pEpEngine/src/keymanagement.c

// This file is under GNU General Public License 3.0
// see LICENSE.txt

#include "platform.h"

#include <string.h>
#include <stdio.h>
#include <stdlib.h>
#include <assert.h>
#include <ctype.h>

#include "pEp_internal.h"
#include "keymanagement.h"

#include "blacklist.h"

static bool key_matches_address(PEP_SESSION session, const char* address,
                                const char* fpr) {
    if (!session || !address || !fpr)
        return false;
    
    bool retval = false;
    stringlist_t *keylist = NULL;
    PEP_STATUS status = find_keys(session, address, &keylist);
    if (status == PEP_STATUS_OK && keylist) {
        stringlist_t* curr = keylist;
        while (curr) {
            if (curr->value) {
                if (strcasecmp(curr->value, fpr)) {
                    retval = true;
                    break;
                }
            }
            curr = curr->next;
        }
    }
    
    free_stringlist(keylist);
    return retval;                             
}

PEP_STATUS elect_pubkey(
        PEP_SESSION session, pEp_identity * identity, bool check_blacklist
    )
{
    PEP_STATUS status;
    stringlist_t *keylist = NULL;
    char *_fpr = "";
    identity->comm_type = PEP_ct_unknown;

    status = find_keys(session, identity->address, &keylist);
    assert(status != PEP_OUT_OF_MEMORY);
    if (status == PEP_OUT_OF_MEMORY)
        return PEP_OUT_OF_MEMORY;
    
    if (!keylist || !keylist->value)
        identity->comm_type = PEP_ct_key_not_found;    
    else {
        stringlist_t *_keylist;
        for (_keylist = keylist; _keylist && _keylist->value; _keylist = _keylist->next) {
            PEP_comm_type _comm_type_key;

            status = get_key_rating(session, _keylist->value, &_comm_type_key);
            assert(status != PEP_OUT_OF_MEMORY);
            if (status == PEP_OUT_OF_MEMORY) {
                free_stringlist(keylist);
                return PEP_OUT_OF_MEMORY;
            }

            if (_comm_type_key != PEP_ct_compromised &&
                _comm_type_key != PEP_ct_unknown)
            {
                if (identity->comm_type == PEP_ct_unknown ||
                    _comm_type_key > identity->comm_type)
                {
                    bool blacklisted = false;
                    bool mistrusted = false;
                    status = is_mistrusted_key(session, _keylist->value, &mistrusted);
                    if (status == PEP_STATUS_OK && check_blacklist)
                        status = blacklist_is_listed(session, _keylist->value, &blacklisted);
                    if (status == PEP_STATUS_OK && !mistrusted && !blacklisted) {
                        identity->comm_type = _comm_type_key;
                        _fpr = _keylist->value;
                    }
                }
            }
        }
    }
    free(identity->fpr);

    if (!_fpr || _fpr[0] == '\0')
        identity->fpr = NULL;
    else {    
        identity->fpr = strdup(_fpr);
        if (identity->fpr == NULL) {
            free_stringlist(keylist);
            return PEP_OUT_OF_MEMORY;
        }
    }
    
    free_stringlist(keylist);
    return PEP_STATUS_OK;
}

static PEP_STATUS validate_fpr(PEP_SESSION session, 
                               pEp_identity* ident,
                               bool check_blacklist) {
    
    PEP_STATUS status = PEP_STATUS_OK;
    
    if (!session || !ident || !ident->fpr || !ident->fpr[0])
        return PEP_ILLEGAL_VALUE;    
        
    char* fpr = ident->fpr;
    
    bool has_private = false;
    
    if (ident->me) {
        status = contains_priv_key(session, fpr, &has_private);
        if (status != PEP_STATUS_OK || !has_private)
            return PEP_KEY_UNSUITABLE;
    }
    
    status = get_trust(session, ident);
    if (status != PEP_STATUS_OK)
        ident->comm_type = PEP_ct_unknown;
            
