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diff --git a/doc/libsbearssl/index.html b/doc/libsbearssl/index.html new file mode 100644 index 0000000..1c797c7 --- /dev/null +++ b/doc/libsbearssl/index.html @@ -0,0 +1,548 @@ +<html> + <head> + <meta name="viewport" content="width=device-width, initial-scale=1.0" /> + <meta http-equiv="Content-Type" content="text/html; charset=UTF-8" /> + <meta http-equiv="Content-Language" content="en" /> + <title>s6-networking: the sbearssl library interface</title> + <meta name="Description" content="s6-networking: the sbearssl interface" /> + <meta name="Keywords" content="s6-networking net sbearssl library TLS SSL BearSSL libbearssl" /> + <!-- <link rel="stylesheet" type="text/css" href="http://skarnet.org/default.css" /> --> + </head> +<body> + +<p> +<a href="../">s6-networking</a><br /> +<a href="http://skarnet.org/software/">Software</a><br /> +<a href="http://skarnet.org/">skarnet.org</a> +</p> + +<h1> The <tt>sbearssl</tt> library interface </h1> + +<h2> General information </h2> + +<p> + <tt>libsbearssl</tt> is a support library for the +<a href="../s6-tlsc.html">s6-tlsc</a> and +<a href="../s6-tlsd.html">s6-tlsd</a> executables when they're built +against the <a href="https://bearssl.org/">BearSSL</a> +backend. Among other things, it offers interfaces to read private +keys and certificates from a Unix filesystem, which BearSSL does +not provide on its own. +</p> + +<h2> Compiling </h2> + +<ul> + <li> Make sure the s6-networking headers, as well as the skalibs headers, +and the <tt>bearssl.h</tt> header, are visible in your header search path. </li> + <li> Use <tt>#include <s6-networking/sbearssl.h></tt> </li> +</ul> + +<h2> Linking </h2> + +<ul> + <li> Make sure the s6-networking libraries, as well as the skalibs +libraries, and the BearSSL libraries, are visible in your library search path. </li> + <li> Link against <tt>-lsbearssl</tt>, <tt>-lskarnet</tt>, <tt>-lbearssl</tt>, +<tt>`cat $sysdeps/socket.lib`</tt>, <tt>`cat $sysdeps/spawn.lib`</tt>, and +<tt>`cat $sysdeps/tainnow.lib`</tt>, where <tt>$sysdeps</tt> is your skalibs +sysdeps directory. </li> +</ul> + +<h2> Programming </h2> + +<h3> General concepts </h3> + +<p> + <a href="https://bearssl.org/">BearSSL</a> provides engines +to decode PEM objects and X.509 certificates, and to run a +TLS/SSL connection. However, it does not store such objects: +it never allocates memory, and does not interact with the +filesystem. <tt>sbearssl</tt> provides functions to +address this. +</p> + +<p> + When reading an object into memory, <tt>sbearssl</tt> stores all +the bytes of the object in a +<a href="http://skarnet.org/software/skalibs/libstddjb/stralloc.html">stralloc</a>, +and the <tt>sbearssl_*</tt> structures contain indices of bytes in that +stralloc. That allows the structures to remain valid even when the stralloc +contents get reallocated and move to some other place in the heap. After +you have finished adding data to the stralloc and are sure its contents +will not move again, you can use the +<tt>sbearssl_*_to</tt> functions to convert <tt>sbearssl_*</tt> structures +to the corresponding <tt>br_*</tt> structures (native BearSSL), which +contain pointers to memory. +</p> + +<h3> Private keys (typically for servers) </h3> + +<p> + BearSSL handles two types of private keys: RSA keys and +EC keys (i.e. points on an elliptic curve). <tt>sbearssl</tt> +adds some generic functions to handle keys no matter their +type. +</p> + +<h4> <code> int sbearssl_rsa_skey_from (sbearssl_rsa_skey *l, br_rsa_private_key const *k, stralloc *sa) </code> </h4> + +<p> + Converts the RSA private key from BearSSL format (reading from a structure pointed to by <em>k</em>) +to <tt>sbearssl</tt> format (writing to a structure pointed to by <em>l</em>). +The data from *<em>k</em>'s contents are copied into the stralloc in *<em>sa</em>. +The function returns 1 on success and 0 (and sets errno) on failure. +</p> + +<h4> <code> void sbearssl_rsa_skey_to (sbearssl_rsa_skey const *l, br_rsa_private_key *k, char *s) </code> </h4> + +<p> + Converts the RSA private key from <tt>sbearssl</tt> format (reading from a structure pointed to by <em>l</em>) +to BearSSL format (writing to a structure pointed to by <em>k</em>). +The indices in <em>l</em> must refer to data stored in the string <em>s</em>. +</p> + +<h4> <code> int sbearssl_ec_skey_from (sbearssl_ec_skey *l, br_ec_private_key const *k, stralloc *sa) </code> </h4> + +<p> + Converts the EC private key from BearSSL format (reading from a structure pointed to by <em>k</em>) +to <tt>sbearssl</tt> format (writing to a structure pointed to by <em>l</em>). +The data from *<em>k</em>'s contents are copied into the stralloc in *<em>sa</em>. +The function returns 1 on success and 0 (and sets errno) on failure. +</p> + +<h4> <code> void sbearssl_ec_skey_to (sbearssl_ec_skey const *l, br_ec_private_key *k, char *s) </code> </h4> + +<p> + Converts the EC private key from <tt>sbearssl</tt> format (reading from a structure pointed to by <em>l</em>) +to BearSSL format (writing to a structure pointed to by <em>k</em>). +The indices in <em>l</em> must refer to data stored in the string <em>s</em>. +</p> + +<h4> <code> int sbearssl_skey_from (sbearssl_skey *l, br_skey const *k, stralloc *sa) </code> </h4> + +<p> + Converts the private key from BearSSL format (reading from a structure pointed to by <em>k</em>) +to <tt>sbearssl</tt> format (writing to a structure pointed to by <em>l</em>). +The data from *<em>k</em>'s contents are copied into the stralloc in *<em>sa</em>. +The function returns 1 on success and 0 (and sets errno) on failure. +</p> + +<h4> <code> void sbearssl_skey_to (sbearssl_skey const *l, br_skey *k, char *s) </code> </h4> + +<p> + Converts the private key from <tt>sbearssl</tt> format (reading from a structure pointed to by <em>l</em>) +to BearSSL format (writing to a structure pointed to by <em>k</em>). +The indices in <em>l</em> must refer to data stored in the string <em>s</em>. +</p> + +<h4> <code> int sbearssl_skey_readfile (char const *fn, sbearssl_skey *key, stralloc *sa) </code> </h4> + +<p> + Reads a private key from the file named <em>fn</em> and stores it +in <tt>sbearssl</tt> format into the structure in *<em>key</em>, +the bytes of the key being added to the stralloc in *<em>sa</em>. +</p> + +<p> +The private key in <em>fn</em> can be either DER-encoded (binary format) +or PEM-encoded (text format). +</p> + +<p> + The function returns 0 on success. It returns a negative value in +case of a system error, in which case <tt>errno</tt> identifies the +error. It returns a positive value in case of an error returned by +a BearSSL decoder, in which case an appropriate message can be +obtained with the <tt>sbearssl_error_str()</tt> function. +</p> + +<h3> Public keys </h3> + +<p> + BearSSL handles two types of public keys: RSA keys and +EC keys (i.e. points on an elliptic curve). <tt>sbearssl</tt> +adds some generic functions to handle keys no matter their +type. +</p> + +<p> + You normally should not handle public keys directly; +you should handle x509 certificate chains instead. +</p> + +<h4> <code> int sbearssl_rsa_pkey_from (sbearssl_rsa_pkey *l, br_rsa_public_key const *k, stralloc *sa) </code> </h4> + +<p> + Converts the RSA public key from BearSSL format (reading from a structure pointed to by <em>k</em>) +to <tt>sbearssl</tt> format (writing to a structure pointed to by <em>l</em>). +The data from *<em>k</em>'s contents are copied into the stralloc in *<em>sa</em>. +The function returns 1 on success and 0 (and sets errno) on failure. +</p> + +<h4> <code> void sbearssl_rsa_pkey_to (sbearssl_rsa_pkey const *l, br_rsa_public_key *k, char *s) </code> </h4> + +<p> + Converts the RSA public key from <tt>sbearssl</tt> format (reading from a structure pointed to by <em>l</em>) +to