diff options
Diffstat (limited to 'plugins/MirOTR/libotr-3.2.0/src/message.c')
| -rw-r--r-- | plugins/MirOTR/libotr-3.2.0/src/message.c | 1446 |
1 files changed, 1446 insertions, 0 deletions
diff --git a/plugins/MirOTR/libotr-3.2.0/src/message.c b/plugins/MirOTR/libotr-3.2.0/src/message.c new file mode 100644 index 0000000000..b385c1f4f1 --- /dev/null +++ b/plugins/MirOTR/libotr-3.2.0/src/message.c @@ -0,0 +1,1446 @@ +/* + * Off-the-Record Messaging library + * Copyright (C) 2004-2008 Ian Goldberg, Chris Alexander, Nikita Borisov + * <otr@cypherpunks.ca> + * + * This library is free software; you can redistribute it and/or + * modify it under the terms of version 2.1 of the GNU Lesser General + * Public License as published by the Free Software Foundation. + * + * This library 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 + * Lesser General Public License for more details. + * + * You should have received a copy of the GNU Lesser General Public + * License along with this library; if not, write to the Free Software + * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA + */ + +/* system headers */ +#include <stdio.h> +#include <stdlib.h> +#include <time.h> + +/* libgcrypt headers */ +#include <gcrypt.h> + +/* libotr headers */ +#include "privkey.h" +#include "proto.h" +#include "auth.h" +#include "message.h" +#include "sm.h" + +/* The API version */ +extern unsigned int otrl_api_version; + +/* How long after sending a packet should we wait to send a heartbeat? */ +#define HEARTBEAT_INTERVAL 60 + +/* How old are messages allowed to be in order to be candidates for + * resending in response to a rekey? */ +#define RESEND_INTERVAL 60 + +/* Deallocate a message allocated by other otrl_message_* routines. */ +void otrl_message_free(char *message) +{ + free(message); +} + +/* Handle a message about to be sent to the network. It is safe to pass + * all messages about to be sent to this routine. add_appdata is a + * function that will be called in the event that a new ConnContext is + * created. It will be passed the data that you supplied, as well as a + * pointer to the new ConnContext. You can use this to add + * application-specific information to the ConnContext using the + * "context->app" field, for example. If you don't need to do this, you + * can pass NULL for the last two arguments of otrl_message_sending. + * + * tlvs is a chain of OtrlTLVs to append to the private message. It is + * usually correct to just pass NULL here. + * + * If this routine returns non-zero, then the library tried to encrypt + * the message, but for some reason failed. DO NOT send the message in + * the clear in that case. + * + * If *messagep gets set by the call to something non-NULL, then you + * should replace your message with the contents of *messagep, and + * send that instead. Call otrl_message_free(*messagep) when you're + * done with it. */ +gcry_error_t otrl_message_sending(OtrlUserState us, + const OtrlMessageAppOps *ops, + void *opdata, const char *accountname, const char *protocol, + const char *recipient, const char *message, OtrlTLV *tlvs, + char **messagep, + void (*add_appdata)(void *data, ConnContext *context), + void *data) +{ + struct context * context; + char * msgtosend; + gcry_error_t err; + OtrlPolicy policy = OTRL_POLICY_DEFAULT; + int context_added = 0; + + *messagep = NULL; + + if (!accountname || !protocol || !recipient || !message || !messagep) + return gcry_error(GPG_ERR_NO_ERROR); + + /* See if we have a fingerprint for this user */ + context = otrl_context_find(us, recipient, accountname, protocol, + 1, &context_added, add_appdata, data); + + /* Update the context list if we added one */ + if (context_added && ops->update_context_list) { + ops->update_context_list(opdata); + } + + /* Check the policy */ + if (ops->policy) { + policy = ops->policy(opdata, context); + } + + /* Should we go on at all? */ + if ((policy & OTRL_POLICY_VERSION_MASK) == 0) { + return