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esp_http_server improvements to allow adding transport layer encryption
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Changes:
- renamed `httpd_free_sess_ctx_fn_t` to `httpd_free_ctx_fn_t`
- added a `httpd_handle_t` argument to `httpd_send_func_t` and `httpd_recv_func_t`
- internal function `httpd_sess_get()` is no longer static, as it's used in other
  files besides httpd_sess.c

Bug fixes:
- removed a trailing semicolon from `HTTPD_DEFAULT_CONFIG()`
- fixed issue with failed `select()`, now it automatically closes invalid sockets
  instead of shutting down the entire server

New features:
- `httpd_resp_send()` and `httpd_resp_send_chunk()` now accept -1 as length to use
  `strlen()` internally
- added `httpd_sess_set_ctx()` to accompany `httpd_sess_get_ctx()`
- added a "transport context" to the session structure (next to user context)
- added `httpd_sess_{get,set}_transport_ctx()` to work with this transport context
- added "global user context" and "global transport context" stored in the server
  config (and then the handle); supports a user-provided free_fn
- added a "pending func" to e.g. check for data in the transport layer receive
  buffer
- added functions `httpd_set_sess_{send,recv,pending}_override()` that target
  a session by ID (i.e. not using a request object)
- added `httpd_set_pending_override()`
- added a "open_fn" and "close_fn" - functions called when creating and closing
  a session. These may be used to set up transport layer encryption or some other
  session-wide feature
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@MightyPork
MightyPork committed Oct 31, 2018
1 parent bd90f53 commit 2efda16
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246 changes: 233 additions & 13 deletions components/esp_http_server/include/esp_http_server.h
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Original file line number Diff line number Diff line change
Expand Up @@ -27,6 +27,10 @@
extern "C" {
#endif

/*
note: esp_https_server.h includes a customized copy of this
initializer that should be kept in sync
*/
#define HTTPD_DEFAULT_CONFIG() { \
.task_priority = tskIDLE_PRIORITY+5, \
.stack_size = 4096, \
Expand All @@ -39,7 +43,13 @@ extern "C" {
.lru_purge_enable = false, \
.recv_wait_timeout = 5, \
.send_wait_timeout = 5, \
};
.global_user_ctx = NULL, \
.global_user_ctx_free_fn = NULL, \
.global_transport_ctx = NULL, \
.global_transport_ctx_free_fn = NULL, \
.open_fn = NULL, \
.close_fn = NULL, \
}

#define ESP_ERR_HTTPD_BASE (0x8000) /*!< Starting number of HTTPD error codes */
#define ESP_ERR_HTTPD_HANDLERS_FULL (ESP_ERR_HTTPD_BASE + 1) /*!< All slots for registering URI handlers have been consumed */
Expand Down Expand Up @@ -70,6 +80,35 @@ typedef void* httpd_handle_t;
*/
typedef enum http_method httpd_method_t;

/**
* @brief Prototype for freeing context data (if any)
* @param[in] ctx : object to free
*/
typedef void (*httpd_free_ctx_fn_t)(void *ctx);

/**
* @brief Function prototype for opening a session.
*
* Called immediately after the socket was opened to set up the send/recv functions and
* other parameters of the socket.
*
* @param[in] hd : server instance
* @param[in] sockfd : session socket file descriptor
* @return status
*/
typedef esp_err_t (*httpd_open_func_t)(httpd_handle_t hd, int sockfd);

/**
* @brief Function prototype for closing a session.
*
* @note It's possible that the socket descriptor is invalid at this point, the function
* is called for all terminated sessions. Ensure proper handling of return codes.
*
* @param[in] hd : server instance
* @param[in] sockfd : session socket file descriptor
*/
typedef void (*httpd_close_func_t)(httpd_handle_t hd, int sockfd);

/**
* @brief HTTP Server Configuration Structure
*
Expand Down Expand Up @@ -99,6 +138,55 @@ typedef struct httpd_config {
bool lru_purge_enable; /*!< Purge "Least Recently Used" connection */
uint16_t recv_wait_timeout; /*!< Timeout for recv function (in seconds)*/
uint16_t send_wait_timeout; /*!< Timeout for send function (in seconds)*/

