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Diffstat (limited to 'INTERNALS')
| -rw-r--r-- | INTERNALS | 140 |
1 files changed, 0 insertions, 140 deletions
diff --git a/INTERNALS b/INTERNALS deleted file mode 100644 index 0badf5b29..000000000 --- a/INTERNALS +++ /dev/null @@ -1,140 +0,0 @@ - _ _ ____ _ - ___| | | | _ \| | - / __| | | | |_) | | - | (__| |_| | _ <| |___ - \___|\___/|_| \_\_____| - -INTERNALS - - The project is kind of split in two. The library and the client. The client - part uses the library, but the library is meant to be designed to allow other - applications to use it. - - Thus, the largest amount of code and complexity is in the library part. - -Windows vs Unix -=============== - - There are a few differences in how to program curl the unix way compared to - 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 - 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. - - (3) is simply avoided by not trying any funny tricks on file descriptors. - - (4) is left alone, giving windows users problems when they pipe binary data - through stdout... - - Inside the source code, I do make an effort to avoid '#ifdef WIN32'. All - conditionals that deal with features *should* instead be in the format - '#ifdef HAVE_THAT_WEIRD_FUNCTION'. Since Windows can't run configure scripts, - I maintain two config-win32.h files (one in / and one in src/) that are - supposed to look exactly as a config.h file would have looked like on a - Windows machine! - -Library -======= - - There is a few 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). - - curl_urlget() takes a variable amount of arguments, and they must all 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. - - 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. - - When connected, the proper function is called. The functions are named after - the protocols they handle. ftp(), http(), dict(), etc. They all reside in - their respective files (ftp.c, http.c and dict.c). - - The protocol-specific functions deal with protocol-specific negotiations and - setup. They have access to the sendf() (from lib/sendf.c) function to send - printf-style formatted data to the remote host and when they're ready to make - the actual file transfer they call the Transfer() function (in - lib/download.c) to do the transfer. All printf()-style functions use the - 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. - - 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(). - - HTTP(S) - - HTTP offers a lot and is the protocol in curl that uses the most lines of - code. There is a special file (lib/formdata.c) that offers all the multipart - post functions. - - base64-functions for user+password stuff is in (lib/base64.c) and all - functions for parsing and sending cookies are found in - (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 - - FTP - - The if2ip() function can be used for getting the IP number of a specified - network interface, and it resides in lib/if2ip.c - - TELNET - - Telnet is implemented in lib/telnet.c. - - FILE - - The file:// protocol is dealt with in lib/file.c. - - LDAP - - Everything LDAP is in lib/ldap.c. - - GENERAL - - URL encoding and decoding, called escaping and unescaping in the source code, - 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. - - 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/netrc.c keeps the .netrc parser - - lib/timeval.c features replacement functions for systems that don't have - - A function named curl_version() that returns the full curl version string is - found in lib/version.c. - -Client -====== - - main() resides in src/main.c together with most of the client - code. src/hugehelp.c is automatically generated by the mkhelp.pl perl script - to display the complete "manual" and the src/urlglob.c file holds the - 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. - |