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| -rw-r--r-- | ChangeLog.md | 5 | ||||
| -rw-r--r-- | LICENSE | 661 | ||||
| -rw-r--r-- | Main.hs | 203 | ||||
| -rw-r--r-- | README.md | 81 | ||||
| -rw-r--r-- | example/README.md | 18 | ||||
| -rw-r--r-- | example/bugs.sql | 37 | ||||
| -rw-r--r-- | example/common.xsl | 40 | ||||
| -rw-r--r-- | example/list.xsl | 92 | ||||
| -rw-r--r-- | example/view.xsl | 26 | ||||
| -rw-r--r-- | pgxhtml.cabal | 37 |
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diff --git a/ChangeLog.md b/ChangeLog.md new file mode 100644 index 0000000..c892bfe --- /dev/null +++ b/ChangeLog.md @@ -0,0 +1,5 @@ +# Revision history for pgxhtml + +## 0.1.0.0 -- 2018-12-30 + +Initial version: XSLT templating, SQL queries, parameter substitution. @@ -0,0 +1,661 @@ + GNU AFFERO GENERAL PUBLIC LICENSE + Version 3, 19 November 2007 + + Copyright (C) 2007 Free Software Foundation, Inc. <http://fsf.org/> + Everyone is permitted to copy and distribute verbatim copies + of this license document, but changing it is not allowed. + + Preamble + + The GNU Affero General Public License is a free, copyleft license for +software and other kinds of works, specifically designed to ensure +cooperation with the community in the case of network server software. + + The licenses for most software and other practical works are designed +to take away your freedom to share and change the works. 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If not, see <http://www.gnu.org/licenses/>. + +Also add information on how to contact you by electronic and paper mail. + + If your software can interact with users remotely through a computer +network, you should also make sure that it provides a way for users to +get its source. For example, if your program is a web application, its +interface could display a "Source" link that leads users to an archive +of the code. There are many ways you could offer source, and different +solutions will be better for different programs; see section 13 for the +specific requirements. + + You should also get your employer (if you work as a programmer) or school, +if any, to sign a "copyright disclaimer" for the program, if necessary. +For more information on this, and how to apply and follow the GNU AGPL, see +<http://www.gnu.org/licenses/>. @@ -0,0 +1,203 @@ +{- +pgxhtml, an XSLT-based PostgreSQL web interface. +Copyright (C) 2018-2019 defanor <defanor@uberspace.net> + +This program is free software: you can redistribute it and/or modify +it under the terms of the GNU Affero General Public License as published by +the Free Software Foundation, either version 3 of the License, or +(at your option) any later version. + +This program is distributed in the hope that it will be useful, +but WITHOUT ANY WARRANTY; without even the implied warranty of +MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the +GNU Affero General Public License for more details. + +You should have received a copy of the GNU Affero General Public License +along with this program. If not, see <http://www.gnu.org/licenses/>. +-} + +{- | +Description : XSLT-based PostgreSQL web interface +Maintainer : defanor <defanor@uberspace.net> +Stability : unstable +Portability : non-portable (uses GHC extensions) + +This is a tool to make custom web (HTTP with XHTML) interfaces to +PostgreSQL databases, using XSLT for templating and SQL for querying, +HTTP basic authentication and PostgreSQL roles for authentication. +-} + +{-# LANGUAGE OverloadedStrings #-} + +import qualified Data.ByteString.Char8 as BS +import qualified Data.HashMap.Lazy as HM +import qualified Data.Text