rpc api: eth_getNatSpec

* xeth, rpc: implement eth_getNatSpec for tx confirmations
* rename silly docserver -> httpclient
* eth/backend: httpclient now accessible via eth.Ethereum init-d via config.DocRoot
* cmd: introduce separate CLI flag for DocRoot (defaults to homedir)
* common/path: delete unused assetpath func, separate HomeDir func

common/httpclient/httpclient.go

@@ -0,0 +1,124 @@
+// Copyright 2015 The go-ethereum Authors
+// This file is part of the go-ethereum library.
+//
+// The go-ethereum library is free software: you can redistribute it and/or modify
+// it under the terms of the GNU Lesser General Public License as published by
+// the Free Software Foundation, either version 3 of the License, or
+// (at your option) any later version.
+//
+// The go-ethereum library 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 Lesser General Public License for more details.
+//
+// You should have received a copy of the GNU Lesser General Public License
+// along with the go-ethereum library. If not, see <http://www.gnu.org/licenses/>.
+
+package httpclient
+
+import (
+	"fmt"
+	"io/ioutil"
+	"net/http"
+	"path/filepath"
+
+	"github.com/ethereum/go-ethereum/common"
+	"github.com/ethereum/go-ethereum/crypto"
+)
+
+type HTTPClient struct {
+	*http.Transport
+	DocRoot string
+	schemes []string
+}
+
+func New(docRoot string) (self *HTTPClient) {
+	self = &HTTPClient{
+		Transport: &http.Transport{},
+		DocRoot:   docRoot,
+		schemes:   []string{"file"},
+	}
+	self.RegisterProtocol("file", http.NewFileTransport(http.Dir(self.DocRoot)))
+	return
+}
+
+// Clients should be reused instead of created as needed. Clients are safe for concurrent use by multiple goroutines.
+
+// A Client is higher-level than a RoundTripper (such as Transport) and additionally handles HTTP details such as cookies and redirects.
+
+func (self *HTTPClient) Client() *http.Client {
+	return &http.Client{
+		Transport: self,
+	}
+}
+
+func (self *HTTPClient) RegisterScheme(scheme string, rt http.RoundTripper) {
+	self.schemes = append(self.schemes, scheme)
+	self.RegisterProtocol(scheme, rt)
+}
+
+func (self *HTTPClient) HasScheme(scheme string) bool {
+	for _, s := range self.schemes {
+		if s == scheme {
+			return true
+		}
+	}
+	return false
+}
+
+func (self *HTTPClient) GetAuthContent(uri string, hash common.Hash) ([]byte, error) {
+	// retrieve content
+	content, err := self.Get(uri, "")
+	if err != nil {
+		return nil, err
+	}
+
+	// check hash to authenticate content
+	chash := crypto.Sha3Hash(content)
+	if chash != hash {
+		return nil, fmt.Errorf("content hash mismatch %x != %x (exp)", hash[:], chash[:])
+	}
+
+	return content, nil
+
+}
+
+// Get(uri, path) downloads the document at uri, if path is non-empty it
+// is interpreted as a filepath to which the contents are saved
+func (self *HTTPClient) Get(uri, path string) ([]byte, error) {
+	// retrieve content
+	resp, err := self.Client().Get(uri)
+	if err != nil {
+		return nil, err
+	}
+	defer func() {
+		if resp != nil {
+			resp.Body.Close()
+		}
+	}()
+
+	var content []byte
+	content, err = ioutil.ReadAll(resp.Body)
+	if err != nil {
+		return nil, err
+	}
+
+	if resp.StatusCode/100 != 2 {
+		return content, fmt.Errorf("HTTP error: %s", resp.Status)
+	}
+
+	if path != "" {
+		var abspath string
+		abspath, err = filepath.Abs(path)
+		if err != nil {
+			return nil, err
+		}
+		err = ioutil.WriteFile(abspath, content, 0600)
+		if err != nil {
+			return nil, err
+		}
+	}
+
+	return content, nil
+
+}