gcry_error(GPG_ERR_NO_ERROR); + } + + /* If this is an OTR Query message, don't encrypt it. */ + if (otrl_proto_message_type(message) == OTRL_MSGTYPE_QUERY) { + /* Replace the "?OTR?" with a custom message */ + char *bettermsg = otrl_proto_default_query_msg(accountname, policy); + if (bettermsg) { + *messagep = bettermsg; + } + return gcry_error(GPG_ERR_NO_ERROR); + } + + /* What is the current message disposition? */ + switch(context->msgstate) { + case OTRL_MSGSTATE_PLAINTEXT: + if ((policy & OTRL_POLICY_REQUIRE_ENCRYPTION)) { + /* We're trying to send an unencrypted message with a policy + * that disallows that. Don't do that, but try to start + * up OTR instead. */ + if ((!(ops->display_otr_message) || + ops->display_otr_message(opdata, accountname, + protocol, recipient, "Attempting to start a " + "private conversation...")) && ops->notify) { + const char *format = "You attempted to send an " + "unencrypted message to %s"; + char *primary = malloc(strlen(format) + + strlen(recipient) - 1); + if (primary) { + sprintf(primary, format, recipient); + ops->notify(opdata, OTRL_NOTIFY_WARNING, accountname, + protocol, recipient, "OTR Policy Violation", + primary, + "Unencrypted messages to this recipient are " + "not allowed. Attempting to start a private " + "conversation.\n\nYour message will be " + "retransmitted when the private conversation " + "starts."); + free(primary); + } + } + context->lastmessage = gcry_malloc_secure(strlen(message) + 1); + if (context->lastmessage) { + char *bettermsg = otrl_proto_default_query_msg(accountname, + policy); + strcpy(context->lastmessage, message); + context->lastsent = time(NULL); + context->may_retransmit = 2; + if (bettermsg) { + *messagep = bettermsg; + } else { + return gcry_error(GPG_ERR_ENOMEM); + } + } + } else { + if ((policy & OTRL_POLICY_SEND_WHITESPACE_TAG) && + context->otr_offer != OFFER_REJECTED) { + /* See if this user can speak OTR. Append the + * OTR_MESSAGE_TAG to the plaintext message, and see + * if he responds. */ + size_t msglen = strlen(message); + size_t basetaglen = strlen(OTRL_MESSAGE_TAG_BASE); + size_t v1taglen = (policy & OTRL_POLICY_ALLOW_V1) ? + strlen(OTRL_MESSAGE_TAG_V1) : 0; + size_t v2taglen = (policy & OTRL_POLICY_ALLOW_V2) ? + strlen(OTRL_MESSAGE_TAG_V2) : 0; + char *taggedmsg = malloc(msglen + basetaglen + v1taglen + +v2taglen + 1); + if (taggedmsg) { + strcpy(taggedmsg, message); + strcpy(taggedmsg + msglen, OTRL_MESSAGE_TAG_BASE); + if (v1taglen) { + strcpy(taggedmsg + msglen + basetaglen, + OTRL_MESSAGE_TAG_V1); + } + if (v2taglen) { + strcpy(taggedmsg + msglen + basetaglen + v1taglen, + OTRL_MESSAGE_TAG_V2); + } + *messagep = taggedmsg; + if (context) { + context->otr_offer = OFFER_SENT; + } + } + } + } + break; + case OTRL_MSGSTATE_ENCRYPTED: + /* Create the new, encrypted message */ + err = otrl_proto_create_data(&msgtosend, context, message, tlvs, + 0); + if (!err) { + context->lastsent = time(NULL); + *messagep = msgtosend; + } else { + /* Uh, oh. Whatever we do, *don't* send the message in the + * clear. */ + *messagep = _strdup("?OTR Error: Error occurred encrypting " + "message"); + if ((!(ops->display_otr_message) || + ops->display_otr_message(opdata, accountname, + protocol, recipient, "An error occurred when " + "encrypting your message. The message was not " + "sent.")) && ops->notify) { + ops->notify(opdata, OTRL_NOTIFY_ERROR, + accountname, protocol, recipient, + "Error encrypting message", + "An error occurred when encrypting your message", + "The message was not sent."); + } + if (!(*messagep)) { + return gcry_error(GPG_ERR_ENOMEM); + } + } + break; + case OTRL_MSGSTATE_FINISHED: + *messagep = _strdup(""); + if ((!