as T +import qualified Data.Map.Lazy as M +import qualified Database.PostgreSQL.Simple.Types as PT +import Database.PostgreSQL.Simple +import Network.Wai +import Network.HTTP.Types as HT +import Database.PostgreSQL.Simple.FromField + (FromField, fromField, returnError, typename) +import Web.FormUrlEncoded (Form(..), urlDecodeForm) +import Database.PostgreSQL.Simple.ToField (Action (..)) +import Database.PostgreSQL.Simple.Internal (withConnection) +import Database.PostgreSQL.LibPQ (getCancel, cancel) +import Text.XML.HXT.Core + (IOSArrow, replaceChildren, arrL, ($<), constA, runX, + writeDocumentToString, withOutputXHTML, withIndent, stringTrim, + XNode(..), mkName) +import Text.XML.HXT.DOM.XmlNode (mkRoot) +import Text.XML.HXT.Parser.XmlParsec (xreadDoc) +import Text.XML.HXT.XSLT.Application (XPathParams, applyStylesheetWParams) +import Text.XML.HXT.XSLT.XsltArrows (xsltCompileStylesheetFromURI) +import Text.XML.HXT.XSLT.Common (XmlTree, ExName(..), Expr(..), (>>>)) +import Data.Tree.Class (mkTree) +import Data.String (fromString) +import Data.Maybe (mapMaybe) +import Data.Text.Encoding (encodeUtf8) +import Network.Wai.Middleware.HttpAuth (extractBasicAuth) +import Network.HTTP.Types.Header (hWWWAuthenticate) +import Network.Wai.Middleware.Timeout (timeout) +import Network.Wai.Cli (defWaiMain) +import Control.Monad (join) +import Control.Arrow ((***)) +import Control.Exception (bracket, finally, handle) +import System.FilePath (replaceExtension, takeFileName, (</>)) +import System.Envy (decodeEnv, FromEnv(..), envMaybe, (.!=)) + +newtype PgXmlTree = PgXmlTree { unPgXmlTree :: XmlTree } + +instance FromField PgXmlTree where + fromField f Nothing = returnError UnexpectedNull f "" + fromField f (Just mdata) = do + tName <- typename f + if tName /= "xml" + then returnError ConversionFailed f $ + "Expected xml type, got " ++ BS.unpack tName + else pure $ PgXmlTree $ + mkRoot [] $ xreadDoc (stringTrim $ BS.unpack mdata) + +data EnvConfig = EnvConfig + { connectionTimeout :: Int + -- ^ HTTP connection timeout, in seconds + , xsltDirectory :: FilePath + -- ^ A directory to read XSLTs from + } + +instance FromEnv EnvConfig where + fromEnv = + EnvConfig <$> envMaybe "TIMEOUT" .!= 10 <*> envMaybe "XSLT_DIR" .!= "" + +formToFields :: Form -> [(T.Text, T.Text)] +formToFields = mapMaybe toField . HM.toList . unForm + where toField (f, [v]) = Just (f, v) + toField _ = Nothing + +xsltApplyStylesheetWParamsFromURI :: XPathParams -> String + -> IOSArrow XmlTree XmlTree +xsltApplyStylesheetWParamsFromURI par uri = replaceChildren + $ arrL . applyStylesheetWParams par + $< (constA uri >>> xsltCompileStylesheetFromURI) + +cancelAndClose :: Connection -> IO (Maybe BS.ByteString) +cancelAndClose c = cancelConn `finally` close c + where cancelConn = withConnection c $ \conn -> do + cl <- getCancel conn + case cl of + Nothing -> pure $ Just "Failed to get a Cancel structure" + Just cl' -> either Just (const Nothing) <$> cancel cl' + +prepareQuery :: Form + -- ^ Form data + -> HT.Query + -- ^ URL query + -> BS.ByteString + -- ^ SQL query template + -> (PT.Query, [Action]) + -- ^ SQL query template and parameters +prepareQuery f gq q = let sub = map substWord $ BS.words q + in (PT.Query $ BS.unwords (map fst sub), concat $ mapMaybe snd sub) + where + fields = formToFields f + bsFields = map (encodeUtf8 *** encodeUtf8) fields + keys = map fst bsFields + vals = map snd bsFields + placeholders = BS.intercalate "," (map (const "?") fields) + substWord ":fields" = (placeholders, Just (map EscapeIdentifier keys)) + substWord ":values" = (placeholders, Just (map Escape vals)) + substWord other = case