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urlcontext.go
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package gocrawl
import (
"bytes"
"net/url"
"strings"
"github.com/PuerkitoBio/purell"
)
const (
robotsTxtPath = "/robots.txt"
)
// U is a convenience type definition, it is a map[*url.URL]interface{}
// that can be used to enqueue URLs with state information.
type U map[*url.URL]interface{}
// S is a convenience type definition, it is a map[string]interface{}
// that can be used to enqueue URLs (the string) with state information.
type S map[string]interface{}
// URLContext contains all information related to an URL to process.
type URLContext struct {
HeadBeforeGet bool
State interface{}
// Internal fields, available through getters
url *url.URL
normalizedURL *url.URL
sourceURL *url.URL
normalizedSourceURL *url.URL
}
// URL returns the URL.
func (uc *URLContext) URL() *url.URL {
return uc.url
}
// NormalizedURL returns the normalized URL (using Options.URLNormalizationFlags)
// of the URL.
func (uc *URLContext) NormalizedURL() *url.URL {
return uc.normalizedURL
}
// SourceURL returns the source URL, if any (the URL that enqueued this
// URL).
func (uc *URLContext) SourceURL() *url.URL {
return uc.sourceURL
}
// NormalizedSourceURL returns the normalized form of the source URL,
// if any (using Options.URLNormalizationFlags).
func (uc *URLContext) NormalizedSourceURL() *url.URL {
return uc.normalizedSourceURL
}
// IsRobotsURL indicates if the URL is a robots.txt URL.
func (uc *URLContext) IsRobotsURL() bool {
return isRobotsURL(uc.normalizedURL)
}
// cloneForRedirect returns a new URLContext with the given
// destination URL with the same sourceURL and normalizedSourceURL.
func (uc *URLContext) cloneForRedirect(dst *url.URL, normFlags purell.NormalizationFlags) *URLContext {
var src, normalizedSrc *url.URL
if uc.sourceURL != nil {
src = &url.URL{}
*src = *uc.sourceURL
}
if src == nil && uc.url != nil {
// if the current context doesn't have a source URL, use its URL as
// source (e.g. for a seed URL that triggers a redirect)
src = &url.URL{}
*src = *uc.url
}
if uc.normalizedSourceURL != nil {
normalizedSrc = &url.URL{}
*normalizedSrc = *uc.normalizedSourceURL
}
if normalizedSrc == nil {
normalizedSrc = &url.URL{}
*normalizedSrc = *uc.normalizedURL
}
rawDst := &url.URL{}
*rawDst = *dst
purell.NormalizeURL(dst, normFlags)
return &URLContext{
HeadBeforeGet: uc.HeadBeforeGet,
State: uc.State,
url: rawDst,
normalizedURL: dst,
sourceURL: src,
normalizedSourceURL: normalizedSrc,
}
}
// Implement in a private func, because called from HttpClient also (without
// an URLContext).
func isRobotsURL(u *url.URL) bool {
if u == nil {
return false
}
return strings.ToLower(u.Path) == robotsTxtPath
}
func toStringArrayContextURL(list []*URLContext) string {
var buf bytes.Buffer
for _, item := range list {
if buf.Len() > 0 {
buf.WriteString(", ")
}
if nurl := item.NormalizedURL(); nurl != nil {
buf.WriteString(nurl.String())
}
}
return buf.String()
}
func (uc *URLContext) getRobotsURLCtx() (*URLContext, error) {
robURL, err := uc.normalizedURL.Parse(robotsTxtPath)
if err != nil {
return nil, err
}
return &URLContext{
false, // Never request HEAD before GET for robots.txt
nil, // Always nil state
robURL,
robURL, // Normalized is same as raw
uc.sourceURL, // Source and normalized source is same as for current context
uc.normalizedSourceURL,
}, nil
}
func (c *Crawler) toURLContexts(raw interface{}, src *url.URL) []*URLContext {
var res []*URLContext
mapString := func(v S) {
res = make([]*URLContext, 0, len(v))
for s, st := range v {
ctx, err := c.stringToURLContext(s, src)
if err != nil {
c.Options.Extender.Error(newCrawlError(nil, err, CekParseURL))
c.logFunc(LogError, "ERROR parsing URL %s", s)
} else {
ctx.State = st
res = append(res, ctx)
}
}
}
mapURL := func(v U) {
res = make([]*URLContext, 0, len(v))
for u, st := range v {
ctx := c.urlToURLContext(u, src)
ctx.State = st
res = append(res, ctx)
}
}
switch v := raw.(type) {
case *URLContext:
res = []*URLContext{v}
case string:
// Convert a single string URL to an URLContext
ctx, err := c.stringToURLContext(v, src)
if err != nil {
c.Options.Extender.Error(newCrawlError(nil, err, CekParseURL))
c.logFunc(LogError, "ERROR parsing URL %s", v)
} else {
res = []*URLContext{ctx}
}
case []string:
// Convert all strings to URLContexts
res = make([]*URLContext, 0, len(v))
for _, s := range v {
ctx, err := c.stringToURLContext(s, src)
if err != nil {
c.Options.Extender.Error(newCrawlError(nil, err, CekParseURL))
c.logFunc(LogError, "ERROR parsing URL %s", s)
} else {
res = append(res, ctx)
}
}
case *url.URL:
res = []*URLContext{c.urlToURLContext(v, src)}
case []*url.URL:
res = make([]*URLContext, 0, len(v))
for _, u := range v {
res = append(res, c.urlToURLContext(u, src))
}
case map[string]interface{}:
mapString(S(v))
case S:
mapString(v)
case map[*url.URL]interface{}:
mapURL(U(v))
case U:
mapURL(v)
default:
if raw != nil {
panic("unsupported URL type passed as empty interface")
}
}
return res
}
func (c *Crawler) stringToURLContext(str string, src *url.URL) (*URLContext, error) {
u, err := url.Parse(str)
if err != nil {
return nil, err
}
return c.urlToURLContext(u, src), nil
}
func (c *Crawler) urlToURLContext(u, src *url.URL) *URLContext {
var rawSrc *url.URL
rawU := *u
purell.NormalizeURL(u, c.Options.URLNormalizationFlags)
if src != nil {
rawSrc = &url.URL{}
*rawSrc = *src
purell.NormalizeURL(src, c.Options.URLNormalizationFlags)
}
return &URLContext{
c.Options.HeadBeforeGet,
nil,
&rawU,
u,
rawSrc,
src,
}
}