(ops->display_otr_message) || + ops->display_otr_message(opdata, accountname, + protocol, recipient, "Your message was not sent. " + "Either end your private conversation, or restart " + "it.")) && ops->notify) { + const char *fmt = "%s has already closed his/her private " + "connection to you"; + char *primary = malloc(strlen(fmt) + strlen(recipient) - 1); + if (primary) { + sprintf(primary, fmt, recipient); + ops->notify(opdata, OTRL_NOTIFY_ERROR, + accountname, protocol, recipient, + "Private connection closed", primary, + "Your message was not sent. Either close your " + "private connection to him, or refresh it."); + } + } + if (!(*messagep)) { + return gcry_error(GPG_ERR_ENOMEM); + } + break; + } + + return gcry_error(GPG_ERR_NO_ERROR); +} + +/* If err == 0, send the last auth message for the given context to the + * appropriate user. Otherwise, display an appripriate error dialog. + * Return the value of err that was passed. */ +static gcry_error_t send_or_error_auth(const OtrlMessageAppOps *ops, + void *opdata, gcry_error_t err, ConnContext *context) +{ + if (!err) { + const char *msg = context->auth.lastauthmsg; + if (msg && *msg) { + otrl_message_fragment_and_send(ops, opdata, context, msg, OTRL_FRAGMENT_SEND_ALL, NULL); + /*if (ops->inject_message) { + ops->inject_message(opdata, context->accountname, + context->protocol, context->username, msg); + }*/ + } + } else { + const char *buf_format = "Error setting up private conversation: %s"; + const char *strerr; + char *buf; + + switch(gcry_err_code(err)) { + case GPG_ERR_INV_VALUE: + strerr = "Malformed message received"; + break; + default: + strerr = gcry_strerror(err); + break; + } + buf = malloc(strlen(buf_format) + strlen(strerr) - 1); + if (buf) { + sprintf(buf, buf_format, strerr); + } + if ((!(ops->display_otr_message) || + ops->display_otr_message(opdata, context->accountname, + context->protocol, context->username, buf)) + && ops->notify) { + ops->notify(opdata, OTRL_NOTIFY_ERROR, context->accountname, + context->protocol, context->username, "OTR error", + buf, NULL); + } + free(buf); + } + return err; +} + +typedef struct { + int gone_encrypted; + OtrlUserState us; + const OtrlMessageAppOps *ops; + void *opdata; + ConnContext *context; + int ignore_message; + char **messagep; +} EncrData; + +static gcry_error_t go_encrypted(const OtrlAuthInfo *auth, void *asdata) +{ + EncrData *edata = asdata; + gcry_error_t err = gcry_error(GPG_ERR_NO_ERROR); + Fingerprint *found_print = NULL; + int fprint_added = 0; + OtrlMessageState oldstate = edata->context->msgstate; + Fingerprint *oldprint = edata->context->active_fingerprint; + + /* See if we're talking to ourselves */ + if (!gcry_mpi_cmp(auth->their_pub, auth->our_dh.pub)) { + /* Yes, we are. */ + if ((!(edata->ops->display_otr_message) || + edata->ops->display_otr_message(edata->opdata, + edata->context->accountname, edata->context->protocol, + edata->context->username, + "We are receiving our own OTR messages. " + "You are either trying to talk to yourself, " + "or someone is reflecting your messages back " + "at you.")) && edata->ops->notify) { + edata->ops->notify(edata->opdata, OTRL_NOTIFY_ERROR, + edata->context->accountname, edata->context->protocol, + edata->context->username, "OTR Error", + "We are receiving our own OTR messages.", + "You are either trying to talk to yourself, " + "or someone is reflecting your messages back " + "at you."); + } + edata->ignore_message = 1; + return gcry_error(GPG_ERR_NO_ERROR); + } + + found_print = otrl_context_find_fingerprint(edata->context, + edata->context->auth.their_fingerprint, 1, &fprint_added); + + if (fprint_added) { + /* Inform the user of the new fingerprint */ + if (edata->ops->new_fingerprint) { + edata->ops->new_fingerprint(edata->opdata, edata->us, + edata->context->accountname, edata->context->protocol, + edata->context->username, + edata->context->auth.their_fingerprint); + } + /* Arrange that the new fingerprint be written to disk */ + if (edata->ops->write_fingerprints) { + edata->ops->write_fingerprints(edata->opdata); + } + } + + /* Is this a new session or just a refresh of an existing one? */ + if (edata->context->msgstate == OTRL_MSGSTATE_ENCRYPTED && + oldprint == found_print && + edata->context->our_keyid - 1 == edata->context->auth.our_keyid && + !gcry_mpi_cmp(edata->context->our_old_dh_key.pub, + edata->context->auth.our_dh.pub) && + ((edata->context->their_keyid > 0 && + edata->context->their_keyid == + edata->context->auth.their_keyid && + !gcry_mpi_cmp(edata->context->their_y, + edata->context->auth.their_pub)) || + (edata->context->their_keyid > 1 && + edata->context->their_keyid - 1 == + edata->context->auth.their_keyid && + edata->context->their_old_y != NULL && + !gcry_mpi_cmp(edata->context->their_old_y, + edata->context->auth.their_pub)))) { + /* This is just a refresh of the existing session. */ + if (edata->ops->still_secure) { + edata->ops->still_secure(edata->opdata, edata->context, + edata->context->auth.initiated); + } + edata->ignore_message = 1; + return gcry_error(GPG_ERR_NO_ERROR); + } + + /* Copy the information from the auth into the context */ + memmove(edata->context->sessionid, + edata->context->auth.secure_session_id, 20); + edata->context->sessionid_len = + edata->context->auth.secure_session_id_len; + edata->context->sessionid_half = + edata->context->auth.session_id_half; + edata->context->protocol_version = + edata->context->auth.protocol_version; + + edata->context->their_keyid = edata->context->auth.their_keyid; + gcry_mpi_release(edata->context->their_y); + gcry_mpi_release(edata->context->their_old_y); + edata->context->their_y = gcry_mpi_copy(edata->context->auth.their_pub); + edata->context->their_old_y = NULL; + + if (edata->context->our_keyid - 1 != edata->context->auth.our_keyid || + gcry_mpi_cmp(edata->context->our_old_dh_key.pub, + edata->context->auth.our_dh.pub)) { + otrl_dh_keypair_free(&(edata->context->our_dh_key)); + otrl_dh_keypair_free(&(edata->context->our_old_dh_key)); + otrl_dh_keypair_copy(&(edata->context->our_old_dh_key), + &(edata->context->auth.our_dh)); + otrl_dh_gen_keypair(edata->context->our_old_dh_key.groupid, + &(edata->context->our_dh_key)); + edata->context->our_keyid = edata->context->auth.our_keyid + 1; + } + + /* Create the session keys from the DH keys */ + otrl_dh_session_free(&(edata->context->sesskeys[0][0])); + err = otrl_dh_session(&(edata->context->sesskeys[0][0]), + &(edata->context->our_dh_key), edata->context->their_y); + if (err) return err; + otrl_dh_session_free(&(edata->context->sesskeys[1][0])); + err = otrl_dh_session(&(edata->context->sesskeys[1][0]), + &(edata->context->our_old_dh_key), edata->context->their_y); + if (err) return err; + + edata->context->generation++; + edata->context->active_fingerprint = found_print; + edata->context->msgstate = OTRL_MSGSTATE_ENCRYPTED; + + if (edata->ops->update_context_list) { + edata->ops->update_context_list(edata->opdata); + } + if (oldstate == OTRL_MSGSTATE_ENCRYPTED && oldprint == found_print) { + if (edata->ops->still_secure) { + edata->ops->still_secure(edata->opdata, edata->context, + edata->context->auth.initiated); + } + } else { + if (edata->ops->gone_secure) { + edata->ops->gone_secure(edata->opdata, edata->context); + } + } + + edata->gone_encrypted = 1; + + return gpg_error(GPG_ERR_NO_ERROR); +} + +static void maybe_resend(EncrData *edata) +{ + gcry_error_t err; + time_t now; + + if (!edata->gone_encrypted) return; + + /* See if there's a message we sent recently that should be resent. */ + now = time(NULL); + if (edata->context->lastmessage != NULL && + edata->context->may_retransmit && + edata->context->lastsent >= (now - RESEND_INTERVAL)) { + char *resendmsg; + int resending = (edata->context->may_retransmit == 1); + + /* Re-encrypt the message with the new keys */ + err = otrl_proto_create_data(&resendmsg, + edata->context, edata->context->lastmessage, NULL, 0); + if (!err) { + const char *format = "<b>The last message " + "to %s was resent.