lnet/utils/lnetconfig/liblnetconfig_netlink.c

   1 /*
   2  * LGPL HEADER START
   3  *
   4  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
   5  *
   6  * All rights reserved. This program and the accompanying materials
   7  * are made available under the terms of the GNU Lesser General Public License
   8  * LGPL version 2.1 or (at your discretion) any later version.
   9  * LGPL version 2.1 accompanies this distribution, and is available at
  10  * http://www.gnu.org/licenses/lgpl-2.1.html
  11  *
  12  * This library is distributed in the hope that it will be useful,
  13  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  14  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
  15  * Lesser General Public License for more details.
  16  *
  17  * LGPL HEADER END
  18  */
  19 /**
  20  * Netlink handling.
  21  *
  22  * Copyright (c) 2021  UT-Battelle, LLC
  23  *
  24  * Author: James Simmons <jsimmons@infradead.org>
  25  */
  26
  27 #include <ctype.h>
  28 #include <unistd.h>
  29 #include <fcntl.h>
  30 #include <yaml.h>
  31
  32 #include <linux/lnet/lnet-nl.h>
  33 #include "liblnetconfig.h"
  34
  35 #ifndef fallthrough
  36 #define fallthrough do {} while (0)  /* fallthrough */
  37 #endif
  38
  39 #ifndef SOL_NETLINK /* for glibc < 2.24 */
  40 # define SOL_NETLINK 270
  41 #endif
  42
  43 #ifndef NETLINK_EXT_ACK
  44 #define NETLINK_EXT_ACK 11
  45 #endif
  46
  47 #ifndef NLM_F_ACK_TLVS
  48 #define NLM_F_ACK_TLVS  0x200   /* extended ACK TVLs were included */
  49 #endif
  50
  51 #ifndef NLA_NUL_STRING
  52 # define NLA_NUL_STRING 10
  53 #endif
  54
  55 #ifndef NLA_S16
  56 # define NLA_S16 13
  57 #endif
  58
  59 #ifndef HAVE_NLA_GET_S32
  60
  61 #define NLA_S32 14
  62
  63 /**
  64  * Return payload of 32 bit signed integer attribute.
  65  *
  66  * @arg nla             32 bit integer attribute.
  67  *
  68  * @return Payload as 32 bit integer.
  69  */
  70 int32_t nla_get_s32(const struct nlattr *nla)
  71 {
  72         return *(const int32_t *) nla_data(nla);
  73 }
  74 #endif /* ! HAVE_NLA_GET_S32 */
  75
  76 #ifndef HAVE_NLA_GET_S64
  77
  78 #define NLA_S64 15
  79
  80 /**
  81  * Return payload of s64 attribute
  82  *
  83  * @arg nla     s64 netlink attribute
  84  *
  85  * @return Payload as 64 bit integer.
  86  */
  87 int64_t nla_get_s64(const struct nlattr *nla)
  88 {
  89         int64_t tmp = 0;
  90
  91         if (nla && nla_len(nla) >= sizeof(tmp))
  92                 memcpy(&tmp, nla_data(nla), sizeof(tmp));
  93
  94         return tmp;
  95 }
  96
  97 #define NLA_PUT_S64(msg, attrtype, value) \
  98         NLA_PUT_TYPE(msg, int64_t, attrtype, value)
  99
 100 #endif /* ! HAVE_NLA_GET_S64 */
 101
 102 /**
 103  * Set NETLINK_BROADCAST_ERROR flags on socket to report ENOBUFS errors.
 104  *
 105  * @sk          Socket to change the flags.
 106  *
 107  * Return       0 on success or a Netlink error code.
 108  */
 109 int nl_socket_enable_broadcast_error(struct nl_sock *sk)
 110 {
 111         const int state = 1; /* enable errors */
 112         int err;
 113
 114         if (nl_socket_get_fd(sk) < 0)
 115                 return -NLE_BAD_SOCK;
 116
 117         err = setsockopt(nl_socket_get_fd(sk), SOL_NETLINK,
 118                          NETLINK_BROADCAST_ERROR, &state, sizeof(state));
 119         if (err < 0)
 120                 return -nl_syserr2nlerr(errno);
 121
 122         return 0;
 123 }
 124
 125 /**
 126  * Enable/disable extending ACK for netlink socket. Used for
 127  * sending extra debugging information.
 128  *
 129  * @arg sk              Netlink socket.
 130  * @arg state           New state (0 - disabled, 1 - enabled)
 131  *
 132  * @return 0 on success or a negative error code
 133  */
 134 int nl_socket_set_ext_ack(struct nl_sock *sk, int state)
 135 {
 136         int err;
 137
 138         if (nl_socket_get_fd(sk) < 0)
 139                 return -NLE_BAD_SOCK;
 140
 141         err = setsockopt(nl_socket_get_fd(sk), SOL_NETLINK,
 142                          NETLINK_EXT_ACK, &state, sizeof(state));
 143         if (err < 0 && errno != ENOPROTOOPT)
 144                 return -nl_syserr2nlerr(errno);
 145
 146         return 0;
 147 }
 148
 149 /**
 150  * Create a Netlink socket
 151  *
 152  * @sk                  The nl_sock which we used to handle the Netlink
 153  *                      connection.
 154  * @async_events        tell the Netlink socket this will receive asynchronous
 155  *                      data
 156  *
 157  * Return               0 on success or a negative error code.
 158  */
 159 int lustre_netlink_register(struct nl_sock *sk, bool async_events)
 160 {
 161         int rc;
 162
 163         rc = genl_connect(sk);
 164         if (rc < 0)
 165                 return rc;
 166
 167         rc = nl_socket_enable_broadcast_error(sk);
 168         if (rc < 0)
 169                 return rc;
 170
 171         rc = nl_socket_set_ext_ack(sk, true);
 172         if (rc < 0)
 173                 return rc;
 174
 175         if (async_events) {
 176                 /* Required to receive async netlink event notifications */
 177                 nl_socket_disable_seq_check(sk);
 178                 /* Don't need ACK for events generated by kernel */
 179                 nl_socket_disable_auto_ack(sk);
 180         }
 181
 182         return rc;
 183 }
 184
 185 /**
 186  * Filter Netlink socket by groups
 187  *
 188  * @nl          Netlink socket
 189  * @family      The family name of the Netlink socket.
 190  * @group       Netlink messages will only been sent if they belong to this
 191  *              group
 192  *
 193  * Return       0 on success or a negative error code.
 194  */
 195 int lustre_netlink_add_group(struct nl_sock *nl, const char *family,
 196                              const char *group)
 197 {
 198         int group_id;
 199
 200         /* Get group ID */
 201         group_id = genl_ctrl_resolve_grp(nl, family, group);
 202         if (group_id < 0)
 203                 return group_id;
 204
 205         /* subscribe to generic netlink multicast group */
 206         return nl_socket_add_membership(nl, group_id);
 207 }
 208
 209 /* A YAML file is used to describe data. In a YAML document the content is
 210  * all about a collection of scalars used to create new data types such as
 211  * key-value pairs. This allows complex documents to represent anything from
 212  * a string to a tree.
 213  *
 214  * Scalar:
 215  * ---------
 216  * YAML scalars are a simple value which can be a string, number or Boolean.
 217  * They are the simplest data types. They can exist in a YAML document but
 218  * are typically used to build more complex data formats.
