/* * implicitclass backend for implementing an implicit-class-like behavior * of redundant print servers managed by cups-browsed. * * Copyright 2015 by Till Kamppeter * * This is based on dnssd.c of CUPS * dnssd.c copyright notice is follows: * * Copyright 2008-2015 by Apple Inc. * * These coded instructions, statements, and computer programs are the * property of Apple Inc. and are protected by Federal copyright * law. Distribution and use rights are outlined in the file "COPYING" * which should have been included with this file. */ /* * Include necessary headers. */ #include "backend-private.h" #include #include /* * Local globals... */ /* IPP Attribute which cups-browsed uses to tell us the destination queue for the current job */ #define CUPS_BROWSED_DEST_PRINTER "cups-browsed-dest-printer" static int job_canceled = 0; /* Set to 1 on SIGTERM */ /* * Local functions... */ static void sigterm_handler(int sig); /* * 'main()' - Browse for printers. */ int /* O - Exit status */ main(int argc, /* I - Number of command-line args */ char *argv[]) /* I - Command-line arguments */ { const char *device_uri; /* URI with which we were called */ char queue_name[1024]; const char *ptr1; char *ptr2; const char *job_id; int i; char dest_host[1024]; /* Destination host */ ipp_t *request, *response; ipp_attribute_t *attr; char uri[HTTP_MAX_URI]; static const char *pattrs[] = { "printer-defaults" }; #if defined(HAVE_SIGACTION) && !defined(HAVE_SIGSET) struct sigaction action; /* Actions for POSIX signals */ #endif /* HAVE_SIGACTION && !HAVE_SIGSET */ /* * Don't buffer stderr, and catch SIGTERM... */ setbuf(stderr, NULL); #ifdef HAVE_SIGSET /* Use System V signals over POSIX to avoid bugs */ sigset(SIGTERM, sigterm_handler); #elif defined(HAVE_SIGACTION) memset(&action, 0, sizeof(action)); sigemptyset(&action.sa_mask); action.sa_handler = sigterm_handler; sigaction(SIGTERM, &action, NULL); #else signal(SIGTERM, sigterm_handler); #endif /* HAVE_SIGSET */ /* * Check command-line... */ if (argc >= 6) { if ((device_uri = getenv("DEVICE_URI")) == NULL) { if (!argv || !argv[0] || !strchr(argv[0], ':')) return (-1); device_uri = argv[0]; } if ((ptr1 = strchr(device_uri, ':')) == NULL) { fprintf(stderr, "ERROR: Incorrect device URI syntax: %s\n", device_uri); return (CUPS_BACKEND_STOP); } ptr1 ++; strncpy(queue_name, ptr1, sizeof(queue_name)); httpAssembleURIf(HTTP_URI_CODING_ALL, uri, sizeof(uri), "ipp", NULL, "localhost", ippPort(), "/printers/%s", queue_name); job_id = argv[1]; for (i = 0; i < 40; i++) { /* Wait up to 20 sec for cups-browsed to supply the destination host */ /* Try reading the option in which cups-browsed has deposited the destination host */ request = ippNewRequest(IPP_OP_GET_PRINTER_ATTRIBUTES); ippAddString(request, IPP_TAG_OPERATION, IPP_TAG_URI, "printer-uri", NULL, uri); ippAddStrings(request, IPP_TAG_OPERATION, IPP_TAG_KEYWORD, "requested-attributes", sizeof(pattrs) / sizeof(pattrs[0]), NULL, pattrs); ippAddString(request, IPP_TAG_OPERATION, IPP_TAG_NAME, "requesting-user-name", NULL, cupsUser()); if ((response = cupsDoRequest(CUPS_HTTP_DEFAULT, request, "/")) == NULL) goto failed; for (attr = ippFirstAttribute(response); attr != NULL; attr = ippNextAttribute(response)) { while (attr != NULL && ippGetGroupTag(attr) != IPP_TAG_PRINTER) attr = ippNextAttribute(response); if (attr == NULL) break; ptr1 = NULL; while (attr != NULL && ippGetGroupTag(attr) == IPP_TAG_PRINTER) { if (!strcmp(ippGetName(attr), CUPS_BROWSED_DEST_PRINTER "-default")) ptr1 = ippGetString(attr, 0, NULL); if (ptr1 != NULL) break; attr = ippNextAttribute(response); } if (ptr1 != NULL) break; } fprintf(stderr, "DEBUG: Read " CUPS_BROWSED_DEST_PRINTER " option: %s\n", ptr1); if (ptr1 == NULL) goto failed; /* Destination host is between double quotes, as double quotes are illegal in host names one easily recognizes whether the option is complete and avoids accepting a partially written host name */ if (*ptr1 != '"') goto failed; ptr1 ++; /* Check whether option was set for this job, if not, keep waiting */ if (strncmp(ptr1, job_id, strlen(job_id)) != 0) goto failed; ptr1 += strlen(job_id); if (*ptr1 != ' ') goto failed; ptr1 ++; /* Read destination host name (or message) and check whether it is complete (second double quote) */ strncpy(dest_host, ptr1, sizeof(dest_host)); ptr1 = dest_host; if ((ptr2 = strchr(ptr1, '"')) != NULL) { *ptr2 = '\0'; ippDelete(response); break; } failed: ippDelete(response); /* Pause half a second before next attempt */ usleep(500000); } if (i >= 40) { /* Timeout, no useful data from cups-browsed received */ fprintf(stderr, "ERROR: No destination host name supplied by cups-browsed for printer \"%s\", is cups-browsed running?