Do not post MG_SIG_CLOSE_CONN if the conn is already closing

tcp_close_tcpip() only closed active TCP PCBs, leaking other types of TCP PCBs
(notably bound only, not yet connected/used).  With time, this led to DoS
situations.

Fix by giving up on the hacky way of searching the LWIP innards for the TCP PCB
needing closing.  The searching was non-comprehensive, hence the problem in
principle, and inherently racy: could close a meanwhile freed & reused PCB.

Pass the pointer to the struct mg_lwip_conn_state of the struct mg_connection
being destroyed to tcp_close_tcpip() instead of the bare PCB pointer, so the PCB
pointer stored within can be used.  Delay unassigning that pointer from the
struct mg_connection until tcp_close_tcpip() finishes, so that
a mg_lwip_tcp_error_cb() meanwhile can clear the PCB pointer stored within.
That ensures no double-closing of the TCP PCB when a concurrent TCP error makes
LWIP close the TCP PCB from the LWIP side.

NB!  At the moment, PCBs can still leak if tcp_close() fails, which is unlikely
but possible as per the API.  Retrying tcp_close() should somehow be
implemented.  For now, at least add logging of tcp_close() failures.

Also: remove the extraneous though benign double-calling of tcp_arg(…, NULL).

h/t @QRPp

.clang-format

@@ -0,0 +1,6 @@
+BasedOnStyle: Google
+AllowShortFunctionsOnASingleLine: false
+SpaceAfterCStyleCast: true
+PointerBindsToType: false
+DerivePointerBinding: false
+IncludeBlocks: Preserve

CONTRIBUTING.md

@@ -1,8 +0,0 @@
-People who have agreed to the
-[Cesanta CLA](https://docs.cesanta.com/contributors_la.shtml)
-can make contributions. Note that the CLA isn't a copyright
-_assigment_ but rather a copyright _license_.
-You retain the copyright on your contributions.
-
-We follow the Google C/C++ style guide: https://google.github.io/styleguide/cppguide.html
-We'd appreciate if your contribution follows the same style guide.

LICENSE

@@ -1,5 +1,5 @@
-Copyright (c) 2004-2013 Sergey Lyubka <valenok@gmail.com>
-Copyright (c) 2013-2016 Cesanta Software Limited
+Copyright (c) 2004-2013 Sergey Lyubka
+Copyright (c) 2013-2020 Cesanta Software Limited
 All rights reserved
 
 This software is dual-licensed: you can redistribute it and/or modify

README.md

@@ -2,71 +2,11 @@
 
 ![](https://img.shields.io/badge/license-GPL_2-green.svg "License")
 
-Mongoose is ideal for embedded environments. It has been designed
-for connecting devices and bringing them online. On the market since 2004,
-used by vast number of open source and
-commercial products - it even runs on the International Space station!
-Mongoose makes embedded network programming fast, robust, and easy.
-
-- [Download Mongoose Source Code here](https://www.cesanta.com)
-
-Looking for a complete IoT firmware solution?
-
-Check out [Mongoose OS](https://mongoose-os.com) - open source embedded operating system for low-power connected microcontrollers. Secure, designed for Internet of Things, complete environment for prototyping, development and managing.
-
-# Support
-- [Study mongoose example code](https://github.com/cesanta/mongoose/tree/master/examples)
-- [Read User Guide and API reference](https://docs.cesanta.com/mongoose)
-- [Support Forum - ask your technical questions here] (http://forum.cesanta.com/index.php?p=/categories/mongoose)
-- [Commercial licensing and support available] (https://www.cesanta.com/services-support)
-- [Check our latest releases] (https://github.com/cesanta/mongoose/releases)
-
-# Features
-
-* Cross-platform: works on Linux/UNIX, MacOS, QNX, eCos, Windows, Android,
-  iPhone, FreeRTOS (TI CC3200, ESP8266), etc
-* Supported hardware platforms: TI CC3200, TI MSP432, NRF52, STM32, PIC32, ESP8266, ESP32 and more
-* Builtin protocols:
-   - plain TCP, plain UDP, SSL/TLS (over TCP, one-way or two-way)
-   - HTTP client, HTTP server
-   - WebSocket client, WebSocket server
-   - MQTT client, MQTT broker
-   - CoAP client, CoAP server
-   - DNS client, DNS server, async DNS resolver
-* Single-threaded, asynchronous, non-blocking core with simple event-based API
-* Native support for [PicoTCP embedded TCP/IP stack](http://www.picotcp.com),
-  [LWIP embedded TCP/IP stack](https://en.wikipedia.org/wiki/LwIP)
-* Tiny static and run-time footprint
-* Source code is both ISO C and ISO C++ compliant
-* Very easy to integrate: just copy
-  [mongoose.c](https://raw.githubusercontent.com/cesanta/mongoose/master/mongoose.c) and
-  [mongoose.h](https://raw.githubusercontent.com/cesanta/mongoose/master/mongoose.h)
-  files to your build tree
+This branch is only for use by [Mongoose OS](https://github.com/cesanta/mongoose-os),
+for other projects please use the master branch.
 
