updated to be more valid for version 7 workings

This commit is contained in:
Daniel Stenberg 2000-06-14 09:16:11 +00:00
parent 72f7f0183b
commit 3b60784f27
1 changed files with 43 additions and 23 deletions

View File

@ -19,15 +19,18 @@ Windows vs Unix
the Windows way. The four most notable details are:
1. Different function names for close(), read(), write()
2. Windows requires a couple of init calls
2. Windows requires a couple of init calls for the socket stuff
3. The file descriptors for network communication and file operations are
not easily interchangable as in unix
4. When writing data to stdout, Windows makes end-of-lines the DOS way, thus
destroying binary data, although you do want that conversion if it is
text coming through... (sigh)
In curl, (1) and (2) are done with defines and macros, so that the source
looks the same at all places except for the header file that defines them.
In curl, (1) is made with defines and macros, so that the source looks the
same at all places except for the header file that defines them.
(2) must be made by the application that uses libcurl, in curl that means
src/main.c has some code #ifdef'ed to do just that.
(3) is simply avoided by not trying any funny tricks on file descriptors.
@ -44,19 +47,26 @@ Windows vs Unix
Library
=======
There is a few entry points to the library, namely each publicly defined
As described elsewhere, libcurl is meant to get two different "layers" of
interface. At the present point only the high-level, the "easy", interface
has been fully implemented and thus documented. We assume the easy-interface
in this description, the low-level interface will be documented when fully
implemented.
There are plenty of entry points to the library, namely each publicly defined
function that libcurl offers to applications. All of those functions are
rather small and easy-to-follow, accept the one single and do-it-all named
curl_urlget() (entry point in lib/url.c).
rather small and easy-to-follow. All the ones prefixed with 'curl_easy' are
put in the lib/easy.c file.
curl_urlget() takes a variable amount of arguments, and they must all be
curl_easy_setopt() takes a three arguments, where the option stuff must be
passed in pairs, the parameter-ID and the parameter-value. The list of
arguments must be ended with a end-of-arguments parameter-ID.
options is documented in the man page.
The function then continues to analyze the URL, get the different components
and connects to the remote host. This may involve using a proxy and/or using
SSL. The GetHost() function in lib/hostip.c is used for looking up host
names.
curl_easy_perform() does a whole lot of things.
The function analyzes the URL, get the different components and connects to
the remote host. This may involve using a proxy and/or using SSL. The
GetHost() function in lib/hostip.c is used for looking up host names.
When connected, the proper function is called. The functions are named after
the protocols they handle. ftp(), http(), dict(), etc. They all reside in
@ -70,12 +80,16 @@ Library
supplied clones in lib/mprintf.c.
While transfering, the progress functions in lib/progress.c are called at a
frequent interval. The speedcheck functions in lib/speedcheck.c are also used
to verify that the transfer is as fast as required.
frequent interval (or at the user's choice, a specified callback might get
called). The speedcheck functions in lib/speedcheck.c are also used to verify
that the transfer is as fast as required.
When the operation is done, the writeout() function in lib/writeout.c may be
called to report about the operation as specified previously in the arguments
to curl_urlget().
to curl_easy_setopt().
When completed curl_easy_cleanup() should be called to free up used
resources.
HTTP(S)
@ -88,12 +102,16 @@ Library
(lib/cookie.c).
HTTPS uses in almost every means the same procedure as HTTP, with only two
exceptions: the connect procedure is different and the function used
exceptions: the connect procedure is different and the function used to read
or write from the socket is different, although the latter fact is hidden in
the source by the use of curl_read() for reading and curl_write() for writing
data to the remote server.
FTP
The if2ip() function can be used for getting the IP number of a specified
network interface, and it resides in lib/if2ip.c
network interface, and it resides in lib/if2ip.c. It is only used for the FTP
PORT command.
TELNET
@ -113,11 +131,12 @@ Library
is found in lib/escape.c.
While transfering data in Transfer() a few functions might get
used. get_date() in lib/getdate.c is for HTTP date comparisons.
used. curl_getdate() in lib/getdate.c is for HTTP date comparisons (and
more).
lib/getenv.c is for reading environment variables in a neat platform
independent way. That's used in the client, but also in lib/url.c when
checking the PROXY variables.
lib/getenv.c offers curl_getenv() which is for reading environment variables
in a neat platform independent way. That's used in the client, but also in
lib/url.c when checking the PROXY variables.
lib/netrc.c keeps the .netrc parser
@ -135,6 +154,7 @@ Client
functions used for the multiple-URL support.
The client mostly mess around to setup its config struct properly, then it
calls the curl_urlget() function in the library and when it gets back control
it checks status and exits.
calls the curl_easy_*() functions of the library and when it gets back
control after the curl_easy_perform() it cleans up the library, checks status
and exits.