BearSSL format (writing to a structure pointed to by <em>k</em>). +The indices in <em>l</em> must refer to data stored in the string <em>s</em>. +</p> + +<h4> <code> int sbearssl_ec_pkey_from (sbearssl_ec_skey *l, br_ec_public_key const *k, stralloc *sa) </code> </h4> + +<p> + Converts the EC public key from BearSSL format (reading from a structure pointed to by <em>k</em>) +to <tt>sbearssl</tt> format (writing to a structure pointed to by <em>l</em>). +The data from *<em>k</em>'s contents are copied into the stralloc in *<em>sa</em>. +The function returns 1 on success and 0 (and sets errno) on failure. +</p> + +<h4> <code> void sbearssl_ec_pkey_to (sbearssl_ec_pkey const *l, br_ec_public_key *k, char *s) </code> </h4> + +<p> + Converts the EC public key from <tt>sbearssl</tt> format (reading from a structure pointed to by <em>l</em>) +to BearSSL format (writing to a structure pointed to by <em>k</em>). +The indices in <em>l</em> must refer to data stored in the string <em>s</em>. +</p> + +<h4> <code> int sbearssl_pkey_from (sbearssl_pkey *l, br_x509_pkey const *k, stralloc *sa) </code> </h4> + +<p> + Converts the public key from BearSSL format (reading from a structure pointed to by <em>k</em>) +to <tt>sbearssl</tt> format (writing to a structure pointed to by <em>l</em>). +The data from *<em>k</em>'s contents are copied into the stralloc in *<em>sa</em>. +The function returns 1 on success and 0 (and sets errno) on failure. +</p> + +<h4> <code> void sbearssl_pkey_to (sbearssl_pkey const *l, br_x509_pkey *k, char *s) </code> </h4> + +<p> + Converts the public key from <tt>sbearssl</tt> format (reading from a structure pointed to by <em>l</em>) +to BearSSL format (writing to a structure pointed to by <em>k</em>). +The indices in <em>l</em> must refer to data stored in the string <em>s</em>. +</p> + +<h3> Generic PEM objects </h3> + +<p> + You normally should not have to call these functions +directly. Instead, you should use the higher-level functions for +private keys, X509 certificate chains and trust anchors, which +will perform the PEM decoding for you. +</p> + +<h4> <code> int sbearssl_pem_decode_from_buffer (buffer *b, genalloc *list, stralloc *sa) </code> </h4> + +<p> + Decodes a PEM object, reading from the +<a href="http://skarnet.org/software/skalibs/libstddjb/buffer.html">buffer</a> +in *<em>b</em>. The decoded bytes are appended to *<em>sa</em>. +<em>list</em> points to a +<a href="http://skarnet.org/software/skalibs/libstddjb/genalloc.html">genalloc</a> +containing objects of type <tt>sbearssl_pemobject</tt>. +One <tt>sbearssl_pemobject</tt> is appended to the genalloc per PEM entity +decoded from the byte stream read from the buffer. +</p> + +<p> + The function returns 0 on success. It returns a negative value in +case of a system error, in which case <tt>errno</tt> identifies the +error. It returns a positive value in case of an error returned by +a BearSSL decoder, in which case an appropriate message can be +obtained with the <tt>sbearssl_error_str()</tt> function. +</p> + +<h4> <code> int sbearssl_pem_decode_from_string (char const *s, size_t len, genalloc *list, stralloc *sa) </code> </h4> + +<p> + Decodes a PEM object from the <em>len</em> bytes pointed to by <em>s</em>. +The decoded bytes are appended to *<em>sa</em>. +<em>list</em> points to a +<a href="http://skarnet.org/software/skalibs/libstddjb/genalloc.html">genalloc</a> +containing objects of type <tt>sbearssl_pemobject</tt>. +One <tt>sbearssl_pemobject</tt> is appended to the genalloc per PEM entity +found in the bytes in <em>s</em>. +</p> + +<p> + The function returns 0 on success. It returns a negative value in +case of a system error, in which case <tt>errno</tt> identifies the +error. It returns a positive value in case of an error returned by +a BearSSL decoder, in which case an appropriate message can be +obtained with the <tt>sbearssl_error_str()</tt> function. +</p> + +<h3> X.509 