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Diffstat (limited to 'lib/command_match.c')
| -rw-r--r-- | lib/command_match.c | 868 |
1 files changed, 868 insertions, 0 deletions
diff --git a/lib/command_match.c b/lib/command_match.c new file mode 100644 index 0000000000..06a50656b6 --- /dev/null +++ b/lib/command_match.c @@ -0,0 +1,868 @@ +/* + * Input matching routines for CLI backend. + * + * -- + * Copyright (C) 2016 Cumulus Networks, Inc. + * + * This file is part of GNU Zebra. + * + * GNU Zebra is free software; you can redistribute it and/or modify it + * under the terms of the GNU General Public License as published by the + * Free Software Foundation; either version 2, or (at your option) any + * later version. + * + * GNU Zebra is distributed in the hope that it will be useful, but + * WITHOUT ANY WARRANTY; without even the implied warranty of + * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU + * General Public License for more details. + * + * You should have received a copy of the GNU General Public License + * along with GNU Zebra; see the file COPYING. If not, write to the Free + * Software Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA + * 02111-1307, USA. + */ + +#include <zebra.h> + +#include "command_match.h" +#include "command_parse.h" +#include "memory.h" + +DEFINE_MTYPE_STATIC(LIB, CMD_TOKENS, "Command Tokens") + +/* matcher helper prototypes */ +static int +add_nexthops (struct list *, struct graph_node *); + +static struct list * +command_match_r (struct graph_node *, vector, unsigned int); + +static int +score_precedence (enum cmd_token_type); + +static enum match_type +min_match_level (enum cmd_token_type); + +static void +del_arglist (struct list *); + +static struct cmd_token * +disambiguate_tokens (struct cmd_token *, struct cmd_token *, char *); + +static struct list * +disambiguate (struct list *, struct list *, vector, unsigned int); + +int +compare_completions (const void *, const void *); + +/* token matcher prototypes */ +static enum match_type +match_token (struct cmd_token *, char *); + +static enum match_type +match_ipv4 (const char *); + +static enum match_type +match_ipv4_prefix (const char *); + +static enum match_type +match_ipv6 (const char *); + +static enum match_type +match_ipv6_prefix (const char *); + +static enum match_type +match_range (struct cmd_token *, const char *); + +static enum match_type +match_word (struct cmd_token *, const char *); + +static enum match_type +match_variable (struct cmd_token *, const char *); + +/* matching functions */ +static enum matcher_rv matcher_rv; + +enum matcher_rv +command_match (struct graph *cmdgraph, + vector vline, + struct list **argv, + const struct cmd_element **el) +{ + matcher_rv = MATCHER_NO_MATCH; + + // prepend a dummy token to match that pesky start node + vector vvline = vector_init (vline->alloced + 1); + vector_set_index (vvline, 0, (void *) XSTRDUP (MTYPE_TMP, "dummy")); + memcpy (vvline->index + 1, vline->index, sizeof (void *) * vline->alloced); + vvline->active = vline->active + 1; + + struct graph_node *start = vector_slot (cmdgraph->nodes, 0); + if ((*argv = command_match_r (start, vvline, 0))) // successful match + { + struct listnode *head = listhead (*argv); + struct listnode *tail = listtail (*argv); + + // delete dummy start node + del_cmd_token ((struct cmd_token *) head->data); + list_delete_node (*argv, head); + + // get cmd_element out of list tail + *el = listgetdata (tail); + list_delete_node (*argv, tail); + + // now argv is an ordered list of cmd_token matching the user + // input, with each cmd_token->arg holding the corresponding input + assert (*el); + } + +#ifdef TRACE_MATCHER + if (!*el) + fprintf (stdout, "No match\n"); + else + fprintf (stdout, "Matched command\n->string %s\n->desc %s\n", (*el)->string, (*el)->doc); +#endif + + // free the leader token we alloc'd + XFREE (MTYPE_TMP, vector_slot (vvline, 0)); + // free vector + vector_free (vvline); + + return matcher_rv; +} + +/** + * Builds an argument list given a DFA and a matching input line. + * + * First the function determines if the node it is passed matches the first + * token of input. If it does not, it returns NULL (MATCHER_NO_MATCH). If it + * does match, then it saves the input token as the head of an argument list. + * + * The next step is to see if there is further input in the input line. If + * there is not, the current node's children are searched to see if any of them + * are leaves (type END_TKN). If this is the case, then the bottom of the + * recursion