lib/ssl/notes.txt
author Franziskus Kiefer <franziskuskiefer@gmail.com>
Thu, 16 Mar 2017 12:32:37 +0100
changeset 13216 2e7133b0da822f9bed3b07d21c6a479cfdd82dbc
parent 11981 0c19072b85372534ecfe9874fb3315cbed8f3eab
permissions -rw-r--r--
Bug 1347473 - don't change user in docker image on aarch64

# This Source Code Form is subject to the terms of the Mozilla Public
# License, v. 2.0. If a copy of the MPL was not distributed with this
# file, You can obtain one at http://mozilla.org/MPL/2.0/.

SSL's Buffers: enumerated and explained.

---------------------------------------------------------------------------
incoming:

gs = ss->gather
hs = ss->ssl3->hs

gs->inbuf   incoming (encrypted) ssl records are placed here,
        and then decrypted (or copied) to gs->buf.

gs->buf     ssl3_HandleHandshake puts decrypted ssl records here.

hs.msg_body When an incoming handshake message spans more
        than one ssl record, the first part(s) of it are accumulated
        here until it all arrives.

hs.msgState an alternative set of pointers/lengths for gs->buf.
        Used only when a handleHandshake function returns SECWouldBlock.
        ssl3_HandleHandshake remembers how far it previously got by
        using these pointers instead of gs->buf when it is called
        after a previous SECWouldBlock return.

---------------------------------------------------------------------------
outgoing:

sec = ss->sec
ci  = ss->sec->ci   /* connect info */

ci->sendBuf Outgoing handshake messages are appended to this buffer.
        This buffer will then be sent as a single SSL record.

sec->writeBuf   outgoing ssl records are constructed here and encrypted in
        place before being written or copied to pendingBuf.

ss->pendingBuf  contains outgoing ciphertext that was saved after a write
        attempt to the socket failed, e.g. EWouldBlock.
        Generally empty with blocking sockets (should be no incomplete
        writes).

ss->saveBuf Used only by socks code.  Intended to be used to buffer
        outgoing data until a socks handshake completes.  However,
        this buffer is always empty.  There is no code to put
        anything into it.

---------------------------------------------------------------------------

SECWouldBlock means that the function cannot make progress because it is
waiting for some event OTHER THAN socket I/O completion (e.g. waiting for
user dialog to finish).  It is not the same as EWOULDBLOCK.

---------------------------------------------------------------------------

Rank (order) of locks

recvLock ->\ firstHandshake -> recvbuf -> ssl3Handshake -> xmitbuf -> "spec"
sendLock ->/

crypto and hash Data that must be protected while turning plaintext into
ciphertext:

SSl3:   (in ssl3_SendPlainText)
    ss->ssl3            (the pointer)
    ss->ssl3->current_write*    (the pointer and the data in the spec
                     and any data referenced by the spec.

    ss->sec->isServer
    ss->sec->writebuf* (ptr & content) locked by xmitBufLock
    "buf"                  locked by xmitBufLock

crypto and hash data that must be protected while turning ciphertext into
plaintext:

SSL3:   (in ssl3_HandleRecord )
    ssl3->current_read* (the pointer and all data refernced)
    ss->sec->isServer


Data that must be protected while being used by a "writer":

ss->pendingBuf.*
ss->saveBuf.*       (which is dead)

in ssl3_sendPlainText

ss->ssl3->current_write-> (spec)
ss->sec->writeBuf.*
ss->sec->isServer

in SendBlock

ss->sec->writeBuf.*
ss->pendingBuf

--------------------------------------------------------------------------

Data variables (not const) protected by the "sslGlobalDataLock".
Note, this really should be a reader/writer lock.

cipherSuites[]      ssl3con.c