identification: Support prefixes in string constructors for an explicit type

src/libstrongswan/tests/suites/test_identification.c

@@ -174,6 +174,10 @@ static struct {
 		.data.c = chunk_from_chars(0x30,0x0d,0x31,0x0b,0x30,0x09,0x06,
 								   0x03,0x55,0x04,0x06,0x13,0x02,0x43,0x48) }},
 	{"C=CH, O",					ID_KEY_ID,		{ .type = ENC_SIMPLE }},
+	{"IPv4:#c0a80101",			ID_IPV4_ADDR,	{ .type = ENC_CHUNK,
+		.data.c = chunk_from_chars(0xc0,0xa8,0x01,0x01) }},
+	{ "email:tester",			ID_RFC822_ADDR,	{ .type = ENC_STRING,
+		.data.s = "tester" }},
 };
 
 START_TEST(test_from_string)

src/libstrongswan/utils/identification.c

@@ -927,6 +927,49 @@ static private_identification_t *identification_create(id_type_t type)
 	return this;
 }
 
+/**
+ * Create an identity for a specific type, determined by prefix
+ */
+static private_identification_t* create_from_string_with_prefix_type(char *str)
+{
+	struct {
+		const char *str;
+		id_type_t type;
+	} prefixes[] = {
+		{ "ipv4:",			ID_IPV4_ADDR			},
+		{ "ipv6:",			ID_IPV6_ADDR			},
+		{ "rfc822:",		ID_RFC822_ADDR			},
+		{ "email:",			ID_RFC822_ADDR			},
+		{ "userfqdn:",		ID_USER_FQDN			},
+		{ "fqdn:",			ID_FQDN					},
+		{ "dns:",			ID_FQDN					},
+		{ "asn1dn:",		ID_DER_ASN1_DN			},
+		{ "asn1gn:",		ID_DER_ASN1_GN			},
+		{ "keyid:",			ID_KEY_ID				},
+	};
+	private_identification_t *this;
+	int i;
+
+	for (i = 0; i < countof(prefixes); i++)
+	{
+		if (strcasepfx(str, prefixes[i].str))
+		{
+			this = identification_create(prefixes[i].type);
+			str += strlen(prefixes[i].str);
+			if (*str == '#')
+			{
+				this->encoded = chunk_from_hex(chunk_from_str(str + 1), NULL);
+			}
+			else
+			{
+				this->encoded = chunk_clone(chunk_from_str(str));
+			}
+			return this;
+		}
+	}
+	return NULL;
+}
+
 /*
  * Described in header.
  */
@@ -939,6 +982,11 @@ identification_t *identification_create_from_string(char *string)
 	{
 		string = "%any";
 	}
+	this = create_from_string_with_prefix_type(string);
+	if (this)
+	{
+		return &this->public;
+	}
 	if (strchr(string, '=') != NULL)
 	{
 		/* we interpret this as an ASCII X.501 ID_DER_ASN1_DN.

src/libstrongswan/utils/identification.h

@@ -302,6 +302,12 @@ struct identification_t {
  * N, G, I, dnQualifier, ID, EN, EmployeeNumber, E, Email, emailAddress, UN,
  * unstructuredName, TCGID.
  *
+ * To skip automatic type detection the following prefixes may be used to
+ * enforce a specific type: ipv4:, ipv6:, rfc822:, email:, userfqdn:, fqdn:,
+ * dns:, asn1dn:, asn1gn: and keyid:. If a # follows the :, the remaining data
+ * is interpreted as hex encoded binary data for that ID, otherwise the raw
+ * string following the prefix is used as identity data, without conversion.
+ *
  * This constructor never returns NULL. If it does not find a suitable
  * conversion function, it will copy the string to an ID_KEY_ID.
  *