docs: networking: convert strparser.txt to ReST

- add SPDX header;
- adjust title markup;
- mark code blocks and literals as such;
- mark tables as such;
- adjust identation, whitespaces and blank lines where needed;
- add to networking/index.rst.

Signed-off-by: Mauro Carvalho Chehab <mchehab+huawei@kernel.org>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 0 insertions, 207 deletions

diff --git a/Documentation/networking/strparser.txt b/Documentation/networking/strparser.txt
deleted file mode 100644
index a7d354ddda7b..000000000000
--- a/Documentation/networking/strparser.txt
+++ /dev/null
@@ -1,207 +0,0 @@
-Stream Parser (strparser)
-
-Introduction
-============
-
-The stream parser (strparser) is a utility that parses messages of an
-application layer protocol running over a data stream. The stream
-parser works in conjunction with an upper layer in the kernel to provide
-kernel support for application layer messages. For instance, Kernel
-Connection Multiplexor (KCM) uses the Stream Parser to parse messages
-using a BPF program.
-
-The strparser works in one of two modes: receive callback or general
-mode.
-
-In receive callback mode, the strparser is called from the data_ready
-callback of a TCP socket. Messages are parsed and delivered as they are
-received on the socket.
-
-In general mode, a sequence of skbs are fed to strparser from an
-outside source. Message are parsed and delivered as the sequence is
-processed. This modes allows strparser to be applied to arbitrary
-streams of data.
-
-Interface
-=========
-
-The API includes a context structure, a set of callbacks, utility
-functions, and a data_ready function for receive callback mode. The
-callbacks include a parse_msg function that is called to perform
-parsing (e.g.  BPF parsing in case of KCM), and a rcv_msg function
-that is called when a full message has been completed.
-
-Functions
-=========
-
-strp_init(struct strparser *strp, struct sock *sk,
-	  const struct strp_callbacks *cb)
-
-     Called to initialize a stream parser. strp is a struct of type
-     strparser that is allocated by the upper layer. sk is the TCP
-     socket associated with the stream parser for use with receive
-     callback mode; in general mode this is set to NULL. Callbacks
-     are called by the stream parser (the callbacks are listed below).
-
-void strp_pause(struct strparser *strp)
-
-     Temporarily pause a stream parser. Message parsing is suspended
-     and no new messages are delivered to the upper layer.
-
-void strp_unpause(struct strparser *strp)
-
-     Unpause a paused stream parser.
-
-void strp_stop(struct strparser *strp);
-
-     strp_stop is called to completely stop stream parser operations.
-     This is called internally when the stream parser encounters an
-     error, and it is called from the upper layer to stop parsing
-     operations.
-
-void strp_done(struct strparser *strp);
-
-     strp_done is called to release any resources held by the stream
-     parser instance. This must be called after the stream processor
-     has been stopped.
-
-int strp_process(struct strparser *strp, struct sk_buff *orig_skb,
-		 unsigned int orig_offset, size_t orig_len,
-		 size_t max_msg_size, long timeo)
-
-    strp_process is called in general mode for a stream parser to
-    parse an sk_buff. The number of bytes processed or a negative
-    error number is returned. Note that strp_process does not
-    consume the sk_buff. max_msg_size is maximum size the stream
-    parser will parse. timeo is timeout for completing a message.
-
-void strp_data_ready(struct strparser *strp);
-
-    The upper layer calls strp_tcp_data_ready when data is ready on
-    the lower socket for strparser to process. This should be called
-    from a data_ready callback that is set on the socket. Note that
-    maximum messages size is the limit of the receive socket
-    buffer and message timeout is the receive timeout for the socket.
-
-void strp_check_rcv(struct strparser *strp);
-
-    strp_check_rcv is called to check for new messages on the socket.
-    This is normally called at initialization of a stream parser
-    instance or after strp_unpause.
-
-Callbacks
-=========
-
-There are six callbacks:
-
-int (*parse_msg)(struct strparser *strp, struct sk_buff *skb);
-
-    parse_msg is called to determine the length of the next message
-    in the stream. The upper layer must implement this function. It
-    should parse the sk_buff as containing the headers for the
-    next application layer message in the stream.
-
