start over
   } else if (msgtype == 5) {          // DHCPACK
     if (ifp->state == MG_TCPIP_STATE_REQ && ip && gw && lease) {  // got an IP
       uint64_t rand;
@@ -2042,9 +2041,6 @@ static void mg_ip_poll(struct mg_tcpip_if *ifp, bool s1) {
   if (ifp->enable_dhcp_client && s1) {
     if (ifp->state == MG_TCPIP_STATE_UP) {
       tx_dhcp_discover(ifp);  // INIT (4.4.1)
-    } else if (ifp->state == MG_TCPIP_STATE_REQ &&
-               ifp->now >= ifp->lease_expire) {
-      ifp->state = MG_TCPIP_STATE_UP;  // REQUEST or ACK lost: DISCOVER again
     } else if (ifp->state == MG_TCPIP_STATE_READY &&
                ifp->lease_expire > 0) {  // BOUND / RENEWING / REBINDING
       if (ifp->now >= ifp->lease_expire) {

test/mesh/Makefile

@@ -1,32 +0,0 @@
-# Mesh simulator. `make` builds and runs an example
-ROOT = ../..
-SRCS = simulator.c l2_mesh.c l2_802154.c star.c $(ROOT)/mongoose.c
-HDRS = simulator.h l2_mesh.h l2_802154.h star.h $(ROOT)/mongoose.h
-WARN = -pedantic -W -Wall -Werror -Wshadow -Wdouble-promotion -fno-common \
-       -Wconversion -Wundef -Wmissing-prototypes -Wstrict-prototypes
-DEFS = -DMG_ENABLE_TCPIP=1 -DMG_ENABLE_TCPIP_DRIVER_INIT=0 -DMG_ENABLE_IPV6=0 \
-       -DMG_ENABLE_CUSTOM_MILLIS=1
-CFLAGS ?= -O2 -g0 $(WARN)
-X ?= 100
-Y ?= 100
-ROWS ?= 10
-COLS ?= 10
-
-# Nodes at every corner of a ROWS x COLS grid over X,Y, edges included
-GRID = $(shell for r in $$(seq 0 $(ROWS)); do \
-         for c in $$(seq 0 $(COLS)); do \
-         echo -node $$((c * $(X) / $(COLS))),$$((r * $(Y) / $(ROWS))); \
-         done; done)
-
-all: mesh_sim
-	./mesh_sim -area $(X),$(Y) \
-	  -bridge $$(($(X) / 2)),$$(($(Y) / 2)) \
-		$(GRID)
-
-mesh_sim: $(SRCS) $(HDRS) Makefile
-	$(CC) $(SRCS) $(CFLAGS) $(DEFS) -I. -I$(ROOT) -o $@
-
-clean:
-	rm -rf mesh_sim mesh_sim.dSYM
-
-.PHONY: all clean