</b>"; + char *buf; + + /* Resend the message */ + otrl_message_fragment_and_send(edata->ops, edata->opdata, edata->context, resendmsg, OTRL_FRAGMENT_SEND_ALL, NULL); + free(resendmsg); + edata->context->lastsent = now; + + if (!resending) { + /* We're actually just sending it + * for the first time. */ + edata->ignore_message = 1; + } else { + /* Let the user know we resent it */ + buf = malloc(strlen(format) + + strlen(edata->context->username) - 1); + if (buf) { + sprintf(buf, format, edata->context->username); + if (edata->ops->display_otr_message) { + if (!edata->ops->display_otr_message( + edata->opdata, edata->context->accountname, + edata->context->protocol, + edata->context->username, buf)) { + edata->ignore_message = 1; + } + } + if (edata->ignore_message != 1) { + *(edata->messagep) = buf; + edata->ignore_message = 0; + } else { + free(buf); + } + } + } + } + } +} + +/* Set the trust level based on the result of the SMP */ +static void set_smp_trust(const OtrlMessageAppOps *ops, void *opdata, + ConnContext *context, int trusted) +{ + otrl_context_set_trust(context->active_fingerprint, trusted ? "smp" : ""); + + /* Write the new info to disk, redraw the ui, and redraw the + * OTR buttons. */ + if (ops->write_fingerprints) { + ops->write_fingerprints(opdata); + } +} + +static void init_respond_smp(OtrlUserState us, const OtrlMessageAppOps *ops, + void *opdata, ConnContext *context, const char *question, + const unsigned char *secret, size_t secretlen, int initiating) +{ + unsigned char *smpmsg = NULL; + int smpmsglen; + unsigned char combined_secret[SM_DIGEST_SIZE]; + gcry_error_t err; + unsigned char our_fp[20]; + unsigned char *combined_buf; + size_t combined_buf_len; + OtrlTLV *sendtlv; + char *sendsmp = NULL; + + if (!context || context->msgstate != OTRL_MSGSTATE_ENCRYPTED) return; + + /* + * Construct the combined secret as a SHA256 hash of: + * Version byte (0x01), Initiator fingerprint (20 bytes), + * responder fingerprint (20 bytes), secure session id, input secret + */ + otrl_privkey_fingerprint_raw(us, our_fp, context->accountname, + context->protocol); + + combined_buf_len = 41 + context->sessionid_len + secretlen; + combined_buf = malloc(combined_buf_len); + combined_buf[0] = 0x01; + if (initiating) { + memmove(combined_buf + 1, our_fp, 20); + memmove(combined_buf + 21, + context->active_fingerprint->fingerprint, 20); + } else { + memmove(combined_buf + 1, + context->active_fingerprint->fingerprint, 20); + memmove(combined_buf + 21, our_fp, 20); + } + memmove(combined_buf + 41, context->sessionid, + context->sessionid_len); + memmove(combined_buf + 41 + context->sessionid_len, + secret, secretlen); + gcry_md_hash_buffer(SM_HASH_ALGORITHM, combined_secret, combined_buf, + combined_buf_len); + free(combined_buf); + + if (initiating) { + otrl_sm_step1(context->smstate, combined_secret, SM_DIGEST_SIZE, + &smpmsg, &smpmsglen); + } else { + otrl_sm_step2b(context->smstate, combined_secret, SM_DIGEST_SIZE, + &smpmsg, &smpmsglen); + } + + /* If we've got a question, attach it to the smpmsg */ + if (question != NULL) { + size_t qlen = strlen(question); + unsigned char *qsmpmsg = malloc(qlen + 1 + smpmsglen); + if (!qsmpmsg) { + free(smpmsg); + return; + } + strcpy((char *)qsmpmsg, question); + memmove(qsmpmsg + qlen + 1, smpmsg, smpmsglen); + free(smpmsg); + smpmsg = qsmpmsg; + smpmsglen += qlen + 1; + } + + /* Send msg with next smp msg content */ + sendtlv = otrl_tlv_new(initiating ? + (question != NULL ? OTRL_TLV_SMP1Q : OTRL_TLV_SMP1) + : OTRL_TLV_SMP2, + smpmsglen, smpmsg); + err = otrl_proto_create_data(&sendsmp, context, "", sendtlv, + OTRL_MSGFLAGS_IGNORE_UNREADABLE); + if (!err) { + /* Send it, and set the next expected message to the + * logical response */ + err = otrl_message_fragment_and_send(ops, opdata, context, + sendsmp, OTRL_FRAGMENT_SEND_ALL, NULL); + context->smstate->nextExpected = + initiating ? OTRL_SMP_EXPECT2 : OTRL_SMP_EXPECT3; + } + free(sendsmp); + otrl_tlv_free(sendtlv); + free(smpmsg); +} + +/* Initiate the Socialist Millionaires' Protocol */ +void otrl_message_initiate_smp(OtrlUserState us, const