1. 1
2. 2
3. 3
4. 4
5. 5
6. 6
7. 7
8. 8
9. 9
10. 10
11. 11
12. 12
13. 13
14. 14
15. 15
16. 16
17. 17
18. 18
19. 19
20. 20
21. 21
22. 22
23. 23
24. 24
25. 25
26. 26
27. 27
28. 28
29. 29
30. 30
31. 31
32. 32
33. 33
34. 34
35. 35
36. 36
37. 37
38. 38
39. 39
40. 40
41. 41
42. 42
43. 43
44. 44
45. 45
46. 46
47. 47
48. 48
49. 49
50. 50
51. 51
52. 52
53. 53
54. 54
55. 55
56. 56
57. 57
58. 58
59. 59
60. 60
61. 61
62. 62
63. 63
64. 64
65. 65
66. 66
67. 67
68. 68
69. 69
70. 70
71. 71
72. 72
73. 73
74. 74
75. 75
76. 76
77. 77
78. 78
79. 79
80. 80
81. 81
82. 82
83. 83

package openid

import (
	"encoding/xml"
	"errors"
	"strings"
)

// TODO: As per 11.2 in openid 2 specs, a service may have multiple
//       URIs. We don't care for discovery really, but we do care for
//       verification though.
type XrdsIdentifier struct {
	Type     []string `xml:"Type"`
	URI      string   `xml:"URI"`
	LocalID  string   `xml:"LocalID"`
	Priority int      `xml:"priority,attr"`
}

type Xrd struct {
	Service []*XrdsIdentifier `xml:"Service"`
}

type XrdsDocument struct {
	XMLName xml.Name `xml:"XRDS"`
	Xrd     *Xrd     `xml:"XRD"`
}

func parseXrds(input []byte) (opEndpoint, opLocalID string, err error) {
	xrdsDoc := &XrdsDocument{}
	err = xml.Unmarshal(input, xrdsDoc)
	if err != nil {
		return
	}

	if xrdsDoc.Xrd == nil {
		return "", "", errors.New("XRDS document missing XRD tag")
	}

	// 7.3.2.2.  Extracting Authentication Data
	// Once the Relying Party has obtained an XRDS document, it
	// MUST first search the document (following the rules
	// described in [XRI_Resolution_2.0]) for an OP Identifier
	// Element. If none is found, the RP will search for a Claimed
	// Identifier Element.
	for _, service := range xrdsDoc.Xrd.Service {
		// 7.3.2.1.1.  OP Identifier Element
		// An OP Identifier Element is an <xrd:Service> element with the
		// following information:
		// An <xrd:Type> tag whose text content is
		//     "http://specs.openid.net/auth/2.0/server".
		// An <xrd:URI> tag whose text content is the OP Endpoint URL
		if service.hasType("http://specs.openid.net/auth/2.0/server") {
			opEndpoint = strings.TrimSpace(service.URI)
			return
		}
	}
	for _, service := range xrdsDoc.Xrd.Service {
		// 7.3.2.1.2.  Claimed Identifier Element
		// A Claimed Identifier Element is an <xrd:Service> element
		// with the following information:
		// An <xrd:Type> tag whose text content is
		//     "http://specs.openid.net/auth/2.0/signon".
		// An <xrd:URI> tag whose text content is the OP Endpoint
		//     URL.
		// An <xrd:LocalID> tag (optional) whose text content is the
		//     OP-Local Identifier.
		if service.hasType("http://specs.openid.net/auth/2.0/signon") {
			opEndpoint = strings.TrimSpace(service.URI)
			opLocalID = strings.TrimSpace(service.LocalID)
			return
		}
	}
	return "", "", errors.New("Could not find a compatible service")
}

func (xrdsi *XrdsIdentifier) hasType(tpe string) bool {
	for _, t := range xrdsi.Type {
		if t == tpe {
			return true
		}
	}
	return false
}