@ -2,13 +2,15 @@
=head1 NAME
OSSL_HTTP_open,
OSSL_HTTP_bio_cb_t,
OSSL_HTTP_proxy_connect,
OSSL_HTTP_set_request,
OSSL_HTTP_exchange,
OSSL_HTTP_get,
OSSL_HTTP_get_asn1,
OSSL_HTTP_post_asn1,
OSSL_HTTP_transfer,
OSSL_HTTP_bio_cb_t,
OSSL_HTTP_proxy_connect
- http client functions
OSSL_HTTP_close
- HTTP client high-level functions
=head1 SYNOPSIS
@ -16,91 +18,53 @@ OSSL_HTTP_proxy_connect
typedef BIO *(*OSSL_HTTP_bio_cb_t)(BIO *bio, void *arg,
int connect, int detail);
OSSL_HTTP_REQ_CTX *OSSL_HTTP_open(const char *server, const char *port,
const char *proxy, const char *no_proxy,
int use_ssl, BIO *bio, BIO *rbio,
OSSL_HTTP_bio_cb_t bio_update_fn, void *arg,
int buf_size, int overall_timeout);
int OSSL_HTTP_proxy_connect(BIO *bio, const char *server, const char *port,
const char *proxyuser, const char *proxypass,
int timeout, BIO *bio_err, const char *prog);
int OSSL_HTTP_set_request(OSSL_HTTP_REQ_CTX *rctx, const char *path,
const STACK_OF(CONF_VALUE) *headers,
const char *content_type, BIO *req,
const char *expected_content_type, int expect_asn1,
size_t max_resp_len, int timeout, int keep_alive);
BIO *OSSL_HTTP_exchange(OSSL_HTTP_REQ_CTX *rctx, char **redirection_url);
BIO *OSSL_HTTP_get(const char *url, const char *proxy, const char *no_proxy,
BIO *bio, BIO *rbio,
OSSL_HTTP_bio_cb_t bio_update_fn, void *arg,
const STACK_OF(CONF_VALUE) *headers,
int maxline, unsigned long max_resp_len, int timeout,
const char *expected_ct, int expect_asn1);
ASN1_VALUE *OSSL_HTTP_get_asn1(const char *url,
const char *proxy, const char *no_proxy,
BIO *bio, BIO *rbio,
OSSL_HTTP_bio_cb_t bio_update_fn, void *arg,
const STACK_OF(CONF_VALUE) *headers,
int maxline, unsigned long max_resp_len,
int timeout, const char *expected_ct,
const ASN1_ITEM *rsp_it);
ASN1_VALUE *OSSL_HTTP_post_asn1(const char *server, const char *port,
const char *path, int use_ssl,
const char *proxy, const char *no_proxy,
BIO *bio, BIO *rbio,
OSSL_HTTP_bio_cb_t bio_update_fn, void *arg,
const STACK_OF(CONF_VALUE) *headers,
const char *content_type,
const ASN1_VALUE *req, const ASN1_ITEM *req_it,
int maxline, unsigned long max_resp_len,
int timeout, const char *expected_ct,
const ASN1_ITEM *rsp_it);
BIO *OSSL_HTTP_transfer(const char *server, const char *port, const char *path,
int use_ssl, const char *proxy, const char *no_proxy,
int buf_size, const STACK_OF(CONF_VALUE) *headers,
const char *expected_content_type, int expect_asn1,
size_t max_resp_len, int timeout);
BIO *OSSL_HTTP_transfer(OSSL_HTTP_REQ_CTX **prctx,
const char *server, const char *port,
const char *path, int use_ssl,
const char *proxy, const char *no_proxy,
BIO *bio, BIO *rbio,
OSSL_HTTP_bio_cb_t bio_update_fn, void *arg,
const STACK_OF(CONF_VALUE) *headers,
const char *content_type, BIO *req_mem,
int maxline, unsigned long max_resp_len, int timeout,
const char *expected_ct, int expect_asn1,
char **redirection_url);
int OSSL_HTTP_proxy_connect(BIO *bio, const char *server, const char *port,
const char *proxyuser, const char *proxypass,
int timeout, BIO *bio_err, const char *prog);
int buf_size, const STACK_OF(CONF_VALUE) *headers,
const char *content_type, BIO *req,
const char *expected_content_type, int expect_asn1,
size_t max_resp_len, int timeout, int keep_alive);
int OSSL_HTTP_close(OSSL_HTTP_REQ_CTX *rctx, int ok);
=head1 DESCRIPTION
OSSL_HTTP_get() uses HTTP GET to obtain data (of any type) from the given I<url>
and returns it as a memory BIO.
If the schema component of the I<url> is C<https> a TLS connection is requested
and the I<bio_update_fn> parameter, described below, must be provided.