-    The skb->cb in the input skb is a struct strp_msg. Only
-    the offset field is relevant in parse_msg and gives the offset
-    where the message starts in the skb.
-
-    The return values of this function are:
-
-    >0 : indicates length of successfully parsed message
-    0  : indicates more data must be received to parse the message
-    -ESTRPIPE : current message should not be processed by the
-          kernel, return control of the socket to userspace which
-          can proceed to read the messages itself
-    other < 0 : Error in parsing, give control back to userspace
-          assuming that synchronization is lost and the stream
-          is unrecoverable (application expected to close TCP socket)
-
-    In the case that an error is returned (return value is less than
-    zero) and the parser is in receive callback mode, then it will set
-    the error on TCP socket and wake it up. If parse_msg returned
-    -ESTRPIPE and the stream parser had previously read some bytes for
-    the current message, then the error set on the attached socket is
-    ENODATA since the stream is unrecoverable in that case.
-
-void (*lock)(struct strparser *strp)
-
-    The lock callback is called to lock the strp structure when
-    the strparser is performing an asynchronous operation (such as
-    processing a timeout). In receive callback mode the default
-    function is to lock_sock for the associated socket. In general
-    mode the callback must be set appropriately.
-
-void (*unlock)(struct strparser *strp)
-
-    The unlock callback is called to release the lock obtained
-    by the lock callback. In receive callback mode the default
-    function is release_sock for the associated socket. In general
-    mode the callback must be set appropriately.
-
-void (*rcv_msg)(struct strparser *strp, struct sk_buff *skb);
-
-    rcv_msg is called when a full message has been received and
-    is queued. The callee must consume the sk_buff; it can
-    call strp_pause to prevent any further messages from being
-    received in rcv_msg (see strp_pause above). This callback
-    must be set.
-
-    The skb->cb in the input skb is a struct strp_msg. This
-    struct contains two fields: offset and full_len. Offset is
-    where the message starts in the skb, and full_len is the
-    the length of the message. skb->len - offset may be greater
-    then full_len since strparser does not trim the skb.
-
-int (*read_sock_done)(struct strparser *strp, int err);
-
-     read_sock_done is called when the stream parser is done reading
-     the TCP socket in receive callback mode. The stream parser may
-     read multiple messages in a loop and this function allows cleanup
-     to occur when exiting the loop. If the callback is not set (NULL
-     in strp_init) a default function is used.
-
-void (*abort_parser)(struct strparser *strp, int err);
-
-     This function is called when stream parser encounters an error
-     in parsing. The default function stops the stream parser and
-     sets the error in the socket if the parser is in receive callback
-     mode. The default function can be changed by setting the callback
-     to non-NULL in strp_init.
-
-Statistics
-==========
-
-Various counters are kept for each stream parser instance. These are in
-the strp_stats structure. strp_aggr_stats is a convenience structure for
-accumulating statistics for multiple stream parser instances.
-save_strp_stats and aggregate_strp_stats are helper functions to save
-and aggregate statistics.
-
-Message assembly limits
-=======================
-
-The stream parser provide mechanisms to limit the resources consumed by
-message assembly.
-
-A timer is set when assembly starts for a new message. In receive
-callback mode the message timeout is taken from rcvtime for the
-associated TCP socket. In general mode, the timeout is passed as an
-argument in strp_process. If the timer fires before assembly completes
-the stream parser is aborted and the ETIMEDOUT error is set on the TCP
-socket if in receive callback mode.
-
-In receive callback mode, message length is limited to the receive
-buffer size of the associated TCP socket. If the length returned by
-parse_msg is greater than the socket buffer size then the stream parser
-is aborted with EMSGSIZE error set on the TCP socket. Note that this
-makes the maximum size of receive skbuffs for a socket with a stream
-parser to be 2*sk_rcvbuf of the TCP socket.
-
-In general mode the message length limit is passed in as an argument
-to strp_process.
-
-Author
-======
-
-Tom Herbert (tom@quantonium.net)
-