BS.splitAt 2 other of + -- POST (form) parameter + ("f:", fieldName) -> ("?", pure . Escape <$> lookup fieldName bsFields) + -- GET (query/link or form) parameter + ("q:", fieldName) -> ("?", pure . Escape <$> join (lookup fieldName gq)) + _ -> (other, Nothing) + +makeParams :: HT.Query -> XPathParams +makeParams = M.fromList . mapMaybe makeParam + where makeParam (k, Just v) = Just ( ExName (BS.unpack k) "" + , LiteralExpr (BS.unpack v)) + makeParam _ = Nothing + +errorXML :: PT.Query -> [Action] -> SqlError -> XmlTree +errorXML q p e = mkRoot [] + [mkTree (XTag (mkName "sql_error") + [ mkAttr "template" (show q) + , mkAttr "parameters" (show p) + , mkAttr "state" (BS.unpack $ sqlState e) + , mkAttr "status" (show $ sqlExecStatus e) + , mkAttr "message" (BS.unpack $ sqlErrorMsg e) + , mkAttr "detail" (BS.unpack $ sqlErrorDetail e) + , mkAttr "hint" (BS.unpack $ sqlErrorHint e) + ]) + []] + where mkAttr k v = mkTree (XAttr $ mkName k) [mkTree (XText v) []] + +serve :: EnvConfig -> IO Connection -> Application +serve conf ioc req respond = do + form' <- urlDecodeForm <$> strictRequestBody req + case form' of + Left _err -> respond $ responseLBS notAcceptable406 [] + "Failed to read form data" + Right form -> case lookup "q" (queryString req) of + Just (Just q) -> do + let qs = queryString req + (q', params) = prepareQuery form qs q + xsltPath = xsltDirectory conf + </> replaceExtension + (takeFileName (BS.unpack $ rawPathInfo req)) "xsl" + resp st xml = do + rc <- runX $ constA xml + >>> xsltApplyStylesheetWParamsFromURI (makeParams qs) xsltPath + >>> writeDocumentToString [withOutputXHTML, withIndent True] + respond $ responseLBS st + [(hContentType, "application/xhtml+xml")] + (fromString $ concat $ + "<?xml version=\"1.0\"?>\n" : "<!DOCTYPE html>\n" : rc) + handle (resp badRequest400 . errorXML q' params) + $ bracket ioc cancelAndClose $ \c -> do + r <- query c q' params + case r of + [Only xmlDoc] -> resp ok200 (unPgXmlTree xmlDoc) + _ -> respond $ responseLBS status500 [] + "Expected a single result, got 0 or more" + _ -> respond $ responseLBS imATeapot418 [] "No query is provided" + +main :: IO () +main = do + conf <- decodeEnv + case conf of + Left err -> putStrLn err + Right conf' -> defWaiMain + $ timeout (connectionTimeout conf') $ \req respond -> + case ("authorised" `elem` pathInfo req, extractBasicAuth + =<< lookup hAuthorization (requestHeaders req)) of + (True, Just (l, p)) -> + serve conf' + (connect $ ConnectInfo "" 0 (BS.unpack l) (BS.unpack p) "") + req respond + (True, Nothing) -> + respond $ responseLBS unauthorized401 + [( hWWWAuthenticate + , "Basic realm=\"Protected area\", charset=\"UTF-8\"")] "" + _ -> serve conf' (connectPostgreSQL "") req respond diff --git a/README.md b/README.md new file mode 100644 index 0000000..7770552 --- /dev/null +++ b/README.md @@ -0,0 +1,81 @@ +# pg×html + +This is a tool to make custom web interfaces to PostgreSQL databases, +using simple and standard technologies: + +- SQL for querying +- XSLT for templating (translation of XML query results into XHTML) +- HTML forms for user input +- Optional HTTP basic authentication for PostgreSQL authentication + +URL query parameters are available for use from XSLTs. SQL query +templates also can use those, as well as HTML form data submitted with +the POST method. + +Request timeouts are enforced and do cancel DB queries, but otherwise +it relies on PostgreSQL for access permissions and security policies, +as well as for any business logic that may be needed. + +It is based on WAI, and can be used with CGI, socket activation, Unix +domain sockets, or as a standalone HTTP