Any userinfo and fragment components in the I<url> are ignored.
Any query component is handled as part of the path component.
OSSL_HTTP_get_asn1() is like OSSL_HTTP_get() but in addition
parses the received contents (e.g., an X.509 certificate)
as an ASN.1 DER encoded value with the expected structure specified by I<rsp_it>
and returns it on success as a pointer to I<ASN1_VALUE>.
OSSL_HTTP_post_asn1() is like OSSL_HTTP_get_asn1() but uses the HTTP POST method
to send a request I<req> with the ASN.1 structure defined in I<req_it> and the
given I<content_type> to the given I<server> and optional I<port> and I<path>.
If I<use_ssl> is nonzero a TLS connection is requested and the I<bio_update_fn>
parameter, described below, must be provided.
OSSL_HTTP_open() initiates an HTTP session using the I<bio> argument if not
NULL, else by connecting to a given I<server> optionally via a I<proxy>.
OSSL_HTTP_transfer() exchanges any form of HTTP request and response.
It implements the core of the functions described above.
If I<path> parameter is NULL it defaults to "/".
If I<use_ssl> is nonzero a TLS connection is requested
and the I<bio_update_fn> parameter, described below, must be provided.
If I<req_mem> is NULL it uses the HTTP GET method, else it uses HTTP POST to
send a request with the contents of the memory BIO and optional I<content_type>.
The optional list I<headers> may contain additional custom HTTP header lines.
If I<req_mem> is NULL (i.e., the HTTP method is GET) and I<redirection_url>
is not NULL the latter pointer is used to provide any new location that
the server may return with HTTP code 301 (MOVED_PERMANENTLY) or 302 (FOUND).
In this case the caller is responsible for deallocating this URL with
L<OPENSSL_free(3)>.
The above functions have the following parameters in common.
Typically the OpenSSL build supports sockets
and the I<bio> and I<rbio> parameters are both NULL.
In this case the client creates a network BIO internally
for connecting to the given I<server>
at the specified I<port> (if any, defaulting to 80 for HTTP or 443 for HTTPS),
optionally via a I<proxy> (respecting I<no_proxy>) as described below.
Then the client uses this internal BIO for exchanging the request and response.
If I<bio> is given and I<rbio> is NULL then the client uses this I<bio> instead.
Typically the OpenSSL build supports sockets and the I<bio> parameter is NULL.
In this case I<rbio> must be NULL as well, and the
library creates a network BIO internally for connecting to the given I<server>
at the specified I<port> if any, defaulting to 80 for HTTP or 443 for HTTPS.
Then this internal BIO is used for setting up a connection
and for exchanging one or more request and response.
If I<bio> is given and I<rbio> is NULL then this I<bio> is used instead.
If both I<bio> and I<rbio> are given (which may be memory BIOs for instance)
then no explicit connection is attempted,
I<bio> is used for writing the request, and I<rbio> for reading the response .
then no explicit connection is set up, but
I<bio> is used for writing requests and I<rbio> for reading responses.
As soon as the client has flushed I<bio> the server must be ready to provide
a response or indicate a waiting condition via I<rbio>.
@ -121,33 +85,12 @@ Proxying plain HTTP is supported directly,
while using a proxy for HTTPS connections requires a suitable callback function
such as OSSL_HTTP_proxy_connect(), described below.
The I<maxline> parameter specifies the response header maximum line length,
where a value <= 0 indicates that the B<HTTP_DEFAULT_MAX_LINE_LENGTH> of 4KiB
should be used.
This length is also used as the number of content bytes that are read at a time.
The I<max_resp_len> parameter specifies the maximum response length,
where 0 indicates B<HTTP_DEFAULT_MAX_RESP_LEN>, which currently is 100 KiB.
An ASN.1-encoded response is expected by OSSL_HTTP_get_asn1() and
OSSL_HTTP_post_asn1(), while for OSSL_HTTP_get() or OSSL_HTTP_transfer()
this is only the case if the I<expect_asn1> parameter is nonzero.
If the response header contains one or more "Content-Length" header lines and/or
an ASN.1-encoded response is expected, which should include a total length,
the length indications received are checked for consistency
and for not exceeding the maximum response length.
If the parameter I<expected_ct>
is not NULL then the HTTP client checks that the given content type string
is included in the HTTP header of the response and returns an error if not.
If the I<timeout> parameter is > 0 this indicates the maximum number of seconds
to wait until the transfer is complete.
A value of 0 enables waiting indefinitely,
while a value < 0 immediately leads to a timeout condition.
If I<use_ssl> is nonzero a TLS connection is requested
and the I<bio_update_fn> parameter must be provided.
