Allow user to set custom DHCP name

Author: cpq

mongoose.c

@@ -4557,14 +4557,22 @@ static void rx_dhcp_server(struct mg_tcpip_if *ifp, struct pkt *pkt) {
         53, 1, msg,                 // Message type
         1,  4, 0,   0,   0,   0,    // Subnet mask
         54, 4, 0,   0,   0,   0,    // Server ID
-        12, 3, 'm', 'i', 'p',       // Host name: "mip"
         51, 4, 255, 255, 255, 255,  // Lease time
-        255                         // End of options
     };
+    // DHCP hostname: guarantee to limit its length by sizeof(ifp->dhcp_name)
+    size_t name_len = strlen(ifp->dhcp_name) % sizeof(ifp->dhcp_name);
+
     memcpy(&res.hwaddr, pkt->dhcp->hwaddr, 6);
     memcpy(opts + 5, &ifp->mask, sizeof(ifp->mask));
     memcpy(opts + 11, &ifp->ip, sizeof(ifp->ip));
     memcpy(&res.options, opts, sizeof(opts));
+
+    // Copy over host name
+    res.options[sizeof(opts)] = 12;
+    res.options[sizeof(opts) + 1] = (uint8_t) (name_len & 255);
+    memcpy(&res.options[sizeof(opts) + 2], ifp->dhcp_name, name_len);
+    res.options[sizeof(opts) + 2 + name_len] = 255;  // End of options
+
     res.magic = pkt->dhcp->magic;
     res.xid = pkt->dhcp->xid;
     if (ifp->enable_get_gateway) {
@@ -4732,7 +4740,8 @@ static void handle_tls_recv(struct mg_connection *c) {
     mg_error(c, "oom");
   } else {
     // Decrypt data directly into c->recv
-    long n = mg_tls_recv(c, io->buf != NULL ? &io->buf[io->len] : io->buf, io->size - io->len);
+    long n = mg_tls_recv(c, io->buf != NULL ? &io->buf[io->len] : io->buf,
+                         io->size - io->len);
     if (n == MG_IO_ERR) {
       mg_error(c, "TLS recv error");
     } else if (n > 0) {
@@ -5113,6 +5122,11 @@ void mg_tcpip_init(struct mg_mgr *mgr, struct mg_tcpip_if *ifp) {
     MG_INFO(("MAC not set. Generated random: %M", mg_print_mac, ifp->mac));
   }
 
+  // Uf DHCP name is not set, use "mip"
+  if (ifp->dhcp_name[0] == '\0') {
+    mg_snprintf(ifp->dhcp_name, sizeof(ifp->dhcp_name), "%s", "mip");
+  }
+
   if (ifp->driver->init && !ifp->driver->init(ifp)) {
     MG_ERROR(("driver init failed"));
   } else {

mongoose.h

@@ -2751,6 +2751,10 @@ bool mg_ota_flash_end(struct mg_flash *flash);
 #endif
 
 
+
+
+
+
 struct mg_wifi_scan_bss_data {
     struct mg_str SSID;
     char *BSSID;
@@ -2823,6 +2827,7 @@ struct mg_tcpip_if {
   mg_tcpip_event_handler_t fn;     // User-specified event handler function
   struct mg_mgr *mgr;              // Mongoose event manager
   struct mg_queue recv_queue;      // Receive queue
+  char dhcp_name[12];              // Name reported to DHCP, "mip" if unset
   uint16_t mtu;                    // Interface MTU
 #define MG_TCPIP_MTU_DEFAULT 1500
 

src/net_builtin.c

@@ -476,14 +476,22 @@ static void rx_dhcp_server(struct mg_tcpip_if *ifp, struct pkt *pkt) {
         53, 1, msg,                 // Message type
         1,  4, 0,   0,   0,   0,    // Subnet mask
         54, 4, 0,   0,   0,   0,    // Server ID
-        12, 3, 'm', 'i', 'p',       // Host name: "mip"
         51, 4, 255, 255, 255, 255,  // Lease time
-        255                         // End of options
     };
+    // DHCP hostname: guarantee to limit its length by sizeof(ifp->dhcp_name)
+    size_t name_len = strlen(ifp->dhcp_name) % sizeof(ifp->dhcp_name);
+
     memcpy(&res.hwaddr, pkt->dhcp->hwaddr, 6);
     memcpy(opts + 5, &ifp->mask, sizeof(ifp->mask));
     memcpy(opts + 11, &ifp->ip, sizeof(ifp->ip));
     memcpy(&res.options, opts, sizeof(opts));
+
+    // Copy over host name
+    res.options[sizeof(opts)] = 12;
+    res.options[sizeof(opts) + 1] = (uint8_t) (name_len & 255);
+    memcpy(&res.options[sizeof(opts) + 2], ifp->dhcp_name, name_len);
+    res.options[sizeof(opts) + 2 + name_len] = 255;  // End of options
+
     res.magic = pkt->dhcp->magic;
     res.xid = pkt->dhcp->xid;
     if (ifp->enable_get_gateway) {
@@ -651,7 +659,8 @@ static void handle_tls_recv(struct mg_connection *c) {
     mg_error(c, "oom");
   } else {
     // Decrypt data directly into c->recv
-    long n = mg_tls_recv(c, io->buf != NULL ? &io->buf[io->len] : io->buf, io->size - io->len);
+    long n = mg_tls_recv(c, io->buf != NULL ? &io->buf[io->len] : io->buf,
+                         io->size - io->len);
     if (n == MG_IO_ERR) {
       mg_error(c, "TLS recv error");
     } else if (n > 0) {
@@ -1032,6 +1041,11 @@ void mg_tcpip_init(struct mg_mgr *mgr, struct mg_tcpip_if *ifp) {
     MG_INFO(("MAC not set. Generated random: %M", mg_print_mac, ifp->mac));
   }
 
+  // Uf DHCP name is not set, use "mip"
+  if (ifp->dhcp_name[0] == '\0') {
+    mg_snprintf(ifp->dhcp_name, sizeof(ifp->dhcp_name), "%s", "mip");
+  }
+
   if (ifp->driver->init && !ifp->driver->init(ifp)) {
     MG_ERROR(("driver init failed"));
   } else {

src/net_builtin.h

@@ -47,6 +47,7 @@ struct mg_tcpip_if {
   mg_tcpip_event_handler_t fn;     // User-specified event handler function
   struct mg_mgr *mgr;              // Mongoose event manager
   struct mg_queue recv_queue;      // Receive queue
+  char dhcp_name[12];              // Name reported to DHCP, "mip" if unset
   uint16_t mtu;                    // Interface MTU
 #define MG_TCPIP_MTU_DEFAULT 1500