/**
* Global user context.
*
* This field can be used to store arbitrary user data within the server context.
* The value can be retrieved using the server handle, available e.g. in the httpd_req_t struct.
*
* When shutting down, the server frees up the user context by
* calling free() on the global_user_ctx field. If you wish to use a custom
* function for freeing the global user context, please specify that here.
*/
void * global_user_ctx;
httpd_free_ctx_fn_t global_user_ctx_free_fn;

/**
* Global transport context.
*
* Similar to global_user_ctx, but used for session encoding or encryption (e.g. to hold the SSL context).
* It will be freed using free(), unless global_transport_ctx_free_fn is specified.
*/
void * global_transport_ctx;
httpd_free_ctx_fn_t global_transport_ctx_free_fn;

/**
* Custom session opening callback.
*
* Called on a new session socket just after accept(), but before reading any data.
*
* This is an opportunity to set up e.g. SSL encryption using global_transport_ctx
* and the send/recv/pending session overrides.
*
* If a context needs to be maintained between these functions, store it in the session using
* httpd_sess_set_transport_ctx() and retrieve it later with httpd_sess_get_transport_ctx()
*/
httpd_open_func_t open_fn;

/**
* Custom session closing callback.
*
* Called when a session is deleted, before freeing user and transport contexts and before
* closing the socket. This is a place for custom de-init code common to all sockets.
*
* Set the user or transport context to NULL if it was freed here, so the server does not
* try to free it again.
*
* This function is run for all terminated sessions, including sessions where the socket
* was closed by the network stack - that is, the file descriptor may not be valid anymore.
*/
httpd_close_func_t close_fn;
} httpd_config_t;

/**
Expand Down Expand Up @@ -180,11 +268,6 @@ esp_err_t httpd_stop(httpd_handle_t handle);
* @{
*/

/**
* @brief Function type for freeing context data (if any)
*/
typedef void (*httpd_free_sess_ctx_fn_t)(void *sess_ctx);

/* Max supported HTTP request header length */
#define HTTPD_MAX_REQ_HDR_LEN CONFIG_HTTPD_MAX_REQ_HDR_LEN

Expand Down Expand Up @@ -232,7 +315,7 @@ typedef struct httpd_req {
* calling free() on the sess_ctx member. If you wish to use a custom
* function for freeing the session context, please specify that here.
*/
httpd_free_sess_ctx_fn_t free_ctx;
httpd_free_ctx_fn_t free_ctx;
} httpd_req_t;

/**
Expand Down Expand Up @@ -360,13 +443,18 @@ esp_err_t httpd_unregister_uri(httpd_handle_t handle, const char* uri);
* HTTPD_SOCK_ERR_ codes, which will eventually be conveyed as
* return value of httpd_send() function
*
* @param[in] hd : server instance
* @param[in] sockfd : session socket file descriptor
* @param[in] buf : buffer with bytes to send
* @param[in] buf_len : data size
* @param[in] flags : flags for the send() function
* @return
* - Bytes : The number of bytes sent successfully
* - HTTPD_SOCK_ERR_INVALID : Invalid arguments
* - HTTPD_SOCK_ERR_TIMEOUT : Timeout/interrupted while calling socket send()
* - HTTPD_SOCK_ERR_FAIL : Unrecoverable error while calling socket send()
*/
typedef int (*httpd_send_func_t)(int sockfd, const char *buf, size_t buf_len, int flags);
typedef int (*httpd_send_func_t)(httpd_handle_t hd, int sockfd, const char *buf, size_t buf_len, int flags);