 # Licensing
 
 Mongoose is released under Commercial and [GNU GPL v.2](http://www.gnu.org/licenses/old-licenses/gpl-2.0.html) open source licenses.
 
-Commercial Projects: [Contact us for commercial license.] (https://www.cesanta.com/contact)
-
-# Dashboard Example
-
-Mongoose is often used to implement device dashboards and real-time
-data exchange over Websocket. Here is a dashboard example that illustrates
-the functionality:
-
-![](http://www.cesanta.com/hubfs/www.cesanta.com/diagrams/dash_mongoose_diagram.png)
-
-[Developing a new product? Contact us today to discuss how Mongoose can help.
-](https://www.cesanta.com/contact)
-
-# Contributions
-
-To submit contributions, sign
-[Cesanta CLA](https://docs.cesanta.com/contributors_la.shtml)
-and send GitHub pull request. You retain the copyright on your contributions.
-
-# Looking for a pre-compiled Mongoose web server Windows or Mac binary?
-- [Download pre-compiled Mongoose web server binary.](https://www.cesanta.com/products/binary)
-
-[![Analytics](https://ga-beacon.appspot.com/UA-42732794-5/project-page)](https://github.com/cesanta/mongoose)
+Commercial Projects: [Contact us for commercial license.](https://www.cesanta.com/contact.html)

docs/c-api/http.h/struct_mg_http_multipart_part.md

@@ -1,16 +0,0 @@
----
-title: "struct mg_http_multipart_part"
-decl_name: "struct mg_http_multipart_part"
-symbol_kind: "struct"
-signature: |
-  struct mg_http_multipart_part {
-    const char *file_name;
-    const char *var_name;
-    struct mg_str data;
-    int status; /* <0 on error */
-    void *user_data;
-  };
----
-
-HTTP multipart part 
-

docs/c-api/http_server.h/mg_http_parse_header.md

@@ -1,23 +0,0 @@
----
-title: "mg_http_parse_header()"
-decl_name: "mg_http_parse_header"
-symbol_kind: "func"
-signature: |
-  int mg_http_parse_header(struct mg_str *hdr, const char *var_name, char *buf,
-                           size_t buf_size);
----
-
-Parses the HTTP header `hdr`. Finds variable `var_name` and stores its value
-in the buffer `buf`, `buf_size`. Returns 0 if variable not found, non-zero
-otherwise.
-
-This function is supposed to parse cookies, authentication headers, etc.
-Example (error handling omitted):
-
-    char user[20];
-    struct mg_str *hdr = mg_get_http_header(hm, "Authorization");
-    mg_http_parse_header(hdr, "username", user, sizeof(user));
-
-Returns the length of the variable's value. If buffer is not large enough,
-or variable not found, 0 is returned. 
-