 219  *
 220  * Collections:
 221  * ------------
 222  * In YAML collections are scalar elements presented in the form of
 223  * an array, called a sequence, or mappings (hashes) that are scalar
 224  * key value pairs. All elements belonging to the same collection are
 225  * the lines that begin at the same indentation level
 226  *
 227  * Sequences use a dash followed by a space.
 228  * Mappings use a colon followed by a space (: ) to mark each key/value pair:
 229  *
 230  * Collections can be represented in two forms, flow and block.
 231  * Note they are equivalent. Example of block sequence is;
 232  *
 233  * - string
 234  * - integer
 235  * - boolean
 236  *
 237  * and a block mapping example is:
 238  *
 239  * string: hello
 240  * integer: 5
 241  * boolean: False
 242  *
 243  * YAML flow styles for collections uses explicit indicators rather than
 244  * indentation to denote scope.
 245  *
 246  * A sequence can be written as a comma separated list within
 247  * square brackets ([]):
 248  *
 249  * [ PHP, Perl, Python ]
 250  *
 251  * A mapping can be written as a comma separated list of key/values within
 252  * curly braces ({}):
 253  *
 254  * { PHP: 5.2, MySQL: 5.1, Apache: 2.2.20 }
 255  *
 256  * NOTE!! flow and block are equivalent.
 257  *
 258  * List:
 259  * ------
 260  * A list is a defined array of data which can be either an flow or block
 261  * sequence. Lists can be nested. Example
 262  *
 263  * numbers: [ 1, 2, 3, 4 ]
 264  *
 265  * numbers:
 266  *  - 1
 267  *  - 2
 268  *  - 3
 269  *  - 4
 270  *
 271  * Dictionaries:
 272  * --------------
 273  * Are comprised of a key: value format with contents indented. This is
 274  * built on top of the flow or block mapping. Like lists they can be nested.
 275  *
 276  * ports:
 277  * - port: 8080
 278  *     targetPort: 8080
 279  *       nodePort: 30012
 280  */
 281
 282 /* In YAML you have the concept of parsers and emitters. Parser
 283  * consume YAML input from a file, character buffer, or in our
 284  * case Netlink and emitters take data from some source and
 285  * present it in a YAML format.
 286  *
 287  * In this section of the code we are handling the parsing of the
 288  * Netlink packets coming in and using them to piece together a
 289  * YAML document. We could in theory just dump a YAML document
 290  * one line at a time over Netlink but the amount of data could
 291  * become very large and impact performance. Additionally, having
 292  * pseudo-YAML code in the kernel would be frowned on. We can
 293  * optimize the network traffic by taking advantage of the fact
 294  * that for key/value pairs the keys rarely change. We can
 295  * break up the data into keys and the values. The first Netlink
 296  * data packets received will be a nested keys table which we
 297  * can cache locally. As we receive the value pairs we can then
 298  * reconstruct the key : value pair by looking up the the key
 299  * in the stored table. In effect we end up with a one key to
 300  * many values stream of data.
 301  *
 302  * The data structures below are used to create a tree data
 303  * structure which is the natural flow of both YAML and
 304  * Netlink.
 305  */
 306 struct yaml_nl_node {
 307         struct nl_list_head     list;
 308         struct nl_list_head     children;
 309         struct ln_key_list      keys;
 310 };
 311
 312 struct yaml_netlink_input {
 313         yaml_parser_t           *parser;
 314         void                    *buffer;
 315         const char              *errmsg;
 316         int                     error;
 317         struct nl_sock          *nl;
 318         bool                    complete;
 319         bool                    async;
 320         unsigned int            indent;
 321         unsigned int            version;
 322         struct yaml_nl_node     *cur;
 323         struct yaml_nl_node     *root;
 324 };
 325
 326 /* Sadly this is not exported out of libyaml. We want to
 327  * give descent error message to help people track down
 328  * issues. This is internal only to this code. The end
 329  * user will never need to use this.
 330  */
 331 static int
 332 yaml_parser_set_reader_error(yaml_parser_t *parser, const char *problem,
 333                              size_t offset, int value)
 334 {
 335         parser->error = YAML_READER_ERROR;
 336         parser->problem = problem;
 337         parser->problem_offset = offset;
 338         parser->problem_value = value;
 339
 340         return 0;
 341 }
 342
 343 /* This is used to handle all the Netlink packets containing the keys
 344  * for the key/value pairs. Instead of creating unique code to handle
 345  * every type of Netlink attributes possible we create a generic
 346  * abstract so the same code be used with everything. To make this
 347  * work the key table trasmitted must report the tree structure and
 348  * state of the keys. We use nested attributes as a way to notify libyaml
 349  * we have a new collection. This is used to create the tree structure
 350  * of the YAML document. Each collection of attributes define the following:
 351  *
 352  * LN_SCALAR_ATTR_INDEX:
 353  *      enum XXX_ATTR that defines which value we are dealing with. This
 354  *      varies greatly depending on the subsystem we have developed for.
 355  *
 356  * LN_SCALAR_ATTR_NLA_TYPE:
 357  *      The Netlink attribute type (NLA_STRING, NLA_U32, etc..) the coming
 358  *      value will be.
 359  *
 360  * LN_SCALAR_ATTR_VALUE:
 361  *      The string represnting key's actually scalar value.
 362  *
 363  * LN_SCALAR_ATTR_INT_VALUE:
 364  *      For this case the key is an integer value. This shouldn't be
 365  *      sent for the receive case since we are going to just turn it
 366  *      into a string for YAML. Sending packets will make use of this.
 367  *
 368  * LN_SCALAR_ATTR_KEY_TYPE:
 369  *      What YAML format is it? block or flow. Only useful for
 370  *      LN_SCALAR_ATTR_NLA_TYPE of type NLA_NESTED or NLA_NUL_STRING
 371  *
 372  * LN_SCALAR_ATTR_LIST + LN_SCALAR_LIST_SIZE:
 373  *      Defined the next collection which is a collection of nested
 374  *      attributes of the above.
