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       imclient - Cyrus IMAP documentation

       Authenticating callback interface to IMAP/IMSP servers


       #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 , int flags);
       void imclient_clearflags (struct imclient *imclient , int flags);
       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);


       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

       All  of  the  imclient  functions begin with the prefix imclient and take  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.

              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.

              Closes and frees the imclient connection.

              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).

              Clears the flags specified by the flags argument on the imclient connection.

              Returns a char * pointer to the name of the server connected to by imclient.

              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 overwrite  the text of untagged data.

              Sends a new command to the imclient connection.  finishproc and finishrock are  the
              function  and  rock  called when the command completes.  functionproc may be a null
              pointer, in which case no callback is made. The callback 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 printf(3) 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)

              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.

              Processes one input or output event on the imclient connection.

              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.

              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

              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.


       The following code is a possible skeleton of  imclient  that  relies  on  Kerberos  to  do
       authentication.  This code performs an IMAP CAPABILITY request and prints out the result.

          #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[] = {
          struct imclient *imclient;
          char server[] = "" ;
          char port[] = "imap";

          void fatal(char* message, int rc) {
              fprintf(stderr, "fatal error: %s\en", message);

          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) {

          main() {
              char* capability_string;
              int nc;

              if (imclient_connect(&imclient, server, port)) {
                          "error: Couldn't connect to %s %s\en",
                          server, port);

              if (imclient_authenticate(imclient, login_sasl_client, "imap"
                                        /* service */,
                                        NULL /* user */, SASL_PROT_ANY)) {

              imclient_addcallback(imclient, "CAPABILITY",

              nc = 1;

              imclient_send(imclient, end_command,
                            (void*) &nc, "CAPABILITY");

              while(nc > 0) {

              if (strstr("LITERAL+", capability_string)) {
                  imclient_setflags(imclient, IMCLIENT_CONN_NONSYNCLITERAL);

              imclient_send(imclient, NULL, NULL, "LOGOUT");

              printf("capability text is: %s\en", capability_string);



       No known bugs.


       cyradm(8),   imapd(8),   RFC   2033   (IMAP   LITERAL+  extension),  RFC  2060  (IMAP4rev1
       specification), and select(2)


       IMAP, ACAP, IMSP, Kerberos, Authentication


       The Cyrus Team, Nic Bernstein (Onlight)


       1993-2017, The Cyrus Team