Add CMS_SignerInfo_get0_signature function.

Add function to retrieve the signature from a CMS_SignerInfo structure:
applications can then read or modify it.

crypto/cms/cms.h

@@ -275,6 +275,7 @@ int CMS_set1_signers_certs(CMS_ContentInfo *cms, STACK_OF(X509) *certs,
 					unsigned int flags);
 void CMS_SignerInfo_get0_algs(CMS_SignerInfo *si, EVP_PKEY **pk, X509 **signer,
 					X509_ALGOR **pdig, X509_ALGOR **psig);
+ASN1_OCTET_STRING *CMS_SignerInfo_get0_signature(CMS_SignerInfo *si);
 int CMS_SignerInfo_sign(CMS_SignerInfo *si);
 int CMS_SignerInfo_verify(CMS_SignerInfo *si);
 int CMS_SignerInfo_verify_content(CMS_SignerInfo *si, BIO *chain);

crypto/cms/cms_sd.c

@@ -616,6 +616,11 @@ void CMS_SignerInfo_get0_algs(CMS_SignerInfo *si, EVP_PKEY **pk, X509 **signer,
 		*psig = si->signatureAlgorithm;
 	}
 
+ASN1_OCTET_STRING *CMS_SignerInfo_get0_signature(CMS_SignerInfo *si)
+	{
+	return si->signature;
+	}
+
 static int cms_SignerInfo_content_sign(CMS_ContentInfo *cms,
 					CMS_SignerInfo *si, BIO *chain)
 	{

doc/crypto/CMS_get0_SignerInfos.pod

@@ -2,7 +2,7 @@
 
 =head1 NAME
 
-CMS_get0_SignerInfos, CMS_SignerInfo_get0_signer_id, CMS_SignerInfo_cert_cmp, CMS_set1_signer_cert - CMS signedData signer functions.
+CMS_get0_SignerInfos, CMS_SignerInfo_get0_signer_id, CMS_SignerInfo_get0_signature, CMS_SignerInfo_cert_cmp, CMS_set1_signer_cert - CMS signedData signer functions.
 
 =head1 SYNOPSIS
 
@@ -11,6 +11,7 @@ CMS_get0_SignerInfos, CMS_SignerInfo_get0_signer_id, CMS_SignerInfo_cert_cmp, CM
  STACK_OF(CMS_SignerInfo) *CMS_get0_SignerInfos(CMS_ContentInfo *cms);
 
  int CMS_SignerInfo_get0_signer_id(CMS_SignerInfo *si, ASN1_OCTET_STRING **keyid, X509_NAME **issuer, ASN1_INTEGER **sno);
+ ASN1_OCTET_STRING *CMS_SignerInfo_get0_signature(CMS_SignerInfo *si);
  int CMS_SignerInfo_cert_cmp(CMS_SignerInfo *si, X509 *cert);
  void CMS_SignerInfo_set1_signer_cert(CMS_SignerInfo *si, X509 *signer);
 
@@ -24,6 +25,11 @@ associated with a specific CMS_SignerInfo structure B<si>. Either the
 keyidentifier will be set in B<keyid> or B<both> issuer name and serial number
 in B<issuer> and B<sno>.
 
+CMS_SignerInfo_get0_signature() retrieves the signature associated with 
+B<si> in a pointer to an ASN1_OCTET_STRING structure. This pointer returned
+corresponds to the internal signature value if B<si> so it may be read or
+modified.
+
 CMS_SignerInfo_cert_cmp() compares the certificate B<cert> against the signer
 identifier B<si>. It returns zero if the comparison is successful and non zero
 if not.