From: Dr. Stephen Henson Date: Sun, 10 Sep 2000 17:36:15 +0000 (+0000) Subject: More new BIO docs, correct some old ones. X-Git-Tag: OpenSSL-engine-0_9_6-beta1~3^2~1 X-Git-Url: https://git.librecmc.org/?a=commitdiff_plain;h=5fd0cd9a9b7ee101c93719b01c5fccf2ae5cee99;p=oweals%2Fopenssl.git More new BIO docs, correct some old ones. --- diff --git a/doc/crypto/BIO_f_md.pod b/doc/crypto/BIO_f_md.pod new file mode 100644 index 0000000000..67ba6e8516 --- /dev/null +++ b/doc/crypto/BIO_f_md.pod @@ -0,0 +1,140 @@ +=pod + +=head1 NAME + + BIO_f_md - message digest BIO + +=head1 SYNOPSIS + + #include + #include + + BIO_METHOD * BIO_f_md(void); + int BIO_set_md(BIO *b,EVP_MD *md); + int BIO_get_md(BIO *b,EVP_MD **mdp); + int BIO_get_md_ctx(BIO *b,EVP_MD_CTX **mdcp); + +=head1 DESCRIPTION + +BIO_f_md() returns the message digest BIO method. This is a filter +BIO that digests any data passed through it, it is a BIO wrapper +for the digest routines EVP_DigestInit(), EVP_DigestUpdate() +and EVP_DigestFinal(). + +Any data written or read through a digest BIO using BIO_read() and +BIO_write() is digested. + +BIO_gets(), if its B parameter is large enough finishes the +digest calculation and returns the digest value. BIO_puts() is +not supported. + +BIO_reset() reinitializes a digest BIO. + +BIO_set_md() sets the message digest of BIO B to B: this +must be called to initialise a digest BIO before any data is +passed through it. It is a BIO_ctrl() macro. + +BIO_get_md() places the a pointer to the digest BIOs digest method +in B, it is a BIO_ctrl() macro. + +BIO_get_md_ctx() returns the digest BIOs context into B. + + + +=head1 NOTES + +The context returned by BIO_get_md_ctx() can be used in calls +to EVP_DigestFinal() and also the signature routines EVP_SignFinal() +and EVP_VerifyFinal(). + +The context returned by BIO_get_md_ctx() is an internal context +structure. Changes made to this context will affect the digest +BIO itself and the context pointer will become invalid when the digest +BIO is freed. + +After the digest has been retrieved from a digest BIO it must be +reinitialized by calling BIO_reset(), or BIO_set_md() before any more +data is passed through it. + +If an application needs to call BIO_gets() or BIO_puts() through +a chain containing digest BIOs then this can be done by prepending +a buffering BIO. + +=head1 RETURN VALUES + +BIO_f_md() returns the digest BIO method. + +BIO_set_md(), BIO_get_md() and BIO_md_ctx() return 1 for success and +0 for failure. + +=head1 EXAMPLES + +The following example creates a BIO chain containing an SHA1 and MD5 +digest BIO and passes the string "Hello World" through it. Error +checking has been omitted for clarity. + + BIO *bio, *mdtmp; + char message[] = "Hello World"; + bio = BIO_new(BIO_s_null()); + mdtmp = BIO_new(BIO_f_md()); + BIO_set_md(mdtmp, EVP_sha1()); + /* For BIO_push() we want to append the sink BIO and keep a note of + * the start of the chain. + */ + bio = BIO_push(mdtmp, bio); + mdtmp = BIO_new(BIO_f_md()); + BIO_set_md(mdtmp, EVP_md5()); + bio = BIO_push(mdtmp, bio); + /* Note: mdtmp can now be discarded */ + BIO_write(bio, message, strlen(message)); + +The next example digests data by reading through a chain instead: + + BIO *bio, *mdtmp; + char buf[1024]; + int rdlen; + bio = BIO_new_file(file, "rb"); + mdtmp = BIO_new(BIO_f_md()); + BIO_set_md(mdtmp, EVP_sha1()); + bio = BIO_push(mdtmp, bio); + mdtmp = BIO_new(BIO_f_md()); + BIO_set_md(mdtmp, EVP_md5()); + bio = BIO_push(mdtmp, bio); + do { + rdlen = BIO_read(bio, buf, sizeof(buf)); + /* Might want to do something with the data here */ + } while(rdlen > 0); + +This next example retrieves the message digests from a BIO chain and +outputs them. This could be used with the examples above. + + BIO *mdtmp; + unsigned char mdbuf[EVP_MAX_MD_SIZE]; + int mdlen; + int i; + mdtmp = bio; /* Assume bio has previously been set up */ + do { + EVP_MD *md; + mdtmp = BIO_find_type(mdtmp, BIO_TYPE_MD); + if(!mdtmp) break; + BIO_get_md(mdtmp, &md); + printf("%s digest", OBJ_nid2sn(EVP_MD_type(md))); + mdlen = BIO_gets(mdtmp, mdbuf, EVP_MAX_MD_SIZE); + for(i = 0; i < mdlen; i++) printf(":%02X", mdbuf[i]); + printf("\n"); + mdtmp = BIO_next(mdtmp); + } while(mdtmp); + + BIO_free_all(bio); + +=head1 BUGS + +The lack of support for BIO_puts() and the non standard behaviour of +BIO_gets() could be regarded as anomalous. It could be argued that BIO_gets() +and BIO_puts() should be passed to the next BIO in the chain and digest +the data passed through and that digests should be retrieved using a +separate BIO_ctrl() call. + +=head1 SEE ALSO + +TBA diff --git a/doc/crypto/BIO_f_null.pod b/doc/crypto/BIO_f_null.pod new file mode 100644 index 0000000000..8156b51b8f --- /dev/null +++ b/doc/crypto/BIO_f_null.pod @@ -0,0 +1,32 @@ +=pod + +=head1 NAME + + BIO_f_null - null filter + +=head1 SYNOPSIS + + #include + + BIO_METHOD * BIO_f_null(void); + +=head1 DESCRIPTION + +BIO_f_null() returns the null filter BIO method. This is a filter BIO +that does nothing. + +All requests to a null filter BIO are passed through to the next BIO in +the chain: this means that a BIO chain containing a null filter BIO +behaves just as though the BIO was not there. + +=head1 NOTES + +As may be apparent a null filter BIO is not particularly useful. + +=head1 RETURN VALUES + +BIO_f_null() returns the null filter BIO method. + +=head1 SEE ALSO + +TBA diff --git a/doc/crypto/BIO_s_null.pod b/doc/crypto/BIO_s_null.pod new file mode 100644 index 0000000000..b9a3c2cf3f --- /dev/null +++ b/doc/crypto/BIO_s_null.pod @@ -0,0 +1,37 @@ +=pod + +=head1 NAME + + BIO_s_null - null data sink + +=head1 SYNOPSIS + + #include + + BIO_METHOD * BIO_s_null(void); + +=head1 DESCRIPTION + +BIO_s_null() returns the null sink BIO method. Data written to +the null sink is discraded, reads return EOF. + +=head1 NOTES + +A null sink BIO behaves in a similar manner to the Unix /dev/null +device. + +A null bio can be placed on the end of a chain to discard any data +passed through it. + +A null sink is useful if, for example, an application wishes to digest some +data but not write the result anywhere. Since a BIO chain must normally +include a source/sink BIO this can be achieved by adding a null sink BIO +to the end of the chain + +=head1 RETURN VALUES + +BIO_s_null() returns the null sink BIO method. + +=head1 SEE ALSO + +TBA diff --git a/doc/crypto/bio.pod b/doc/crypto/bio.pod index 0214804dcf..987ec838fb 100644 --- a/doc/crypto/bio.pod +++ b/doc/crypto/bio.pod @@ -34,7 +34,7 @@ if it is being read from. BIOs can be joined together to form a chain (a single BIO is a chain with one component). A chain normally consist of one source/sink BIO and one or more filter BIOs. Data read from or written to the -end BIO then traverses the chain to the end (normally a source/sink +first BIO then traverses the chain to the end (normally a source/sink BIO). =head1 SEE ALSO