nss: convert findMACs to use json-c

While the parsing is still done by 1K buffers, the results
are no longer filtered during the parsing, but the whole JSON
has to live in memory at once, which was also the case before
the NSS plugin dropped its dependency on libvirt_util.

Also, the new parser might be more forgiving of missing elements.

Signed-off-by: Ján Tomko <jtomko@redhat.com>
Reviewed-by: Peter Krempa <pkrempa@redhat.com>

tools/nss/libvirt_nss_macs.c

@@ -25,179 +25,89 @@
 #include <stdlib.h>
 #include <fcntl.h>
 
-#include <yajl/yajl_gen.h>
+#include <json.h>
-#include <yajl/yajl_parse.h>
 
 #include "libvirt_nss_macs.h"
 #include "libvirt_nss.h"
 
-enum {
-    FIND_MACS_STATE_START,
-    FIND_MACS_STATE_LIST,
-    FIND_MACS_STATE_ENTRY,
-    FIND_MACS_STATE_ENTRY_MACS,
-};
-
-typedef struct {
-    const char *name;
-    char ***macs;
-    size_t *nmacs;
-    int state;
-
-    char *key;
-    struct {
-        char *name;
-        char **macs;
-        size_t nmacs;
-    } entry;
-} findMACsParser;
-
 
+/**
+ * findMACsFromJSON
+ *
+ * @jobj: JSON object containing the leases
+ * @name: requested hostname
+ * @macs: returned array of MAC addresses leased to the hostname
+ * @nmacs: size of the returned array
+ */
 static int
-findMACsParserString(void *ctx,
+findMACsFromJSON(json_object *jobj,
-                     const unsigned char *stringVal,
+                 const char *name,
-                     size_t stringLen)
+                 char ***macs,
+                 size_t *nmacs)
 {
-    findMACsParser *parser = ctx;
-
-    DEBUG("Parse string state=%d '%.*s' (map key '%s')",
-          parser->state, (int)stringLen, (const char *)stringVal,
-          NULLSTR(parser->key));
-    if (!parser->key)
-        return 0;
-
-    if (parser->state == FIND_MACS_STATE_ENTRY) {
-        if (strcmp(parser->key, "domain"))
-            return 1;
-
-        free(parser->entry.name);
-        if (!(parser->entry.name = strndup((char *)stringVal, stringLen)))
-            return 0;
-    } else if (parser->state == FIND_MACS_STATE_ENTRY_MACS) {
-        char **macs;
-        if (strcmp(parser->key, "macs"))
-            return 1;
-
-        if (!(macs = realloc(parser->entry.macs,
-                             sizeof(char *) * (parser->entry.nmacs + 1))))
-            return 0;
-
-        parser->entry.macs = macs;
-        if (!(macs[parser->entry.nmacs++] = strndup((char *)stringVal, stringLen)))
-            return 0;
-    } else {
-        return 0;
-    }
-    return 1;
-}
-
-
-static int
-findMACsParserMapKey(void *ctx,
-                     const unsigned char *stringVal,
-                     size_t stringLen)
-{
-    findMACsParser *parser = ctx;
-
-    DEBUG("Parse map key state=%d '%.*s'",
-          parser->state, (int)stringLen, (const char *)stringVal);
-
-    free(parser->key);
-    if (!(parser->key = strndup((char *)stringVal, stringLen)))
-        return 0;
-
-    return 1;
-}
-
-
-static int
-findMACsParserStartMap(void *ctx)
-{
-    findMACsParser *parser = ctx;
-
-    DEBUG("Parse start map state=%d", parser->state);
-
-    if (parser->state != FIND_MACS_STATE_LIST)
-        return 0;
-
-    free(parser->key);
-    parser->key = NULL;
-    parser->state = FIND_MACS_STATE_ENTRY;
-
-    return 1;
-}
-
-
-static int
-findMACsParserEndMap(void *ctx)
-{
-    findMACsParser *parser = ctx;
     size_t i;
+    int len;
 
-    DEBUG("Parse end map state=%d", parser->state);
+    if (!json_object_is_type(jobj, json_type_array)) {
-
+        ERROR("parsed JSON does not contain the leases array");
-    if (parser->entry.name == NULL)
+        return -1;
-        return 0;
-
-    if (parser->state != FIND_MACS_STATE_ENTRY)
-        return 0;
-
-    if (!strcasecmp(parser->entry.name, parser->name)) {
-        char **macs = realloc(*parser->macs,
-                              sizeof(char *) * ((*parser->nmacs) + parser->entry.nmacs));
-        if (!macs)
-            return 0;
-
-        *parser->macs = macs;
-        for (i = 0; i < parser->entry.nmacs; i++)
-            (*parser->macs)[(*parser->nmacs)++] = parser->entry.macs[i];
-    } else {
-        for (i = 0; i < parser->entry.nmacs; i++)
-            free(parser->entry.macs[i]);
     }
-    free(parser->entry.macs);
-    parser->entry.macs = NULL;
-    parser->entry.nmacs = 0;
 
-    parser->state = FIND_MACS_STATE_LIST;
+    len = json_object_array_length(jobj);
+    DEBUG("Found an array of length: %zu", len);
+    for (i = 0; i < len; i++) {
+        json_object *entry = NULL;
+        json_object *domain = NULL;
+        const char *domainName;
+        char **tmpMacs = NULL;
+        size_t newmacs = 0;
+        json_object *macsArray = NULL;
+        size_t j;
 
-    return 1;
+        entry = json_object_array_get_idx(jobj, i);
-}
+        if (!entry)
+            continue;
 
+        DEBUG("Processing item %zu", i);
 
