pEpEngine/src/keymanagement.c

#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"

#ifndef EMPTYSTR
#define EMPTYSTR(STR) ((STR) == NULL || (STR)[0] == '\0')
#endif

#define KEY_EXPIRE_DELTA (60 * 60 * 24 * 365)

// Space tolerant and case insensitive fingerprint string compare
static int _same_fpr(
        const char* fpra,
        size_t fpras,
        const char* fprb,
        size_t fprbs
    )
{
    size_t ai = 0;
    size_t bi = 0;
    
    do
    {
        if(fpra[ai] == 0 || fprb[bi] == 0)
        {
            return 0;
        }
        else if(fpra[ai] == ' ')
        {
            ai++;
        }
        else if(fprb[bi] == ' ')
        {
            bi++;
        }
        else if(toupper(fpra[ai]) == toupper(fprb[bi]))
        {
            ai++;
            bi++;
        }
        else
        {
            return 0;
        }
        
    }
    while(ai < fpras && bi < fprbs);
    
    return ai == fpras && bi == fprbs;
}

PEP_STATUS elect_pubkey(
        PEP_SESSION session, pEp_identity * identity
    )
{
    PEP_STATUS status;
    stringlist_t *keylist;
    char *_fpr = NULL;
    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;

    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_compromized &&
            _comm_type_key != PEP_ct_unknown)
        {
            if (identity->comm_type == PEP_ct_unknown ||
                _comm_type_key > identity->comm_type)
            {
                identity->comm_type = _comm_type_key;
                _fpr = _keylist->value;
            }
        }
    }

    if (_fpr) {
        free(identity->fpr);

        identity->fpr = strdup(_fpr);
        if (identity->fpr == NULL) {
            free_stringlist(keylist);
            return PEP_OUT_OF_MEMORY;
        }
    }
    free_stringlist(keylist);
    return PEP_STATUS_OK;
}

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

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

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

    int _no_user_id = EMPTYSTR(identity->user_id);

    if (_no_user_id)
    {
        status = get_identity(session, identity->address, PEP_OWN_USERID,
                &stored_identity);
        if (status == PEP_STATUS_OK) {
            free_identity(stored_identity);
            return myself(session, identity);
        }

        free(identity->user_id);

        identity->user_id = calloc(1, strlen(identity->address) + 6);
        if (!identity->user_id)
        {
            return PEP_OUT_OF_MEMORY;
        }
        snprintf(identity->user_id, strlen(identity->address) + 6,
                 "TOFU_%s", identity->address);
    }
 
    status = get_identity(session,
                          identity->address,
                          identity->user_id,
                          &stored_identity);
    
    assert(status != PEP_OUT_OF_MEMORY);
    if (status == PEP_OUT_OF_MEMORY)
        goto exit_free;

    if (stored_identity) {
        PEP_comm_type _comm_type_key;
        status = get_key_rating(session, stored_identity->fpr, &_comm_type_key);
        assert(status != PEP_OUT_OF_MEMORY);
        if (status == PEP_OUT_OF_MEMORY)
            goto exit_free;

        if (EMPTYSTR(identity->username)) {
            free(identity->username);
            identity->username = strdup(stored_identity->username);
            assert(identity->username);
            if (identity->username == NULL){
                status = PEP_OUT_OF_MEMORY;
                goto exit_free;
            }
        }

        if (EMPTYSTR(identity->fpr)) {
            identity->fpr = strdup(stored_identity->fpr);
            assert(identity->fpr);
            if (identity->fpr == NULL)
                return PEP_OUT_OF_MEMORY;
            if (_comm_type_key < PEP_ct_unconfirmed_encryption) {
                PEP_STATUS status = elect_pubkey(session, identity);
                if (status != PEP_STATUS_OK)
                    goto exit_free;
            }
            else {
                identity->comm_type = stored_identity->comm_type;
            }
        }
        else /* !EMPTYSTR(identity->fpr) */ {
            if (_same_fpr(identity->fpr,
                          strlen(identity->fpr),
                          stored_identity->fpr,
                          strlen(stored_identity->fpr))) {
                if (_comm_type_key < PEP_ct_unconfirmed_encryption) {
                    identity->comm_type = _comm_type_key;
                }else{
                    identity->comm_type = stored_identity->comm_type;
                    if (identity->comm_type == PEP_ct_unknown) {
                        identity->comm_type = _comm_type_key;
                    }
                }
            } else {
                status = get_trust(session, identity);
                assert(status != PEP_OUT_OF_MEMORY);
                if (status == PEP_OUT_OF_MEMORY)
                    goto exit_free;
                if (identity->comm_type < stored_identity->comm_type)
                    identity->comm_type = PEP_ct_unknown;
            }
        }

        if (identity->lang[0] == 0) {
            identity->lang[0] = stored_identity->lang[0];
            identity->lang[1] = stored_identity->lang[1];
            identity->lang[2] = 0;
        }

