HTTP Proxy Client v0.8.x

Description

HTTP Proxy Client is the small set of libraries and scripts, which provides transparent access to Internet via HTTP proxy for programs, which uses TCP/IP for communication.

The list of programs includes: telnet, ftp, licq, cvs, smth else? Project implements dynamic library, that can be preloaded before program run. The library substitutes some system calls (connect(), gethostbyaddr(), gethostbyname()), with calls, which makes TCP/IP connection through HTTP proxy. This allows client programs behind HTTP proxy work with Internet without limitations.

At the moment tested on i386 Linux, i386/sparc Solaris.

The library provides the following functions as replacement for system functions:

socket()	monitoring
connect()	connect via proxy in case of external host
gethostbyname()	DNS resolving
gethostbyname_r()*	DNS resolving
gethostbyaddr()	DNS reverse resolving
gethostbyaddr_r()*	DNS reverse resolving
getaddrinfo()	network address and service translation

*: Only for systems, which supports gethostbyname_r() and gethostbyaddr_r().

Usage

1. httppc and httppcd libraries.

Library httppcd can be used to add proxy tunneling capability to any program. All you need - is to make final link with -lhttppcd or set LD_PRELOAD to `libhttppcd.so' full path.

2. `proxed' script.

The package provides also aliases for common Internet tools: telnetx, ftpx, cvsx, licqx which invokes `proxed *' command.

NOTE: instead of setting LD_PRELOAD to full path of `libhttppcd.so', you can specify the path in LD_LIBRARY_PATH variable.

Options

• $prefix/etc/httppcrc
• $HOME/.httppcrc

.httppcrc	Environment	Description
proxy host:port	HTTP_PROXY	HTTP proxy host in format <host>[:<port>]. Default port is 8080.
auth user:pass	HTTP_PROXY_AUTH	HTTP proxy user and password in format <user>:<password>.
log verbose|quiet	HTTP_PROXY_LOG	Driver mode: verbose quiet.
libs lib1:lib2:...	HTTP_PROXY_LIBS	Libraries, separated by ':', where original functions are located.
xdns dnsip	HTTP_PROXY_XDNS	External DNS server address, must be in dot notation; by default is set to isi.edu (128.9.176.32).
ldns		Use local DNS resolving with native gethostbyname() prior external resolving with ADNS; disabled by default.
local network/mask ...	HTTP_PROXY_LOCAL	The list of local networks in format <network>/<mask>, separated by space.
extern network/mask ...	HTTP_PROXY_EXTERN	The list of external networks in format <network>/<mask>, separated by space.
useragent Mozilla...	HTTP_PROXY_USERAGENT	Add to connection request header string: User-Agent: <useragent>
nocache		Add to connection request header strings: Pragma: no-cache Cache-Control: no-cache
keepalive		Add to connection request header string: Connection: Keep-Alive
timeout 5	HTTP_PROXY_TIMEOUT	Connection timeout in seconds. -1 wait forever.

Networks checking algorithm:

1. First, driver checks the list of external hosts, if it's not empty and target address in dot format matches some entry, driver runs connect via HTTP proxy.
2. If list of external hosts is not specified, driver check in the same manner the list of local hosts, and if target address matches some entry, driver runs system connect routine.
3. If neither list of external hosts, nor list of internal hosts is not specified, driver runs system connect routine and in case of error runs connect via HTTP proxy.

Programs, reported to work with library

• ftp, telnet, cvs, mc
• host (host -T 128.9.176.20)
• dig (dig +tcp @128.9.176.20 )
• ssh (not in suid mode yet)
• smth else?

• xchat
• licq

Limitations and bugs

• httppc can work only with proxies, which supports "CONNECT" method (rfc2616); so the following:

          httppc: <- CONNECT 195.110.124.188:80 HTTP/1.1
          httppc: -> HTTP/1.0 405 Method Not Allowed

  mean, that your proxy doesn't supports "CONNECT" and httppc will not work at all;
  support for "GET"/"PUT" methods requires external server part of httppc, if you have interest and some proxy-free resources, contact the author;
• connect() under Linux for external site returns -1 and sets errno to ENETUNREACH. connect() under Solaris falls into endless wait loop. Don't know how to decide, local host or not. Could be some way to decrease timeout. You can solve the problem by specifying HTTP_PROXY_LOCAL or HTTP_PROXY_EXTERN shell variables.
• proxed ssh core dumps under solaris 5.8. Dumps while loading libhttppcd.so library. Don't know why...
• gethostbyaddr_r() implementation in libhttppcd.so works buggy under FreeBSD 5.0. Does "Bus error". Don't know about other versions of BSD.

Troubleshooting

The message appears, when there is incorrect path to installed `libhttppcd.so' in `proxed' script. Edit `proxed' file and set correct path or specify LD_LIBRARY_PATH.

Library tries direct connect to the host before any proxy traversal. In some systems the connect() method awaits timeout too long. To solve the problem you may specify HTTP_PROXY_LOCAL or HTTP_PROXY_EXTERN. Check the description of these variables above.

See also