 375  */
 376 static struct nla_policy scalar_attr_policy[LN_SCALAR_MAX + 1] = {
 377         [LN_SCALAR_ATTR_LIST]           = { .type = NLA_NESTED },
 378         [LN_SCALAR_ATTR_LIST_SIZE]      = { .type = NLA_U16 },
 379         [LN_SCALAR_ATTR_INDEX]          = { .type = NLA_U16 },
 380         [LN_SCALAR_ATTR_NLA_TYPE]       = { .type = NLA_U16 },
 381         [LN_SCALAR_ATTR_VALUE]          = { .type = NLA_STRING },
 382         [LN_SCALAR_ATTR_INT_VALUE]      = { .type = NLA_S64 },
 383         [LN_SCALAR_ATTR_KEY_FORMAT]     = { .type = NLA_U16 },
 384 };
 385
 386 static int yaml_parse_key_list(struct yaml_netlink_input *data,
 387                                struct yaml_nl_node *parent,
 388                                struct nlattr *list)
 389 {
 390         struct nlattr *tbl_info[LN_SCALAR_MAX + 1];
 391         struct yaml_nl_node *node = NULL;
 392         struct nlattr *attr;
 393         int rem;
 394
 395         nla_for_each_nested(attr, list, rem) {
 396                 uint16_t index = 0;
 397
 398                 if (nla_parse_nested(tbl_info, LN_SCALAR_MAX, attr,
 399                                      scalar_attr_policy))
 400                         break;
 401
 402                 if (tbl_info[LN_SCALAR_ATTR_LIST_SIZE]) {
 403                         size_t cnt;
 404
 405                         cnt = nla_get_u16(tbl_info[LN_SCALAR_ATTR_LIST_SIZE]) + 1;
 406                         if (!node) {
 407                                 size_t len = sizeof(struct nl_list_head) * 2;
 408
 409                                 len += sizeof(struct ln_key_props) * cnt;
 410                                 node = calloc(1, len);
 411                                 if (!node)
 412                                         return NL_STOP;
 413
 414                                 node->keys.lkl_maxattr = cnt;
 415                                 NL_INIT_LIST_HEAD(&node->children);
 416                                 nl_init_list_head(&node->list);
 417
 418                                 if (!data->root)
 419                                         data->root = node;
 420                                 if (!data->cur)
 421                                         data->cur = node;
 422                                 if (parent)
 423                                         nl_list_add_tail(&node->list,
 424                                                          &parent->children);
 425                         }
 426                 }
 427
 428                 if (tbl_info[LN_SCALAR_ATTR_INDEX])
 429                         index = nla_get_u16(tbl_info[LN_SCALAR_ATTR_INDEX]);
 430
 431                 if (!node || index == 0)
 432                         return NL_STOP;
 433
 434                 if (tbl_info[LN_SCALAR_ATTR_KEY_FORMAT]) {
 435                         uint16_t format;
 436
 437                         format = nla_get_u16(tbl_info[LN_SCALAR_ATTR_KEY_FORMAT]);
 438                         node->keys.lkl_list[index].lkp_key_format = format;
 439                 }
 440
 441                 if (tbl_info[LN_SCALAR_ATTR_NLA_TYPE]) {
 442                         uint16_t type;
 443
 444                         type = nla_get_u16(tbl_info[LN_SCALAR_ATTR_NLA_TYPE]);
 445                         node->keys.lkl_list[index].lkp_data_type = type;
 446                 }
 447
 448                 if (tbl_info[LN_SCALAR_ATTR_VALUE]) {
 449                         char *name;
 450
 451                         name = nla_strdup(tbl_info[LN_SCALAR_ATTR_VALUE]);
 452                         if (!name)
 453                                 return NL_STOP;
 454                         node->keys.lkl_list[index].lkp_value = name;
 455                 }
 456
 457                 if (tbl_info[LN_SCALAR_ATTR_LIST]) {
 458                         int rc = yaml_parse_key_list(data, node,
 459                                                      tbl_info[LN_SCALAR_ATTR_LIST]);
 460                         if (rc != NL_OK)
 461                                 return rc;
 462                 }
 463         }
 464         return NL_OK;
 465 }
 466
 467 static struct yaml_nl_node *get_next_child(struct yaml_nl_node *node,
 468                                            unsigned int idx)
 469 {
 470         struct yaml_nl_node *child;
 471         unsigned int i = 0;
 472
 473         nl_list_for_each_entry(child, &node->children, list)
 474                 if (idx == i++)
 475                         return child;
 476
 477         return NULL;
 478 }
 479
 480 /**
 481  * In the YAML C implementation the scanner transforms the input stream
 482  * (Netlink in this case) into a sequence of keys. First we need to
 483  * examine the potential keys involved to see the mapping to Netlink.
 484  * We have chosen to examine the YAML stack with keys since they are
 485  * more detailed when compared to yaml_document_t / yaml_nodes and
 486  * yaml_event_t.
 487  *
 488  *      STREAM-START(encoding)          # The stream start.
 489  *      STREAM-END                      # The stream end.
 490  *      VERSION-DIRECTIVE(major,minor)  # The '%YAML' directive.
 491  *      TAG-DIRECTIVE(handle,prefix)    # The '%TAG' directive.
 492  *      DOCUMENT-START                  # '---'
 493  *      DOCUMENT-END                    # '...'
 494  *      BLOCK-SEQUENCE-START            # Indentation increase denoting a block
 495  *      BLOCK-MAPPING-START             # sequence or a block mapping.
 496  *      BLOCK-END                       # Indentation decrease.
 497  *      FLOW-SEQUENCE-START             # '['
 498  *      FLOW-SEQUENCE-END               # ']'
 499  *      FLOW-MAPPING-START              # '{'
 500  *      FLOW-MAPPING-END                # '}'
 501  *      BLOCK-ENTRY                     # '-'
 502  *      FLOW-ENTRY                      # ','
 503  *      KEY                             # '?' or nothing (simple keys).
 504  *      VALUE                           # ':'
 505  *      ALIAS(anchor)                   # '*anchor'
 506  *      ANCHOR(anchor)                  # '&anchor'
 507  *      TAG(handle,suffix)              # '!handle!suffix'
 508  *      SCALAR(value,style)             # A scalar.
 509  *
 510  * For our read_handler / write_handler STREAM-START / STREAM-END,
 511  * VERSION-DIRECTIVE, and TAG-DIRECTIVE are hanndler by the libyaml
 512  * internal scanner so we don't need to deal with it. Normally for
 513  * LNet / Lustre DOCUMENT-START / DOCUMENT-END are not needed but it
 514  * could be easily handled. In the case of multiplex streams we could
 515  * see these used to differentiate data coming in.
 516  *
 517  * It is here we handle any simple scalars or values of the key /value
 518  * pair. How the YAML document is formated is dependent on the key
 519  * table's data.
 520  */
 521 static void yaml_parse_value_list(struct yaml_netlink_input *data, int *size,
 522                                   struct nlattr *attr_array[],
 523                                   struct ln_key_props *parent)
 524 {
 525         struct yaml_nl_node *node = data->cur;
 526         struct ln_key_props *keys = node->keys.lkl_list;
 527         int mapping = parent->lkp_key_format;
 528         int child_idx = 0, len = 0, i;
 529
 530         for (i = 1; i < node->keys.lkl_maxattr; i++) {
 531                 struct nlattr *attr;
 532
 533                 attr = attr_array[i];
 534                 if (!attr && !keys[i].lkp_value)
 535                         continue;
 536
 537                 if (keys[i].lkp_data_type != NLA_NUL_STRING &&
 538                     keys[i].lkp_data_type != NLA_NESTED) {
 539                         if (!attr && keys[i].lkp_data_type != NLA_FLAG)
 540                                 continue;
 541
 542                         if (!(mapping & LNKF_FLOW)) {
 543                                 unsigned int indent = data->indent ?