test/mesh/README.md

@@ -1,189 +0,0 @@
-# Ethernet over a radio mesh
-
-## The idea
-
-Small radio devices, e.g. IEEE 802.15.4, sub-GHz or LoRa boards, should run
-Mongoose as if they were on an ordinary Ethernet LAN: get an IP address over
-DHCP, answer HTTP, talk MQTT. No 6LoWPAN, no Thread, no special stack.
-
-To do that, the radio interface looks like Ethernet to Mongoose
-(`MG_TCPIP_L2_ETH`). Its driver splits each Ethernet frame into radio
-frames, sends them over the air, and the receiver puts them back together.
-One or more bridges connect the radio network to the wired LAN: a bridge has
-an Ethernet port and a radio. A node in range of a bridge talks to it
-directly; a node out of range reaches a bridge through other nodes, which
-forward its frames. That makes the radio network a mesh. With several
-bridges, each node uses one of them, e.g. the nearest; the mesh covers a
-bigger area, and keeps working if a bridge goes down. A PC on the LAN sees
-the radio nodes as regular hosts on the same LAN.
-
-```
-             +---- bridge 1 ~~~ node ~~~ node
-             |                    ~
-  PC ---- LAN                    node
-             |                    ~
-             +---- bridge 2 ~~~ node ~~~ node ~~~ node
-```
-
-`~~~` and `~` are radio hops. Nodes far from a bridge send their frames
-through nearer nodes. A node in the middle can reach either bridge.
-
-## Two parts plug in
-
-- `struct mg_radio`, a radio standard: how big a radio frame is, how
-  addresses are written into it. `mg_radio_802154` is the first one.
-- `struct mg_mesh`, a mesh strategy: how nodes find a bridge, and where each
-  frame goes next. `mg_mesh_star` is the first and simplest one: every node
-  talks to a bridge directly, one hop.
-
-Everything else, splitting and reassembling frames, sending again when a
-frame is lost, is common code that works the same for every radio and every
-mesh. The goal is to swap radios and mesh strategies without touching
-anything else.
-
-## Why a simulator
-
-Real boards are slow to test with, and you can't put 500 of them on a desk.
-The simulator runs a whole network in one process: every node is a real
-Mongoose instance, only the radio and the air between nodes are emulated.
-That lets us try mesh strategies with many nodes, and measure how long it
-takes nodes to join, get an address, and answer a request.
-
-## Virtual time
-
-The simulator has its own clock, `simulator::now`, in microseconds, and
-Mongoose reads it through `mg_millis()`. Nothing waits for real time: the
-simulator moves the clock forward itself, 250 us per step, and polls every
-station once per step. A minute of network traffic takes about a second to
-simulate. `-t SEC` sets how long to run, 10 minutes by default.
-
-The step is a trade-off. Each step polls every station's Mongoose, and even
-an idle poll costs something, so a smaller step means a slower run. A
-bigger step makes frames wait longer in queues, see below. Measured with
-121 nodes and 10 simulated minutes:
-
-| Step | Request time, mean | Run time |
-|------|--------------------|----------|
-| 1 ms | 6.1 ms | 0.9 s |
-| 250 us | 1.5 ms | 3.0 s |
-| 100 us | 0.6 ms | 7.2 s |
-| 10 us | 0.06 ms | 72 s |
-
-## The setup
-
-```
-  DHCP server ---------+
-   10.0.0.1            |
-   02:01:00:00:00:00   +-- LAN ---- bridge ~~~ nodes
-                       |
-  test station --------+
-   10.0.0.2
-   02:02:00:00:00:00
-```
-
-The LAN is assumed infinitely fast, see "How frames move on the LAN" below.
-Two stations are on it:
-
-- The DHCP server, 10.0.0.1, MAC 02:01:00:00:00:00, gives each node an
-  address made from its MAC: 02:00:00:X:Y:Z gets 10.X+1.Y.Z, so node
-  addresses never clash with the LAN stations' 10.0.0.x.
-- The test station, 10.0.0.2, MAC 02:02:00:00:00:00, is a Mongoose
-  instance. It waits for the mesh to settle, 60 seconds by default
-  (`-w SEC`), then sends `GET /` to each node in turn, one at a time, at the
-  node's own IP address. A node with no address, or one that doesn't answer
-  within 10 seconds, counts as failed. At the end it prints how many
-  requests succeeded and how long they took.
-
-Bridges are on the LAN too, and get every frame, as if in promiscuous mode:
-a frame for one of their radio nodes isn't addressed to the bridge itself.
-A bridge forwards every frame it gets from the LAN to the radio, and every
-frame from the radio to the LAN, with no filtering yet.
-
-Bridges and radio nodes get MACs 02:00:00:xx:xx:xx, numbered from 1 in
-command-line order: 02:00:00:00:00:01, 02:00:00:00:00:02, and so on.
-
-### How frames move on the LAN
-
-Every LAN station, the DHCP server, the test station and each bridge, has a
-LAN interface, `lif`: a `struct mg_tcpip_if` with a receive queue. All of
-them use the same driver, `s_lan_driver`. There are no cables and no switch:
-
-- **Sending (tx).** A station sends a frame with its driver's `tx`, which is
-  `lan_tx()`. It looks at the destination MAC and copies the frame into the
-  receive queues of the stations it is for:
-  - a broadcast or multicast goes to every station but the sender;
-  - a unicast goes to the station with that MAC;
-  - bridges get every frame, as a real bridge in promiscuous mode would:
-    a frame for a radio node is addressed to the node, not to its bridge.
-
-  That's all `tx` does. Nobody's code runs on the receiving side yet.
-- **Receiving (rx).** Each station takes the frames from its own queue when
-  the main loop polls it:
-  - the test station runs Mongoose, which reads the queue by itself, as it
-    would with a real Ethernet driver that queues frames from an interrupt;
-  - the DHCP server reads it in `dhcp_poll()`, and replies by sending
-    through its own `lif`;
-  - bridges read it in `bridges_poll()`, and forward it to the radio.
-
-So a frame waits in a queue until its receiver's next poll, at most one
-step of virtual time, 250 us. Ethernet is hundreds of times faster than the radio, so that
-doesn't matter for what we measure. And since sending never calls the
-receiver's code, a reply is never sent from inside another station's send.
-
-For example, a node asking for an address:
-
-1. The node's DHCP DISCOVER crosses the radio to a bridge, which sends it
-   out of its `lif`. It is a broadcast, so `lan_tx()` puts it into the
-   queues of the DHCP server, the test station and the other bridges.
-2. On its next poll, the DHCP server reads it and sends an OFFER, also a
-   broadcast, which lands in the test station's and the bridges' queues.
-3. On their next poll, the bridges read the OFFER and send it over the
-   radio to the node. The test station's Mongoose drops it: the test station
-   has a fixed address and no DHCP client.
-
-## Files
-
-| File | What |
-|------|------|
-| `l2_mesh.h`, `l2_mesh.c` | `struct mg_radio`, `struct mg_mesh`, common code |
-| `l2_802154.h`, `l2_802154.c` | `mg_radio_802154`, IEEE 802.15.4 |
-| `star.h`, `star.c` | `mg_mesh_star`, the star mesh |
-| `simulator.h`, `simulator.c` | The simulator |
-| `Makefile` | Builds and runs the simulator |
-
-## Where we are
-
-It works end to end: nodes get addresses over DHCP, and the test station's
-requests reach them through the bridges. But the radio is ideal for now:
-
-- The radio driver works like the LAN's: it puts whole Ethernet frames
-  straight into receive queues, all of them for a broadcast, else the one
-  with the destination MAC, and bridges get every frame. No range, no
-  loss, no airtime.
-- Bridges forward everything, with no filtering.
-- So use one bridge for now. With two, a broadcast from the LAN goes to the
-  radio through both, each hears the other's copy and sends it back to the
-  LAN, and that never ends. Deciding who forwards what, without loops, is
-  the job of `mg_mesh`.
-
-`mg_radio` and `mg_mesh` are still stubs. Next steps, one at a time: the
-air (range, loss, airtime), fragmenting frames into radio frames with
-`mg_radio`, choosing a bridge and forwarding through nodes with `mg_mesh`,
-and filtering at the bridges.
-
-## Running
-
-```sh
-make                          # 100x100 m, a bridge, 11x11 nodes
-make X=200 Y=50 ROWS=2 COLS=8 # Another area and grid
-```
-
-`make` puts a bridge in the middle of the area, and a node at every corner
-of a `ROWS` x `COLS` grid over it. The simulator itself takes:
-
-```
-./mesh_sim -area X,Y,Z -bridge X,Y,Z -node X,Y,Z ... -t SEC -w SEC
-```
-
-Positions are in metres; `X,Y` means `Z` is 0. Repeat `-bridge` and `-node`
-for more.