    PEP_comm_type ct = ident->comm_type;

    if (ct == PEP_ct_unknown) {
        // If status is bad, it's ok, we get the rating
        // we should use then (PEP_ct_unknown)
        get_key_rating(session, fpr, &ct);
        ident->comm_type = ct;
    }
    
    bool pEp_user = false;
    
    is_pEp_user(session, ident, &pEp_user);

    if (pEp_user) {
        switch (ct) {
            case PEP_ct_OpenPGP:
            case PEP_ct_OpenPGP_unconfirmed:
                ct += 0x47; // difference between PEP and OpenPGP values;
                ident->comm_type = ct;
                break;
            default:
                break;
        }
    }
    
    bool revoked, expired;
    bool blacklisted = false;
    
    status = key_revoked(session, fpr, &revoked);    
        
    if (status != PEP_STATUS_OK) {
        return status;
    }
    
    if (!revoked) {
        time_t exp_time = (ident->me ? 
                           time(NULL) + (7*24*3600) : time(NULL));
                           
        status = key_expired(session, fpr, 
                             exp_time,
                             &expired);
                             
        assert(status == PEP_STATUS_OK);
        if (status != PEP_STATUS_OK)
            return status;

        if (check_blacklist && IS_PGP_CT(ct) &&
            !ident->me) {
            status = blacklist_is_listed(session, 
                                         fpr, 
                                         &blacklisted);
                                         
            if (status != PEP_STATUS_OK)
                return status;
        }
    }
            
    if (ident->me && (ct >= PEP_ct_strong_but_unconfirmed) && !revoked && expired) {
        // extend key
        timestamp *ts = new_timestamp(time(NULL) + KEY_EXPIRE_DELTA);
        status = renew_key(session, fpr, ts);
        free_timestamp(ts);

        if (status == PEP_STATUS_OK) {
            // if key is valid (second check because pEp key might be extended above)
            //      Return fpr        
            status = key_expired(session, fpr, time(NULL), &expired);            
            if (status != PEP_STATUS_OK) {
                 ident->comm_type = PEP_ct_key_expired;
                 return status;
             }
            // communicate key(?)
        }        
    }
     
    if (revoked) 
        ct = PEP_ct_key_revoked;
    else if (expired)
        ct = PEP_ct_key_expired;        
    else if (blacklisted) { // never true for .me
        ident->comm_type = ct = PEP_ct_key_not_found;
        free(ident->fpr);
            ident->fpr = strdup("");
        status = PEP_KEY_BLACKLISTED;
    }
    
    switch (ct) {
        case PEP_ct_key_expired:
        case PEP_ct_key_revoked:
        case PEP_ct_key_b0rken:
            // delete key from being default key for all users/identities
            status = remove_fpr_as_default(session, fpr);
            status = update_trust_for_fpr(session, 
                                          fpr, 
                                          ct);
        case PEP_ct_mistrusted:                                  
            free(ident->fpr);
            ident->fpr = NULL;
            ident->comm_type = ct;            
            status = PEP_KEY_UNSUITABLE;
        default:
            break;
    }            

    return status;
}

PEP_STATUS get_all_keys_for_user(PEP_SESSION session, 
                                 const char* user_id,
                                 stringlist_t** keys) {

    if (!session || EMPTYSTR(user_id) || !keys)
        return PEP_ILLEGAL_VALUE;
        
    PEP_STATUS status = PEP_STATUS_OK;
        
    *keys = NULL;
    stringlist_t* _kl = NULL;
    
    sqlite3_reset(session->get_all_keys_for_user);
    sqlite3_bind_text(session->get_all_keys_for_user, 1, user_id, -1, SQLITE_STATIC);

    int result = -1;
    
    while ((result = sqlite3_step(session->get_all_keys_for_user)) == SQLITE_ROW) {
        const char* keyres = (const char *) sqlite3_column_text(session->get_all_keys_for_user, 0);
        if (keyres) {
            if (_kl)
                stringlist_add(_kl, keyres);
            else
                _kl = new_stringlist(keyres);
        }
    }
    
    if (!_kl)
        return PEP_KEY_NOT_FOUND;
        
    *keys = _kl;
    
    sqlite3_reset(session->get_all_keys_for_user);

    return status;
}

PEP_STATUS get_user_default_key(PEP_SESSION session, const char* user_id,
                                char** default_key) {
    assert(session);
    assert(user_id);
    
    if (!session || !user_id)
        return PEP_ILLEGAL_VALUE;

    PEP_STATUS status = PEP_STATUS_OK;
            