certificates (typically for servers) </h3> + +<h4> <code> int sbearssl_cert_from (sbearssl_cert *l, br_x509_certificate const *k, stralloc *sa) </code> </h4> + +<p> + Converts a certificate from BearSSL format (reading from a structure pointed to by <em>k</em>) +to <tt>sbearssl</tt> format (writing to a structure pointed to by <em>l</em>). +The data from *<em>k</em>'s contents are copied into the stralloc in *<em>sa</em>. +The function returns 1 on success and 0 (and sets errno) on failure. +</p> + +<h4> <code> void sbearssl_cert_to (sbearssl_cert const *l, br_x509_certificate *k, char *s) </code> </h4> + +<p> + Converts a certificate from <tt>sbearssl</tt> format (reading from a structure pointed to by <em>l</em>) +to BearSSL format (writing to a structure pointed to by <em>k</em>). +The indices in <em>l</em> must refer to data stored in the string <em>s</em>. +</p> + +<h4> <code> int sbearssl_cert_readfile (char const *fn, genalloc *list, stralloc *sa) </code> </h4> + +<p> + Reads one or more certificates from the file named <em>fn</em> and appends +them to the <a href="http://skarnet.org/software/skalibs/libstddjb/genalloc.html">genalloc</a> +in *<em>list</em>, which is a dynamically growing list of +<tt>sbearssl_cert</tt> structures. The bytes of the +(maybe PEM-decoded, but still DER-encoded) certificate are +appended to the stralloc in *<em>sa</em>. +</p> + +<p> + The <em>fn</em> file can be either DER-encoded (binary format) +or PEM-encoded (text format). If it is DER-encoded, it must +contain exactly one X.509 certificate. If it is PEM-encoded, +it may contain a chain of certificates as long as the PEM +file fits within the size limits. +</p> + +<p> + <em>fn</em> must not be bigger than SBEARSSL_MAXCERTFILESIZE, +which is 8 kB. This function is meant to read individual +certificates, not files containing large certificate chains or +sets of trust anchors. To do that, use +<tt>sbearssl_cert_readbigpem()</tt> instead. +</p> + +<p> + The function returns 0 on success. It returns a negative value in +case of a system error, in which case <tt>errno</tt> identifies the +error. It returns a positive value in case of an error returned by +a BearSSL decoder, in which case an appropriate message can be +obtained with the <tt>sbearssl_error_str()</tt> function. +</p> + +<h4> <code> int sbearssl_cert_readbigpem (char const *fn, genalloc *, stralloc *sa) </code> </h4> + +<p> + Reads one or more PEM-encoded certificates from the file named +<em>fn</em> and appends them to the +<a href="http://skarnet.org/software/skalibs/libstddjb/genalloc.html">genalloc</a> +in *<em>list</em>, which is a dynamically growing list of +<tt>sbearssl_cert</tt> structures. The bytes of the PEM-decoded (but +still DER-encoded) certificates are appended to the stralloc +in *<em>sa</em>. +</p> + +<p> + The function will refuse to read a file that is not valid PEM. +Inside the file, It will ignore PEM objects that are +not X.509 certificates. +</p> + +<p> + The function returns 0 on success. It returns a negative value in +case of a system error, in which case <tt>errno</tt> identifies the +error. It returns a positive value in case of an error returned by +a BearSSL decoder, in which case an appropriate message can be +obtained with the <tt>sbearssl_error_str()</tt> function. +</p> + +<h3> Trust anchors (typically for clients) </h3> + +<p> + BearSSL clients do not use X.509-encoded certificates, +they use sets of <em>trust anchors</em>, i.e. structures +decoded from certificates representing (intermediate or) +root CAs. +</p> + +<h4> <code> int sbearssl_ta_from (sbearssl_ta *l, br_x509_trust_anchor const *k, stralloc *sa) </code> </h4> + +<p> + Converts a trust anchor from BearSSL format (reading from a structure pointed to by <em>k</em>) +to <tt>sbearssl</tt> format (writing to a structure pointed to by <em>l</em>). +The data from *<em>k</em>'s contents are copied into