        identity->flags = stored_identity->flags;
    }
    else /* stored_identity == NULL */ {
        identity->flags = 0;

        if (!EMPTYSTR(identity->fpr)) {
            PEP_comm_type _comm_type_key;

            status = get_key_rating(session, identity->fpr, &_comm_type_key);
            assert(status != PEP_OUT_OF_MEMORY);
            if (status == PEP_OUT_OF_MEMORY)
                goto exit_free;

            identity->comm_type = _comm_type_key;
        }
        else /* EMPTYSTR(identity->fpr) */ {
            PEP_STATUS status = elect_pubkey(session, identity);
            if (status != PEP_STATUS_OK)
                goto exit_free;
        }
    }

    status = PEP_STATUS_OK;

    if (identity->comm_type != PEP_ct_unknown && !EMPTYSTR(identity->user_id)) {
        assert(!EMPTYSTR(identity->username)); // this should not happen

        if (EMPTYSTR(identity->username)) { // mitigate
            free(identity->username);
            identity->username = strdup("anonymous");
            assert(identity->username);
            if (identity->username == NULL){
                status = PEP_OUT_OF_MEMORY;
                goto exit_free;
            }
        }

        // Identity doesn't get stored if call was just about checking existing
        // user by address (i.e. no user id given but already stored)
        if (!(_no_user_id && stored_identity))
        {
            status = set_identity(session, identity);
            assert(status == PEP_STATUS_OK);
            if (status != PEP_STATUS_OK) {
                goto exit_free;
            }
        }
    }

    if (identity->comm_type != PEP_ct_compromized &&
            identity->comm_type < PEP_ct_strong_but_unconfirmed)
        if (session->examine_identity)
            session->examine_identity(identity, session->examine_management);

exit_free :
    
    if (stored_identity){
        free_identity(stored_identity);
    }

    return status;
}

PEP_STATUS elect_ownkey(
        PEP_SESSION session, pEp_identity * identity
    )
{
    PEP_STATUS status;
    stringlist_t *keylist = NULL;

    free(identity->fpr);
    identity->fpr = NULL;

    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 != NULL && keylist->value != NULL)
    {
        char *_fpr = NULL;
        identity->comm_type = PEP_ct_unknown;

        stringlist_t *_keylist;
        for (_keylist = keylist; _keylist && _keylist->value; _keylist = _keylist->next) {
            bool is_own = false;
            
            if (session->use_only_own_private_keys)
            {
                status = own_key_is_listed(session, _keylist->value, &is_own);
                assert(status == PEP_STATUS_OK);
                if (status != PEP_STATUS_OK) {
                    free_stringlist(keylist);
                    return status;
                }
            }

            // TODO : also accept synchronized device group keys ?
            
            if (!session->use_only_own_private_keys || is_own)
            {
                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_compromized &&
                    _comm_type_key != PEP_ct_unknown)
                {
                    if (identity->comm_type == PEP_ct_unknown ||
                        _comm_type_key > identity->comm_type)
                    {
                        identity->comm_type = _comm_type_key;
                        _fpr = _keylist->value;
                    }
                }
            }
        }
        
        if (_fpr)
        {
            identity->fpr = strdup(_fpr);
            assert(identity->fpr);
            if (identity->fpr == NULL)
            {
                free_stringlist(keylist);
                return PEP_OUT_OF_MEMORY;
            }
        }
        free_stringlist(keylist);
    }
    return PEP_STATUS_OK;
}

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

    assert(session);
    assert(identity);

    assert(EMPTYSTR(identity->user_id) ||
           strcmp(identity->user_id, PEP_OWN_USERID) == 0);

    if (!(session && identity &&
            (EMPTYSTR(identity->user_id) ||
            strcmp(identity->user_id, PEP_OWN_USERID) == 0)))
        return PEP_ILLEGAL_VALUE;

    identity->comm_type = PEP_ct_pEp;
    identity->me = true;
    
    if (EMPTYSTR(identity->user_id))
    {
        free(identity->user_id);
        identity->user_id = strdup(PEP_OWN_USERID);
        assert(identity->user_id);
        if (identity->user_id == NULL)
            return PEP_OUT_OF_MEMORY;
    }

    if (!identity->address)
    {
        identity->address = strdup("");
        assert(identity->address);
        if (!identity->address)
            return PEP_OUT_OF_MEMORY;
    }

    DEBUG_LOG("myself", "debug", EMPTYSTR(identity->address) ?
            "<default address>" : identity->address);
    
    status = get_identity(session,
                          identity->address,
                          identity->user_id,
                          &stored_identity);
    
    assert(status != PEP_OUT_OF_MEMORY);
    if (status == PEP_OUT_OF_MEMORY)
        return PEP_OUT_OF_MEMORY;
    
    if (stored_identity)
    {
        if (EMPTYSTR(identity->fpr)) {
            identity->fpr = strdup(stored_identity->fpr);
            assert(identity->fpr);
            if (identity->fpr == NULL)
            {
                return PEP_OUT_OF_MEMORY;
            }
        }

        identity->flags = stored_identity->flags;
    }
    else if (!EMPTYSTR(identity->fpr))
    {
        // App must have a good reason to give fpr, such as explicit
        // import of private key, or similar.