 544                                                       data->indent : 2;
 545
 546                                 memset(data->buffer, ' ', indent);
 547                                 if (mapping & LNKF_SEQUENCE) {
 548                                         ((char *)data->buffer)[indent - 2] = '-';
 549                                         if (mapping & LNKF_MAPPING)
 550                                                 mapping &= ~LNKF_SEQUENCE;
 551                                 }
 552                                 data->buffer += indent;
 553                                 *size -= indent;
 554                         }
 555
 556                         if (mapping & LNKF_MAPPING) {
 557                                 len = snprintf(data->buffer, *size, "%s: ",
 558                                                keys[i].lkp_value);
 559                                 if (len < 0)
 560                                         goto unwind;
 561                                 data->buffer += len;
 562                                 *size -= len;
 563                         }
 564                 }
 565
 566                 switch (keys[i].lkp_data_type) {
 567                 case NLA_NESTED: {
 568                         struct yaml_nl_node *next = get_next_child(node,
 569                                                                    child_idx++);
 570                         int num = next->keys.lkl_maxattr;
 571                         struct nla_policy nest_policy[num];
 572                         struct yaml_nl_node *old;
 573                         struct nlattr *cnt_attr;
 574                         uint16_t indent = 0;
 575                         int rem, j;
 576
 577                         if (!attr)
 578                                 continue;
 579
 580                         memset(nest_policy, 0, sizeof(struct nla_policy) * num);
 581                         for (j = 1; j < num; j++)
 582                                 nest_policy[j].type = next->keys.lkl_list[j].lkp_data_type;
 583
 584                         if (keys[i].lkp_key_format & LNKF_FLOW) {
 585                                 char brace = '{';
 586
 587                                 if (keys[i].lkp_key_format &
 588                                     LNKF_SEQUENCE)
 589                                         brace = '[';
 590                                 len = snprintf(data->buffer, *size,
 591                                                "%*s%s: %c ",
 592                                                data->indent, "",
 593                                                keys[i].lkp_value,
 594                                                brace);
 595                         } else {
 596                                 if (keys[i].lkp_key_format &
 597                                     LNKF_MAPPING)
 598                                         indent += 2;
 599                                 if (keys[i].lkp_key_format &
 600                                     LNKF_SEQUENCE)
 601                                         indent += 2;
 602
 603                                 if (keys[i].lkp_value) {
 604                                         len = snprintf(data->buffer,
 605                                                        *size,
 606                                                        "%*s%s:\n",
 607                                                        data->indent, "",
 608                                                        keys[i].lkp_value);
 609                                 } else {
 610                                         len = 0;
 611                                 }
 612                         }
 613                         if (len < 0)
 614                                 goto unwind;
 615                         data->buffer += len;
 616                         *size -= len;
 617                         len = 0;
 618
 619                         old = data->cur;
 620                         data->cur = next;
 621                         nla_for_each_nested(cnt_attr, attr, rem) {
 622                                 struct nlattr *nest_info[num];
 623
 624                                 if (nla_parse_nested(nest_info, num, cnt_attr,
 625                                                      nest_policy))
 626                                         break;
 627
 628                                 data->indent += indent;
 629                                 yaml_parse_value_list(data, size, nest_info,
 630                                                       &keys[i]);
 631                                 data->indent -= indent;
 632                         }
 633
 634                         if (keys[i].lkp_key_format & LNKF_FLOW) {
 635                                 char *tmp = (char *)data->buffer - 2;
 636                                 char *brace = " }\n";
 637
 638                                 if (keys[i].lkp_key_format &
 639                                     LNKF_SEQUENCE)
 640                                         brace = " ]\n";
 641
 642                                 memcpy(tmp, brace, strlen(brace));
 643                                 data->buffer++;
 644                                 *size -= 1;
 645                         }
 646                         data->cur = old;
 647                         break;
 648                 }
 649
 650                 case NLA_NUL_STRING:
 651                         if (i == 1) {
 652                                 if (data->cur != data->root)
 653                                         goto not_first;
 654
 655                                 /* The top level is special so only print
 656                                  * once
 657                                  */
 658                                 if (strlen(keys[i].lkp_value)) {
 659                                         len = snprintf(data->buffer,
 660                                                        *size, "%s:\n",
 661                                                        keys[i].lkp_value);
 662                                         if (len < 0)
 663                                                 goto unwind;
 664                                         data->buffer += len;
 665                                         *size -= len;
 666                                         len = 0;
 667                                 }
 668                                 data->indent = 0;
 669                                 if (!(mapping & LNKF_FLOW)) {
 670                                         if (mapping & LNKF_SEQUENCE)
 671                                                 data->indent += 2;
 672                                         else if (mapping & LNKF_MAPPING)
 673                                                 data->indent += 2;
 674                                 }
 675 not_first:
 676                                 if (attr && parent->lkp_value) {
 677                                         free(parent->lkp_value);
 678                                         parent->lkp_value = nla_strdup(attr);
 679                                 }
 680                         }
 681                         break;
 682
 683                 case NLA_STRING:
 684                         len = snprintf(data->buffer, *size, "%s",
 685                                        nla_get_string(attr));
 686                         break;
 687
 688                 case NLA_FLAG:
 689                         len = snprintf(data->buffer, *size, "%s",
 690                                        attr ? "true" : "false");
 691                         break;
 692
 693                 case NLA_U16:
 694                         len = snprintf(data->buffer, *size, "%hu",
 695                                        nla_get_u16(attr));
 696                         break;
 697
 698                 case NLA_U32:
 699                         len = snprintf(data->buffer, *size, "%u",
 700                                        nla_get_u32(attr));
 701                         break;
 702
 703                 case NLA_U64:
 704                         len = snprintf(data->buffer, *size, "%ju",
 705                                        nla_get_u64(attr));
 706                         break;
 707
 708                 case NLA_S16:
 709                         len = snprintf(data->buffer, *size, "%hd",
 710                                        nla_get_u16(attr));
 711                         break;
 712
 713                 case NLA_S32:
 714                         len = snprintf(data->buffer, *size, "%d",
 715                                        nla_get_s32(attr));
 716                         break;
 717
 718                 case NLA_S64:
 719                         len = snprintf(data->buffer, *size, "%jd",
 720                                        nla_get_s64(attr));
 721                         fallthrough;
 722                 default:
 723                         break;
 724                 }
 725
 726                 if (len) {
 727                         if (mapping & LNKF_FLOW) {
 728                                 strcat((char *)data->buffer, ", ");
 729                                 len += 2;
 730                         } else {
 731                                 if ((mapping == LNKF_SEQUENCE) &&
 732                                     !keys[i].lkp_value)
 733                                         ((char *)data->buffer)[len++] = ':';
 734
 735                                 ((char *)data->buffer)[len++] = '\n';
 736                         }
 737                         data->buffer += len;
 738                         *size += len;
 739                 } else if (len < 0) {
 740 unwind:
 741                         data->buffer -= data->indent + 2;
 742                         *size -= data->indent + 2;
 743                 }
 744         }
 745 }
 746
 747 /* This is the CB_VALID callback for the Netlink library that we
 748  * have hooked into. Any successful Netlink message is passed to
 749  * this function which handles both the incoming key tables and
 750  * the values of the key/value pairs being received. We use
 751  * the NLM_F_CREATE flag to determine if the incoming Netlink
 752  * message is a key table or a packet containing value pairs.
 753  */
 754 static int yaml_netlink_msg_parse(struct nl_msg *msg, void *arg)
 755 {
 756         struct yaml_netlink_input *data = arg;
 757         struct nlmsghdr *nlh = nlmsg_hdr(msg);
 758
 759         if (nlh->nlmsg_flags & NLM_F_CREATE) {
 760                 struct genlmsghdr *ghdr = genlmsg_hdr(nlh);
 761                 struct nlattr *attrs[LN_SCALAR_MAX + 1];
 762
 763                 if (genlmsg_parse(nlh, 0, attrs, LN_SCALAR_MAX,
 764                                   scalar_attr_policy))
 765                         return NL_SKIP;
 766
 767                 if (attrs[LN_SCALAR_ATTR_LIST]) {
 768                         int rc = yaml_parse_key_list(data, NULL,
 769                                                      attrs[LN_SCALAR_ATTR_LIST]);
 770                         if (rc != NL_OK)
 771                                 return rc;
 772
 773                         /* reset to root node */
 774                         data->cur = data->root;
 775                 }
 776
 777                 /* For streaming insert '---' to define start of
 778                  * YAML document. This allows use to extract
 779                  * documents out of a multiplexed stream.