server. + + +## Usage + +### Invocation + +See [wai-cli](https://hackage.haskell.org/package/wai-cli) for CLI +arguments. The used environment variables are: + +- `TIMEOUT`: request timeout in seconds, 10 by default. +- `XSLT_DIR`: a directory to read XSLT files from, current working + directory by default. + +Regular [libpq environment +variables](https://www.postgresql.org/docs/current/libpq-envars.html) +are used for database connections. + +### Templating + +URL query parameters are made visible to XSLTs as `xsl:param` +parameters. The documents they get applied to are either the results +of SQL queries (which are expected to return a single XML document, +using `query_to_xml` or similar functions), or error documents (which +contain error details) in case of an SQL error. + +The XSLTs are taken from `XSLT_DIR`, using file name from the URL +query, with its extension changed to `xsl`. + +### Querying + +SQL queries provided in the `q` URL query parameter get executed, with +some substitutions to handle HTML forms: + +- `f:<name>` for POST parameters +- `q:<name>` for GET parameters +- `:fields` for POST parameter names +- `:values` for POST parameter values (in the same order as the names) + +`:fields` and `:values` are unnecessary, but are provided for +convenience of insert/upsert operations. + +SQL queries get tokenized by splitting into words and reassembled +afterwards, hence some whitespace separation is needed. + +### Authentication + +Presence of `authorised` in the URL path requires HTTP basic +authentication, and the provided credentials are used directly for +PostgreSQL authentication. + +### Web server + +This is intended to be used with an HTTP server, which would take care +of encryption, compression, static files, redirects, and so on, while +pgxhtml only focuses on providing a web interface to a database. + + +## See also + +[PostgREST](http://postgrest.org/), "a standalone web server that +turns your PostgreSQL database directly into a RESTful API". diff --git a/example/README.md b/example/README.md new file mode 100644 index 0000000..b6cfbfa --- /dev/null +++ b/example/README.md @@ -0,0 +1,18 @@ +# pg×html usage example + +Here is an example that implements a very basic bug reporting system: +users can just report, view, and list (search) the bugs. + +First of all, a database should be designed: `bugs.sql` contains +definitions and comments. + +A common template, `common.xsl`, includes error handling and some +shared HTML. One can choose to show error details to users, or to hide +them. + +`view.xsl` is a basic template for bug viewing. + +`list.xsl` includes report and search forms, and lists the bugs. + +To quickly try it, run `pgxhtml --devlogging` in this directory, +with database connection environment variables set if needed. diff --git a/example/bugs.sql b/example/bugs.sql new file mode 100644 index 0000000..033a1f7 --- /dev/null +++ b/example/bugs.sql @@ -0,0 +1,37 @@ +-- pgcrypto is needed for UUIDs. +create extension pgcrypto; + +-- A table with defaults and constraints. +create table bugs ( + id uuid not null primary key default gen_random_uuid(), + reported timestamp with time zone not null default now(), + reporter varchar not null default current_user, + project varchar(256) not null check (project <> ''), + description varchar(10240) not null check (description <> '') +); + +-- No indexes, since they are irrelevant to this example (but normally +-- they should be there). + +-- Additional restrictions. +create policy bugs_select_policy on bugs for select using (true); +create policy bugs_insert_policy on bugs for insert + with check (reported = now() and reporter = current_user); +-- Update and delete policies can be added later. +alter table bugs enable row level security; + +-- A search function for convenience. +create or replace function bug_search (proj varchar, descr varchar, lim int, offs int) +returns xml +as $$ + select query_to_xml( + 'select id, date_trunc(''second'', reported) as reported, reporter, ' + || 'project, substring(description from ''[^\n\r]+'') as summary from bugs ' + || 'where (project like ' || quote_literal('%' || proj || '%') + || ') and (description like ' || quote_literal('%' || descr || '%') + || ') order by reported desc limit ' || lim || ' offset ' || offs, + false, false, 'bugs') +$$ language sql; + +-- Now users can be added with select and/or insert privileges, +-- including a guest user for unauthenticated requests. diff --git a/example/common.xsl b/example/common.xsl new file mode 100644 index 0000000..1db0229 --- /dev/null +++ b/example/common.xsl @@ -0,0 +1,40 @@ +<?xml version="1.0" encoding="UTF-8"?> + +<xsl:stylesheet xmlns:xsl="http://www.w3.org/1999/XSL/Transform" + xmlns:xhtml="http://www.w3.org/1999/xhtml" + xmlns="http://www.w3.org/1999/xhtml" + version="1.0"> + <xsl:output method="xml" indent="yes"/> + + <xsl:template match="/"> + <html xmlns="http://www.w3.org/1999/xhtml"> + <head> + <title>Bugs</title> + </head> + <body> + <xsl:apply-templates select="*" /> + </body> + </html> + </xsl:template> + + <xsl:template match="sql_error"> + <h1>SQL error</h1> + <dl> + <dt>State</dt> + <dd><xsl:copy-of select="@state/text()" /></dd> + <dt>Status</dt> + <dd><xsl:copy-of select="@status/text()" /></dd> + <dt>Message</dt> + <dd><xsl:copy-of select="@message/text()" /></dd> + <dt>Detail</dt> + <dd><xsl:copy-of select="@detail/text()" /></dd> + <dt>Hint</dt> + <dd><xsl:copy-of select="@hint/text()" /></dd> + <dt>Query template</dt> + <dd><xsl:copy-of select="@template/text()" /></dd> + <dt>Query parameters</dt> + <dd><xsl:copy-of select="@parameters/text()" /></dd> + </dl> + </xsl:template> + +</xsl:stylesheet> diff --git a/example/list.xsl b/example/list.xsl new file mode 100644 index 0000000..86c3150 --- /dev/null +++ b/example/list.xsl @@ -0,0 +1,92 @@ +<?xml version="1.0" encoding="UTF-8"?> + +<xsl:stylesheet xmlns:xsl="http://www.w3.org/1999/XSL/Transform" + xmlns:xhtml="http://www.w3.org/1999/xhtml" + xmlns="http://www.w3.org/1999/xhtml" + version="1.0"> + <xsl:output method="xml" indent="yes"/> + <xsl:include href="common.xsl"/> + <xsl:param name="project" /> + <xsl:param name="description" /> + <xsl:param name="limit" select="10" /> + <xsl:param name="offset" select="0" /> + + <xsl:template match="table"> + <!-- Report form --> + <h2>Report</h2> + <form method="post" action="view.xhtml?q=insert%20into%20bugs%20(%20:fields%20)%20values%20(%20:values%20)%20returning%20xmlelement(name%20table,xmlelement(name%20row,xmlelement(name%20id,id),xmlelement(name%20reported,reported),xmlelement(name%20reporter,reporter),xmlelement(name%20project,project),xmlelement(name%20description,description)))"> + <dl> + <dt><label for="report_project">Project</label></dt> + <dd> + <input type="text" name="project" id="report_project" + required="required" maxlength="128" + placeholder="Project name or URL" /> + </dd> + <dt><label for="report_description">Description</label></dt> + <dd> + <textarea name="description" required="required" + id="report_description" maxlength="10240" + placeholder="Issue description" /> + </dd> + </dl> + <input type="submit" value="Report" /> + </form> + + <!