test/mesh/l2_802154.c

@@ -1,6 +0,0 @@
-// Copyright (c) 2026 Cesanta Software Limited
-// All rights reserved
-
-#include "l2_802154.h"
-
-const struct mg_radio mg_radio_802154 = {"802.15.4"};

test/mesh/l2_802154.h

@@ -1,10 +0,0 @@
-// Copyright (c) 2026 Cesanta Software Limited
-// All rights reserved
-//
-// IEEE 802.15.4 radio
-
-#pragma once
-
-#include "l2_mesh.h"
-
-extern const struct mg_radio mg_radio_802154;

test/mesh/l2_mesh.c

@@ -1,4 +0,0 @@
-// Copyright (c) 2026 Cesanta Software Limited
-// All rights reserved
-
-#include "l2_mesh.h"

test/mesh/l2_mesh.h

@@ -1,21 +0,0 @@
-// Copyright (c) 2026 Cesanta Software Limited
-// All rights reserved
-//
-// Ethernet over radio, through a mesh. Mongoose sees an Ethernet interface,
-// its driver splits Ethernet frames into radio frames. Two parts plug in:
-// - struct mg_radio: a radio standard, e.g. mg_radio_802154
-// - struct mg_mesh: how the mesh is built and routed, e.g. mg_mesh_star
-
-#pragma once
-
-#include "mongoose.h"
-
-// A radio standard
-struct mg_radio {
-  const char *name;  // For logs
-};
-
-// A mesh strategy
-struct mg_mesh {
-  const char *name;  // For logs
-};