/**
* @brief Prototype for HTTPDs low-level recv function
Expand All @@ -376,14 +464,37 @@ typedef int (*httpd_send_func_t)(int sockfd, const char *buf, size_t buf_len, in
* HTTPD_SOCK_ERR_ codes, which will eventually be conveyed as
* return value of httpd_req_recv() function
*
* @param[in] hd : server instance
* @param[in] sockfd : session socket file descriptor
* @param[in] buf : buffer with bytes to send
* @param[in] buf_len : data size
* @param[in] flags : flags for the send() function
* @return
* - Bytes : The number of bytes received successfully
* - 0 : Buffer length parameter is zero / connection closed by peer
* - HTTPD_SOCK_ERR_INVALID : Invalid arguments
* - HTTPD_SOCK_ERR_TIMEOUT : Timeout/interrupted while calling socket recv()
* - HTTPD_SOCK_ERR_FAIL : Unrecoverable error while calling socket recv()
*/
typedef int (*httpd_recv_func_t)(int sockfd, char *buf, size_t buf_len, int flags);
typedef int (*httpd_recv_func_t)(httpd_handle_t hd, int sockfd, char *buf, size_t buf_len, int flags);

/**
* @brief Prototype for HTTPDs low-level "get pending bytes" function
*
* @note User specified pending function must handle errors internally,
* depending upon the set value of errno, and return specific
* HTTPD_SOCK_ERR_ codes, which will be handled accordingly in
* the server task.
*
* @param[in] hd : server instance
* @param[in] sockfd : session socket file descriptor
* @return
* - Bytes : The number of bytes waiting to be received
* - HTTPD_SOCK_ERR_INVALID : Invalid arguments
* - HTTPD_SOCK_ERR_TIMEOUT : Timeout/interrupted while calling socket pending()
* - HTTPD_SOCK_ERR_FAIL : Unrecoverable error while calling socket pending()
*/
typedef int (*httpd_pending_func_t)(httpd_handle_t hd, int sockfd);

/** End of TX / RX
* @}
Expand Down Expand Up @@ -435,6 +546,64 @@ esp_err_t httpd_set_recv_override(httpd_req_t *r, httpd_recv_func_t recv_func);
*/
esp_err_t httpd_set_send_override(httpd_req_t *r, httpd_send_func_t send_func);

/**
* @brief Override web server's pending function
*
* This function overrides the web server's pending function. This function is
* used to test for pending bytes in a socket.
*
* @note This API is supposed to be called only from the context of
* a URI handler where httpd_req_t* request pointer is valid.
*
* @param[in] r The request being responded to
* @param[in] pending_func The pending function to be set for this request
*
* @return
* - ESP_OK : On successfully registering override
* - ESP_ERR_INVALID_ARG : Null arguments
* - ESP_ERR_HTTPD_INVALID_REQ : Invalid request pointer
*/
esp_err_t httpd_set_pending_override(httpd_req_t *r, httpd_pending_func_t pending_func);

/**
* @brief Override web server's send function (by session FD)
*
* @see httpd_set_send_override()
*
* @param[in] hd HTTPD instance handle
* @param[in] fd session socket FD
* @param[in] send_func The send function to be set for this session
*
* @return status code
*/
esp_err_t httpd_set_sess_send_override(httpd_handle_t hd, int sockfd, httpd_send_func_t send_func);

/**
* @brief Override web server's receive function (by session FD)
*
* @see httpd_set_recv_override()
*
* @param[in] hd HTTPD instance handle
* @param[in] fd session socket FD
* @param[in] recv_func The receive function to be set for this session
*
* @return status code
*/
esp_err_t httpd_set_sess_recv_override(httpd_handle_t hd, int sockfd, httpd_recv_func_t recv_func);

/**
* @brief Override web server's pending function (by session FD)
*
* @see httpd_set_pending_override()
*
* @param[in] hd HTTPD instance handle
* @param[in] fd session socket FD
* @param[in] pending_func The receive function to be set for this session
*
* @return status code
*/
esp_err_t httpd_set_sess_pending_override(httpd_handle_t hd, int sockfd, httpd_pending_func_t pending_func);