-- Search form --> + <h2>Search</h2> + <form method="get" action="list.xhtml"> + <dl> + <dt><label for="search_project">Project</label></dt> + <dd> + <input id="search_project" type="search" name="project" + value="{$project}" /> + </dd> + <dt><label for="search_description">Description</label></dt> + <dd> + <input id="search_description" type="search" name="description" + value="{$description}" /> + </dd> + <dt><label for="search_limit">Limit</label></dt> + <dd> + <input id="search_limit" type="number" name="limit" min="1" + value="{$limit}" /> + </dd> + <dt><label for="search_offset">Offset</label></dt> + <dd> + <input id="search_offset" type="number" name="offset" min="0" + value="{$offset}" /> + </dd> + <input type="hidden" name="q" + value="select bug_search( q:project , q:description , q:limit , q:offset )" /> + </dl> + <input type="submit" value="Search" /> + </form> + + <!-- Search results --> + <table> + <tr> + <th>Reported</th> + <th>Reporter</th> + <th>Project</th> + <th>Summary</th> + </tr> + <xsl:for-each select="row"> + <tr> + <td><xsl:copy-of select="reported/text()" /></td> + <td><xsl:copy-of select="reporter/text()" /></td> + <td> + <a href="list.xhtml?q=select%20bug_search('{project/text()}','',{$limit},{$offset})"> + <xsl:copy-of select="project/text()" /> + </a> + </td> + <td> + <a href="view.xhtml?q=select%20query_to_xml('select%20*%20from%20bugs%20where%20id=''{id}''',false,false,'foo')"> + <xsl:copy-of select="summary/text()" /> + </a> + </td> + </tr> + </xsl:for-each> + </table> + </xsl:template> + +</xsl:stylesheet> diff --git a/example/view.xsl b/example/view.xsl new file mode 100644 index 0000000..af0e090 --- /dev/null +++ b/example/view.xsl @@ -0,0 +1,26 @@ +<?xml version="1.0" encoding="UTF-8"?> + +<xsl:stylesheet xmlns:xsl="http://www.w3.org/1999/XSL/Transform" + xmlns:xhtml="http://www.w3.org/1999/xhtml" + xmlns="http://www.w3.org/1999/xhtml" + version="1.0"> + <xsl:output method="xml" indent="yes"/> + <xsl:include href="common.xsl"/> + + <xsl:template match="table/row"> + <a href="list.xhtml?q=select%20bug_search(%27%27,%20%27%27,%2010,%200)">back to listing</a> + <dl> + <dt>ID</dt> + <dd><xsl:copy-of select="id/text()" /></dd> + <dt>Reported</dt> + <dd><xsl:copy-of select="reported/text()" /></dd> + <dt>Reporter</dt> + <dd><xsl:copy-of select="reporter/text()" /></dd> + <dt>Project</dt> + <dd><xsl:copy-of select="project/text()" /></dd> + <dt>Description</dt> + <dd><pre><xsl:copy-of select="description/text()" /></pre></dd> + </dl> + </xsl:template> + +</xsl:stylesheet> diff --git a/pgxhtml.cabal b/pgxhtml.cabal new file mode 100644 index 0000000..6430b31 --- /dev/null +++ b/pgxhtml.cabal @@ -0,0 +1,37 @@ +name: pgxhtml +version: 0.1.0.0 +synopsis: XSLT-based PostgreSQL web interface +description: This is a tool to make custom web interfaces to PostgreSQL + databases, using simple and standard technologies. +license: AGPL-3 +license-file: LICENSE +author: defanor +maintainer: defanor@uberspace.net +category: Database +build-type: Simple +extra-source-files: ChangeLog.md + , README.md +cabal-version: >=1.10 + +executable pgxhtml + main-is: Main.hs + other-extensions: OverloadedStrings + build-depends: base >=4.9 && <5 + , bytestring >=0.10 && <0.11 + , unordered-containers >=0.2 && <0.3 + , text >=1.2 && <1.3 + , containers >=0.5 && <0.6 + , postgresql-simple >=0.5 && <0.6 + , postgresql-libpq >=0.9 && <0.10 + , http-types >=0.12 && <0.13 + , hxt >=9.3 && <9.4 + , hxt-xslt >=9.1 && <9.2 + , http-api-data >=0.3 && <0.4 + , wai >=3.2 && <3.3 + , wai-extra >=3.0 && <3.1 + , wai-cli >=0.1 && <0.2 + , warp >=3.2 && <3.3 + , filepath >=1.4 && <1.5 + , envy >=1.5 && <1.6 + default-language: Haskell2010 + ghc-options: -Wall |