 780                  */
 781                 if (data->async) {
 782                         char *start_doc = "---\n";
 783                         size_t len = strlen(start_doc) + 1;
 784
 785                         strncpy(data->buffer, start_doc, len);
 786                         data->buffer += len - 1;
 787                 }
 788                 data->version = ghdr->version;
 789         } else {
 790                 uint16_t maxtype = data->cur->keys.lkl_maxattr;
 791                 struct nla_policy policy[maxtype];
 792                 struct nlattr *attrs[maxtype];
 793                 int size, i;
 794
 795                 memset(policy, 0, sizeof(struct nla_policy) * maxtype);
 796                 for (i = 1; i < maxtype; i++)
 797                         policy[i].type = data->cur->keys.lkl_list[i].lkp_data_type;
 798
 799                 if (genlmsg_parse(nlh, 0, attrs, maxtype, policy))
 800                         return NL_SKIP;
 801
 802                 size = data->parser->raw_buffer.end -
 803                        (unsigned char *)data->buffer;
 804                 yaml_parse_value_list(data, &size, attrs,
 805                                       &data->cur->keys.lkl_list[1]);
 806         }
 807
 808         /* Let yaml_netlink_msg_complete end collecting data */
 809         return NL_OK;
 810 }
 811
 812 /* This is the libnl callback for when an error has happened
 813  * kernel side. An error message is sent back to the user.
 814  */
 815 static int yaml_netlink_msg_error(struct sockaddr_nl *who,
 816                                   struct nlmsgerr *errmsg, void *arg)
 817 {
 818         struct nlmsghdr *nlh = (void *)errmsg - NLMSG_HDRLEN;
 819         struct yaml_netlink_input *data = arg;
 820
 821         if ((nlh->nlmsg_type == NLMSG_ERROR ||
 822              nlh->nlmsg_flags & NLM_F_ACK_TLVS) && errmsg->error) {
 823                 /* libyaml stomps on the reader error so we need to
 824                  * cache the source of the error.
 825                  */
 826                 const char *errstr = nl_geterror(nl_syserr2nlerr(errmsg->error));
 827
 828 #ifdef HAVE_USRSPC_NLMSGERR
 829                 /* Newer kernels support NLM_F_ACK_TLVS in nlmsg_flags
 830                  * which gives greater detail why we failed.
 831                  */
 832                 if ((nlh->nlmsg_flags & NLM_F_ACK_TLVS) &&
 833                     !(nlh->nlmsg_flags & NLM_F_CAPPED)) {
 834                         struct nlattr *head = ((void *)&errmsg->msg);
 835                         struct nlattr *tb[NLMSGERR_ATTR_MAX];
 836
 837                         if (nla_parse(tb, NLMSGERR_ATTR_MAX, head,
 838                                       nlmsg_attrlen(nlh, 0), NULL) == 0) {
 839                                 if (tb[NLMSGERR_ATTR_MSG])
 840                                         errstr = nla_strdup(tb[NLMSGERR_ATTR_MSG]);
 841                         }
 842                 }
 843 #endif /* HAVE_USRSPC_NLMSGERR */
 844                 data->errmsg = errstr;
 845                 data->error = errmsg->error;
 846                 data->parser->error = YAML_READER_ERROR;
 847                 data->complete = true;
 848         }
 849         return NL_STOP;
 850 }
 851
 852 static bool cleanup_children(struct yaml_nl_node *parent)
 853 {
 854         struct yaml_nl_node *child;
 855
 856         if (nl_list_empty(&parent->children)) {
 857                 struct ln_key_props *keys = parent->keys.lkl_list;
 858                 int i;
 859
 860                 for (i = 1; i < parent->keys.lkl_maxattr; i++)
 861                         if (keys[i].lkp_value)
 862                                 free(keys[i].lkp_value);
 863                 nl_list_del(&parent->list);
 864                 return true;
 865         }
 866
 867         while ((child = get_next_child(parent, 0)) != NULL) {
 868                 if (cleanup_children(child))
 869                         free(child);
 870         }
 871
 872         return false;
 873 }
 874
 875 /* This is the libnl callback for when the last Netlink packet
 876  * is finished being parsed or its called right away in case
 877  * the Linux kernel reports back an error from the Netlink layer.
 878  */
 879 static int yaml_netlink_msg_complete(struct nl_msg *msg, void *arg)
 880 {
 881         struct yaml_netlink_input *data = arg;
 882         struct nlmsghdr *nlh = nlmsg_hdr(msg);
 883
 884         /* For the case of NLM_F_DUMP the kernel will send error msgs
 885          * yet not be labled NLMSG_ERROR which results in this code
 886          * path being executed.
 887          */
 888         yaml_netlink_msg_error(NULL, nlmsg_data(nlh), arg);
 889         if (data->parser->error == YAML_READER_ERROR)
 890                 return NL_STOP;
 891
 892         /* Free internal data. */
 893         if (data->root) {
 894                 cleanup_children(data->root);
 895                 free(data->root);
 896                 data->root = NULL;
 897         }
 898
 899         /* For streaming insert '...' to define end of
 900          * YAML document
 901          */
 902         if (data->async) {
 903                 char *end_doc = "...\n";
 904                 size_t len = strlen(end_doc) + 1;
 905
 906                 strncpy(data->buffer, end_doc, len);
 907                 data->buffer += len - 1;
 908         } else {
 909                 data->complete = true;
 910         }
 911
 912         return data->async ? NL_OK : NL_STOP;
 913 }
 914
 915 /**
 916  * In order for yaml_parser_set_input_netlink() to work we have to
 917  * register a yaml_read_handler_t callback. This is that call back
 918  * which listens for Netlink packets. Internally nl_recvmsg_report()
 919  * calls the various callbacks discussed above.
 920  */
 921 static int yaml_netlink_read_handler(void *arg, unsigned char *buffer,
 922                                      size_t size, size_t *size_read)
 923 {
 924         struct yaml_netlink_input *data = arg;
 925         struct nl_sock *nl = data->nl;
 926         struct nl_cb *cb;
 927         int rc = 0;
 928
 929         if (data->complete) {
 930                 *size_read = 0;
 931                 return 1;
 932         }
 933
 934         data->buffer = buffer;
 935
 936         cb = nl_socket_get_cb(nl);
 937         rc = nl_recvmsgs_report(nl, cb);
 938         if (rc == -NLE_INTR) {
 939                 *size_read = 0;
 940                 return 1;
 941         } else if (!data->errmsg && rc < 0) {
 942                 data->errmsg = nl_geterror(rc);
 943                 return 0;
 944         } else if (data->parser->error) {
 945                 /* data->errmsg is set in NL_CB_FINISH */
 946                 return 0;
 947         }
 948
 949         rc = (unsigned char *)data->buffer - buffer;
 950         if ((int)size > rc)
 951                 size = rc;
 952
 953         *size_read = size;
 954         return 1;
 955 }
 956
 957 /* libyaml by default just reports "input error" for parser read_handler_t
 958  * issues which is not useful. This provides away to get better debugging
 959  * info.