    // try to get default key for user_data
    sqlite3_reset(session->get_user_default_key);
    sqlite3_bind_text(session->get_user_default_key, 1, user_id, 
                      -1, SQLITE_STATIC);
    
    const int result = sqlite3_step(session->get_user_default_key);
    char* user_fpr = NULL;
    if (result == SQLITE_ROW) {
        const char* u_fpr =
            (char *) sqlite3_column_text(session->get_user_default_key, 0);
        if (u_fpr)
            user_fpr = strdup(u_fpr);
    }
    else
        status = PEP_GET_KEY_FAILED;
        
    sqlite3_reset(session->get_user_default_key);
    
    *default_key = user_fpr;
    return status;     
}

// Only call on retrieval of previously stored identity!
// Also, we presume that if the stored_identity was sent in
// without an fpr, there wasn't one in the trust DB for this
// identity.
PEP_STATUS get_valid_pubkey(PEP_SESSION session,
                         pEp_identity* stored_identity,
                         bool* is_identity_default,
                         bool* is_user_default,
                         bool* is_address_default,
                         bool check_blacklist) {
    
    PEP_STATUS status = PEP_STATUS_OK;

    if (!stored_identity || EMPTYSTR(stored_identity->user_id)
        || !is_identity_default || !is_user_default || !is_address_default)
        return PEP_ILLEGAL_VALUE;
        
    *is_identity_default = *is_user_default = *is_address_default = false;

    PEP_comm_type first_reject_comm_type = PEP_ct_key_not_found;
    PEP_STATUS first_reject_status = PEP_KEY_NOT_FOUND;
    
    char* stored_fpr = stored_identity->fpr;
    // Input: stored identity retrieved from database
    // if stored identity contains a default key
    if (!EMPTYSTR(stored_fpr)) {
        status = validate_fpr(session, stored_identity, check_blacklist);    
        if (status == PEP_STATUS_OK && !EMPTYSTR(stored_identity->fpr)) {
            *is_identity_default = *is_address_default = true;
            return status;
        }
        else if (status != PEP_KEY_NOT_FOUND) {
            first_reject_status = status;
            first_reject_comm_type = stored_identity->comm_type;
        }
    }
    // if no valid default stored identity key found
    free(stored_identity->fpr);
    stored_identity->fpr = NULL;
    
    char* user_fpr = NULL;
    status = get_user_default_key(session, stored_identity->user_id, &user_fpr);
    
    if (!EMPTYSTR(user_fpr)) {             
        // There exists a default key for user, so validate
        stored_identity->fpr = user_fpr;
        status = validate_fpr(session, stored_identity, check_blacklist);
        if (status == PEP_STATUS_OK && stored_identity->fpr) {
            *is_user_default = true;
            *is_address_default = key_matches_address(session, 
                                                      stored_identity->address,
                                                      stored_identity->fpr);
            return status;
        }        
        else if (status != PEP_KEY_NOT_FOUND && first_reject_status != PEP_KEY_NOT_FOUND) {
            first_reject_status = status;
            first_reject_comm_type = stored_identity->comm_type;
        }
    }
    
    status = elect_pubkey(session, stored_identity, check_blacklist);
    if (status == PEP_STATUS_OK) {
        if (!EMPTYSTR(stored_identity->fpr))
            validate_fpr(session, stored_identity, false); // blacklist already filtered of needed
    }    
    else if (status != PEP_KEY_NOT_FOUND && first_reject_status != PEP_KEY_NOT_FOUND) {
        first_reject_status = status;
        first_reject_comm_type = stored_identity->comm_type;
    }
    
    switch (stored_identity->comm_type) {
        case PEP_ct_key_revoked:
        case PEP_ct_key_b0rken:
        case PEP_ct_key_expired:
        case PEP_ct_compromised:
        case PEP_ct_mistrusted:
            // this only happens when it's all there is
            status = first_reject_status;
            free(stored_identity->fpr);
            stored_identity->fpr = NULL;
            stored_identity->comm_type = first_reject_comm_type;
            break;    
        default:
            if (check_blacklist && status == PEP_KEY_BLACKLISTED) {
                free(stored_identity->fpr);
                stored_identity->fpr = NULL;
                stored_identity->comm_type = PEP_ct_key_not_found;
            }
            break;
    }
    return status;
}

