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patterns.go
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patterns.go
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// SPDX-License-Identifier: Apache-2.0
// Copyright Authors of Hubble
package filters
import (
"errors"
"fmt"
"regexp"
"strings"
)
var (
// fqdnRegexpStr matches an FQDN, inluding underscores.
// FIXME this should not match components that begin or end with hyphens, e.g. -foo-
fqdnRegexpStr = `(?:[-0-9_a-z]+(?:\.[-0-9_a-z]+)*)`
_ = regexp.MustCompile(fqdnRegexpStr) // compile regexp to ensure that it is valid
errEmptyPattern = errors.New("empty pattern")
errMultipleTrailingDotsInPattern = errors.New("multiple trailing dots in pattern")
errTooManySlashesInPattern = errors.New("too many slashes in pattern")
)
// canonicalizeFQDNPattern canonicalizes fqdnPattern by trimming space, trimming
// up to one trailing dot, and converting it to lowercase.
func canonicalizeFQDNPattern(fqdnPattern string) string {
fqdnPattern = strings.TrimSpace(fqdnPattern)
fqdnPattern = strings.TrimSuffix(fqdnPattern, ".")
fqdnPattern = strings.ToLower(fqdnPattern)
return fqdnPattern
}
// appendFQDNPatternRegexp appends the regular expression equivalent to
// fqdnPattern to sb.
func appendFQDNPatternRegexp(sb *strings.Builder, fqdnPattern string) error {
fqdnPattern = canonicalizeFQDNPattern(fqdnPattern)
switch {
case fqdnPattern == "":
return errEmptyPattern
case strings.HasSuffix(fqdnPattern, "."):
return errMultipleTrailingDotsInPattern
}
for _, r := range fqdnPattern {
switch {
case r == '.':
sb.WriteString(`\.`)
case r == '*':
sb.WriteString(`[-.0-9a-z]*`)
case r == '-':
fallthrough
case '0' <= r && r <= '9':
fallthrough
case r == '_':
fallthrough
case 'a' <= r && r <= 'z':
sb.WriteRune(r)
default:
return fmt.Errorf("%q: invalid rune in pattern", r)
}
}
return nil
}
// appendNodeNamePatternRegexp appends the regular expression equivalent to
// nodeNamePattern to sb. The returned regular expression matches node names
// that include a cluster name.
//
// Node name patterns consist of a cluster pattern element and a node pattern
// element separated by a forward slash. Each element is an FQDN pattern, with
// an empty pattern matching everything. If there is no forward slash then the
// pattern is treated as a node pattern and matches all clusters.
func appendNodeNamePatternRegexp(sb *strings.Builder, nodeNamePattern string) error {
if nodeNamePattern == "" {
return errEmptyPattern
}
clusterPattern := ""
nodePattern := ""
elems := strings.Split(nodeNamePattern, "/")
switch len(elems) {
case 1:
nodePattern = elems[0]
case 2:
clusterPattern = elems[0]
nodePattern = elems[1]
default:
return errTooManySlashesInPattern
}
if clusterPattern == "" {
sb.WriteString(fqdnRegexpStr)
} else if err := appendFQDNPatternRegexp(sb, clusterPattern); err != nil {
return err
}
sb.WriteByte('/')
if nodePattern == "" {
sb.WriteString(fqdnRegexpStr)
} else if err := appendFQDNPatternRegexp(sb, nodePattern); err != nil {
return err
}
return nil
}
// compileFQDNPattern returns a regular expression equivalent to the FQDN
// patterns in fqdnPatterns.
func compileFQDNPattern(fqdnPatterns []string) (*regexp.Regexp, error) {
var sb strings.Builder
sb.WriteString(`\A(?:`)
for i, fqdnPattern := range fqdnPatterns {
if i > 0 {
sb.WriteByte('|')
}
if err := appendFQDNPatternRegexp(&sb, fqdnPattern); err != nil {
return nil, err
}
}
sb.WriteString(`)\z`)
return regexp.Compile(sb.String())
}
// compileNodeNamePattern returns a regular expression equivalent to the node
// name patterns in nodeNamePatterns.
func compileNodeNamePattern(nodeNamePatterns []string) (*regexp.Regexp, error) {
sb := strings.Builder{}
sb.WriteString(`\A(?:`)
for i, nodeNamePattern := range nodeNamePatterns {
if i > 0 {
sb.WriteByte('|')
}
if err := appendNodeNamePatternRegexp(&sb, nodeNamePattern); err != nil {
return nil, err
}
}
sb.WriteString(`)\z`)
return regexp.Compile(sb.String())
}