Dkim C Reference Documentation
Dkim
Current Version: 10.1.0
DomainKeys API for creating and verifying DKIM-Signature and DomainKey-Signature MIME (email) header fields. This API is included with the "Chilkat MIME" license. ("Chilkat MIME" may be referred to as "Chilkat S/MIME" on some chilkatsoft.com web pages. They are the same product.)
Create/Dispose
HCkDkim instance = CkDkim_Create(); // ... CkDkim_Dispose(instance);
Creates an instance of the HCkDkim object and returns a handle ("void *" pointer). The handle is passed in the 1st argument for the functions listed on this page.
Objects created by calling CkDkim_Create must be freed by calling this method. A memory leak occurs if a handle is not disposed by calling this function. Also, any handle returned by a Chilkat "C" function must also be freed by the application by calling the appropriate Dispose method, such as CkDkim_Dispose.
Callback Functions
Provides the opportunity for a method call to be aborted. If TRUE is returned, the operation in progress is aborted. Return FALSE to allow the current method call to continue. This callback function is called periodically based on the value of the HeartbeatMs property. (If HeartbeatMs is 0, then no callbacks are made.) As an example, to make 5 AbortCheck callbacks per second, set the HeartbeatMs property equal to 200.
See Also:C Example using Callback Functions
Provides the percentage completed for any method that involves network communications or time-consuming processing (assuming it is a method where a percentage completion can be measured). This callback is only called when it is possible to know a percentage completion, and when it makes sense to express the operation as a percentage completed. The pctDone argument will have a value from 1 to 100. For methods that complete very quickly, the number of PercentDone callbacks will vary, but the final callback should have a value of 100. For long running operations, no more than one callback per percentage point will occur (for example: 1, 2, 3, ... 98, 99, 100).
This callback counts as an AbortCheck callback, and takes the place of the AbortCheck event when it fires.
The return value indicates whether the method call should be aborted, or whether it should proceed. Return TRUE to abort, and FALSE to proceed.
This is a general callback that provides name/value information about what is happening at certain points during a method call. To see the information provided in ProgressInfo callbacks, if any, write code to handle this event and log the name/value pairs. Most are self-explanatory.
Called in the background thread when an asynchronous task completes. (Note: When an async method is running, all callbacks are in the background thread.)
Properties
AbortCurrent
void CkDkim_putAbortCurrent(HCkDkim cHandle, BOOL newVal);
When set to TRUE, causes the currently running method to abort. Methods that always finish quickly (i.e.have no length file operations or network communications) are not affected. If no method is running, then this property is automatically reset to FALSE when the next method is called. When the abort occurs, this property is reset to FALSE. Both synchronous and asynchronous method calls can be aborted. (A synchronous method call could be aborted by setting this property from a separate thread.)
topDebugLogFilePath
void CkDkim_putDebugLogFilePath(HCkDkim cHandle, const char *newVal);
const char *CkDkim_debugLogFilePath(HCkDkim cHandle);
If set to a file path, causes each Chilkat method or property call to automatically append it's LastErrorText to the specified log file. The information is appended such that if a hang or crash occurs, it is possible to see the context in which the problem occurred, as well as a history of all Chilkat calls up to the point of the problem. The VerboseLogging property can be set to provide more detailed information.
This property is typically used for debugging the rare cases where a Chilkat method call hangs or generates an exception that halts program execution (i.e. crashes). A hang or crash should generally never happen. The typical causes of a hang are:
- a timeout related property was set to 0 to explicitly indicate that an infinite timeout is desired,
- the hang is actually a hang within an event callback (i.e. it is a hang within the application code), or
- there is an internal problem (bug) in the Chilkat code that causes the hang.
DkimAlg
void CkDkim_putDkimAlg(HCkDkim cHandle, const char *newVal);
const char *CkDkim_dkimAlg(HCkDkim cHandle);
The signing algorithm to be used in creating the DKIM-Signature. Possible values are "rsa-sha256" and "rsa-sha1". The default value is "rsa-sha256".
topDkimBodyLengthCount
void CkDkim_putDkimBodyLengthCount(HCkDkim cHandle, int newVal);
Optional body length count to set a maximum number of body bytes to be hashed when creating the DKIM-Signature field. The default value is 0, indicating that the entire body should be hashed.
topDkimCanon
void CkDkim_putDkimCanon(HCkDkim cHandle, const char *newVal);
const char *CkDkim_dkimCanon(HCkDkim cHandle);
Canonicalization algorithm to be used for both header and body when creating the DKIM-Signature. Possible values are "simple" and "relaxed". The default value is "relaxed".