stack has been reached, the leaf is pushed onto the argument list, + * the current node is pushed, and the resulting argument list is + * returned (MATCHER_OK). If it is not the case, NULL is returned, indicating + * that there is no match for the input along this path (MATCHER_INCOMPLETE). + * + * If there is further input, then the function recurses on each of the current + * node's children, passing them the input line minus the token that was just + * matched. For each child, the return value of the recursive call is + * inspected. If it is null, then there is no match for the input along the + * subgraph headed by that child. If it is not null, then there is at least one + * input match in that subgraph (more on this in a moment). + * + * If a recursive call on a child returns a non-null value, then it has matched + * the input given it on the subgraph that starts with that child. However, due + * to the flexibility of the grammar, it is sometimes the case that two or more + * child graphs match the same input (two or more of the recursive calls have + * non-NULL return values). This is not a valid state, since only one true + * match is possible. In order to resolve this conflict, the function keeps a + * reference to the child node that most specifically matches the input. This + * is done by assigning each node type a precedence. If a child is found to + * match the remaining input, then the precedence values of the current + * best-matching child and this new match are compared. The node with higher + * precedence is kept, and the other match is discarded. Due to the recursive + * nature of this function, it is only necessary to compare the precedence of + * immediate children, since all subsequent children will already have been + * disambiguated in this way. + * + * In the event that two children are found to match with the same precedence, + * then the input is ambiguous for the passed cmd_element and NULL is returned. + * + * @param[in] start the start node. + * @param[in] vline the vectorized input line. + * @param[in] n the index of the first input token. + * @return A linked list of n elements. The first n-1 elements are pointers to + * struct cmd_token and represent the sequence of tokens matched by the input. + * The ->arg field of each token points to a copy of the input matched on it. + * The final nth element is a pointer to struct cmd_element, which is the + * command that was matched. + * + * If no match was found, the return value is NULL. + */ +static struct list * +command_match_r (struct graph_node *start, vector vline, unsigned int n) +{ + assert (n < vector_active (vline)); + + // get the minimum match level that can count as a full match + struct cmd_token *token = start->data; + enum match_type minmatch = min_match_level (token->type); + + // get the current operating input token + char *input_token = vector_slot (vline, n); + +#ifdef TRACE_MATCHER + fprintf (stdout, "\"%-20s\" matches \"%-30s\" ? ", input_token, token->text); + enum match_type mt = match_token (token, input_token); + fprintf (stdout, "min: %d - ", minmatch); + switch (mt) + { + case trivial_match: + fprintf (stdout, "trivial_match "); + break; + case no_match: + fprintf (stdout, "no_match "); + break; + case partly_match: + fprintf (stdout, "partly_match "); + break; + case exact_match: + fprintf (stdout, "exact_match "); + break; + } + if (mt >= minmatch) fprintf (stdout, " MATCH"); + fprintf (stdout, "\n"); +#endif + + // if we don't match this node, die + if (match_token (token, input_token) < minmatch) + return NULL; + + // pointers for iterating linklist + struct listnode *ln; + struct graph_node *gn; + + // get all possible nexthops + struct list *next = list_new(); + add_nexthops (next, start); + + // determine the best match + int ambiguous = 0; + struct list *currbest = NULL; + for (ALL_LIST_ELEMENTS_RO (next,ln,gn)) + { + // if we've matched all input we're looking for END_TKN + if (n+1 == vector_active (vline)) + { + struct cmd_token *tok = gn->data; + if (tok->type == END_TKN) + { + if (currbest) // there is more than one END_TKN in the follow set + { + ambiguous = 1; + break; + } + currbest = list_new(); + // node should have one child node with the element + struct graph_node *leaf = vector_slot (gn->to, 0); + // last node in the list will hold the cmd_element; + // this is important because list_delete() expects + // that all nodes have the same data type, so when + // deleting this list the last node must be + // manually deleted + struct cmd_element *el = leaf->data; + listnode_add (currbest, el); + currbest->del = (void (*)(void *)) &del_cmd_token; + // do not break immediately; continue walking through the follow set + // to ensure that there is exactly one END_TKN + } + continue; + } + + // else recurse on candidate child node + struct list *result = command_match_r (gn, vline, n+1); + + // save the best match + if (result && currbest) + { + // pick the best of two matches + struct list *newbest = disambiguate (currbest, result, vline, n+1); + // set ambiguity flag + ambiguous = !newbest || (ambiguous && newbest == currbest); + // delete the unnecessary result + struct list *todelete = ((newbest && newbest == result) ? currbest : result); + del_arglist (todelete); + + currbest = newbest ? newbest : currbest; + } + else if (result) + currbest = result; + } + + if (currbest) + { + if (ambiguous) + { + del_arglist (currbest); + currbest = NULL; + matcher_rv = MATCHER_AMBIGUOUS; + } + else + { + // copy token, set arg and prepend to currbest + struct cmd_token *token = start->data; + struct cmd_token *copy = copy_cmd_token (token); + copy->arg = XSTRDUP (MTYPE_CMD_TOKENS, input_token); + listnode_add_before (currbest, currbest->head, copy); + matcher_rv = MATCHER_OK; + } + } + else if (n+1 == vector_active (vline) && matcher_rv == MATCHER_NO_MATCH) + matcher_rv = MATCHER_INCOMPLETE; + + // cleanup + list_delete (next); + + return currbest; +} + +enum matcher_rv +command_complete (struct graph *graph, + vector vline, + struct list **completions) +{ + // pointer to next input token to match + char *input_token; + + struct list *current = list_new(), // current nodes to match input token against + *next = list_new(); // possible next hops after current input token + + // pointers used for iterating lists + struct graph_node *gn; + struct listnode *node; + + // add all children of start node to list + struct graph_node *start = vector_slot (graph->nodes, 0); + add_nexthops (next, start); + + unsigned int idx; + for (idx = 0; idx < vector_active (vline) && next->count > 0; idx++) + { + list_delete (current); + current = next; + next = list_new(); + + input_token = vector_slot (vline, idx); + + for (ALL_LIST_ELEMENTS_RO (current,node,gn)) + { + struct cmd_token *token = gn->data; + + if (token->attr == CMD_ATTR_HIDDEN || token->attr == CMD_ATTR_DEPRECATED) + continue; + + enum match_type minmatch = min_match_level (token->type); +#ifdef TRACE_MATCHER + fprintf (stdout, "\"%s\" matches \"%s\" (%d) ? ", input_token, token->text, token->type); +#endif + + switch (match_token (token, input_token)) + { + case trivial_match: +#ifdef TRACE_MATCHER + fprintf (stdout, "trivial_match\n"); +#endif + case partly_match: +#ifdef TRACE_MATCHER + fprintf (stdout, "partly_match\n"); +#endif + if (idx == vector_active (vline) - 1) + { + listnode_add (next, gn); + break; + } + if (minmatch > partly_match) + break; + case exact_match: +#ifdef TRACE_MATCHER + fprintf (stdout, "exact_match\n"); +#endif + add_nexthops (next, gn); + break; + default: +#ifdef TRACE_MATCHER + fprintf (stdout, "no_match\n"); +#endif + break; + } + } + } + + /* Variable summary + * ----------------------------------------------------------------- + * token = last input token processed + * idx = index in `command` of last token processed + * current = set of all transitions from the previous input token + * next = set of all nodes reachable from all nodes in `matched` + */ + + matcher_rv = + idx == vector_active(vline) && next->count ? + MATCHER_OK : + MATCHER_NO_MATCH; + + *completions = NULL; + if (!MATCHER_ERROR(matcher_rv)) + { + // extract cmd_token into list + *completions = list_new (); + for (ALL_LIST_ELEMENTS_RO (next,node,gn)) + listnode_add (*completions, gn->data); + } + + list_delete (current); + list_delete (next); + + return matcher_rv; +} + +/** + * Adds all children that are reachable by one parser hop to the given list. + * NUL_TKN, SELECTOR_TKN, and OPTION_TKN nodes are treated as transparent. + * + * @param[in] list to add the nexthops to + * @param[in] node to start calculating nexthops from + * @return the number of children added to the list + */ +static int +add_nexthops (struct list *list, struct graph_node *node) +{ + int added = 0; + struct graph_node *child; + for (unsigned int i = 0; i < vector_active (node->to); i++) + { + child = vector_slot (node->to, i); + struct cmd_token *token = child->data; + switch (token->type) + { + case OPTION_TKN: + case SELECTOR_TKN: + case NUL_TKN: + added += add_nexthops (list, child); + break; + default: + listnode_add (list, child); + added++; + } + } + + return added; +} + +/** + * Determines the node types for which a partial match may count as a full + * match. Enables command abbrevations. + * + * @param[in] type node type + * @return minimum match level needed to for a token to fully match + */ +static enum match_type +min_match_level (enum cmd_token_type type) +{ + switch (type) + { + // anything matches a start node, for the sake of recursion + case START_TKN: + return no_match; + // allowing words to partly match enables command abbreviation + case WORD_TKN: + return partly_match; + default: + return exact_match; + } +} + +/** + * Assigns precedence scores to node types. + * + * @param[in] type node type to score + * @return precedence score + */ +static int +score_precedence (enum cmd_token_type type) +{ + switch (type) + { + // some of these are mutually exclusive, so they share + // the same precedence value + case IPV4_TKN: + case IPV4_PREFIX_TKN: + case IPV6_TKN: + case IPV6_PREFIX_TKN: + case RANGE_TKN: + return 2; + case WORD_TKN: + return 3; + case VARIABLE_TKN: + return 4; + default: + return 10; + } +} + +/** + * Picks the better of two possible matches for a token. + * + * @param[in] first candidate node matching token + * @param[in] second candidate node matching token + * @param[in] token the token being matched + * @return the best-matching node, or NULL if the two are entirely ambiguous + */ +static struct cmd_token * +disambiguate_tokens (struct cmd_token *first, + struct cmd_token *second, + char *input_token) +{ + // if the types are different, simply go off of type precedence + if (first->type != second->type) + { + int firstprec = score_precedence (first->type); + int secndprec = score_precedence (second->type); + if (firstprec != secndprec) + return firstprec < secndprec ? first : second; + else + return NULL; + } + + // if they're the same, return the more exact match + enum match_type fmtype = match_token (first, input_token); + enum match_type smtype = match_token (second, input_token); + if (fmtype != smtype) + return fmtype > smtype ? first : second; + + return NULL; +} + +/** + * Picks the better of two possible matches for an input line. + * + * @param[in] first candidate list of cmd_token matching vline + * @param[in] second candidate list of cmd_token matching vline + * @param[in] vline the input line being matched + * @param[in] n index into vline to start comparing at + * @return the best-matching list, or NULL if the two are entirely ambiguous + */ +static struct list * +disambiguate (struct list *first, + struct list *second, + vector vline, + unsigned int n) +{ + // doesn't make sense for these to be inequal length + assert (first->count == second->count); + assert (first->count == vector_active (vline) - n+1); + + struct listnode *fnode = listhead (first), + *snode = listhead (second); + struct cmd_token *ftok = listgetdata (fnode), + *stok = listgetdata (snode), + *best = NULL; + + // compare each token, if one matches better use that one + for (unsigned int i = n; i < vector_active (vline); i++) + { + char *token = vector_slot(vline, i); + if ((best = disambiguate_tokens (ftok, stok, token))) + return best == ftok ? first : second; + fnode = listnextnode (fnode); + snode = listnextnode (snode); + ftok = listgetdata (fnode); + stok = listgetdata (snode); + } + + return NULL; +} + +/* + * Deletion function for arglist. + * + * Since list->del for arglists expects all listnode->data to hold cmd_token, + * but arglists have cmd_element as the data for the tail, this function + * manually deletes the tail before deleting the rest of the list as usual. + * + * The cmd_element at the end is *not* a copy. It is the one and only. + * + * @param list the arglist to delete + */ +static void +del_arglist (struct list *list) +{ + // manually delete last node + struct listnode *tail = listtail (list); + tail->data = NULL; + list_delete_node (list, tail); + + // delete the rest of the list as usual + list_delete (list); +} + +/*---------- token level matching functions ----------*/ + +static enum match_type +match_token (struct cmd_token *token, char *input_token) +{ + // nothing trivially matches everything + if (!input_token) + return trivial_match; + + switch (token->type) { + case WORD_TKN: + return match_word (token, input_token); + case IPV4_TKN: + return match_ipv4 (input_token); + case IPV4_PREFIX_TKN: + return match_ipv4_prefix (input_token); + case IPV6_TKN: + return match_ipv6 (input_token); + case IPV6_PREFIX_TKN: + return match_ipv6_prefix (input_token); + case RANGE_TKN: + return match_range (token, input_token); + case VARIABLE_TKN: + return match_variable (token, input_token); + case END_TKN: + default: + return no_match; + } +} + +#define IPV4_ADDR_STR "0123456789." +#define IPV4_PREFIX_STR "0123456789./" + +static enum match_type +match_ipv4 (const char *str) +{ + const char *sp; + int dots = 0, nums = 0; + char buf[4]; + + for (;;) + { + memset (buf, 0, sizeof (buf)); + sp = str; + while (*str != '\0') + { + if (*str == '.') + { + if (dots >= 3) + return no_match; + + if (*(str + 1) == '.') + return no_match; + + if (*(str + 1) == '\0') + return partly_match; + + dots++; + break; + } + if (!isdigit ((int) *str)) + return no_match; + + str++; + } + + if (str - sp > 3) + return no_match; + + strncpy (buf, sp, str - sp); + if (atoi (buf) > 255) + return no_match; + + nums++; + + if (*str == '\0') + break; + + str++; + } + + if (nums < 4) + return partly_match; + + return exact_match; +} + +static enum match_type +match_ipv4_prefix (const char *str) +{ + const char *sp; + int dots = 0; + char buf[4]; + + for (;;) + { + memset (buf, 0, sizeof (buf)); + sp = str; + while (*str != '\0' && *str != '/') + { + if (*str == '.') + { + if (dots == 3) + return no_match; + + if (*(str + 1) == '.' || *(str + 1) == '/') + return no_match; + + if (*(str + 1) == '\0') + return partly_match; + + dots++; + break; + } + + if (!isdigit ((int) *str)) + return no_match; + + str++; + } + + if (str - sp > 3) + return no_match; + + strncpy (buf, sp, str - sp); + if (atoi (buf) > 255) + return no_match; + + if (dots == 3) + { + if (*str == '/') + { + if (*(str + 1) == '\0') + return partly_match; + + str++; + break; + } + else if (*str == '\0') + return partly_match; + } + + if (*str == '\0') + return partly_match; + + str++; + } + + sp = str; + while (*str != '\0') + { + if (!isdigit ((int) *str)) + return no_match; + + str++; + } + + if (atoi (sp) > 32) + return no_match; + + return exact_match; +} + +#ifdef HAVE_IPV6 +#define IPV6_ADDR_STR "0123456789abcdefABCDEF:." +#define IPV6_PREFIX_STR "0123456789abcdefABCDEF:./" + +static enum match_type +match_ipv6 (const char *str) +{ + struct sockaddr_in6 sin6_dummy; + int ret; + + if (strspn (str, IPV6_ADDR_STR) != strlen (str)) + return no_match; + + ret = inet_pton(AF_INET6, str, &sin6_dummy.sin6_addr); + + if (ret == 1) + return exact_match; + + return no_match; +} + +static enum match_type +match_ipv6_prefix (const char *str) +{ + struct sockaddr_in6 sin6_dummy; + const char *delim = "/\0"; + char *tofree, *dupe, *prefix, *mask, *endptr; + int nmask = -1; + + if (strspn (str, IPV6_PREFIX_STR) != strlen (str)) + return no_match; + + /* tokenize to prefix + mask */ + tofree = dupe = XSTRDUP (MTYPE_TMP, str); + prefix = strsep (&dupe, delim); + mask = dupe; + + /* validate prefix */ + if (inet_pton (AF_INET6, prefix, &sin6_dummy.sin6_addr) != 1) + { + XFREE (MTYPE_TMP, tofree); + return no_match; + } + + /* validate mask */ + if (!mask) + { + XFREE (MTYPE_TMP, tofree); + return partly_match; + } + + nmask = strtoimax (mask, &endptr, 10); + if (*endptr != '\0' || nmask < 0 || nmask > 128) + { + XFREE (MTYPE_TMP, tofree); + return no_match; + } + + XFREE (MTYPE_TMP, tofree); + return exact_match; +} +#endif + +static enum match_type +match_range (struct cmd_token *token, const char *str) +{ + assert (token->type == RANGE_TKN); + + char *endptr = NULL; + long long val; + + val = strtoll (str, &endptr, 10); + if (*endptr != '\0') + return no_match; + + if (val < token->min || val > token->max) + return no_match; + else + return exact_match; +} + +static enum match_type +match_word (struct cmd_token *token, const char *word) +{ + assert (token->type == WORD_TKN); + + // if the passed token is 0 length, partly match + if (!strlen(word)) + return partly_match; + + // if the passed token is strictly a prefix of the full word, partly match + if (strlen (word) < strlen (token->text)) + return !strncmp (token->text, word, strlen (word)) ? + partly_match : + no_match; + + // if they are the same length and exactly equal, exact match + else if (strlen (word) == strlen (token->text)) + return !strncmp (token->text, word, strlen (word)) ? exact_match : no_match; + + return no_match; +} + +#define VARIABLE_ALPHABET \ +"ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz1234567890:/._-" + +static enum match_type +match_variable (struct cmd_token *token, const char *word) +{ + assert (token->type == VARIABLE_TKN); + + return strlen (word) == strspn(word, VARIABLE_ALPHABET) ? + exact_match : no_match; +} |