 960  */
 961 YAML_DECLARE(const char *)
 962 yaml_parser_get_reader_error(yaml_parser_t *parser)
 963 {
 964         struct yaml_netlink_input *buf = parser->read_handler_data;
 965
 966         if (!buf)
 967                 return NULL;
 968
 969         errno = buf->error;
 970         return buf->errmsg;
 971 }
 972
 973 YAML_DECLARE(int)
 974 yaml_parser_get_reader_proto_version(yaml_parser_t *parser)
 975 {
 976         struct yaml_netlink_input *buf = parser->read_handler_data;
 977
 978         if (!buf)
 979                 return 0;
 980
 981         return buf->version;
 982 }
 983
 984 /* yaml_parser_set_input_netlink() mirrors the libyaml function
 985  * yaml_parser_set_input_file(). Internally it does setup of the
 986  * libnl socket callbacks to parse the Netlink messages received
 987  * as well as register the special yaml_read_handler_t for libyaml.
 988  * This is exposed for public use.
 989  */
 990 YAML_DECLARE(int)
 991 yaml_parser_set_input_netlink(yaml_parser_t *reply, struct nl_sock *nl,
 992                               bool stream)
 993 {
 994         struct yaml_netlink_input *buf;
 995         int rc;
 996
 997         buf = calloc(1, sizeof(*buf));
 998         if (!buf) {
 999                 reply->error = YAML_MEMORY_ERROR;
1000                 return false;
1001         }
1002
1003         rc = lustre_netlink_register(nl, stream);
1004         if (rc < 0) {
1005                 yaml_parser_set_reader_error(reply,
1006                                              "netlink setup failed", 0,
1007                                              -rc);
1008                 goto failed;
1009         }
1010
1011         buf->nl = nl;
1012         buf->async = stream;
1013         buf->parser = reply;
1014         yaml_parser_set_input(buf->parser, yaml_netlink_read_handler, buf);
1015
1016         rc = nl_socket_modify_cb(buf->nl, NL_CB_VALID, NL_CB_CUSTOM,
1017                                  yaml_netlink_msg_parse, buf);
1018         if (rc < 0) {
1019                 yaml_parser_set_reader_error(reply,
1020                                              "netlink msg recv setup failed",
1021                                              0, -rc);
1022                 goto failed;
1023         }
1024
1025         rc = nl_socket_modify_cb(buf->nl, NL_CB_FINISH, NL_CB_CUSTOM,
1026                                  yaml_netlink_msg_complete, buf);
1027         if (rc < 0) {
1028                 yaml_parser_set_reader_error(reply,
1029                                              "netlink msg cleanup setup failed",
1030                                              0, -rc);
1031                 goto failed;
1032         }
1033
1034         rc = nl_socket_modify_err_cb(nl, NL_CB_CUSTOM, yaml_netlink_msg_error,
1035                                      buf);
1036         if (rc < 0) {
1037                 yaml_parser_set_reader_error(reply,
1038                                              "failed to register error handling",
1039                                              0, -rc);
1040 failed:
1041                 free(buf);
1042         }
1043
1044         return rc < 0 ? false : true;
1045 }
1046
1047 /* The role of the YAML emitter for us is to take a YAML document and
1048  * change into a Netlink stream to send to the kernel to be processed.
1049  * This provides the infrastructure to do this.
1050  */
1051 struct yaml_netlink_output {
1052         yaml_emitter_t          *emitter;
1053         struct nl_sock          *nl;
1054         char                    *family;
1055         int                     family_id;
1056         int                     version;
1057         int                     cmd;
1058         int                     pid;
1059         int                     flags;
1060 };
1061
1062 /* Internal use for this file only. We fill in details of why creating
1063  * a Netlink packet to send failed. The end user will be able to debug
1064  * what went wrong.
1065  */
1066 static int
1067 yaml_emitter_set_writer_error(yaml_emitter_t *emitter, const char *problem)
1068 {
1069         emitter->error = YAML_WRITER_ERROR;
1070         emitter->problem = problem;
1071
1072         return 0;
1073 }
1074
1075 static unsigned int indent_level(const char *str)
1076 {
1077         char *tmp = (char *)str;
1078
1079         while (isspace(*tmp))
1080                 ++tmp;
1081         return tmp - str;
1082 }
1083
1084 #define LNKF_END 8
1085
1086 static enum lnet_nl_key_format yaml_format_type(yaml_emitter_t *emitter,
1087                                                 char *line,
1088                                                 unsigned int *offset)
1089 {
1090         unsigned int indent = *offset, new_indent = 0;
1091         enum lnet_nl_key_format fmt = 0;
1092         char *tmp, *flow;
1093
1094         new_indent = indent_level(line);
1095         if (new_indent < indent) {
1096                 *offset = indent - emitter->best_indent;
1097                 return LNKF_END;
1098         }
1099
1100         if (strncmp(line + new_indent, "- ", 2) == 0) {
1101                 memset(line + new_indent, ' ', 2);
1102                 new_indent += 2;
1103         }
1104
1105         /* hdr: [ a : 1, b : 2, c : 3 ] */
1106         tmp = strstr(line + new_indent, ": ");
1107         if (!tmp)
1108                 tmp = line + new_indent;
1109         else
1110                 fmt |= LNKF_MAPPING;
1111
1112         flow = strchr(line + new_indent, '{');
1113         if (!flow)
1114                 flow = strchr(line + new_indent, '[');
1115         if (flow) {
1116                 if (flow < tmp)
1117                         fmt &= ~LNKF_MAPPING;
1118                 fmt |= LNKF_FLOW;
1119         } else if (strchr(tmp, '}') || strchr(tmp, ']')) {
1120                 if (strchr(tmp, ']'))
1121                         fmt &= ~LNKF_MAPPING;
1122                 fmt |= LNKF_FLOW;
1123         }
1124
1125         if (indent != new_indent) {
1126                 *offset = new_indent;
1127                 fmt |= LNKF_SEQUENCE;
1128         }
1129
1130         return fmt;
1131 }
1132
1133 static int yaml_fill_scalar_data(struct nl_msg *msg,
1134                                  enum lnet_nl_key_format fmt,
1135                                  char *line)
1136 {
1137         char *sep = strstr(line, ": "); /* handle mappings */
1138         int rc = 0;
1139         long num;
1140
1141         if (!sep) {
1142                 char *tmp = strchr(line, ':');
1143
1144                 if (tmp && strlen(tmp) == 1) /* handle simple scalar */
1145                         sep = tmp;
1146         }
1147         if (sep)
1148                 *sep++ = '\0';
1149
1150         if (strspn(line, "-0123456789") == strlen(line)) {
1151                 num = strtoll(line, NULL, 0);
1152
1153                 NLA_PUT_S64(msg, LN_SCALAR_ATTR_INT_VALUE, num);
1154         } else {
1155                 NLA_PUT_STRING(msg, LN_SCALAR_ATTR_VALUE, line);
1156         }
1157
1158         if (fmt & LNKF_FLOW) {
1159                 memset(line, ' ', strlen(line) + 1);
1160                 goto nla_put_failure;
1161         }
1162
1163         if (fmt & LNKF_MAPPING && sep) {
1164                 while (isspace(*sep))
1165                         ++sep;
1166
1167                 if (!strlen(sep))
1168                         goto nla_put_failure;
1169
1170                 if (strspn(sep, "-0123456789") == strlen(sep)) {
1171                         num = strtoll(sep, NULL, 0);
1172                         NLA_PUT_S64(msg, LN_SCALAR_ATTR_INT_VALUE, num);
1173                 } else {
1174                         NLA_PUT_STRING(msg, LN_SCALAR_ATTR_VALUE, sep);
1175                 }