docs/c-api/intro.md

@@ -1,16 +1,16 @@
 ---
 items:
   - { name: mbuf.h }
-  - { name: net.h }
-  - { name: http.h }
-  - { name: http_server.h }
-  - { name: http_client.h }
-  - { name: dns.h }
-  - { name: dns_server.h }
-  - { name: resolv.h }
-  - { name: mqtt.h }
-  - { name: mqtt_server.h }
-  - { name: coap.h }
-  - { name: util.h }
-  - { name: uri.h }
+  - { name: mg_net.h }
+  - { name: mg_http.h }
+  - { name: mg_http_server.h }
+  - { name: mg_http_client.h }
+  - { name: mg_dns.h }
+  - { name: mg_dns_server.h }
+  - { name: mg_resolv.h }
+  - { name: mg_mqtt.h }
+  - { name: mg_mqtt_server.h }
+  - { name: mg_coap.h }
+  - { name: mg_util.h }
+  - { name: mg_uri.h }
 ---

docs/c-api/mbuf.h/intro.md

@@ -1,12 +1,15 @@
 ---
-title: "Memory Buffers"
+title: "mbuf.h"
 symbol_kind: "intro"
 decl_name: "mbuf.h"
 items:
   - { name: mbuf_append.md }
+  - { name: mbuf_append_and_free.md }
+  - { name: mbuf_clear.md }
   - { name: mbuf_free.md }
   - { name: mbuf_init.md }
   - { name: mbuf_insert.md }
+  - { name: mbuf_move.md }
   - { name: mbuf_remove.md }
   - { name: mbuf_resize.md }
   - { name: mbuf_trim.md }

docs/c-api/mbuf.h/mbuf_append_and_free.md

@@ -0,0 +1,13 @@
+---
+title: "mbuf_append_and_free()"
+decl_name: "mbuf_append_and_free"
+symbol_kind: "func"
+signature: |
+  size_t mbuf_append_and_free(struct mbuf *, void *data, size_t data_size);
+---
+
+Appends data to the Mbuf and frees it (data must be heap-allocated).
+
+Returns the number of bytes appended or 0 if out of memory.
+data is freed irrespective of return value. 
+

docs/c-api/mbuf.h/mbuf_clear.md

@@ -0,0 +1,10 @@
+---
+title: "mbuf_clear()"
+decl_name: "mbuf_clear"
+symbol_kind: "func"
+signature: |
+  void mbuf_clear(struct mbuf *);
+---
+
+Removes all the data from mbuf (if any). 
+

docs/c-api/mbuf.h/mbuf_move.md

@@ -0,0 +1,10 @@
+---
+title: "mbuf_move()"
+decl_name: "mbuf_move"
+symbol_kind: "func"
+signature: |
+  void mbuf_move(struct mbuf *from, struct mbuf *to);
+---
+
+Moves the state from one mbuf to the other. 
+

docs/c-api/mg_coap.h/intro.md

@@ -1,7 +1,7 @@
 ---
 title: "CoAP API reference"
 symbol_kind: "intro"
-decl_name: "coap.h"
+decl_name: "mg_coap.h"
 items:
   - { name: mg_coap_add_option.md }
   - { name: mg_coap_compose.md }

docs/c-api/mg_dns.h/intro.md

@@ -1,7 +1,7 @@
 ---
 title: "DNS API reference"
 symbol_kind: "intro"
-decl_name: "dns.h"
+decl_name: "mg_dns.h"
 items:
   - { name: mg_dns_copy_questions.md }
   - { name: mg_dns_encode_name.md }

docs/c-api/mg_dns_server.h/intro.md

@@ -1,7 +1,7 @@
 ---
 title: "DNS server API reference"
 symbol_kind: "intro"
-decl_name: "dns_server.h"
+decl_name: "mg_dns_server.h"
 items:
   - { name: mg_dns_create_reply.md }
   - { name: mg_dns_reply_record.md }

docs/c-api/mg_http.h/intro.md

@@ -1,10 +1,12 @@
 ---
 title: "Common API reference"
 symbol_kind: "intro"
-decl_name: "http.h"
+decl_name: "mg_http.h"
 items:
   - { name: mg_connect_ws.md }
   - { name: mg_connect_ws_opt.md }
+  - { name: mg_http_is_authorized.md }
+  - { name: mg_http_send_digest_auth_request.md }
   - { name: mg_printf_websocket_frame.md }
   - { name: mg_send_websocket_frame.md }
   - { name: mg_send_websocket_framev.md }

