lib: add web.go

For challenge 13.

1 files changed, 96 insertions, 0 deletions

diff --git a/lib/web.go b/lib/web.go
new file mode 100644
index 0000000..ab50fc8
--- /dev/null
+++ b/lib/web.go
@@ -0,0 +1,96 @@
+// Copyright © 2020 rsiddharth <s@ricketyspace.net>
+// SPDX-License-Identifier: ISC
+
+package lib
+
+import (
+	"crypto/rand"
+)
+
+type Profile map[string]string
+
+var webSessionEncryptionKey []byte = make([]byte, 16)
+var webUidCounter int64
+var webUserProfiles map[string]Profile = make(map[string]Profile, 0)
+
+func init() {
+	_, err := rand.Read(webSessionEncryptionKey)
+	if err != nil {
+		panic(err)
+	}
+	webUidCounter = 10000
+}
+
+func WebGenUid() int64 {
+	uid := webUidCounter
+	webUidCounter += 1
+
+	return uid
+}
+
+func WebParseKeyValue(encoded string) map[string]string {
+	m := make(map[string]string, 0)
+
+	kvs := StrSplitAt('&', encoded)
+	for i := 0; i < len(kvs); i++ {
+		kv := StrSplitAt('=', kvs[i])
+		m[stripSpaceChars(kv[0])] = kv[1]
+	}
+	return m
+}
+
+func WebProfileFor(email string) string {
+	e := WebSanitizeEmail(email)
+	if len(e) == 0 {
+		panic("email invalid")
+	}
+
+	if p, ok := webUserProfiles[e]; ok {
+		// Profile already exists.
+		return WebEncodeProfile(p)
+	}
+
+	// Create profile.
+	p := make(Profile, 0)
+	p["email"] = e
+	p["uid"] = NumToStr(WebGenUid())
+	p["role"] = "user"
+	webUserProfiles[e] = p
+
+	return WebEncodeProfile(p)
+}
+
+func WebEncodeProfile(p Profile) string {
+	ep := "email=" + p["email"] // Encoded profile.
+	ep += "&uid=" + p["uid"]
+	ep += "&role=" + p["role"]
+	return ep
+}
+
+func WebDecodeProfile(encoded string) Profile {
+	return WebParseKeyValue(encoded)
+}
+
+func WebEncryptProfile(encoded string) []byte {
+	return AESEncryptECB(StrToBytes(encoded), webSessionEncryptionKey)
+}
+
+func WebDecryptProfile(cipher []byte) string {
+	return BytesToStr(AESDecryptECB(cipher, webSessionEncryptionKey))
+}
+
+func WebSanitizeEmail(email string) string {
+	if len(email) < 1 {
+		return ""
+	}
+	se := "" // sanitized email
+
+	// Strip meta characters
+	for i := 0; i < len(email); i++ {
+		if email[i] == '&' || email[i] == '=' {
+			continue
+		}
+		se += string(email[i])
+	}
+	return se
+}