1176         }
1177 nla_put_failure:
1178         return rc;
1179 }
1180
1181 static int yaml_create_nested_list(struct yaml_netlink_output *out,
1182                                    struct nl_msg *msg, char **hdr,
1183                                    char **entry, unsigned int *indent,
1184                                    enum lnet_nl_key_format fmt)
1185 {
1186         bool nested = fmt & LNKF_SEQUENCE;
1187         struct nlattr *list = NULL;
1188         char *line;
1189         int rc = 0;
1190
1191         /* Not needed for FLOW only case */
1192         if (nested) {
1193                 list = nla_nest_start(msg, LN_SCALAR_ATTR_LIST);
1194                 if (!list) {
1195                         yaml_emitter_set_writer_error(out->emitter,
1196                                                       "Emmitter netlink list creation failed");
1197                         rc = -EINVAL;
1198                         goto nla_put_failure;
1199                 }
1200         }
1201
1202         if (fmt != LNKF_FLOW) {
1203                 rc = yaml_fill_scalar_data(msg, fmt, *hdr + *indent);
1204                 if (rc < 0)
1205                         goto nla_put_failure;
1206         }
1207
1208         if (fmt & LNKF_FLOW) {
1209                 char *tmp = strchr(*hdr, '{'), *split = NULL;
1210                 bool format = false;
1211
1212                 if (!tmp) {
1213                         tmp = strchr(*hdr, '[');
1214                         if (!tmp) {
1215                                 yaml_emitter_set_writer_error(out->emitter,
1216                                                               "Emmitter flow format invalid");
1217                                 rc = -EINVAL;
1218                                 goto nla_put_failure;
1219                         }
1220                         fmt |= LNKF_SEQUENCE;
1221                 } else
1222                         fmt |= LNKF_MAPPING;
1223                 *tmp = ' ';
1224
1225                 list = nla_nest_start(msg, LN_SCALAR_ATTR_LIST);
1226                 if (!list) {
1227                         yaml_emitter_set_writer_error(out->emitter,
1228                                                       "Emmitter netlink list creation failed");
1229                         rc = -EINVAL;
1230                         goto nla_put_failure;
1231                 }
1232
1233                 fmt &= ~LNKF_FLOW;
1234                 while ((line = strsep(hdr, ",")) != NULL) {
1235                         while (!isalnum(line[0]))
1236                                 line++;
1237
1238                         /* Flow can be splt across lines by libyaml library. */
1239                         if (strchr(line, ',')) {
1240                                 split = line;
1241                                 *hdr = line;
1242                                 continue;
1243                         }
1244
1245                         tmp = strchr(line, '}');
1246                         if (!tmp)
1247                                 tmp = strchr(line, ']');
1248                         if (tmp) {
1249                                 format = true;
1250                                 *tmp = '\0';
1251                         }
1252
1253                         rc = yaml_fill_scalar_data(msg, fmt, line);
1254                         if (rc < 0)
1255                                 goto nla_put_failure;
1256
1257                         /* Move to next YAML line */
1258                         if (format) {
1259                                 if (!split)
1260                                         line = *entry;
1261                                 else
1262                                         *entry = NULL;
1263                                 break;
1264                         }
1265                 }
1266
1267                 if (!format) {
1268                         yaml_emitter_set_writer_error(out->emitter,
1269                                                       "Emmitter flow format invalid");
1270                         rc = -EINVAL;
1271                         goto nla_put_failure;
1272                 }
1273
1274                 if (line && line[0] == '-')
1275                         *indent = 0;
1276
1277                 nla_nest_end(msg, list);
1278         } else {
1279                 do {
1280                         line = strsep(entry, "\n");
1281 have_next_line:
1282                         if (!line || !strlen(line) || strcmp(line, "...") == 0)
1283                                 break;
1284
1285                         fmt = yaml_format_type(out->emitter, line, indent);
1286                         if (fmt == LNKF_END)
1287                                 break;
1288
1289                         if (fmt & ~LNKF_MAPPING) { /* Filter out mappings */
1290                                 rc = yaml_create_nested_list(out, msg, &line,
1291                                                              entry, indent,
1292                                                              fmt);
1293                                 if (rc < 0)
1294                                         goto nla_put_failure;
1295                                 if (line)
1296                                         goto have_next_line;
1297                         } else {
1298                                 rc = yaml_fill_scalar_data(msg, fmt,
1299                                                            line + *indent);
1300                                 if (rc < 0)
1301                                         goto nla_put_failure;
1302                         }
1303                 } while (strcmp(*entry, ""));
1304
1305                 if (line && line[*indent] == '-') {
1306                         line[*indent] = ' ';
1307                         *indent += 2;
1308                         goto have_next_line;
1309                 }
1310                 if (*entry && !strlen(*entry))
1311                         line = NULL;
1312                 /* strsep in the above loop moves entry to a value pass the
1313                  * end of the nested list. So to avoid losing this value we
1314                  * replace hdr with line.
1315                  */
1316                 *hdr = line;
1317         }
1318
1319         if (nested)
1320                 nla_nest_end(msg, list);
1321 nla_put_failure:
1322         return rc;
1323 }
1324
1325 /* YAML allows ' and " in its documents but those characters really
1326  * confuse libc string handling. The workaround is to replace
1327  * ' and " with another reserved character for YAML '%' which is
1328  * for tags which shouldn't matter if we send in a Netlink packet.
1329  * The kernel side will need to handle % in a special way.
1330  */
1331 static void yaml_quotation_handling(char *buf)
1332 {
1333         char *tmp = buf, *line;
1334
1335         line = strstr(tmp, "! \'");
1336         if (line)
1337                 line[0] = ' ';
1338
1339         while ((line = strchr(tmp, '\"')) != NULL) {
1340                 line[0] = ' ';
1341                 tmp = strchr(line, '\"');
1342                 tmp[0] = ' ';
1343         }
1344
1345         while ((line = strchr(tmp, '\'')) != NULL) {
1346                 line[0] = ' ';
1347                 tmp = strchr(line, '\'');
1348                 tmp[0] = ' ';
1349         }
1350 }
1351
1352 /* libyaml takes the YAML documents and places the data into an
1353  * internal buffer to the library. We take each line and turn it
1354  * into a Netlink message using the same format as the key table.
1355  * The reason for this approach is that we can do filters at the
1356  * key level or the key + value level.