topDkimDomain
void CkDkim_putDkimDomain(HCkDkim cHandle, const char *newVal);
const char *CkDkim_dkimDomain(HCkDkim cHandle);
The domain name of the signing domain when creating the DKIM-Signature.
topDkimHeaders
void CkDkim_putDkimHeaders(HCkDkim cHandle, const char *newVal);
const char *CkDkim_dkimHeaders(HCkDkim cHandle);
A colon-separated list of header field names that identify headers presented to the signing algorithm when creating the DKIM-Signature. The default value is: "mime-version:date:message-id:subject:from:to:content-type".
topDkimSelector
void CkDkim_putDkimSelector(HCkDkim cHandle, const char *newVal);
const char *CkDkim_dkimSelector(HCkDkim cHandle);
The selector to be used to form the DNS query for the public key. This property applies to creating a DKIM-Signature. For example, if the selector is "reykjavik" and the domain is "example-code.com", then the DNS query would be for "reykjavik._domainkey.example-code.com".
topDomainKeyAlg
void CkDkim_putDomainKeyAlg(HCkDkim cHandle, const char *newVal);
const char *CkDkim_domainKeyAlg(HCkDkim cHandle);
The signing algorithm to be used in creating the DomainKey-Signature. The only possible value is "rsa-sha1". The default value is "rsa-sha1".
topDomainKeyCanon
void CkDkim_putDomainKeyCanon(HCkDkim cHandle, const char *newVal);
const char *CkDkim_domainKeyCanon(HCkDkim cHandle);
Canonicalization algorithm to be used for when creating the DomainKey-Signature. Possible values are "simple" and "nofws". The default value is "nofws".
topDomainKeyDomain
void CkDkim_putDomainKeyDomain(HCkDkim cHandle, const char *newVal);
const char *CkDkim_domainKeyDomain(HCkDkim cHandle);
The domain name of the signing domain when creating the DomainKey-Signature.
topDomainKeyHeaders
void CkDkim_putDomainKeyHeaders(HCkDkim cHandle, const char *newVal);
const char *CkDkim_domainKeyHeaders(HCkDkim cHandle);
A colon-separated list of header field names that identify headers presented to the signing algorithm when creating the DomainKey-Signature. The default value is: "mime-version:date:message-id:subject:from:to:content-type".
topDomainKeySelector
void CkDkim_putDomainKeySelector(HCkDkim cHandle, const char *newVal);
const char *CkDkim_domainKeySelector(HCkDkim cHandle);
The selector to be used to form the DNS query for the public key. This property applies to creating a DomainKey-Signature. For example, if the selector is "reykjavik" and the domain is "example-code.com", then the DNS query would be for "reykjavik._domainkey.example-code.com".
topHeartbeatMs
void CkDkim_putHeartbeatMs(HCkDkim cHandle, int newVal);
The number of milliseconds between each AbortCheck event callback. The AbortCheck callback allows an application to abort any method call prior to completion. If HeartbeatMs is 0 (the default), no AbortCheck event callbacks will fire.
topLastErrorHtml
const char *CkDkim_lastErrorHtml(HCkDkim cHandle);
Provides information in HTML format about the last method/property called. If a method call returns a value indicating failure, or behaves unexpectedly, examine this property to get more information.
topLastErrorText
const char *CkDkim_lastErrorText(HCkDkim cHandle);
Provides information in plain-text format about the last method/property called. If a method call returns a value indicating failure, or behaves unexpectedly, examine this property to get more information.
LastErrorXml
const char *CkDkim_lastErrorXml(HCkDkim cHandle);
Provides information in XML format about the last method/property called. If a method call returns a value indicating failure, or behaves unexpectedly, examine this property to get more information.
topLastMethodSuccess
void CkDkim_putLastMethodSuccess(HCkDkim cHandle, BOOL newVal);
Indicate whether the last method call succeeded or failed. A value of TRUE indicates success, a value of FALSE indicates failure. This property is automatically set for method calls. It is not modified by property accesses. The property is automatically set to indicate success for the following types of method calls:
- Any method that returns a string.
- Any method returning a Chilkat object, binary bytes, or a date/time.
- Any method returning a standard boolean status value where success = TRUE and failure = FALSE.
- Any method returning an integer where failure is defined by a return value less than zero.