The optional parameter I<bio_update_fn> with its optional argument I<arg> may
be used to modify the connection BIO used by the HTTP client (and cannot be
used when both I<bio> and I<rbio> are given) .
The parameter I<bio_update_fn>, which is optional if I<use_ssl> is 0,
may be used to modify the connection BIO used by the HTTP client,
but cannot be used when both I<bio> and I<rbio> are given.
I<bio_update_fn> is a BIO connect/disconnect callback function with prototype
BIO *(*OSSL_HTTP_bio_cb_t)(BIO *bio, void *arg, int connect, int detail)
@ -157,7 +100,7 @@ whereby it may make use of a custom defined argument I<arg>,
which may for instance refer to an I<SSL_CTX> structure.
During connection establishment, just after calling BIO_do_connect_retry(),
the function is invoked with the I<connect> argument being 1 and the I<detail>
argument being 1 if HTTPS is requested, i.e., SSL/TLS should be enabled.
argument being 1 if HTTPS is requested, i.e., SSL/TLS should be enabled, else 0 .
On disconnect I<connect> is 0 and I<detail> is 1 if no error occurred, else 0.
For instance, on connect the function may prepend a TLS BIO to implement HTTPS;
after disconnect it may do some diagnostic output and/or specific cleanup.
@ -166,10 +109,10 @@ Here is a simple example that supports TLS connections (but not via a proxy):
BIO *http_tls_cb(BIO *hbio, void *arg, int connect, int detail)
{
SSL_CTX *ctx = (SSL_CTX *)arg;
if (connect && detail) { /* connecting with TLS */
SSL_CTX *ctx = (SSL_CTX *)arg;
BIO *sbio = BIO_new_ssl(ctx, 1);
hbio = sbio != NULL ? BIO_push(sbio, hbio) : NULL;
} else if (!connect && !detail) { /* disconnecting after error */
/* optionally add diagnostics here */
@ -179,6 +122,16 @@ Here is a simple example that supports TLS connections (but not via a proxy):
After disconnect the modified BIO will be deallocated using BIO_free_all().
The I<buf_size> parameter specifies the response header maximum line length.
A value <= 0 indicates that
the B<HTTP_DEFAULT_MAX_LINE_LENGTH> of 4KiB should be used.
I<buf_size> is also used as the number of content bytes that are read at a time.
If the I<overall_timeout> parameter is > 0 this indicates the maximum number of
seconds the overall HTTP transfer (i.e., connection setup if needed,
sending requests, and receiving responses) is allowed to take until completion.
A value <= 0 enables waiting indefinitely, i.e., no timeout.
OSSL_HTTP_proxy_connect() may be used by an above BIO connect callback function
to set up an SSL/TLS connection via an HTTPS proxy.
It promotes the given BIO I<bio> representing a connection
@ -186,11 +139,86 @@ pre-established with a TLS proxy using the HTTP CONNECT method,
optionally using proxy client credentials I<proxyuser> and I<proxypass>,
to connect with TLS protection ultimately to I<server> and I<port>.
If the I<port> argument is NULL or the empty string it defaults to "443".
The I<timeout> parameter is used as described above.
If the I<timeout> parameter is > 0 this indicates the maximum number of
seconds the connection setup is allowed to take.
A value <= 0 enables waiting indefinitely, i.e., no timeout.
Since this function is typically called by applications such as
L<openssl-s_client(1)> it uses the I<bio_err> and I<prog> parameters (unless
NULL) to print additional diagnostic information in a user-oriented way.
OSSL_HTTP_set_request() sets up in I<rctx> the request header and content data
and expectations on the response using the following parameters.
If I<path> is NULL it defaults to "/".
If I<req> is NULL the HTTP GET method will be used to send the request
else HTTP POST with the contents of I<req> and optional I<content_type>, where
the length of the data in I<req> does not need to be determined in advance: the
BIO will be read on-the-fly while sending the request, which supports streaming.
The optional list I<headers> may contain additional custom HTTP header lines.
If the parameter I<expected_content_type>
is not NULL then the client will check that the given content type string
is included in the HTTP header of the response and return an error if not.
If the I<expect_asn1> parameter is nonzero,
a structure in ASN.1 encoding will be expected as response content.
The I<max_resp_len> parameter specifies the maximum allowed
response content length, where the value 0 indicates no limit.
If the I<timeout> parameter is > 0 this indicates the maximum number of seconds
the subsequent HTTP transfer (sending the request and receiving a response)
is allowed to take.
A value of 0 enables waiting indefinitely, i.e., no timeout.
A value < 0 indicates that the I<overall_timeout> parameter value given
when opening the HTTP transfer will be used instead.
If I<keep_alive> is 0 the connection is not kept open
after receiving a response, which is the default behavior for HTTP 1.0.
