*
NAME¶
imclient - (library) authenticating callback interface to IMAP/IMSP servers
SYNOPSIS¶
#include <cyrus/imclient.h>
int imclient_connect(struct imclient **imclient, const char
*host, const char *port);
void imclient_close (struct imclient *imclient);
void imclient_setflags(struct imclient *imclient,
intflags);
void imclient_clearflags (struct imclient *imclient,
intflags);
char* imclient_servername (struct imclient *imclient);
void imclient_addcallback (struct imclient * imclient ,...);
void imclient_send (struct imclient *imclient, void
(*finishproc)(), void *finishrock, const char
*fmt, ...);
void imclient_getselectinfo (struct imclient *imclient, int
*fd, int * wanttowrite);
void imclient_processoneevent (struct imclient *imclient);
int imclient_authenticate (struct imclient *imclient, struct
sasl_client **availmech, const char *service,
const char *user, int protallowed);
int imclient_havetls ();
int imclient_starttls (struct imclient *imclient, char
*cert_file, char *key_file, char
*CAfile, char *CApath);
DESCRIPTION¶
The imclient library functions are distributed with Cyrus IMAP and IMSP. These
functions are used for building IMAP/IMSP client software. These functions
handle Kerberos authentication and can set callbacks based on the keyword in
untagged replies or based on the command tag at the end of command replies.
Users must link with the -lcyrus switch, and must supply a function called
fatal to be called in case of any error within
libcyrus.a.
All of the
imclient functions begin with the prefix
imclient and
takes an argument of type
struct imclient * as the first argument which
is initialized by
imclient_connect and freed by
imclient_close.
See below for a description of each function.
- imclient_connect()
- Connects the client server to the host. If successful, it
returns 0 and sets the imclient argument to a pointer to an
imclient struct. The imclient struct represents the current
connection, flags, and callbacks. On failure, the current errno is
returned if a system call failed, -1 is returned if the host name was not
found, and -2 is returned if the service name was not found.
- imclient_close()
- Closes and frees the imclient connection.
- imclient_setflags()
- Sets the flags specified by the flags argument on
the imclient connection. Currently the only flag allowed is
IMCLIENT_CONN_NONSYNCLITERAL (this flag indicates that the server
supports non-synchronizing literals described by the LITERAL+
extension).
- imclient_clearflags()
- Clears the flags specified by the flags argument on
the imclient connection.
- imclient_servername()
- Returns a char * pointer to the name of the server
connected to by imclient.
- imclient_addcallback()
- Adds an untagged data callback to the imclient
connection. The function imclient_addcallback takes callbacks of
the type imclient_proc_t which is defined to be:
typedef void imclient_proc_t (struct imclient *imclient, void *rock, struct
imclient_reply *reply);
and struct imclient_reply * is defined to be:
struct imclient_reply {
char *keyword;
long msgno;
char *text;
};
After the first argument imclient, there can be zero or more
instances of the set of keyword, flags, proc, and
rock, each adding or changing a single callback. Each instance adds
or changes the callback for keyword. The argument, flags,
specifies information about the parsing of the untagged data. proc
and rock specify the callback function and rock to invoke when the
untagged data is received. proc may be a null pointer, in which
case no function is invoked. The callback function may not call the
functions imclient_close(), imclient_send(), imclient_eof(),
imclient_processoneevent(), or imclient_authenticate() on
the connection. The callback function may over write the text of untagged
data.
- imclient_send()
- Sends a new command to the imclient connection.
finishproc and finnishrock are the function and rock called
when the command completes. functionproc may be a null pointer, in
which case no callback is made. The call back function may not call the
functions imclient_close(), imclient_send(), imclient_eof(),
imclient_processoneevent(), or imclient_authenticate() on the
connection. The argument, fmt , is a print like specification of
the command. It must not include the tag as the tag is automatically added
by imclient_send(). The defined %-sequences are:
%% for %
%a for an IMAP atom
%s for an astring (which will be quoted or literalized as needed)
%d for a decimal
%u for an unsigned decimal
%v for #astring (argument is a null-terminated array of char *
which are written as space separated astrings)
- imclient_getselectinfo()
- Gets the information for calling select(2).
fd is filled in with the file descriptor to select(2) for
read. wanttowrite is filled in with a nonzero value if select
should be used for write as well.