static void transfer_ident_lang_and_flags(pEp_identity* new_ident,
                                          pEp_identity* stored_ident) {
    if (new_ident->lang[0] == 0) {
      new_ident->lang[0] = stored_ident->lang[0];
      new_ident->lang[1] = stored_ident->lang[1];
      new_ident->lang[2] = 0;
    }

    new_ident->flags = stored_ident->flags;
    new_ident->me = new_ident->me || stored_ident->me;
}

static void adjust_pEp_trust_status(PEP_SESSION session, pEp_identity* identity) {
    assert(session);
    assert(identity);
    
    if (identity->comm_type < PEP_ct_strong_but_unconfirmed ||
        (identity->comm_type | PEP_ct_confirmed) == PEP_ct_pEp)
        return;
    
    bool pEp_user;
    
    is_pEp_user(session, identity, &pEp_user);
    
    if (pEp_user) {
        PEP_comm_type confirmation_status = identity->comm_type & PEP_ct_confirmed;
        identity->comm_type = PEP_ct_pEp_unconfirmed | confirmation_status;    
    }
}


static PEP_STATUS prepare_updated_identity(PEP_SESSION session,
                                                 pEp_identity* return_id,
                                                 pEp_identity* stored_ident,
                                                 bool store) {
    
    if (!session || !return_id || !stored_ident)
        return PEP_ILLEGAL_VALUE;
    
    PEP_STATUS status;
    
    bool is_identity_default, is_user_default, is_address_default;
    status = get_valid_pubkey(session, stored_ident,
                                &is_identity_default,
                                &is_user_default,
                                &is_address_default,
                              false);
                                
    if (status == PEP_STATUS_OK && stored_ident->fpr && *(stored_ident->fpr) != '\0') {
    // set identity comm_type from trust db (user_id, FPR)
        status = get_trust(session, stored_ident);
        if (status == PEP_CANNOT_FIND_IDENTITY || stored_ident->comm_type == PEP_ct_unknown) {
            // This is OK - there is no trust DB entry, but we
            // found a key. We won't store this, but we'll
            // use it.
            PEP_comm_type ct = PEP_ct_unknown;
            status = get_key_rating(session, stored_ident->fpr, &ct);
            stored_ident->comm_type = ct;
        }
    }
    else {
        if (stored_ident->comm_type == PEP_ct_unknown)
            stored_ident->comm_type = PEP_ct_key_not_found;
    }
    free(return_id->fpr);
    return_id->fpr = NULL;
    if (status == PEP_STATUS_OK && !EMPTYSTR(stored_ident->fpr))
        return_id->fpr = strdup(stored_ident->fpr);
        
    return_id->comm_type = stored_ident->comm_type;
                    
    // We patch the DB with the input username, but if we didn't have
    // one, we pull it out of storage if available.
    // (also, if the input username is "anonymous" and there exists
    //  a DB username, we replace)
    if (!EMPTYSTR(stored_ident->username)) {
        if (!EMPTYSTR(return_id->username) && 
            (strcasecmp(return_id->username, return_id->address) == 0)) {
            free(return_id->username);
            return_id->username = NULL;
        }
        if (EMPTYSTR(return_id->username)) {
            free(return_id->username);
            return_id->username = strdup(stored_ident->username);
        }
    }
    else {
        if (EMPTYSTR(return_id->username))
            return_id->username = strdup(return_id->address);
    }
    
    return_id->me = stored_ident->me;
    
    // FIXME: Do we ALWAYS do this? We probably should...
    if (EMPTYSTR(return_id->user_id)) {
        free(return_id->user_id);
        return_id->user_id = strdup(stored_ident->user_id);
    } 
    
    adjust_pEp_trust_status(session, return_id);
   