test/mesh/simulator.c

@@ -1,433 +0,0 @@
-// Copyright (c) 2026 Cesanta Software Limited
-// All rights reserved
-//
-// Radio mesh simulator. Bridges and nodes are stations at positions in an
-// area. Time is virtual: see mg_millis(). On the LAN: a DHCP server, and a
-// test station that sends HTTP requests to the nodes
-
-#include "simulator.h"
-
-#define STEP_MICROSECONDS 250  // Virtual time per main loop step, see README.md
-
-static struct simulator s_sim;  // The simulator
-
-// Mongoose's clock: virtual time. A minute of network traffic takes far less
-// than a minute to simulate
-uint64_t mg_millis(void) {
-  return s_sim.now / 1000;
-}
-
-// Parse "X,Y,Z", or "X,Y" with Z 0. Return false if it is not that
-static bool parse_pos(const char *s, struct pos *p) {
-  int n = 0;  // Characters parsed
-  p->x = p->y = p->z = 0;
-  return (sscanf(s, "%lf,%lf,%lf%n", &p->x, &p->y, &p->z, &n) == 3 ||
-          sscanf(s, "%lf,%lf%n", &p->x, &p->y, &n) == 2) &&
-         s[n] == 0;
-}
-
-// Is position p inside the area of sim
-static bool inside(const struct simulator *sim, const struct pos *p) {
-  return p->x >= 0 && p->x <= sim->area.x && p->y >= 0 && p->y <= sim->area.y &&
-         p->z >= 0 && p->z <= sim->area.z;
-}
-
-static void usage(const struct simulator *sim, const char *prog) {
-  fprintf(stderr,
-          "Usage: %s OPTIONS\n"
-          "Positions: X,Y,Z in metres, or X,Y with Z 0\n"
-          "  -area X,Y,Z    - area, a box, default: %g,%g,%g\n"
-          "  -bridge X,Y,Z  - a bridge; repeat for more\n"
-          "  -node X,Y,Z    - a radio node; repeat for more\n"
-          "  -t SEC         - simulated time, seconds, default: %g\n"
-          "  -w SEC         - mesh settle time before requests, default: %g\n",
-          prog, sim->area.x, sim->area.y, sim->area.z,
-          (double) sim->duration / 1e6, (double) sim->tester.wait / 1e6);
-  exit(EXIT_FAILURE);
-}
-
-// The next radio MAC, to mac: 02:00:00:xx:xx:xx, numbered from 1
-static void next_mac(struct simulator *sim, uint8_t *mac) {
-  uint32_t n = ++sim->last_mac;
-  mac[0] = 2, mac[1] = mac[2] = 0, mac[3] = (uint8_t) (n >> 16);
-  mac[4] = (uint8_t) (n >> 8), mac[5] = (uint8_t) n;
-}
-
-// Add a bridge at position s. Return false if s is not a position
-static bool add_bridge(struct simulator *sim, const char *s) {
-  struct bridge *b = (struct bridge *) calloc(1, sizeof(*b));
-  if (b == NULL || !parse_pos(s, &b->pos)) return free(b), false;
-  next_mac(sim, b->rif.mac);
-  LIST_ADD_TAIL(struct bridge, &sim->bridges, b);
-  sim->num_bridges++;
-  return true;
-}
-
-// Add a radio node at position s. Return false if s is not a position
-static bool add_node(struct simulator *sim, const char *s) {
-  struct radio_node *n = (struct radio_node *) calloc(1, sizeof(*n));
-  if (n == NULL || !parse_pos(s, &n->pos)) return free(n), false;
-  next_mac(sim, n->rif.mac);
-  LIST_ADD_TAIL(struct radio_node, &sim->nodes, n);
-  sim->num_nodes++;
-  return true;
-}
-
-// Exit if position x is outside the area of sim
-static void check_inside(const struct simulator *sim, const struct pos *x) {
-  if (!inside(sim, x)) {
-    fprintf(stderr, "%g,%g,%g is outside the area\n", x->x, x->y, x->z);
-    exit(EXIT_FAILURE);
-  }
-}
-
-// Check that all bridges and nodes are inside the area of sim
-static void check_area(const struct simulator *sim) {
-  struct bridge *b;
-  struct radio_node *n;
-  for (b = sim->bridges; b != NULL; b = b->next) check_inside(sim, &b->pos);
-  for (n = sim->nodes; n != NULL; n = n->next) check_inside(sim, &n->pos);
-}
-
-#define LAN_QUEUE_SIZE (64 * 1024)  // Receive queue of a LAN interface
-
-// Put frame buf, len bytes, into the receive queue of LAN interface to, if
-// it is not the sender, from
-static void lan_put(struct mg_tcpip_if *to, struct mg_tcpip_if *from,
-                    const void *buf, size_t len) {
-  if (to != from) mg_tcpip_qwrite((void *) buf, len, to);
-}
-
-// LAN driver, all LAN interfaces share it. The LAN is infinitely fast: tx
-// puts the frame straight into the receive queues of the interfaces it is
-// for: all, if broadcast; else the one with the destination MAC. Bridges get
-// every frame: some are for their radio nodes. Each station takes frames