docs/c-api/mg_http.h/mg_http_is_authorized.md

@@ -0,0 +1,16 @@
+---
+title: "mg_http_is_authorized()"
+decl_name: "mg_http_is_authorized"
+symbol_kind: "func"
+signature: |
+  int mg_http_is_authorized(struct http_message *hm, struct mg_str path,
+                            const char *domain, const char *passwords_file,
+                            int flags);
+---
+
+Checks whether an http request is authorized. `domain` is the authentication
+realm, `passwords_file` is a htdigest file (can be created e.g. with
+`htdigest` utility). If either `domain` or `passwords_file` is NULL, this
+function always returns 1; otherwise checks the authentication in the
+http request and returns 1 only if there is a match; 0 otherwise. 
+

docs/c-api/mg_http.h/mg_http_send_digest_auth_request.md

@@ -0,0 +1,11 @@
+---
+title: "mg_http_send_digest_auth_request()"
+decl_name: "mg_http_send_digest_auth_request"
+symbol_kind: "func"
+signature: |
+  void mg_http_send_digest_auth_request(struct mg_connection *c,
+                                        const char *domain);
+---
+
+Sends 401 Unauthorized response. 
+

docs/c-api/mg_http.h/mg_send_websocket_framev.md

@@ -7,8 +7,6 @@ signature: |
                                 const struct mg_str *strings, int num_strings);
 ---
 
-Sends multiple websocket frames.
-
-Like `mg_send_websocket_frame()`, but composes a frame from multiple
-*buffers. 
+Like `mg_send_websocket_frame()`, but composes a single frame from multiple
+buffers. 
 

docs/c-api/mg_http.h/mg_set_protocol_http_websocket.md

@@ -30,7 +30,9 @@ The user-defined event handler will receive following extra events:
 - MG_EV_WEBSOCKET_HANDSHAKE_REQUEST: server has received the WebSocket
   handshake request. `ev_data` contains parsed HTTP request.
 - MG_EV_WEBSOCKET_HANDSHAKE_DONE: server has completed the WebSocket
-  handshake. `ev_data` is `NULL`.
+  handshake. `ev_data` is a `struct http_message` containing the
+  client's request (server mode) or server's response (client).
+  In client mode handler can examine `resp_code`, which should be 101.
 - MG_EV_WEBSOCKET_FRAME: new WebSocket frame has arrived. `ev_data` is
   `struct websocket_message *`
 

docs/c-api/mg_http.h/struct_http_message.md

@@ -29,6 +29,12 @@ signature: |
     /* Headers */
     struct mg_str header_names[MG_MAX_HTTP_HEADERS];
     struct mg_str header_values[MG_MAX_HTTP_HEADERS];
+  
+    /*
+     * Value of the Content-Length header if present,
+     * otherwise MG_HTTP_CONTENT_LENGTH_UNKNOWN.
+     */
+    size_t content_length;
   };
 ---
 

docs/c-api/mg_http.h/struct_mg_http_multipart_part.md

@@ -0,0 +1,24 @@
+---
+title: "struct mg_http_multipart_part"
+decl_name: "struct mg_http_multipart_part"
+symbol_kind: "struct"
+signature: |
+  struct mg_http_multipart_part {
+    const char *file_name;
+    const char *var_name;
+    struct mg_str data;
+    int status; /* <0 on error */
+    void *user_data;
+    /*
+     * User handler can indicate how much of the data was consumed
+     * by setting this variable. By default, it is assumed that all
+     * data has been consumed by the handler.
+     * If not all data was consumed, user's handler will be invoked again later
+     * with the remainder.
+     */
+    size_t num_data_consumed;
+  };
+---
+
+HTTP multipart part 
+

docs/c-api/mg_http_client.h/intro.md

@@ -1,7 +1,7 @@
 ---
 title: "Client API reference"
 symbol_kind: "intro"
-decl_name: "http_client.h"
+decl_name: "mg_http_client.h"
 items:
   - { name: mg_connect_http.md }
   - { name: mg_connect_http_opt.md }

docs/c-api/mg_http_client.h/mg_http_create_digest_auth_header.md

@@ -6,7 +6,7 @@ signature: |
   int mg_http_create_digest_auth_header(char *buf, size_t buf_len,
                                         const char *method, const char *uri,
                                         const char *auth_domain, const char *user,
-                                        const char *passwd);
+                                        const char *passwd, const char *nonce);
 ---
 