    // Call set_identity() to store
    if ((is_identity_default || is_user_default) &&
         is_address_default) {                 
         // if we got an fpr which is default for either user
         // or identity AND is valid for this address, set in DB
         // as default
         status = set_identity(session, return_id);
    }
    else {
        // Store without default fpr/ct, but return the fpr and ct 
        // for current use
        char* save_fpr = return_id->fpr;
        PEP_comm_type save_ct = return_id->comm_type;
        return_id->fpr = NULL;
        return_id->comm_type = PEP_ct_unknown;
        PEP_STATUS save_status = status;
        status = set_identity(session, return_id);
        if (save_status != PEP_STATUS_OK)
            status = save_status;
        return_id->fpr = save_fpr;
        return_id->comm_type = save_ct;
    }
    
    transfer_ident_lang_and_flags(return_id, stored_ident);
    
    if (return_id->comm_type == PEP_ct_unknown)
        return_id->comm_type = PEP_ct_key_not_found;
    
    return status;
}

DYNAMIC_API PEP_STATUS update_identity(
        PEP_SESSION session, pEp_identity * identity
    )
{
    PEP_STATUS status;

    assert(session);
    assert(identity);
    assert(!EMPTYSTR(identity->address));

    if (!(session && identity && !EMPTYSTR(identity->address)))
        return PEP_ILLEGAL_VALUE;

    char* default_own_id = NULL;
    status = get_default_own_userid(session, &default_own_id);    

    // Is this me, temporary or not? If so, BAIL.
    if (identity->me || 
       (default_own_id && identity->user_id && (strcmp(default_own_id, identity->user_id) == 0))) 
    {
        free(default_own_id);
        return PEP_ILLEGAL_VALUE;
    }

    // We have, at least, an address.
    // Retrieve stored identity information!    
    pEp_identity* stored_ident = NULL;

    if (!EMPTYSTR(identity->user_id)) {            
        // (we're gonna update the trust/fpr anyway, so we use the no-fpr-from-trust-db variant)
        //      * do get_identity() to retrieve stored identity information
        status = get_identity_without_trust_check(session, identity->address, identity->user_id, &stored_ident);

        // Before we start - if there was no stored identity, we should check to make sure we don't
        // have a stored identity with a temporary user_id that differs from the input user_id. This
        // happens in multithreaded environments sometimes.
        if (!stored_ident) {
            identity_list* id_list = NULL;
            status = get_identities_by_address(session, identity->address, &id_list);

            if (id_list) {
                identity_list* id_curr = id_list;
                bool input_is_TOFU = strstr(identity->user_id, "TOFU_") == identity->user_id;
                while (id_curr) {
                    pEp_identity* this_id = id_curr->ident;
                    if (this_id) {
                        char* this_uid = this_id->user_id;
                        bool curr_is_TOFU = strstr(this_uid, "TOFU_") == this_uid;
                        if (this_uid) {
                            if (curr_is_TOFU && !input_is_TOFU) {
                                // FIXME: should we also be fixing pEp_own_userId in this
                                // function here?
                                
                                // if usernames match, we replace the userid. Or if the temp username
                                // is anonymous.
                                // FIXME: do we need to create an address match function which
                                // matches the whole dot-and-case rigamarole from 
                                if (EMPTYSTR(this_id->username) ||
                                    strcasecmp(this_id->username, this_id->address) == 0 ||
                                    (identity->username && 
                                     strcasecmp(identity->username, 
                                                this_id->username) == 0)) {
                                    
                                    // Ok, we have a temp ID. We have to replace this
                                    // with the real ID.
                                    status = replace_userid(session, 
                                                            this_uid, 
                                                            identity->user_id);
                                    if (status != PEP_STATUS_OK) {
                                        free_identity_list(id_list);
                                        free(default_own_id);
                                        return status;
                                    }
                                        
                                    free(this_uid);
                                    this_uid = NULL;
                                    
                                    // Reflect the change we just made to the DB
                                    this_id->user_id = strdup(identity->user_id);
                                    stored_ident = this_id;
                                    // FIXME: free list.
                                    break;                                
                                }
                            }
                            else if (input_is_TOFU && !curr_is_TOFU) {
                                // Replace ruthlessly - this is NOT supposed to happen.
                                // BAD APP BEHAVIOUR.
                                free(identity->user_id);
                                identity->user_id = strdup(this_id->user_id);
                                stored_ident = this_id;
                                // FIXME: free list.
                                break;                                
                            }                            
                        } 
                    }
                    id_curr = id_curr->next;
                }
            }
        } 
                
        if (status == PEP_STATUS_OK && stored_ident) { 
            //  * if identity available
            //      * patch it with username
            //          (note: this will happen when 
            //           setting automatically below...)
            //      * elect valid key for identity
            //    * if valid key exists
            //        * set return value's fpr
            status = prepare_updated_identity(session,
                                              identity,
                                              stored_ident, true);
        }
        //  * else (identity unavailable)
        else {
            status = PEP_STATUS_OK;