Note: Methods that do not fit the above requirements will always set this property equal to TRUE. For example, a method that returns no value (such as a "void" in C++) will technically always succeed.
topUtf8
void CkDkim_putUtf8(HCkDkim cHandle, BOOL newVal);
When set to TRUE, all "const char *" arguments are interpreted as utf-8 strings. If set to FALSE (the default), then "const char *" arguments are interpreted as ANSI strings. Also, when set to TRUE, and Chilkat method returning a "const char *" is returning the utf-8 representation. If set to FALSE, all "const char *" return values are ANSI strings.
topVerboseLogging
void CkDkim_putVerboseLogging(HCkDkim cHandle, BOOL newVal);
If set to TRUE, then the contents of LastErrorText (or LastErrorXml, or LastErrorHtml) may contain more verbose information. The default value is FALSE. Verbose logging should only be used for debugging. The potentially large quantity of logged information may adversely affect peformance.
topVerifyInfo
const char *CkDkim_verifyInfo(HCkDkim cHandle);
Contains JSON with information about the last DKIM or DomainKey signature verified (or verification failure). The JSON will contain information like this:
{
"domain": "amazonses.com",
"selector": "7v7vs6w47njt4pimodk5mmttbegzsi6n",
"publicKey": "MIGfMA0GCSq...z6uqeQIDAQAB",
"canonicalization": "relaxed/simple",
"algorithm": "rsa-sha256",
"signedHeaders": "Subject:From:To:Date:Mime-Version:Content-Type:References:Message-Id:Feedback-ID",
"verified": "yes"
}
Version
const char *CkDkim_version(HCkDkim cHandle);
Methods
DkimSign
Constructs and prepends a DKIM-Signature header to the MIME passed in mimeData. Prior to calling this method, your program must set both the DkimDomain and DkimSelector properties, and it must load a private key by calling SetDkimPrivateKey.
Returns TRUE for success, FALSE for failure.
DkimVerify
Verifies the Nth DKIM-Signature header in the mimeData. (In most cases, there is only one signature.) The 1st signature is at sigIndex 0.
On return, the VerifyInfo property will contain additional information about the DKIM-Signature that was verified (or not verified).
Returns TRUE for success, FALSE for failure.
DomainKeySign
Constructs and prepends a DomainKey-Signature header to the MIME passed in mimeData. Prior to calling this method, your program must set both the DomainKeyDomain and DomainKeySelector properties, and it must load a private key by calling SetDomainKeyPrivateKey.
Returns TRUE for success, FALSE for failure.
topDomainKeyVerify
Verifies the Nth DomainKey-Signature header in the mimeData. (In most cases, there is only one signature.) The 1st signature is at sigIndex 0.
On return, the VerifyInfo property will contain additional information about the DKIM-Signature that was verified (or not verified).
Returns TRUE for success, FALSE for failure.
LoadPublicKey
Caches a public key to be used for verifying DKIM and DomainKey signatures for a given selector and domain. The publicKey is a string containing an RSA public key in any text format, such as XML, PEM, etc. This method will automatically detect the format and load the public key correctly. This method is useful for testing DKIM and DomainKey verification when your public key has not yet been installed in DNS.
Returns TRUE for success, FALSE for failure.
topLoadPublicKeyFile
Caches a public key to be used for verifying DKIM and DomainKey signatures for a given selector and domain. The publicKeyFilepath is a filepath of an RSA public key in any format. This method will automatically detect the format and load the public key correctly. This method is useful for testing DKIM and DomainKey verification when your public key has not yet been installed in DNS.
Returns TRUE for success, FALSE for failure.
topLoadTaskCaller
NumDkimSigs
Returns the number of DKIM-Signature header fields found in mimeData.
NumDomainKeySigs
Returns the number of DomainKey-Signature header fields found in mimeData.
PrefetchPublicKey
Useful if your application is going to verify many emails from a single domain (or a few domains). This eliminates the need to do a DNS lookup to fetch the public key each time an email's DKIM or DomainKey signature is verified.
This method may be called multiple times -- once for each selector/domain to be pre-fetched. The verify methods (VerifyDkimSignature and VerifyDomainKeySignature) will use a pre-fetched key if the selector and domain match.
Returns TRUE for success, FALSE for failure.
topPrefetchPublicKeyAsync (1)
Creates an asynchronous task to call the PrefetchPublicKey method with the arguments provided. (Async methods are available starting in Chilkat v9.5.0.52.)
Returns NULL on failure
topSetDkimPrivateKey
Sets the private key file to be used for creating a DKIM-Signature.
Returns TRUE for success, FALSE for failure.
topSetDomainKeyPrivateKey
Sets the private key file to be used for creating a DomainKey-Signature.
Returns TRUE for success, FALSE for failure.
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