        // Take given fpr as-is.

        identity->flags = 0;
    }
    else
    {
        status = elect_ownkey(session, identity);
        assert(status == PEP_STATUS_OK);
        if (status != PEP_STATUS_OK) {
            return status;
        }

        identity->flags = 0;
    }

    bool revoked = false;
    char *r_fpr = NULL;
    if (!EMPTYSTR(identity->fpr))
    {
        status = key_revoked(session, identity->fpr, &revoked);

        // Forces re-election if key is missing and own-key-only not forced
        if (!session->use_only_own_private_keys && status == PEP_KEY_NOT_FOUND) 
        {
            status = elect_ownkey(session, identity);
            assert(status == PEP_STATUS_OK);
            if (status != PEP_STATUS_OK) {
                return status;
            }
        } 
        else if (status != PEP_STATUS_OK) 
        {
            return status;
        }
    }
    
    if (EMPTYSTR(identity->fpr) || revoked)
    {        
        if(revoked)
        {
            r_fpr = identity->fpr;
            identity->fpr = NULL;
        }
        
        DEBUG_LOG("generating key pair", "debug", identity->address);
        status = generate_keypair(session, identity);
        assert(status != PEP_OUT_OF_MEMORY);
        if (status != PEP_STATUS_OK) {
            char buf[11];
            snprintf(buf, 11, "%d", status);
            DEBUG_LOG("generating key pair failed", "debug", buf);
            if(revoked && r_fpr)
                free(r_fpr);
            return status;
        }
        
        if(revoked)
        {
            status = set_revoked(session, r_fpr,
                                 identity->fpr, time(NULL));
            free(r_fpr);
            if (status != PEP_STATUS_OK) {
                return status;
            }
        }
    }
    else
    {
        bool expired;
        status = key_expired(session, identity->fpr, 
                             time(NULL) + (7*24*3600), // In a week
                             &expired);

        assert(status == PEP_STATUS_OK);
        if (status != PEP_STATUS_OK) {
            return status;
        }

        if (status == PEP_STATUS_OK && expired) {
            timestamp *ts = new_timestamp(time(NULL) + KEY_EXPIRE_DELTA);
            renew_key(session, identity->fpr, ts);
            free_timestamp(ts);
        }
    }

    status = set_identity(session, identity);
    assert(status == PEP_STATUS_OK);
    if (status != PEP_STATUS_OK) {
        return status;
    }

    return PEP_STATUS_OK;

}

DYNAMIC_API PEP_STATUS register_examine_function(
        PEP_SESSION session, 
        examine_identity_t examine_identity,
        void *management
    )
{
    assert(session);
    if (!session)
        return PEP_ILLEGAL_VALUE;

    session->examine_management = management;
    session->examine_identity = examine_identity;

    return PEP_STATUS_OK;
}

DYNAMIC_API PEP_STATUS do_keymanagement(
        retrieve_next_identity_t retrieve_next_identity,
        void *management
    )
{
    PEP_SESSION session;
    pEp_identity *identity;
    PEP_STATUS status;

    assert(retrieve_next_identity);
    assert(management);

    if (!retrieve_next_identity || !management)
        return PEP_ILLEGAL_VALUE;

    status = init(&session);
    assert(status == PEP_STATUS_OK);
    if (status != PEP_STATUS_OK)
        return status;

    log_event(session, "keymanagement thread started", "pEp engine", NULL, NULL);

    while ((identity = retrieve_next_identity(management))) 
    {
        assert(identity->address);
        if(identity->address)
        {
            DEBUG_LOG("do_keymanagement", "retrieve_next_identity", identity->address);

            if (identity->me) {
                status = myself(session, identity);
            } else {
                status = recv_key(session, identity->address);
            }

            assert(status != PEP_OUT_OF_MEMORY);
            if(status == PEP_OUT_OF_MEMORY)
                return PEP_OUT_OF_MEMORY;
        }
        free_identity(identity);
    }

    log_event(session, "keymanagement thread shutdown", "pEp engine", NULL, NULL);

    release(session);
    return PEP_STATUS_OK;
}

DYNAMIC_API PEP_STATUS key_compromized(
        PEP_SESSION session,
        pEp_identity *ident
    )
{
    PEP_STATUS status = PEP_STATUS_OK;

    assert(session);
    assert(ident);
    assert(!EMPTYSTR(ident->fpr));

