1SSL_alert_type_string(3)            OpenSSL           SSL_alert_type_string(3)
2
3
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NAME

6       SSL_alert_type_string, SSL_alert_type_string_long,
7       SSL_alert_desc_string, SSL_alert_desc_string_long - get textual
8       description of alert information
9

SYNOPSIS

11        #include <openssl/ssl.h>
12
13        const char *SSL_alert_type_string(int value);
14        const char *SSL_alert_type_string_long(int value);
15
16        const char *SSL_alert_desc_string(int value);
17        const char *SSL_alert_desc_string_long(int value);
18

DESCRIPTION

20       SSL_alert_type_string() returns a one letter string indicating the type
21       of the alert specified by value.
22
23       SSL_alert_type_string_long() returns a string indicating the type of
24       the alert specified by value.
25
26       SSL_alert_desc_string() returns a two letter string as a short form
27       describing the reason of the alert specified by value.
28
29       SSL_alert_desc_string_long() returns a string describing the reason of
30       the alert specified by value.
31

NOTES

33       When one side of an SSL/TLS communication wants to inform the peer
34       about a special situation, it sends an alert. The alert is sent as a
35       special message and does not influence the normal data stream (unless
36       its contents results in the communication being canceled).
37
38       A warning alert is sent, when a non-fatal error condition occurs. The
39       "close notify" alert is sent as a warning alert. Other examples for
40       non-fatal errors are certificate errors ("certificate expired",
41       "unsupported certificate"), for which a warning alert may be sent.
42       (The sending party may however decide to send a fatal error.) The
43       receiving side may cancel the connection on reception of a warning
44       alert on it discretion.
45
46       Several alert messages must be sent as fatal alert messages as
47       specified by the TLS RFC. A fatal alert always leads to a connection
48       abort.
49

RETURN VALUES

51       The following strings can occur for SSL_alert_type_string() or
52       SSL_alert_type_string_long():
53
54       "W"/"warning"
55       "F"/"fatal"
56       "U"/"unknown"
57           This indicates that no support is available for this alert type.
58           Probably value does not contain a correct alert message.
59
60       The following strings can occur for SSL_alert_desc_string() or
61       SSL_alert_desc_string_long():
62
63       "CN"/"close notify"
64           The connection shall be closed. This is a warning alert.
65
66       "UM"/"unexpected message"
67           An inappropriate message was received. This alert is always fatal
68           and should never be observed in communication between proper
69           implementations.
70
71       "BM"/"bad record mac"
72           This alert is returned if a record is received with an incorrect
73           MAC. This message is always fatal.
74
75       "DF"/"decompression failure"
76           The decompression function received improper input (e.g. data that
77           would expand to excessive length). This message is always fatal.
78
79       "HF"/"handshake failure"
80           Reception of a handshake_failure alert message indicates that the
81           sender was unable to negotiate an acceptable set of security
82           parameters given the options available. This is a fatal error.
83
84       "NC"/"no certificate"
85           A client, that was asked to send a certificate, does not send a
86           certificate (SSLv3 only).
87
88       "BC"/"bad certificate"
89           A certificate was corrupt, contained signatures that did not verify
90           correctly, etc
91
92       "UC"/"unsupported certificate"
93           A certificate was of an unsupported type.
94
95       "CR"/"certificate revoked"
96           A certificate was revoked by its signer.
97
98       "CE"/"certificate expired"
99           A certificate has expired or is not currently valid.
100
101       "CU"/"certificate unknown"
102           Some other (unspecified) issue arose in processing the certificate,
103           rendering it unacceptable.
104
105       "IP"/"illegal parameter"
106           A field in the handshake was out of range or inconsistent with
107           other fields. This is always fatal.
108
109       "DC"/"decryption failed"
110           A TLSCiphertext decrypted in an invalid way: either it wasn't an
111           even multiple of the block length or its padding values, when
112           checked, weren't correct. This message is always fatal.
113
114       "RO"/"record overflow"
115           A TLSCiphertext record was received which had a length more than
116           2^14+2048 bytes, or a record decrypted to a TLSCompressed record
117           with more than 2^14+1024 bytes. This message is always fatal.
118
119       "CA"/"unknown CA"
120           A valid certificate chain or partial chain was received, but the
121           certificate was not accepted because the CA certificate could not
122           be located or couldn't be matched with a known, trusted CA.  This
123           message is always fatal.
124
125       "AD"/"access denied"
126           A valid certificate was received, but when access control was
127           applied, the sender decided not to proceed with negotiation.  This
128           message is always fatal.
129
130       "DE"/"decode error"
131           A message could not be decoded because some field was out of the
132           specified range or the length of the message was incorrect. This
133           message is always fatal.
134
135       "CY"/"decrypt error"
136           A handshake cryptographic operation failed, including being unable
137           to correctly verify a signature, decrypt a key exchange, or
138           validate a finished message.
139
140       "ER"/"export restriction"
141           A negotiation not in compliance with export restrictions was
142           detected; for example, attempting to transfer a 1024 bit ephemeral
143           RSA key for the RSA_EXPORT handshake method. This message is always
144           fatal.
145
146       "PV"/"protocol version"
147           The protocol version the client has attempted to negotiate is
148           recognized, but not supported. (For example, old protocol versions
149           might be avoided for security reasons). This message is always
150           fatal.
151
152       "IS"/"insufficient security"
153           Returned instead of handshake_failure when a negotiation has failed
154           specifically because the server requires ciphers more secure than
155           those supported by the client. This message is always fatal.
156
157       "IE"/"internal error"
158           An internal error unrelated to the peer or the correctness of the
159           protocol makes it impossible to continue (such as a memory
160           allocation failure). This message is always fatal.
161
162       "US"/"user canceled"
163           This handshake is being canceled for some reason unrelated to a
164           protocol failure. If the user cancels an operation after the
165           handshake is complete, just closing the connection by sending a
166           close_notify is more appropriate. This alert should be followed by
167           a close_notify. This message is generally a warning.
168
169       "NR"/"no renegotiation"
170           Sent by the client in response to a hello request or by the server
171           in response to a client hello after initial handshaking.  Either of
172           these would normally lead to renegotiation; when that is not
173           appropriate, the recipient should respond with this alert; at that
174           point, the original requester can decide whether to proceed with
175           the connection. One case where this would be appropriate would be
176           where a server has spawned a process to satisfy a request; the
177           process might receive security parameters (key length,
178           authentication, etc.) at startup and it might be difficult to
179           communicate changes to these parameters after that point. This
180           message is always a warning.
181
182       "UP"/"unknown PSK identity"
183           Sent by the server to indicate that it does not recognize a PSK
184           identity or an SRP identity.
185
186       "UK"/"unknown"
187           This indicates that no description is available for this alert
188           type.  Probably value does not contain a correct alert message.
189

SEE ALSO

191       ssl(3), SSL_CTX_set_info_callback(3)
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1951.0.2o                            2019-09-10          SSL_alert_type_string(3)
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