jitterbug/match.c

#include <stdlib.h>
#include <string.h>
#include <stdio.h>
#include <stdbool.h>
#include "match.h"
#include "util.h"
#include "wire.h"
#include "try.h"
#include "server.h"

void match_rule_free(match_rule_t *rule)
{
    if (rule) {
        free(rule->rule_string);
        free(rule->sender);
        free(rule->interface);
        free(rule->member);
        free(rule->path);
        free(rule->path_namespace);
        free(rule->destination);
        free(rule->arg0namespace);
        for (int i = 0; i < MATCH_RULE_MAX_ARG; i++) {
            free(rule->arg[i]);
            free(rule->arg_path[i]);
        }
        free(rule);
    }
}

match_rule_t *match_rule_from_string(char *d)
{
    char *key = NULL;
    char acc[MATCH_RULE_MAX];
    int acci = 0;
    match_rule_t *rule;

    if (strlen(d) >= MATCH_RULE_MAX) {
        return NULL;
    }

    rule = calloc(sizeof(match_rule_t), 1);
    if (!rule) {
        return NULL;
    }

    rule->rule_string = string_dup(d);

    while (*d) {
        /* key */
        key = d;
        while (*d && *d != '=') d++;
        if (*d != '=') {
            goto fail;
        }
        *d = '\0';
        d++;
        if (!*d) {
            goto fail;
        }

        /* value */
        bool quote = false;
        acci = 0;
        acc[acci] = '\0';
        for (;;) {
            if (*d == '\'') {
                /* '\'' starts a quoted region */
                quote = !quote;
                d++;
            } else if (!quote && *d == ',') {
                /* ',' outside quoted region means next key-value pair */
                acc[acci] = '\0';
                acci = 0;
                d++;
                break;
            } else if (!quote && *d == '\\') {
                /* '\\' outside quoted region means escaped character */
                /* TODO: not entirely to spec */
                d++;
                if (*d != '\'') {
                    goto fail;
                }
                if (acci >= MATCH_RULE_MAX) {
                    goto fail;
                }
                acc[acci++] = *d;
                d++;
            } else if (!*d) {
                /* end of string */
                if (quote) {
                    /* end of string, yet we were insinde a quoted region */
                    /* unexpected end of input */
                    goto fail;
                }
                acc[acci] = '\0';
                acci = 0;
                break;
            } else if (quote) {
                if (acci >= MATCH_RULE_MAX) {
                    goto fail;
                }
                acc[acci++] = *d;
                d++;
            } else {
                goto fail;
            }
        }

        if (strcmp(key, "type") == 0 && !rule->type) {
            if (strcmp(acc, "signal") == 0) rule->type = DBUS_MESSAGE_SIGNAL;
            else if (strcmp(acc, "method_call") == 0) rule->type = DBUS_MESSAGE_METHOD_CALL;
            else if (strcmp(acc, "method_return") == 0) rule->type = DBUS_MESSAGE_METHOD_RETURN;
            else if (strcmp(acc, "error") == 0) rule->type = DBUS_MESSAGE_ERROR;
            else goto fail;
        } else if (strcmp(key, "sender") == 0 && !rule->sender) {
            rule->sender = string_dup(acc);
        } else if (strcmp(key, "interface") == 0 && !rule->interface) {
            rule->interface = string_dup(acc);
        } else if (strcmp(key, "member") == 0 && !rule->member) {
            rule->member = string_dup(acc);
        } else if (strcmp(key, "path") == 0 && !rule->path && !rule->path_namespace) {
            rule->path = string_dup(acc);
        } else if (strcmp(key, "path_namespace") == 0 && !rule->path && !rule->path_namespace) {
            rule->path_namespace = string_dup(acc);
        } else if (strcmp(key, "destination") == 0 && !rule->destination) {
            rule->destination = string_dup(acc);
        } else if (strcmp(key, "arg0namespace") == 0 && !rule->arg0namespace) {
            rule->arg0namespace = string_dup(acc);
        } else if (strncmp(key, "arg", 3) == 0) {
            char *part = key + 3;
            if (!*part) {
                goto fail;
            }

            // thanks: https://github.com/bus1/dbus-broker/blob/55fe5443d88ee2b93afa340b82ad89508ff017e2/src/bus/match.c#L105
            size_t partn = strlen(part);
            uint32_t index = 0;
            for (unsigned int i = 0; i < 2 && partn; i++, part++, --partn) {
                if (*part >= '0' && *part <= '9') {
                    index = index * 10 + *part - '0';   
                } else {
                    break;
                }
            }

            if (index == 0 && rule->arg0namespace) {
                goto fail;
            }
            if (index >= MATCH_RULE_MAX_ARG) {
                goto fail;
            }
            if (rule->arg[index] || rule->arg_path[index]) {
                goto fail;
            }

            if (*part == '\0') {
                rule->arg[index] = string_dup(acc);
            } else if (strcmp(part, "path") == 0) {
                rule->arg_path[index] = string_dup(acc);
            } else {
                goto fail;
            }
        } else {
            goto fail;
        }
    }

    return rule;
fail:
    match_rule_free(rule);
    return NULL;
}

#define _check_header_field_str(M_rule_field, M_header_field) \
    do { \
        if (rule->M_rule_field && (!msg->fields[M_header_field].present || strcmp(rule->M_rule_field, msg->fields[M_header_field].t.str) != 0)) { \
            return -1; \
        } \
    } while(0)

int match_check_sender(bus_t *s, int sender_index, match_rule_t *rule)
{
    bus_client_t *sender_client = &s->clients[sender_index];
    if (rule->sender) {
        if (sender_client->unique_name_index >= 0) {
            if (strcmp(rule->sender, s->names[sender_client->unique_name_index].name) == 0) {
                return 1;
            }
        }
        for (int i = 0; i < BUS_NAMES_PER_CLIENT; i++) {
            if (sender_client->owned_names[i] >= 0 && strcmp(rule->sender, s->names[sender_client->owned_names[i]].name) == 0) {
                return 1;
            }
        }
    }

    return -1;
}

int match_rule_check(bus_t *s, int sender_index, match_rule_t *rule, wire_message_t *msg, wire_context_t *ctx)
{
    if (rule->type && msg->type != rule->type) {
        return -1;
    }

    if (sender_index < 0) {
        // if the sender is negative, we assume the message is coming from the message bus
        if (rule->sender && strcmp(rule->sender, "org.freedesktop.DBus") != 0) {
            return -1;
        }
    } else {
        if (match_check_sender(s, sender_index, rule) < 0) {
            return -1;
        }
    }
    
    _check_header_field_str(interface, DBUS_HEADER_FIELD_INTERFACE);
    _check_header_field_str(member, DBUS_HEADER_FIELD_MEMBER);
    _check_header_field_str(path, DBUS_HEADER_FIELD_PATH);
    /* todo: path_namespace */
    _check_header_field_str(destination, DBUS_HEADER_FIELD_DESTINATION);

    wire_message_body_string_t strings[MATCH_RULE_MAX_ARG];
    memset(strings, 0, sizeof(strings));
    /* TODO: handle failure */
    TRYST(wire_collect_strings(ctx, msg, strings, MATCH_RULE_MAX_ARG));

    for (int i = 0; i < MATCH_RULE_MAX_ARG; i++) {
        if (rule->arg[i] && (!strings[i].str || strcmp(strings[i].str, rule->arg[i]) != 0)) {
            return -1;
        }
        /* todo: arg_path */
    }

    /* todo: arg0namespace */

    return 0;
}