/**
* @brief Get the Socket Descriptor from the HTTP request
*
Expand Down Expand Up @@ -631,7 +800,7 @@ esp_err_t httpd_query_key_value(const char *qry, const char *key, char *val, siz
*
* @param[in] r The request being responded to
* @param[in] buf Buffer from where the content is to be fetched
* @param[in] buf_len Length of the buffer
* @param[in] buf_len Length of the buffer, -1 to use strlen()
*
* @return
* - ESP_OK : On successfully sending the response packet
Expand All @@ -640,7 +809,7 @@ esp_err_t httpd_query_key_value(const char *qry, const char *key, char *val, siz
* - ESP_ERR_HTTPD_RESP_SEND : Error in raw send
* - ESP_ERR_HTTPD_INVALID_REQ : Invalid request
*/
esp_err_t httpd_resp_send(httpd_req_t *r, const char *buf, size_t buf_len);
esp_err_t httpd_resp_send(httpd_req_t *r, const char *buf, ssize_t buf_len);

/**
* @brief API to send one HTTP chunk
Expand Down Expand Up @@ -670,7 +839,7 @@ esp_err_t httpd_resp_send(httpd_req_t *r, const char *buf, size_t buf_len);
*
* @param[in] r The request being responded to
* @param[in] buf Pointer to a buffer that stores the data
* @param[in] buf_len Length of the data from the buffer that should be sent out
* @param[in] buf_len Length of the data from the buffer that should be sent out, -1 to use strlen()
*
* @return
* - ESP_OK : On successfully sending the response packet chunk
Expand All @@ -679,7 +848,7 @@ esp_err_t httpd_resp_send(httpd_req_t *r, const char *buf, size_t buf_len);
* - ESP_ERR_HTTPD_RESP_SEND : Error in raw send
* - ESP_ERR_HTTPD_INVALID_REQ : Invalid request pointer
*/
esp_err_t httpd_resp_send_chunk(httpd_req_t *r, const char *buf, size_t buf_len);
esp_err_t httpd_resp_send_chunk(httpd_req_t *r, const char *buf, ssize_t buf_len);

/* Some commonly used status codes */
#define HTTPD_200 "200 OK" /*!< HTTP Response 200 */
Expand Down Expand Up @@ -901,6 +1070,57 @@ int httpd_send(httpd_req_t *r, const char *buf, size_t buf_len);
*/
void *httpd_sess_get_ctx(httpd_handle_t handle, int sockfd);

/**
* @brief Set session context by socket descriptor
*
* @param[in] handle Handle to server returned by httpd_start
* @param[in] sockfd The socket descriptor for which the context should be extracted.
* @param[in] ctx Context object to assign to the session
* @param[in] free_fn Function that should be called to free the context
*/
void httpd_sess_set_ctx(httpd_handle_t handle, int sockfd, void *ctx, httpd_free_ctx_fn_t free_fn);

/**
* @brief Get session 'transport' context by socket descriptor
* @see httpd_sess_get_ctx()
*
* This context is used by the send/receive functions, for example to manage SSL context.
*
* @param[in] handle Handle to server returned by httpd_start
* @param[in] sockfd The socket descriptor for which the context should be extracted.
* @return
* - void* : Pointer to the transport context associated with this session
* - NULL : Empty context / Invalid handle / Invalid socket fd
*/
void *httpd_sess_get_transport_ctx(httpd_handle_t handle, int sockfd);

/**
* @brief Set session 'transport' context by socket descriptor
* @see httpd_sess_set_ctx()
*
* @param[in] handle Handle to server returned by httpd_start
* @param[in] sockfd The socket descriptor for which the context should be extracted.
* @param[in] ctx Transport context object to assign to the session
* @param[in] free_fn Function that should be called to free the transport context
*/
void httpd_sess_set_transport_ctx(httpd_handle_t handle, int sockfd, void *ctx, httpd_free_ctx_fn_t free_fn);

/**
* @brief Get HTTPD global user context (it was set in the server config struct)
*
* @param[in] handle Handle to server returned by httpd_start
* @return global user context
*/
void *httpd_get_global_user_ctx(httpd_handle_t handle);

/**
* @brief Get HTTPD global transport context (it was set in the server config struct)
*
* @param[in] handle Handle to server returned by httpd_start
* @return global transport context
*/
void *httpd_get_global_transport_ctx(httpd_handle_t handle);

/**
* @brief Trigger an httpd session close externally
*
Expand Down
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