-// from its queue when polled, see dhcp_poll(), bridges_poll(); Mongoose does
-// it for the test station
-static size_t lan_tx(const void *buf, size_t len, struct mg_tcpip_if *ifp) {
-  const uint8_t *dst = (const uint8_t *) buf;
-  bool all = dst[0] & 1;  // Broadcast, multicast
-  struct bridge *b;
-  if (all || memcmp(dst, s_sim.dhcp.lif.mac, 6) == 0) {
-    lan_put(&s_sim.dhcp.lif, ifp, buf, len);
-  }
-  if (all || memcmp(dst, s_sim.tester.lif.mac, 6) == 0) {
-    lan_put(&s_sim.tester.lif, ifp, buf, len);
-  }
-  for (b = s_sim.bridges; b != NULL; b = b->next) {
-    lan_put(&b->lif, ifp, buf, len);
-  }
-  return len;
-}
-
-static bool lan_init(struct mg_tcpip_if *ifp) {
-  (void) ifp;
-  return true;
-}
-
-static bool lan_link(struct mg_tcpip_if *ifp, bool s1) {
-  (void) ifp, (void) s1;
-  return true;
-}
-
-static struct mg_tcpip_driver s_lan_driver = {lan_init, lan_tx, NULL, lan_link};
-
-// Internet checksum of len bytes
-static uint16_t ip_csum(const uint8_t *buf, size_t len) {
-  uint32_t sum = 0;
-  size_t i;
-  for (i = 0; i + 1 < len; i += 2) sum += (uint32_t) (buf[i] << 8 | buf[i + 1]);
-  if (len & 1) sum += (uint32_t) (buf[len - 1] << 8);
-  while (sum >> 16) sum = (sum & 0xffff) + (sum >> 16);
-  return (uint16_t) ~sum;
-}
-
-// A node's address, from its MAC 02:00:00:X:Y:Z: 10.X+1.Y.Z, so it never
-// clashes with the LAN stations' 10.0.0.x
-static void node_ip(const uint8_t *mac, uint8_t *ip) {
-  ip[0] = 10, ip[1] = (uint8_t) (mac[3] + 1), ip[2] = mac[4], ip[3] = mac[5];
-}
-
-// DHCP server, a frame from its queue: a DISCOVER gets an OFFER, a REQUEST
-// an ACK. Replies are broadcast. The address comes from the client's MAC
-static void dhcp_rx(struct simulator *sim, const uint8_t *buf, size_t len) {
-  static const uint8_t opts[] = {53, 1, 0,  // Message type, set below
-                                 1,  4, 255, 0, 0,  0,   // Mask
-                                 3,  4, 10,  0, 0,  1,   // Router
-                                 54, 4, 10,  0, 0,  1,   // Server
-                                 51, 4, 0,   0, 14, 16,  // Lease, 3600 s
-                                 255};
-  uint8_t r[14 + 20 + 8 + 240 + sizeof(opts)], type = 0;
-  const uint8_t *dh, *p, *end = buf + len;
-  size_t ihl, rlen = sizeof(r);
-  if ((buf[0] & 1) == 0) return;  // Bcast
-  if (len < 34 || buf[12] != 8 || buf[13] != 0 || buf[23] != 17) return;  // UDP
-  ihl = (size_t) (buf[14] & 15) * 4, dh = buf + 14 + ihl + 8;  // DHCP
-  if (dh + 240 > end || buf[14 + ihl + 2] != 0 || buf[14 + ihl + 3] != 67) {
-    return;
-  }
-  for (p = dh + 240; p + 2 <= end && p[0] != 255; p += p[0] ? p[1] + 2 : 1) {
-    if (p[0] == 53 && p[1] == 1 && p + 3 <= end) type = p[2];
-  }
-  if (type != 1 && type != 3) return;  // DISCOVER, REQUEST
-  memset(r, 0, sizeof(r));
-  memset(r, 0xff, 6), memcpy(r + 6, sim->dhcp.lif.mac, 6),
-      r[12] = 8;                                       // Ethernet
-  r[14] = 0x45, r[16] = (uint8_t) ((rlen - 14) >> 8);  // IPv4
-  r[17] = (uint8_t) (rlen - 14), r[22] = 64, r[23] = 17;
-  r[26] = 10, r[29] = 1, memset(r + 30, 0xff, 4);  // 10.0.0.1 -> bcast
-  r[24] = (uint8_t) (ip_csum(r + 14, 20) >> 8);
-  r[25] = (uint8_t) ip_csum(r + 14, 20);
-  r[35] = 67, r[37] = 68;  // UDP, csum 0: none
-  r[38] = (uint8_t) ((rlen - 34) >> 8), r[39] = (uint8_t) (rlen - 34);
-  r[42] = 2, r[43] = 1, r[44] = 6;                      // DHCP: reply, Ethernet
-  memcpy(r + 46, dh + 4, 4);                            // xid
-  memcpy(r + 52, dh + 10, 2);                           // flags
-  node_ip(dh + 28, r + 58);                             // yiaddr
-  r[62] = 10, r[65] = 1;                                // siaddr
-  memcpy(r + 70, dh + 28, 16);                          // chaddr
-  r[278] = 99, r[279] = 130, r[280] = 83, r[281] = 99;  // Magic
-  memcpy(r + 282, opts, sizeof(opts));
-  r[284] = type == 1 ? 2 : 5;  // OFFER, ACK
-  sim->dhcp.lif.driver->tx(r, rlen, &sim->dhcp.lif);
-}
-
-// DHCP server's work: take the frames from its queue
-static void dhcp_poll(struct simulator *sim) {
-  char *buf;
-  size_t len;
-  while ((len = mg_queue_next(&sim->dhcp.lif.recv_queue, &buf)) > 0) {