            // FIXME: We may need to roll this back.
            // FIXME: change docs if we don't
            //  if we only have user_id and address and identity not available
            //      * return error status (identity not found)
            if (EMPTYSTR(identity->username)) {
                free(identity->username);
                identity->username = strdup(identity->address);
            }
            
            // Otherwise, if we had user_id, address, and username:
            //    * create identity with user_id, address, username
            //      (this is the input id without the fpr + comm type!)

            if (status == PEP_STATUS_OK) {
                elect_pubkey(session, identity, false);
            }
                        
            //    * We've already checked and retrieved
            //      any applicable temporary identities above. If we're 
            //      here, none of them fit.
            //    * call set_identity() to store
            if (status == PEP_STATUS_OK) {
                // FIXME: Do we set if we had to copy in the address?
                adjust_pEp_trust_status(session, identity);
                status = set_identity(session, identity);
            }
            //  * Return: created identity
        }        
    }
    else if (!EMPTYSTR(identity->username)) {
        /*
         * Temporary identity information with username supplied
            * Input: address, username (no others)
         */
         
        //  * See if there is an own identity that uses this address. If so, we'll
        //    prefer that
        stored_ident = NULL;
        
        if (default_own_id) {
            status = get_identity(session, 
                                  identity->address, 
                                  default_own_id, 
                                  &stored_ident);
        }
        // If there isn't an own identity, search for a non-temp stored ident
        // with this address.                      
        if (status == PEP_CANNOT_FIND_IDENTITY || !stored_ident) { 
 
            identity_list* id_list = NULL;
            status = get_identities_by_address(session, identity->address, &id_list);

            if (id_list) {
                identity_list* id_curr = id_list;
                while (id_curr) {
                    pEp_identity* this_id = id_curr->ident;
                    if (this_id) {
                        char* this_uid = this_id->user_id;
                        if (this_uid && (strstr(this_uid, "TOFU_") != this_uid)) {
                            // if usernames match, we replace the userid.
                            if (identity->username && 
                                strcasecmp(identity->username, 
                                           this_id->username) == 0) {
                                
                                // Ok, we have a real ID. Copy it!
                                identity->user_id = strdup(this_uid);
                                assert(identity->user_id);
                                if (!identity->user_id)
                                    goto enomem;

                                stored_ident = this_id;
                                
                                break;                                
                            }                            
                        } 
                    }
                    id_curr = id_curr->next;
                }
            }
        }
        
        if (stored_ident) {
            status = prepare_updated_identity(session,
                                              identity,
                                              stored_ident, true);
        }
        else {
            identity->user_id = calloc(1, strlen(identity->address) + 6);
            if (!identity->user_id)
                goto enomem;

            snprintf(identity->user_id, strlen(identity->address) + 6,
                     "TOFU_%s", identity->address);        

            status = get_identity(session, 
                                  identity->address, 
                                  identity->user_id, 
                                  &stored_ident);

            if (status == PEP_STATUS_OK && stored_ident) {
                status = prepare_updated_identity(session,
                                                  identity,
                                                  stored_ident, true);
            }
            else {
                         
                //    * We've already checked and retrieved
                //      any applicable temporary identities above. If we're 
                //      here, none of them fit.
                
                status = elect_pubkey(session, identity, false);
                             
                //    * call set_identity() to store
                if (identity->fpr)
                    status = get_key_rating(session, identity->fpr, &identity->comm_type);
            
                //    * call set_identity() to store
                adjust_pEp_trust_status(session, identity);            
                status = set_identity(session, identity);
            }
        }
    }
    else {
        /*
        * Input: address (no others)
         * Temporary identity information without username suplied
         */
         
        //  * Again, see if there is an own identity that uses this address. If so, we'll
        //    prefer that
        stored_ident = NULL;
         
        if (default_own_id) {
            status = get_identity(session, 
                                  identity->address, 
                                  default_own_id, 
                                  &stored_ident);
        }
        // If there isn't an own identity, search for a non-temp stored ident
        // with this address.                      
        if (status == PEP_CANNOT_FIND_IDENTITY || !stored_ident) { 
 
            identity_list* id_list = NULL;