the stralloc in *<em>sa</em>. +The function returns 1 on success and 0 (and sets errno) on failure. +</p> + +<h4> <code> void sbearssl_ta_to (sbearssl_ta const *l, br_x509_trust_anchor *k, char *s) </code> </h4> + +<p> + Converts a trust anchor from <tt>sbearssl</tt> format (reading from a structure pointed to by <em>l</em>) +to BearSSL format (writing to a structure pointed to by <em>k</em>). +The indices in <em>l</em> must refer to data stored in the string <em>s</em>. +</p> + +<h4> <code> int sbearssl_ta_readfile (char const *fn, genalloc *list, stralloc *sa) </code> </h4> + +<p> + Reads a set of trust anchors from a PEM file named <em>fn</em> +which must contain a list of (intermediate or) root CA certificates. +The trust anchors are appended to the +<a href="http://skarnet.org/software/skalibs/libstddjb/genalloc.html">genalloc</a> +in *<em>list</em>, which is a dynamically growing list of +<tt>sbearssl_ta</tt> structures. The contents of the trust anchors +are appended to *<em>sa</em>, which is a +<a href="http://skarnet.org/software/skalibs/libstddjb/stralloc.html">stralloc</a> +used for storage. +</p> + +<p> + The function returns 0 on success. It returns a negative value in +case of a system error, in which case <tt>errno</tt> identifies the +error. It returns a positive value in case of an error returned by +a BearSSL decoder, in which case an appropriate message can be +obtained with the <tt>sbearssl_error_str()</tt> function. +</p> + +<h4> <code> int sbearssl_ta_readdir (char const *dir, genalloc *list, stralloc *sa) </code> </h4> + +<p> + Reads a set of trust anchors from a directory named <em>dir</em>, +which must contain a list of (intermediate or) root CA certificates +stored as individual DER- or PEM-encoded files. +The trust anchors are appended to the +<a href="http://skarnet.org/software/skalibs/libstddjb/genalloc.html">genalloc</a> +in *<em>list</em>, which is a dynamically growing list of +<tt>sbearssl_ta</tt> structures. The contents of the trust anchors +are appended to *<em>sa</em>, which is a +<a href="http://skarnet.org/software/skalibs/libstddjb/stralloc.html">stralloc</a> +used for storage. +</p> + +<p> + The function ignores files that do not contain valid DER +or PEM objects containing X.509 certificates representing +certification authorities. +</p> + +<p> + The function returns 0 on success. It returns a negative value in +case of a system error, in which case <tt>errno</tt> identifies the +error. It returns a positive value in case of an error returned by +a BearSSL decoder, in which case an appropriate message can be +obtained with the <tt>sbearssl_error_str()</tt> function. +</p> + +<h3> Miscellaneous utilities </h3> + +<p> + You probably shouldn't need to call any of these functions +directly, except for the first one. +</p> + +<h4> <code> char const *sbearssl_error_str (int err) </code> </h4> + +<p> + Returns a fixed string containing an error message corresponding +to the <em>err</em> code, which must be non-negative. The return +value from a few <tt>sbearssl</tt> functions, if positive, can be +interpreted via this function. +</p> + +<h4> <code> int sbearssl_isder (unsigned char const *s, size_t len) </code> </h4> + +<p> + Tests whether the array of <em>len</em> bytes pointed to by <em>s</em> +looks like a DER-encoded object. Returns 1 if it does and 0 otherwise. +</p> + +<h4> <code> int sbearssl_x509_minimal_set_tai (br_x509_minimal_context *ctx, tai_t t) </code> </h4> + +<p> + Sets the validation time for the X.509 context in *<em>ctx</em> to +the absolute time contained in *<em>t</em>, which is a +<a href="http://skarnet.org/software/skalibs/libstddjb/tai.html">tai_t</a>. +Returns 1 if it succeeds, or 0 if it fails - probably +because *<em>t</em> does not represent a valid time. +</p> + +<h4> <code> int sbearssl_x509_minimal_set_tain (br_x509_minimal_context *ctx, tain_t a) </code> </h4> + +<p> + Same as the above