-    dhcp_rx(sim, (const uint8_t *) buf, len);
-    mg_queue_del(&sim->dhcp.lif.recv_queue, len);
-  }
-}
-
-// The request on the way finished: ok, or failed
-static void tester_done(struct lan_tester *t, uint64_t now, bool ok) {
-  double ms = (double) (now - t->start) / 1000;
-  if (ok) {
-    t->ok++, t->sum += ms;
-    if (t->ok == 1 || ms < t->min) t->min = ms;
-    if (ms > t->max) t->max = ms;
-  } else {
-    t->failed++;
-  }
-  if (t->c != NULL) t->c->is_closing = 1, t->c->fn_data = NULL;
-  t->c = NULL;
-}
-
-// HTTP client: GET /, the reply ends the request
-static void tester_fn(struct mg_connection *c, int ev, void *ev_data) {
-  struct lan_tester *t = (struct lan_tester *) c->fn_data;
-  if (t == NULL) return;  // Done with
-  if (ev == MG_EV_CONNECT) {
-    mg_printf(c, "GET / HTTP/1.0\r\n\r\n");
-  } else if (ev == MG_EV_HTTP_MSG) {
-    tester_done(t, s_sim.now, true);
-  } else if (ev == MG_EV_ERROR || ev == MG_EV_CLOSE) {
-    tester_done(t, s_sim.now, false);
-  }
-  (void) ev_data;
-}
-
-// Test station's work: Mongoose, then requests, one at a time, once the mesh
-// had time to settle. A node without an IP address fails at once
-static void tester_poll(struct simulator *sim) {
-  struct radio_node *n;
-  char url[64];
-  mg_mgr_poll(&sim->tester.mgr, 0);
-  if (sim->tester.c != NULL && sim->now - sim->tester.start >
-                                   (uint64_t) sim->request_timeout_ms * 1000) {
-    tester_done(&sim->tester, sim->now, false);
-  }
-  if (sim->now < sim->tester.wait || sim->tester.c != NULL ||
-      sim->tester.next == NULL)
-    return;
-  n = sim->tester.next;
-  sim->tester.next = n->next, sim->tester.start = sim->now;
-  if (n->rif.ip == 0) {
-    tester_done(&sim->tester, sim->now, false);
-    return;
-  }
-  mg_snprintf(url, sizeof(url), "http://%M/", mg_print_ip4, &n->rif.ip);
-  if ((sim->tester.c = mg_http_connect(&sim->tester.mgr, url, tester_fn,
-                                       &sim->tester)) == NULL) {
-    tester_done(&sim->tester, sim->now, false);
-  }
-}
-
-// Set up sim: defaults, LAN stations
-static void init(struct simulator *sim) {
-  static const uint8_t dmac[6] = {2, 1, 0, 0, 0, 0},  // DHCP server MAC
-      tmac[6] = {2, 2, 0, 0, 0, 0};                   // Test station MAC
-  memset(sim, 0, sizeof(*sim));
-  sim->area.x = sim->area.y = 100;
-  sim->duration = 600 * 1000000ULL, sim->tester.wait = 60 * 1000000ULL;
-  sim->request_timeout_ms = 10000;
-  memcpy(sim->dhcp.lif.mac, dmac, 6), sim->dhcp.lif.driver = &s_lan_driver;
-  mg_queue_init(&sim->dhcp.lif.recv_queue, (char *) calloc(1, LAN_QUEUE_SIZE),
-                LAN_QUEUE_SIZE);
-  memcpy(sim->tester.lif.mac, tmac, 6);
-  sim->tester.lif.ip = MG_IPV4(10, 0, 0, 2),
-  sim->tester.lif.mask = MG_IPV4(255, 0, 0, 0);
-  sim->tester.lif.driver = &s_lan_driver,
-  sim->tester.lif.enable_mac_check = true;
-  sim->tester.lif.recv_queue.size = 128 * 1024;
-}
-
-// Radio driver, all radio interfaces share it. An ideal radio for now:
-// whole Ethernet frames, no range, no loss, no airtime. It works like the
-// LAN, see lan_tx(): a frame goes into the receive queues of all other
-// radio interfaces if broadcast, else of the one with the destination MAC.
-// Bridges get every frame: some are for the LAN. Who forwards what, and
-// loops with several bridges, are for mg_mesh
-static size_t radio_tx(const void *buf, size_t len, struct mg_tcpip_if *ifp) {
-  const uint8_t *dst = (const uint8_t *) buf;
-  bool all = dst[0] & 1;  // Broadcast, multicast
-  struct bridge *b;
-  struct radio_node *n;
-  for (b = s_sim.bridges; b != NULL; b = b->next) {
-    lan_put(&b->rif, ifp, buf, len);
-  }
-  for (n = s_sim.nodes; n != NULL; n = n->next) {
-    if (all || memcmp(dst, n->rif.mac, 6) == 0) {
-      lan_put(&n->rif, ifp, buf, len);
-    }
-  }
-  return len;
-}
-
-static bool radio_init(struct mg_tcpip_if *ifp) {
-  (void) ifp;
-  return true;
-}
-
-static bool radio_link(struct mg_tcpip_if *ifp, bool s1) {
-  (void) ifp, (void) s1;
-  return true;
-}
-
-static struct mg_tcpip_driver s_radio_driver = {radio_init, radio_tx, NULL,
-                                                radio_link};
-
-// A node's HTTP server: the test station requests GET /