 Creates digest authentication header for a client request. 

docs/c-api/mg_http_server.h/intro.md

@@ -1,14 +1,16 @@
 ---
 title: "Server API reference"
 symbol_kind: "intro"
-decl_name: "http_server.h"
+decl_name: "mg_http_server.h"
 items:
+  - { name: mg_check_digest_auth.md }
   - { name: mg_file_upload_handler.md }
   - { name: mg_get_http_basic_auth.md }
   - { name: mg_get_http_header.md }
   - { name: mg_get_http_var.md }
   - { name: mg_http_check_digest_auth.md }
   - { name: mg_http_parse_header.md }
+  - { name: mg_http_parse_header2.md }
   - { name: mg_http_reverse_proxy.md }
   - { name: mg_http_send_error.md }
   - { name: mg_http_send_redirect.md }

docs/c-api/mg_http_server.h/mg_check_digest_auth.md

@@ -0,0 +1,17 @@
+---
+title: "mg_check_digest_auth()"
+decl_name: "mg_check_digest_auth"
+symbol_kind: "func"
+signature: |
+  int mg_check_digest_auth(struct mg_str method, struct mg_str uri,
+                           struct mg_str username, struct mg_str cnonce,
+                           struct mg_str response, struct mg_str qop,
+                           struct mg_str nc, struct mg_str nonce,
+                           struct mg_str auth_domain, FILE *fp);
+---
+
+Authenticates given response params against an opened password file.
+Returns 1 if authenticated, 0 otherwise.
+
+It's used by mg_http_check_digest_auth(). 
+

docs/c-api/mg_http_server.h/mg_http_parse_header.md

@@ -0,0 +1,15 @@
+---
+title: "mg_http_parse_header()"
+decl_name: "mg_http_parse_header"
+symbol_kind: "func"
+signature: |
+  int mg_http_parse_header(struct mg_str *hdr, const char *var_name, char *buf,
+                           size_t buf_size);
+---
+
+DEPRECATED: use mg_http_parse_header2() instead.
+
+Same as mg_http_parse_header2(), but takes buffer as a `char *` (instead of
+`char **`), and thus it cannot allocate a new buffer if the provided one
+is not enough, and just returns 0 in that case. 
+

docs/c-api/mg_http_server.h/mg_http_parse_header2.md

@@ -0,0 +1,30 @@
+---
+title: "mg_http_parse_header2()"
+decl_name: "mg_http_parse_header2"
+symbol_kind: "func"
+signature: |
+  int mg_http_parse_header2(struct mg_str *hdr, const char *var_name, char **buf,
+                            size_t buf_size);
+---
+
+Parses the HTTP header `hdr`. Finds variable `var_name` and stores its value
+in the buffer `*buf`, `buf_size`. If the buffer size is not enough,
+allocates a buffer of required size and writes it to `*buf`, similar to
+asprintf(). The caller should always check whether the buffer was updated,
+and free it if so.
+
+This function is supposed to parse cookies, authentication headers, etc.
+Example (error handling omitted):
+
+    char user_buf[20];
+    char *user = user_buf;
+    struct mg_str *hdr = mg_get_http_header(hm, "Authorization");
+    mg_http_parse_header2(hdr, "username", &user, sizeof(user_buf));
+    // ... do something useful with user
+    if (user != user_buf) {
+      free(user);
+    }
+
+Returns the length of the variable's value. If variable is not found, 0 is
+returned. 
+

docs/c-api/mg_mqtt.h/intro.md

@@ -1,7 +1,7 @@
 ---
 title: "MQTT API reference"
 symbol_kind: "intro"
-decl_name: "mqtt.h"
+decl_name: "mg_mqtt.h"
 items:
   - { name: mg_mqtt_connack.md }
   - { name: mg_mqtt_disconnect.md }