1357  */
1358 static int yaml_netlink_write_handler(void *data, unsigned char *buffer,
1359                                       size_t size)
1360 {
1361         struct yaml_netlink_output *out = data;
1362         char *buf = strndup((char *)buffer, size);
1363         char *entry = buf, *tmp = buf, *line;
1364         enum lnet_nl_key_format fmt = 0;
1365         struct nl_msg *msg = NULL;
1366         unsigned int indent = 0;
1367         bool nogroups = true;
1368         int rc = 0;
1369
1370         yaml_quotation_handling(entry);
1371
1372         while (entry && strcmp(line = strsep(&entry, "\n"), "")) {
1373 already_have_line:
1374                 if (strcmp(line, "---") == 0 || strcmp(line, "...") == 0)
1375                         continue;
1376
1377                 /* In theory we could have a sequence of groups but a bug in
1378                  * libyaml prevents this from happing
1379                  */
1380                 if (line[0] != ' ' && line[0] != '-') {
1381                         bool extra = false;
1382
1383                         if (strchr(line, '{') || strchr(line, '['))
1384                                 extra = true;
1385
1386                         tmp = strchr(line, ':');
1387                         if (!tmp)
1388                                 continue;
1389                         *tmp = '\0';
1390
1391                         rc = lustre_netlink_add_group(out->nl, out->family,
1392                                                       line);
1393                         if (rc < 0) {
1394                                 yaml_emitter_set_writer_error(out->emitter,
1395                                                               "Netlink group does not exist");
1396                                 goto nla_put_failure;
1397                         }
1398                         nogroups = false;
1399                         /* Handle case first line contains more than a
1400                          * simple key
1401                          */
1402                         if (extra) {
1403                                 *tmp = ' ';
1404                                 line = tmp;
1405                                 goto already_have_line;
1406                         }
1407                 } else {
1408                         if (!msg) {
1409                                 void *usr_hdr;
1410
1411                                 msg = nlmsg_alloc();
1412                                 if (!msg) {
1413                                         out->emitter->error = YAML_MEMORY_ERROR;
1414                                         goto nla_put_failure;
1415                                 }
1416
1417                                 usr_hdr = genlmsg_put(msg, out->pid,
1418                                                       NL_AUTO_SEQ,
1419                                                       out->family_id, 0,
1420                                                       out->flags, out->cmd,
1421                                                       out->version);
1422                                 if (!usr_hdr) {
1423                                         out->emitter->error = YAML_MEMORY_ERROR;
1424                                         nlmsg_free(msg);
1425                                         goto nla_put_failure;
1426                                 }
1427
1428                                 if (line[0] != '-')
1429                                         indent = 2;
1430                         }
1431
1432                         fmt = yaml_format_type(out->emitter, line, &indent);
1433                         if (fmt & ~LNKF_MAPPING) {
1434                                 rc = yaml_create_nested_list(out, msg, &line,
1435                                                              &entry, &indent,
1436                                                              fmt);
1437                                 if (rc < 0) {
1438                                         yaml_emitter_set_writer_error(out->emitter,
1439                                                                       nl_geterror(rc));
1440                                         nlmsg_free(msg);
1441                                         goto nla_put_failure;
1442                                 }
1443                                 /* yaml_create_nested_list set line to the next
1444                                  * entry. We can just add it to the msg directly.
1445                                  */
1446                                 if (line)
1447                                         goto already_have_line;
1448                         } else {
1449                                 rc = yaml_fill_scalar_data(msg, fmt,
1450                                                            line + indent);
1451                                 if (rc < 0) {
1452                                         yaml_emitter_set_writer_error(out->emitter,
1453                                                                       nl_geterror(rc));
1454                                         nlmsg_free(msg);
1455                                         goto nla_put_failure;
1456                                 }
1457                         }
1458                 }
1459         }
1460
1461         /* Don't success if no valid groups found */
1462         if (nogroups) {
1463                 yaml_emitter_set_writer_error(out->emitter,
1464                                               "Emitter contains no valid Netlink groups");
1465                 goto nla_put_failure;
1466         }
1467
1468         if (msg) {
1469                 rc = nl_send_auto(out->nl, msg);
1470                 nlmsg_free(msg);
1471         } else {
1472                 rc = genl_send_simple(out->nl, out->family_id, out->cmd,
1473                                       out->version, out->flags);
1474         }
1475         if (rc < 0)
1476                 yaml_emitter_set_writer_error(out->emitter,
1477                                               nl_geterror(rc));
1478 nla_put_failure:
1479         free(buf);
1480         return out->emitter->error == YAML_NO_ERROR ? 1 : 0;
1481 }
1482
1483 /* This function is used by external utilities to use Netlink with
1484  * libyaml so we can turn YAML documentations into Netlink message
1485  * to send. This behavior mirrors yaml_emitter_set_output_file()
1486  * which is used to write out a YAML document to a file.
1487  */
1488 YAML_DECLARE(int)
1489 yaml_emitter_set_output_netlink(yaml_emitter_t *sender, struct nl_sock *nl,
1490                                 char *family, int version, int cmd, int flags)
1491 {
1492         struct yaml_netlink_output *out;
1493
1494         out = calloc(1, sizeof(*out));
1495         if (!out) {
1496                 sender->error = YAML_MEMORY_ERROR;
1497                 return false;
1498         }
1499
1500         /* Get family ID */
1501         out->family_id = genl_ctrl_resolve(nl, family);
1502         if (out->family_id < 0) {
1503                 yaml_emitter_set_writer_error(sender,
1504                                               "failed to resolve Netlink family id");
1505                 free(out);
1506                 return false;
1507         }
1508
1509         out->emitter = sender;
1510         out->nl = nl;
1511         out->family = family;
1512         out->version = version;
1513         out->cmd = cmd;
1514         out->flags = flags;
1515         out->pid = nl_socket_get_local_port(nl);
1516         yaml_emitter_set_output(sender, yaml_netlink_write_handler, out);
1517         return true;
1518 }
1519
1520 /* Error handling helpers */
1521 void yaml_emitter_log_error(yaml_emitter_t *emitter, FILE *log)
1522 {
1523         /* YAML_WRITER_ERROR means no Netlink support so use old API */
1524         switch (emitter->error) {
1525         case YAML_MEMORY_ERROR:
1526                 fprintf(log, "Memory error: Not enough memory for emitting\n");
1527                         break;
1528         case YAML_WRITER_ERROR:
1529                 fprintf(log, "Writer error: %s\n", emitter->problem);
1530                 break;
1531         case YAML_EMITTER_ERROR:
1532                 fprintf(log, "Emitter error: %s\n", emitter->problem);
1533         default:
1534                 break;
1535         }
1536 }
1537
1538 void yaml_parser_log_error(yaml_parser_t *parser, FILE *log, const char *errmsg)
1539 {
1540         const char *extra;
1541
1542         switch (parser->error) {
1543         case YAML_MEMORY_ERROR:
1544                 fprintf(log, "Memory error: Not enough memory for parser\n");
1545                 break;
1546
1547         case YAML_SCANNER_ERROR:
1548         case YAML_PARSER_ERROR:
1549                 if (parser->context) {
1550                         fprintf(log,
1551                                 "%s error: %s at line %d, column %d\n%s at line %d, column %d\n",
1552                                 parser->error == YAML_SCANNER_ERROR ? "Scanner" : "Parser",
1553                                 parser->context,
1554                                 (int)parser->context_mark.line + 1,
1555                                 (int)parser->context_mark.column + 1,
1556                                 parser->problem,
1557                                 (int)parser->problem_mark.line + 1,
1558                                 (int)parser->problem_mark.column + 1);
1559                 } else {
1560                         fprintf(log, "%s error: %s at line %d, column %d\n",
1561                                 parser->error == YAML_SCANNER_ERROR ? "Scanner" : "Parser",
1562                                 parser->problem,
1563                                 (int)parser->problem_mark.line + 1,
1564                                 (int)parser->problem_mark.column + 1);
1565                 }
1566                 break;
1567
1568         case YAML_READER_ERROR:
1569                 extra = yaml_parser_get_reader_error(parser);
1570                 if (!extra)
1571                         extra = parser->problem;
1572
1573                 if (parser->problem_value != -1) {
1574                         fprintf(log, "Reader error: '%s':#%X at %ld'\n",
1575                                 extra, parser->problem_value,
1576                                 (long)parser->problem_offset);
1577                 } else {
1578                         fprintf(log, "Reader error: '%s' at %ld\n",
1579                                 extra, (long)parser->problem_offset);
1580                 }
1581                 fallthrough;
1582         default:
1583                 break;
1584         }
1585 }