-static void node_http_ev_handler(struct mg_connection *c, int ev,
-                                 void *ev_data) {
-  if (ev == MG_EV_HTTP_MSG) {
-    mg_http_reply(c, 200, "", "Hi from Mongoose, my MAC is %M\n", mg_print_mac,
-                  c->fn_data);
-  }
-  (void) ev_data;
-}
-
-// Start each node's Mongoose: its radio interface, no IP address, so DHCP,
-// and an HTTP server
-static void nodes_init(struct simulator *sim) {
-  struct radio_node *n;
-  for (n = sim->nodes; n != NULL; n = n->next) {
-    n->rif.driver = &s_radio_driver;
-    n->rif.recv_queue.size = LAN_QUEUE_SIZE;
-    mg_mgr_init(&n->mgr);
-    mg_tcpip_init(&n->mgr, &n->rif);
-    mg_http_listen(&n->mgr, "http://0.0.0.0:80", node_http_ev_handler,
-                   n->rif.mac);
-  }
-}
-
-// Start each bridge: its LAN and radio drivers. No Mongoose, no IP
-static void bridges_init(struct simulator *sim) {
-  struct bridge *b;
-  for (b = sim->bridges; b != NULL; b = b->next) {
-    b->lif.driver = &s_lan_driver, b->rif.driver = &s_radio_driver;
-    mg_queue_init(&b->lif.recv_queue, (char *) calloc(1, LAN_QUEUE_SIZE),
-                  LAN_QUEUE_SIZE);
-    mg_queue_init(&b->rif.recv_queue, (char *) calloc(1, LAN_QUEUE_SIZE),
-                  LAN_QUEUE_SIZE);
-    b->lif.driver->init(&b->lif), b->rif.driver->init(&b->rif);
-  }
-}
-
-// Move the frames waiting in the receive queue of interface from out of
-// interface to
-static void bridge_forward(struct mg_tcpip_if *from, struct mg_tcpip_if *to) {
-  char *buf;
-  size_t len;
-  while ((len = mg_queue_next(&from->recv_queue, &buf)) > 0) {
-    // MG_DEBUG(("Bridging ETH frame, size %zu", len));
-    to->driver->tx(buf, len, to);
-    mg_queue_del(&from->recv_queue, len);
-  }
-}
-
-// Bridges' work: forward every frame, LAN to radio and radio to LAN. No
-// filtering yet
-static void bridges_poll(struct simulator *sim) {
-  struct bridge *b;
-  for (b = sim->bridges; b != NULL; b = b->next) {
-    bridge_forward(&b->lif, &b->rif);
-    bridge_forward(&b->rif, &b->lif);
-  }
-}
-
-// Poll each node's Mongoose
-static void nodes_poll(struct simulator *sim) {
-  struct radio_node *n;
-  for (n = sim->nodes; n != NULL; n = n->next) mg_mgr_poll(&n->mgr, 0);
-}
-
-int main(int argc, char *argv[]) {
-  clock_t started;  // CPU time, to show how fast the simulation runs
-  int i;
-
-  init(&s_sim);
-  for (i = 1; i < argc; i++) {
-    if (i + 1 >= argc) {
-      usage(&s_sim, argv[0]);
-    } else if (strcmp(argv[i], "-area") == 0) {
-      if (!parse_pos(argv[++i], &s_sim.area)) usage(&s_sim, argv[0]);
-    } else if (strcmp(argv[i], "-bridge") == 0) {
-      if (!add_bridge(&s_sim, argv[++i])) usage(&s_sim, argv[0]);
-    } else if (strcmp(argv[i], "-node") == 0) {
-      if (!add_node(&s_sim, argv[++i])) usage(&s_sim, argv[0]);
-    } else if (strcmp(argv[i], "-t") == 0) {
-      s_sim.duration = (uint64_t) (atof(argv[++i]) * 1e6);
-    } else if (strcmp(argv[i], "-w") == 0) {
-      s_sim.tester.wait = (uint64_t) (atof(argv[++i]) * 1e6);
-    } else {
-      usage(&s_sim, argv[0]);
-    }
-  }
-
-  printf("Area %gx%gx%g m, radio %s, mesh %s, bridges: %d, nodes: %d\n",
-         s_sim.area.x, s_sim.area.y, s_sim.area.z, mg_radio_802154.name,
-         mg_mesh_star.name, s_sim.num_bridges, s_sim.num_nodes);
-  check_area(&s_sim);
-
-  // mg_log_set(MG_LL_INFO);
-
-  mg_mgr_init(&s_sim.tester.mgr);
-  mg_tcpip_init(&s_sim.tester.mgr, &s_sim.tester.lif);
-  s_sim.tester.next = s_sim.nodes;
-  bridges_init(&s_sim);
-  nodes_init(&s_sim);
-
-  // Main loop: STEP_MICROSECONDS of virtual time per step
-  started = clock();
-  while (s_sim.now < s_sim.duration) {
-    dhcp_poll(&s_sim);
-    tester_poll(&s_sim);
-    bridges_poll(&s_sim);
-    nodes_poll(&s_sim);
-    s_sim.now += STEP_MICROSECONDS;
-  }
-  printf("Requests: %d ok, %d failed, of %d nodes", s_sim.tester.ok,
-         s_sim.tester.failed, s_sim.num_nodes);
-  if (s_sim.tester.ok > 0) {
-    printf("; ms: min %.1f, mean %.1f, max %.1f", s_sim.tester.min,
-           s_sim.tester.sum / s_sim.tester.ok, s_sim.tester.max);
-  }
-  printf("\nSimulated %g s in %.3f s\n", (double) s_sim.now / 1e6,
-         (double) (clock() - started) / CLOCKS_PER_SEC);
-
-  return 0;
-}