If the value is 1 or 2 then a persistent connection is requested.
If the value is 2 then a persistent connection is required,
i.e., an error occurs in case the server does not grant it.
OSSL_HTTP_exchange() exchanges any form of HTTP request and response
as specified by I<rctx>, which must include both connection and request data,
typically set up using OSSL_HTTP_open() and OSSL_HTTP_set_request().
It implements the core of the functions described below.
If the HTTP method is GET and I<redirection_url>
is not NULL the latter pointer is used to provide any new location that
the server may return with HTTP code 301 (MOVED_PERMANENTLY) or 302 (FOUND).
In this case the function returns NULL and the caller is
responsible for deallocating the URL with L<OPENSSL_free(3)>.
If the response header contains one or more "Content-Length" header lines and/or
an ASN.1-encoded response is expected, which should include a total length,
the length indications received are checked for consistency
and for not exceeding any given maximum response length.
On receiving a response, the function returns the contents as a memory BIO,
which does not support streaming, in case an ASN.1-encoded response is expected.
Else it returns directly the read BIO that holds the response contents,
which allows a response of indefinite length and may support streaming.
OSSL_HTTP_get() uses HTTP GET to obtain data from I<bio> if non-NULL,
else from the server contained in the I<url>, and returns it as a BIO.
It supports redirection via HTTP status code 301 or 302. It is meant for
transfers with a single round trip, so does not support persistent connections.
If I<bio> is non-NULL, any host and port components in the I<url> are not used
for connecting but the hostname is used, as usual, for the C<Host> header.
Any userinfo and fragment components in the I<url> are ignored.
Any query component is handled as part of the path component.
If the scheme component of the I<url> is C<https> a TLS connection is requested
and the I<bio_update_fn>, as described for OSSL_HTTP_open(), must be provided.
Also the remaining parameters are interpreted as described for OSSL_HTTP_open()
and OSSL_HTTP_set_request(), respectively.
OSSL_HTTP_transfer() exchanges an HTTP request and response
over a connection managed via I<prctx> without supporting redirection.
It combines OSSL_HTTP_open(), OSSL_HTTP_set_request(), OSSL_HTTP_exchange(),
and OSSL_HTTP_close().
If I<prctx> is not NULL it reuses any open connection represented by a non-NULL
I<*prctx>. It keeps the connection open if a persistent connection is requested
or required and this was granted by the server, else it closes the connection
and assigns NULL to I<*prctx>.
The remaining parameters are interpreted as described for OSSL_HTTP_open()
and OSSL_HTTP_set_request(), respectively.
OSSL_HTTP_close() closes the connection and releases I<rctx>.
The I<ok> parameter is passed to any BIO update function
given during setup as described above for OSSL_HTTP_open().
=head1 NOTES
The names of the environment variables used by this implementation:
@ -200,23 +228,29 @@ other HTTP client implementations such as wget, curl, and git.
=head1 RETURN VALUES
On success, OSSL_HTTP_get(), OSSL_HTTP_get_asn1(), OSSL_HTTP_post_asn1(), and
OSSL_HTTP_transfer() return a memory BIO containing the data received via HTTP.
This must be freed by the caller. On failure, NULL is returned.
OSSL_HTTP_open() returns on success a B<OSSL_HTTP_REQ_CTX>, else NULL.
OSSL_HTTP_proxy_connect() and OSSL_HTTP_set_request()
return 1 on success, 0 on error.
On success, OSSL_HTTP_exchange(), OSSL_HTTP_get(), and OSSL_HTTP_transfer()
return a memory BIO containing the data received if an ASN.1-encoded response
is expected, else a BIO that may support streaming.
The BIO must be freed by the caller.
On failure, they return NULL.
Failure conditions include connection/transfer timeout, parse errors, etc.
OSSL_HTTP_proxy_connect() returns 1 on success, 0 on error.
OSSL_HTTP_close() returns 0 if anything went wrong while disconnecting, else 1 .
=head1 SEE ALSO
L<OSSL_HTTP_parse_url(3)>
L<BIO_set_conn_port(3)>
L<OSSL_HTTP_parse_url(3)>, L<BIO_set_conn_port(3)>
L<ASN1_item_i2d_mem_bio(3)>, L<ASN1_item_d2i_bio(3)>,
L<OSSL_HTTP_is_alive(3)>
=head1 HISTORY
OSSL_HTTP_get(), OSSL_HTTP_get_asn1(), OSSL_HTTP_post_asn1(),
OSSL_HTTP_transfer(), and OSSL_HTTP_proxy_connect()
were added in OpenSSL 3.0.
All the functions described here were added in OpenSSL 3.0.
=head1 COPYRIGHT
Dr. David von Oheimb
2 years ago
committed by