-static int
+        domain = json_object_object_get(entry, "domain");
-findMACsParserStartArray(void *ctx)
+        if (!domain)
-{
+            continue;
-    findMACsParser *parser = ctx;
 
-    DEBUG("Parse start array state=%d", parser->state);
+        domainName = json_object_get_string(domain);
+        if (!domainName)
+            continue;
 
-    if (parser->state == FIND_MACS_STATE_START)
+        DEBUG("Processing domain %s", domainName);
-        parser->state = FIND_MACS_STATE_LIST;
-    else if (parser->state == FIND_MACS_STATE_ENTRY)
-        parser->state = FIND_MACS_STATE_ENTRY_MACS;
-    else
-        return 0;
 
-    return 1;
+        if (strcasecmp(domainName, name))
-}
+            continue;
 
+        macsArray = json_object_object_get(entry, "macs");
+        if (!macsArray)
+            continue;
 
-static int
+        newmacs = json_object_array_length(macsArray);
-findMACsParserEndArray(void *ctx)
+        DEBUG("Found %zu MAC addresses", newmacs);
-{
-    findMACsParser *parser = ctx;
 
-    DEBUG("Parse end array state=%d", parser->state);
+        tmpMacs = realloc(*macs, sizeof(char *) * (*nmacs + newmacs + 1));
+        if (!tmpMacs)
+            return -1;
 
-    if (parser->state == FIND_MACS_STATE_LIST)
+        *macs = tmpMacs;
-        parser->state = FIND_MACS_STATE_START;
-    else if (parser->state == FIND_MACS_STATE_ENTRY_MACS)
-        parser->state = FIND_MACS_STATE_ENTRY;
-    else
-        return 0;
 
-    return 1;
+        for (j = 0; j < newmacs; j++) {
+            json_object *macobj = NULL;
+            char *macstr;
+
+            macobj = json_object_array_get_idx(macsArray, j);
+            macstr = strdup(json_object_get_string(macobj));
+            if (!macstr)
+                return -1;
+            (*macs)[(*nmacs)++] = macstr;
+        }
+    }
+    return 0;
 }
 
 
@@ -209,66 +119,50 @@ findMACs(const char *file,
 {
     int fd = -1;
     int ret = -1;
-    const yajl_callbacks parserCallbacks = {
-        NULL, /* null */
-        NULL, /* bool */
-        NULL, /* integer */
-        NULL, /* double */
-        NULL, /* number */
-        findMACsParserString,
-        findMACsParserStartMap,
-        findMACsParserMapKey,
-        findMACsParserEndMap,
-        findMACsParserStartArray,
-        findMACsParserEndArray,
-    };
-    findMACsParser parserState = {
-        .name = name,
-        .macs = macs,
-        .nmacs = nmacs,
-    };
-    yajl_handle parser = NULL;
     char line[1024];
-    size_t i;
+    json_object *jobj = NULL;
+    json_tokener *tok = NULL;
+    enum json_tokener_error jerr;
+    int jsonflags = JSON_TOKENER_STRICT | JSON_TOKENER_VALIDATE_UTF8;
+    ssize_t nreadTotal = 0;
     int rv;
+    size_t i;
 
     if ((fd = open(file, O_RDONLY)) < 0) {
         ERROR("Cannot open %s", file);
         goto cleanup;
     }
 
-    parser = yajl_alloc(&parserCallbacks, NULL, &parserState);
+    tok = json_tokener_new();
-    if (!parser) {
+    json_tokener_set_flags(tok, jsonflags);
-        ERROR("Unable to create JSON parser");
-        goto cleanup;
-    }
 
-    while (1) {
+    do {
         rv = read(fd, line, sizeof(line));
         if (rv < 0)
             goto cleanup;
         if (rv == 0)
             break;
+        nreadTotal += rv;
 
-        if (yajl_parse(parser, (const unsigned char *)line, rv)  !=
+        jobj = json_tokener_parse_ex(tok, line, rv);
-            yajl_status_ok) {
+        jerr = json_tokener_get_error(tok);
-            unsigned char *err = yajl_get_error(parser, 1,
+    } while (jerr == json_tokener_continue);
-                                                (const unsigned char*)line, rv);
-            ERROR("Parse failed %s", (const char *) err);
-            yajl_free_error(parser, err);
-            goto cleanup;
-        }
-    }
 
-    if (yajl_complete_parse(parser) != yajl_status_ok) {
+    if (jerr == json_tokener_continue) {
-        ERROR("Parse failed %s",
+        ERROR("Cannot parse %s: incomplete json found", file);
-              yajl_get_error(parser, 1, NULL, 0));
         goto cleanup;
     }
 
-    ret = 0;
+    if (nreadTotal > 0 && jerr != json_tokener_success) {
+        ERROR("Cannot parse %s: %s", file, json_tokener_error_desc(jerr));
+        goto cleanup;
+    }
+
+    ret = findMACsFromJSON(jobj, name, macs, nmacs);
 
  cleanup:
+    json_object_put(jobj);
+    json_tokener_free(tok);
     if (ret != 0) {
         for (i = 0; i < *nmacs; i++) {
             char *mac = (*macs)[i];
@@ -278,13 +172,6 @@ findMACs(const char *file,
         *macs = NULL;
         *nmacs = 0;
     }
-    if (parser)
-        yajl_free(parser);
-    for (i = 0; i < parserState.entry.nmacs; i++)
-        free(parserState.entry.macs[i]);
-    free(parserState.entry.macs);
-    free(parserState.entry.name);
-    free(parserState.key);
     if (fd != -1)
         close(fd);
     return ret;