\n", queue_name); return (CUPS_BACKEND_STOP); } if (!strcmp(dest_host, "NO_DEST_FOUND")) { /* All remote queues are either disabled or not accepting jobs, let CUPS retry after the usual interval */ fprintf(stderr, "ERROR: No suitable destination host found by cups-browsed.\n"); return (CUPS_BACKEND_RETRY); } else if (!strcmp(dest_host, "ALL_DESTS_BUSY")) { /* We queue on the client and all remote queues are busy, so we wait 5 sec and check again then */ fprintf(stderr, "DEBUG: No free destination host found by cups-browsed, retrying in 5 sec.\n"); sleep(5); return (CUPS_BACKEND_RETRY_CURRENT); } else { /* We have the destination host name now, do the job */ char server_str[1024]; const char *title; int num_options = 0; cups_option_t *options = NULL; int fd, job_id; char buffer[8192]; fprintf(stderr, "DEBUG: Received destination host name from cups-browsed: %s\n", dest_host); /* Instead of feeding the job into the IPP backend, we re-print it into the server's CUPS queue. This way the job gets spooled on the server and we are not blocked until the job is printed. So a subsequent job will be immediately processed and sent out to another server */ /* Set destination server */ snprintf(server_str, sizeof(server_str), "%s", dest_host); cupsSetServer(server_str); /* Parse the command line option and prepare them for the new print job */ cupsSetUser(argv[2]); title = argv[3]; if (title == NULL) { if (argc == 7) { if ((title = strrchr(argv[6], '/')) != NULL) title ++; else title = argv[6]; } else title = "(stdin)"; } num_options = cupsAddOption("copies", argv[4], num_options, &options); num_options = cupsParseOptions(argv[5], num_options, &options); if (argc == 7) fd = open(argv[6], O_RDONLY); else fd = 0; /* stdin */ /* Queue the job directly on the server */ if ((job_id = cupsCreateJob(CUPS_HTTP_DEFAULT, queue_name, title ? title : "(stdin)", num_options, options)) > 0) { http_status_t status; /* Write status */ const char *format; /* Document format */ ssize_t bytes; /* Bytes read */ if (cupsGetOption("raw", num_options, options)) format = CUPS_FORMAT_RAW; else if ((format = cupsGetOption("document-format", num_options, options)) == NULL) format = CUPS_FORMAT_AUTO; status = cupsStartDocument(CUPS_HTTP_DEFAULT, queue_name, job_id, NULL, format, 1); while (status == HTTP_CONTINUE && (bytes = read(fd, buffer, sizeof(buffer))) > 0) status = cupsWriteRequestData(CUPS_HTTP_DEFAULT, buffer, (size_t)bytes); if (status != HTTP_CONTINUE) { fprintf(stderr, "ERROR: %s: Unable to queue the print data - %s. Retrying.", argv[0], httpStatus(status)); cupsFinishDocument(CUPS_HTTP_DEFAULT, queue_name); cupsCancelJob2(CUPS_HTTP_DEFAULT, queue_name, job_id, 0); return (CUPS_BACKEND_RETRY); } if (cupsFinishDocument(CUPS_HTTP_DEFAULT, queue_name) != IPP_OK) { fprintf(stderr, "ERROR: %s: Unable to complete the job - %s. Retrying.", argv[0], cupsLastErrorString()); cupsCancelJob2(CUPS_HTTP_DEFAULT, queue_name, job_id, 0); return (CUPS_BACKEND_RETRY); } } if (job_id < 1) { fprintf(stderr, "ERROR: %s: Unable to create job - %s. Retrying.", argv[0], cupsLastErrorString()); return (CUPS_BACKEND_RETRY); } return (CUPS_BACKEND_OK); } } else if (argc != 1) { fprintf(stderr, "Usage: %s job-id user title copies options [file]", argv[0]); return (CUPS_BACKEND_FAILED); } /* * No discovery mode at all for this backend */ return (CUPS_BACKEND_OK); } /* * 'sigterm_handler()' - Handle termination signals. */ static void sigterm_handler(int sig) /* I - Signal number (unused) */ { (void)sig; if (job_canceled) _exit(CUPS_BACKEND_OK); else job_canceled = 1; }