- imclient_processoneevent()
- Processes one input or output event on the imclient
connection.
- imclient_authenticate()
- Authenticates the imclient connection using one of
the mechanisms in availmech. The argument, user, if not
NULL, specifies the user to authenticate as. If the user is NULL, the
current user is used. The argument protallowed is a bitmask of
permissible protection mechanisms.
On success, 0 is returned. On failure (i.e., "BAD" keyboard, or no
authentication mechanisms worked), 1 is returned. On extreme failure
(premature "OK"), 2 is returned.
- imclient_havetls()
- Returns a Boolean indicating whether the imclient
library was compiled with TLS (SSL) support. If so,
imclient_starttls() may be used to secure the IMAP connection.
- imclient_starttls()
- Issues a STARTTLS command on an existing IMAP connection
and negotiates the secure link. The cert_file and key_file
arguments specify the client certificate and secret key to use to
authenticate ourselves to the server. If client authentication is not
needed, set both of these arguments to NULL.
The CAfile and CApath arguments specify a file or directory,
respectively, of CA certificates for validating server certificates. (See
SSL_CTX_load_verify_locations(3) for details.) If both of these are
NULL, the client will be unable to validate the server's certificate, in
which case the connection may succeed but a warning will be printed to
stdout.
EXAMPLES¶
The following code is a possible skeletion of
imclient that relies on
Kerberos to do authentication. This code preforms an IMAP CAPABILITY request
and prints out the result.
struct sasl_client;
#include <cyrus/xmalloc.h> /* example uses xstrdup */
#include <cyrus/sasl.h>
#include <cyrus/imclient.h>
#include <stdio.h>
extern struct sasl_client krb_sasl_client;
struct sasl_client *login_sasl_client[] = {
&krb_sasl_client,
NULL
};
struct imclient *imclient;
char server[] = "cyrus.andrew.cmu.edu" ;
char port[] = "imap";
void fatal(char* message, int rc) {
fprintf(stderr, "fatal error: %s\n", message);
exit(rc);
}
static void callback_capability(struct imclient *imclient,
void *rock,
struct imclient_reply *reply) {
if (reply->text != NULL) {
*((char**)rock) = xstrdup( reply->text );
}
}
static void end_command (struct imclient *connection, void*
rock, struct imclient_reply *inmsg) {
(*(int*)rock)--;
}
main() {
char* capability_string;
int nc;
if (imclient_connect(&imclient, server, port)) {
fprintf(stderr,
"error: Couldn't connect to %s %s\n",
server, port);
exit(1);
}
if (imclient_authenticate(imclient, login_sasl_client, "imap"
/* service */,
NULL /* user */, SASL_PROT_ANY)) {
exit(1);
}
imclient_addcallback(imclient, "CAPABILITY",
CALLBACK_NOLITERAL,
callback_capability,
&capability_string,
NULL);
nc = 1;
imclient_send(imclient, end_command,
(void*) &nc, "CAPABILITY");
while(nc > 0) {
imclient_processoneevent(imclient);
}
if (strstr("LITERAL+", capability_string)) {
imclient_setflags(imclient, IMCLIENT_CONN_NONSYNCLITERAL);
}
imclient_send(imclient, NULL, NULL, "LOGOUT");
imclient_close(imclient);
printf("capability text is: %s\n", capability_string);
free(capability_string);
}
BUGS¶
No known bugs.
SEE ALSO¶
cyradm, imapd, imspd, RFC2033 (IMAP LITERAL+ extension), RFC2060
(IMAP4rev1 specification), and
select(2)
KEYWORDS¶
IMAP, ACAP, IMSP, Kerberos, Authentication