test/mesh/simulator.h

@@ -1,67 +0,0 @@
-// Copyright (c) 2026 Cesanta Software Limited
-// All rights reserved
-
-#pragma once
-
-#define MG_ENABLE_TCPIP 1
-
-#include "l2_802154.h"
-#include "l2_mesh.h"
-#include "mongoose.h"
-#include "star.h"
-
-// A position in metres
-struct pos {
-  double x, y, z;  // Coordinates
-};
-
-// A bridge: forwards frames between the LAN and the radio, no IP stack
-struct bridge {
-  struct bridge *next;     // Next in simulator::bridges
-  struct pos pos;          // Where it is
-  struct mg_tcpip_if lif;  // LAN side: LAN driver, gets every LAN frame
-  struct mg_tcpip_if rif;  // Radio side: radio driver, gets every frame
-};
-
-// A radio node: Mongoose on a radio interface
-struct radio_node {
-  struct radio_node *next;  // Next in simulator::nodes
-  struct pos pos;           // Where it is
-  struct mg_mgr mgr;        // Mongoose event manager
-  struct mg_tcpip_if rif;   // Radio interface. rif.ip from DHCP, 0: none yet
-};
-
-struct simulator;
-
-// LAN station: a DHCP server, 10.0.0.1. Gives each client an address made
-// from its MAC, see node_ip()
-struct lan_dhcp_server {
-  struct mg_tcpip_if lif;  // Its LAN interface, no Mongoose on it
-};
-
-// LAN station: the test station, 10.0.0.2, a Mongoose instance. Waits for
-// the mesh to settle, then sends GET / to each node
-struct lan_tester {
-  struct mg_mgr mgr;        // Its Mongoose
-  struct mg_tcpip_if lif;   // Its LAN interface
-  uint64_t wait;            // Mesh settle time: start requests then, us
-  struct radio_node *next;  // Node to request next, NULL: all done
-  struct mg_connection *c;  // Request on the way, NULL: none
-  uint64_t start;           // When it started, us
-  int ok, failed;           // Requests done, by result
-  double min, max, sum;     // Times of successful requests, ms
-};
-
-// Simulator state
-struct simulator {
-  struct pos area;              // A box: all positions inside
-  struct bridge *bridges;       // Bridges, a list
-  struct radio_node *nodes;     // Radio nodes, a list
-  int num_bridges, num_nodes;   // How many
-  uint64_t now;                 // Virtual time, us since the start
-  uint64_t duration;            // Run this long, us
-  uint32_t last_mac;            // Low 3 bytes of the last MAC given
-  int request_timeout_ms;       // A request that takes longer failed
-  struct lan_dhcp_server dhcp;  // DHCP server on the LAN
-  struct lan_tester tester;     // Test station on the LAN
-};

test/mesh/star.c

@@ -1,6 +0,0 @@
-// Copyright (c) 2026 Cesanta Software Limited
-// All rights reserved
-
-#include "star.h"
-
-const struct mg_mesh mg_mesh_star = {"star"};

test/mesh/star.h

@@ -1,10 +0,0 @@
-// Copyright (c) 2026 Cesanta Software Limited
-// All rights reserved
-//
-// Star mesh: one hop, nodes talk to a bridge
-
-#pragma once
-
-#include "l2_mesh.h"
-
-extern const struct mg_mesh mg_mesh_star;

test/mip_test.c

@@ -80,10 +80,6 @@ static void test_statechange(void) {
   onstatechange(&iface);
   ASSERT(executed == true);
   executed = false;
-  iface.enable_dhcp_client = true;  // DHCP REQUEST unanswered: start over
-  iface.state = MG_TCPIP_STATE_REQ, iface.lease_expire = 0;
-  mg_ip_poll(&iface, true);
-  ASSERT(iface.state == MG_TCPIP_STATE_UP);
 }
 #if MG_ENABLE_IPV6
 static void mif6_fn(struct mg_tcpip_if *ifp, int ev, void *ev_data) {

test/unit_test.c

@@ -2399,10 +2399,15 @@ static void test_str(void) {
   ASSERT(sn("%.*s", 1, "ab"));
   ASSERT(sn("%.1s", "ab"));
   ASSERT(sn("%.99s", "a"));
+  ASSERT(sn("%10.8s", "abc"));
+  ASSERT(sn("%-6.4s", "ab"));
+  ASSERT(sn("%5.1s", ""));
   ASSERT(sn("%11s", "a"));
   ASSERT(sn("%s", "a\0b"));
   ASSERT(sn("%2s", "a"));
   ASSERT(sn("%.*s", 3, "a\0b"));
+  ASSERT(mg_snprintf(NULL, 0, "%.8s", (char *) NULL) == 0);
+  ASSERT(mg_snprintf(NULL, 0, "%8.4s", (char *) NULL) == 8);
   ASSERT(sn("%d", 7));
   ASSERT(sn("%d", 123));
 #if MG_ARCH == MG_ARCH_UNIX