function, except the time is given as a +<a href="http://skarnet.org/software/skalibs/libstddjb/tai.html">tain_t</a>, +i.e. a <tt>tai_t</tt> plus nanoseconds (which are simply ignored). +</p> + + +<h3> Running the TLS/SSL engine (both clients and servers) </h3> + +<h4> <code> int sbearssl_run (br_ssl_engine_context *ctx, int *fds, unsigned int verbosity, uint32_t options, tain_t const *tto) </code> </h4> + +<p> + This function runs a full-duplex TLS/SSL engine, reading/writing +clear text from/to two file descriptors, and writing/reading +ciphertext to/from two other file descriptors, until the +connection is closed both ways (either with a SSL close, or +with EOF). +</p> + +<ul> + <li> <em>ctx</em> is a pointer to a fully initialized context, +connected to <em>fds</em>[2] and <em>fds</em>[3]. The +TLS/SSL handshake does not have to be completed. </li> + <li> <em>fds</em> is an array of 4 file descriptors, in this +order: fd reading clear text, fd writing clear text, fd reading +ciphertext, fd writing ciphertext. </li> + <li> <em>verbosity</em> defines the engine's verbosity: the +higher the more verbose. This parameter is currently ignored. </li> + <li> <em>options</em> is a bitfield. + <ul> + <li> bit 0 tells the engine how to behave when +the local application closes the connection (i.e. when the engine +reads EOF on <em>fds</em>[0]). If the bit is clear, then the +engine will perform as SSL close: it will send a SSL close_notify, +and stop processing incoming records, waiting for a peer +acknowledgement of the close_notify. If the bit is set, then the +engine will not send a close_notify but simply transmit EOF to +the peer, while continuing to process incoming records until it +gets EOF back. close_notify is secure when handling protocols that +are not auto-terminated (such as HTTP 0.9), but it does not permit +separate closing of both ways. EOF allows full-duplex until the +very end, but is insecure if the application protocol does not +know in advance how many bytes it should get. Modern application +protocols should all work with EOF. </li> + </ul> </li> + <li> <em>tto</em> is a pointer to a + <a href="http://skarnet.org/software/skalibs/libstddjb/tai.html">tain_t</a> +containing a relative time (i.e. a timeout) If *<em>tto</em> time elapses +with no application data being exchanged, the engine will forcibly close the +connection (with the method defined by <tt><em>options</em> & 1</tt>). + You can use <tt>&tain_infinite_relative</tt> as a value for <em>tto</em> +if you don't want the engine to ever timeout. </li> +</ul> + +<p> + <tt>sbearssl_run</tt> will make the process die with an appropriate error +message if it encounters an unrecoverable error. If there were no problems +and the SSL/TLS connection closed cleanly, it returns 0. If a SSL/TLS-level +error occurred, it returns nonzero; a corresponding error message for the +return value can be obtained via <tt>sbearssl_error_str()</tt>. +All four descriptors in <em>fds</em> are closed when +<tt>sbearssl_run</tt> returns. +</p> + +<h4> <code> int sbearssl_s6tlsc (char const *const *argv, char const *const *envp, tain_t const *tto, uint32_t preoptions, uint32_t options, uid_t uid, gid_t gid, unsigned int verbosity, char const *servername, int *sfd) </code> </h4> + +<p> + This function implements <a href="../s6-tlsc.html">s6-tlsc</a> on top of BearSSL. +It has no other practical purpose; you're better off directly invoking +<a href="../s6-tlsc.html">s6-tlsc</a>. +</p> + +<h4> <code> int sbearssl_s6tlsd (char const *const *argv, char const *const *envp, tain_t const *tto, uint32_t preoptions, uint32_t options, uid_t uid, gid_t gid, unsigned int verbosity) </code> </h4> + +<p> + This function implements <a href="../s6-tlsd.html">s6-tlsd</a> on top of BearSSL. +It has no other practical purpose; you're better off directly invoking +<a href="../s6-tlsd.html">s6-tlsd</a>. +</p> + +</body> +</html> |