    if (!(session && ident && ident->fpr))
        return PEP_ILLEGAL_VALUE;

    if (ident->me)
    {
        revoke_key(session, ident->fpr, NULL);
        myself(session, ident);
    }
    else
    {
        status = mark_as_compromized(session, ident->fpr);
    }

    return status;
}

DYNAMIC_API PEP_STATUS key_reset_trust(
        PEP_SESSION session,
        pEp_identity *ident
    )
{
    PEP_STATUS status = PEP_STATUS_OK;

    assert(session);
    assert(ident);
    assert(!ident->me);
    assert(!EMPTYSTR(ident->fpr));
    assert(!EMPTYSTR(ident->address));
    assert(!EMPTYSTR(ident->user_id));

    if (!(session && ident && !ident->me && ident->fpr && ident->address &&
            ident->user_id))
        return PEP_ILLEGAL_VALUE;

    status = update_identity(session, ident);
    if (status != PEP_STATUS_OK)
        return status;

    if (ident->comm_type == PEP_ct_mistrusted)
        ident->comm_type = PEP_ct_unknown;
    else
        ident->comm_type &= ~PEP_ct_confirmed;

    status = set_identity(session, ident);
    if (status != PEP_STATUS_OK)
        return status;

    if (ident->comm_type == PEP_ct_unknown)
        status = update_identity(session, ident);
    return status;
}

DYNAMIC_API PEP_STATUS trust_personal_key(
        PEP_SESSION session,
        pEp_identity *ident
    )
{
    PEP_STATUS status = PEP_STATUS_OK;

    assert(session);
    assert(ident);
    assert(!EMPTYSTR(ident->address));
    assert(!EMPTYSTR(ident->user_id));
    assert(!EMPTYSTR(ident->fpr));
    assert(!ident->me);

    if (!ident || EMPTYSTR(ident->address) || EMPTYSTR(ident->user_id) ||
            EMPTYSTR(ident->fpr) || ident->me)
        return PEP_ILLEGAL_VALUE;

    status = update_identity(session, ident);
    if (status != PEP_STATUS_OK)
        return status;

    if (ident->comm_type > PEP_ct_strong_but_unconfirmed) {
        ident->comm_type |= PEP_ct_confirmed;
        status = set_identity(session, ident);
    }
    else {
        // MISSING: S/MIME has to be handled depending on trusted CAs
        status = PEP_CANNOT_SET_TRUST;
    }

    return status;
}

DYNAMIC_API PEP_STATUS own_key_is_listed(
        PEP_SESSION session,
        const char *fpr,
        bool *listed
    )
{
    PEP_STATUS status = PEP_STATUS_OK;
    int count;
    
    assert(session && fpr && fpr[0] && listed);
    
    if (!(session && fpr && fpr[0] && listed))
        return PEP_ILLEGAL_VALUE;
    
    *listed = false;
    
    sqlite3_reset(session->own_key_is_listed);
    sqlite3_bind_text(session->own_key_is_listed, 1, fpr, -1, SQLITE_STATIC);
    
    int result;
    
    result = sqlite3_step(session->own_key_is_listed);
    switch (result) {
        case SQLITE_ROW:
            count = sqlite3_column_int(session->own_key_is_listed, 0);
            *listed = count > 0;
            status = PEP_STATUS_OK;
            break;
            
        default:
            status = PEP_UNKNOWN_ERROR;
    }
    
    sqlite3_reset(session->own_key_is_listed);
    return status;
}

DYNAMIC_API PEP_STATUS own_identities_retrieve(
        PEP_SESSION session,
        identity_list **own_identities
      )
{
    PEP_STATUS status = PEP_STATUS_OK;
    
    assert(session && own_identities);
    if (!(session && own_identities))
        return PEP_ILLEGAL_VALUE;
    
    *own_identities = NULL;
    identity_list *_own_identities = new_identity_list(NULL);
    if (_own_identities == NULL)
        goto enomem;
    
    sqlite3_reset(session->own_identities_retrieve);
    
    int result;
    // address, fpr, username, user_id, comm_type, lang, flags
    const char *address = NULL;
    const char *fpr = NULL;
    const char *username = NULL;
    const char *user_id = NULL;
    PEP_comm_type comm_type = PEP_ct_unknown;
    const char *lang = NULL;
    unsigned int flags = 0;
    
    identity_list *_bl = _own_identities;
    do {
        result = sqlite3_step(session->own_identities_retrieve);
        switch (result) {
            case SQLITE_ROW:
                address = (const char *)
                    sqlite3_column_text(session->own_identities_retrieve, 0);
                fpr = (const char *)
                    sqlite3_column_text(session->own_identities_retrieve, 1);
                username = (const char *)
                    sqlite3_column_text(session->own_identities_retrieve, 2);
                user_id = (const char *)