OtrlMessageAppOps *ops, + void *opdata, ConnContext *context, const unsigned char *secret, + size_t secretlen) +{ + init_respond_smp(us, ops, opdata, context, NULL, secret, secretlen, 1); +} + +/* Initiate the Socialist Millionaires' Protocol and send a prompt + * question to the buddy */ +void otrl_message_initiate_smp_q(OtrlUserState us, + const OtrlMessageAppOps *ops, void *opdata, ConnContext *context, + const char *question, const unsigned char *secret, size_t secretlen) +{ + init_respond_smp(us, ops, opdata, context, question, secret, secretlen, 1); +} + +/* Respond to a buddy initiating the Socialist Millionaires' Protocol */ +void otrl_message_respond_smp(OtrlUserState us, const OtrlMessageAppOps *ops, + void *opdata, ConnContext *context, const unsigned char *secret, + size_t secretlen) +{ + init_respond_smp(us, ops, opdata, context, NULL, secret, secretlen, 0); +} + +/* Abort the SMP. Called when an unexpected SMP message breaks the + * normal flow. */ +void otrl_message_abort_smp(OtrlUserState us, const OtrlMessageAppOps *ops, + void *opdata, ConnContext *context) +{ + OtrlTLV *sendtlv = otrl_tlv_new(OTRL_TLV_SMP_ABORT, 0, + (const unsigned char *)""); + char *sendsmp = NULL; + gcry_error_t err; + + context->smstate->nextExpected = OTRL_SMP_EXPECT1; + + err = otrl_proto_create_data(&sendsmp, + context, "", sendtlv, + OTRL_MSGFLAGS_IGNORE_UNREADABLE); + if (!err) { + /* Send the abort signal so our buddy knows we've stopped */ + err = otrl_message_fragment_and_send(ops, opdata, context, + sendsmp, OTRL_FRAGMENT_SEND_ALL, NULL); + } + free(sendsmp); + otrl_tlv_free(sendtlv); +} + +/* Handle a message just received from the network. It is safe to pass + * all received messages to this routine. add_appdata is a function + * that will be called in the event that a new ConnContext is created. + * It will be passed the data that you supplied, as well as + * a pointer to the new ConnContext. You can use this to add + * application-specific information to the ConnContext using the + * "context->app" field, for example. If you don't need to do this, you + * can pass NULL for the last two arguments of otrl_message_receiving. + * + * If otrl_message_receiving returns 1, then the message you received + * was an internal protocol message, and no message should be delivered + * to the user. + * + * If it returns 0, then check if *messagep was set to non-NULL. If + * so, replace the received message with the contents of *messagep, and + * deliver that to the user instead. You must call + * otrl_message_free(*messagep) when you're done with it. If tlvsp is + * non-NULL, *tlvsp will be set to a chain of any TLVs that were + * transmitted along with this message. You must call + * otrl_tlv_free(*tlvsp) when you're done with those. + * + * If otrl_message_receiving returns 0 and *messagep is NULL, then this + * was an ordinary, non-OTR message, which should just be delivered to + * the user without modification. */ +int otrl_message_receiving(OtrlUserState us, const OtrlMessageAppOps *ops, + void *opdata, const char *accountname, const char *protocol, + const char *sender, const char *message, char **newmessagep, + OtrlTLV **tlvsp, + void (*add_appdata)(void *data, ConnContext *context), + void *data) +{ + ConnContext *context; + OtrlMessageType msgtype; + int context_added = 0; + OtrlMessageState msgstate; + OtrlPolicy policy = OTRL_POLICY_DEFAULT; + int fragment_assembled = 0; + char *unfragmessage = NULL; + EncrData edata; + + if (!accountname || !protocol || !sender || !message || !newmessagep) + return 0; + + *newmessagep = NULL; + if (tlvsp) *tlvsp = NULL; + + /* Find our context and state with this correspondent */ + context = otrl_context_find(us, sender, accountname, + protocol, 1, &context_added, add_appdata, data); + + /* Update the context list if we added one */ + if (context_added && ops->update_context_list) { + ops->update_context_list(opdata); + } + + /* Check the policy */ + if (ops->policy) { + policy = ops->policy(opdata, context); + } + + /* Should we go on at all? */ + if ((policy & OTRL_POLICY_VERSION_MASK) == 0) { + return 0; + } + + /* See if we have a fragment */ + switch(otrl_proto_fragment_accumulate(&unfragmessage, context, message)) { + case OTRL_FRAGMENT_UNFRAGMENTED: + /* Do nothing */ + break; + case OTRL_FRAGMENT_INCOMPLETE: + /* We've accumulated this fragment, but we don't have a + * complete message yet */ + return 1; + case OTRL_FRAGMENT_COMPLETE: + /* We've got a new complete message, in unfragmessage. */ + fragment_assembled = 1; + message = unfragmessage; + break; + } + + /* What type of message is it? Note that this just checks the + * header; it's not necessarily a _valid_ message of this type. */ + msgtype = otrl_proto_message_type(message); + msgstate = context->msgstate; + + /* See if they responded to our OTR offer */ + if ((policy & OTRL_POLICY_SEND_WHITESPACE_TAG)) { + if (msgtype != OTRL_MSGTYPE_NOTOTR) { + context->otr_offer = OFFER_ACCEPTED; + } else if (context->otr_offer == OFFER_SENT) { + context->otr_offer = OFFER_REJECTED; + } + } + + edata.gone_encrypted = 0; + edata.us = us; + edata.context = context; + edata.ops = ops; + edata.opdata = opdata; + edata.ignore_message = -1; + edata.messagep = newmessagep; + + switch(msgtype) { + unsigned int bestversion; + const char *startwhite, *endwhite; + DH_keypair *our_dh; + unsigned int our_keyid; + OtrlPrivKey *privkey; + gcry_error_t err; + int haveauthmsg; + case OTRL_MSGTYPE_QUERY: + /* See if we should use an existing DH keypair, or generate + * a fresh one. */ + if (context->msgstate == OTRL_MSGSTATE_ENCRYPTED) { + our_dh = &(context->our_old_dh_key); + our_keyid = context->our_keyid - 1; + } else { + our_dh = NULL; + our_keyid = 0; + } + + /* Find the best version of OTR that we both speak */ + switch(otrl_proto_query_bestversion(message, policy)) { + case 2: + err = otrl_auth_start_v2(&(context->auth)); + send_or_error_auth(ops, opdata, err, context); + break; + case 1: + /* Get our private key */ + privkey = otrl_privkey_find(us, context->accountname, + context->protocol); + if (privkey == NULL) { + /* We've got no private key! */ + if (ops->create_privkey) { + ops->create_privkey(opdata, context->accountname, + context->protocol); + privkey = otrl_privkey_find(us, + context->accountname, context->protocol); + } + } + if (privkey) { + err = otrl_auth_start_v1(&(context->auth), our_dh, + our_keyid, privkey); + send_or_error_auth(ops, opdata, err, context); + } + break; + default: + /* Just ignore this message */ + break; + } + /* Don't display the Query message to the user. */ + if (edata.ignore_message == -1) edata.ignore_message = 1; + break; + + case OTRL_MSGTYPE_DH_COMMIT: + if ((policy & OTRL_POLICY_ALLOW_V2)) { + err = otrl_auth_handle_commit(&(context->auth), message); + send_or_error_auth(ops, opdata, err, context); + } + + if (edata.ignore_message == -1) edata.ignore_message = 1; + break; + + case OTRL_MSGTYPE_DH_KEY: + if ((policy & OTRL_POLICY_ALLOW_V2)) { + /* Get our private key */ + privkey = otrl_privkey_find(us, context->accountname, + context->protocol); + if (privkey == NULL) { + /* We've got no private key! */ + if (ops->create_privkey) { + ops->create_privkey(opdata, context->accountname, + context->protocol); + privkey = otrl_privkey_find(us, + context->accountname, context->protocol); + } + } + if (privkey) { + err = otrl_auth_handle_key(&(context->auth), message, + &haveauthmsg, privkey); + if (err || haveauthmsg) { + send_or_error_auth(ops, opdata, err, context); + } + } + } + + if (edata.ignore_message == -1) edata.ignore_message = 1; + break; + + case OTRL_MSGTYPE_REVEALSIG: + if ((policy & OTRL_POLICY_ALLOW_V2)) { + /* Get our private key */ + privkey = otrl_privkey_find(us, context->accountname, + context->protocol); + if (privkey == NULL) { + /* We've got no private key! */ + if (ops->create_privkey) { + ops->create_privkey(opdata, context->accountname, + context->protocol); + privkey = otrl_privkey_find(us, + context->accountname, context->protocol); + } + } + if (privkey) { + err = otrl_auth_handle_revealsig(&(context->auth), + message, &haveauthmsg, privkey, go_encrypted, + &edata); + if (err || haveauthmsg) { + send_or_error_auth(ops, opdata, err, context); + maybe_resend(&edata); + } + } + } + + if (edata.ignore_message == -1) edata.ignore_message = 1; + break; + + case OTRL_MSGTYPE_SIGNATURE: + if ((policy & OTRL_POLICY_ALLOW_V2)) { + err = otrl_auth_handle_signature(&(context->auth), + message, &haveauthmsg, go_encrypted, &edata); + if (err || haveauthmsg) { + send_or_error_auth(ops, opdata, err, context); + maybe_resend(&edata); + } + } + + if (edata.ignore_message == -1) edata.ignore_message = 1; + break; + + case OTRL_MSGTYPE_V1_KEYEXCH: + if ((policy & OTRL_POLICY_ALLOW_V1)) { + /* See if we should use an existing DH keypair, or generate + * a fresh one. */ + if (context->msgstate == OTRL_MSGSTATE_ENCRYPTED) { + our_dh = &(context->our_old_dh_key); + our_keyid = context->our_keyid - 1; + } else { + our_dh = NULL; + our_keyid = 0; + } + + /* Get our private key */ + privkey = otrl_privkey_find(us, context->accountname, + context->protocol); + if (privkey == NULL) { + /* We've got no private key! */ + if (ops->create_privkey) { + ops->create_privkey(opdata, context->accountname, + context->protocol); + privkey = otrl_privkey_find(us, + context->accountname, context->protocol); + } + } + if (privkey) { + err = otrl_auth_handle_v1_key_exchange(&(context->auth), + message, &haveauthmsg, privkey, our_dh, our_keyid, + go_encrypted, &edata); + if (err || haveauthmsg) { + send_or_error_auth(ops, opdata, err, context); + maybe_resend(&edata); + } + } + } + + if (edata.ignore_message == -1) edata.ignore_message = 1; + break; + + case OTRL_MSGTYPE_DATA: + switch(context->msgstate) { + gcry_error_t err; + OtrlTLV *tlvs, *tlv; + char *plaintext; + char *buf; + const char *format; + const char *displayaccountname; + unsigned char flags; + NextExpectedSMP nextMsg; + + case OTRL_MSGSTATE_PLAINTEXT: + case OTRL_MSGSTATE_FINISHED: + /* See if we're supposed to ignore this message in + * the event it's unreadable. */ + err = otrl_proto_data_read_flags(message, &flags); + if ((flags & OTRL_MSGFLAGS_IGNORE_UNREADABLE)) { + edata.ignore_message = 1; + break; + } + + /* Don't use g_strdup_printf here, because someone + * (not us) is going to free() the *newmessagep pointer, + * not g_free() it. */ + format = "<b>The encrypted message received from %s is " + "unreadable, as you are not currently communicating " + "privately.</b>"; + buf = malloc(strlen(format) + strlen(context->username) + - 1); /* Remove "%s", add username + '\0' */ + if (buf) { + sprintf(buf, format, context->username); + if (ops->display_otr_message) { + if (!ops->display_otr_message(opdata, accountname, + protocol, sender, buf)) { + edata.ignore_message = 1; + } + } + if (edata.ignore_message != 1) { + *newmessagep = buf; + edata.ignore_message = 0; + } else { + free(buf); + } + } + format = "?OTR Error: You sent encrypted " + "data to %s, who wasn't expecting it."; + if (otrl_api_version >= 0x00030100 && + ops->account_name) { + displayaccountname = ops->account_name(opdata, + context->accountname, protocol); + } else { + displayaccountname = NULL; + } + buf = malloc(strlen(format) + strlen(displayaccountname ? + displayaccountname : context->accountname) + - 1); + if (buf) { + sprintf(buf, format, displayaccountname ? + displayaccountname : context->accountname); + if (ops->inject_message) { + ops->inject_message(opdata, accountname, protocol, + sender, buf); + } + free(buf); + } + if (displayaccountname && otrl_api_version >= 0x00030100 && + ops->account_name_free) { + ops->account_name_free(opdata, displayaccountname); + } + + break; + + case OTRL_MSGSTATE_ENCRYPTED: + err = otrl_proto_accept_data(&plaintext, &tlvs, context, + message, &flags); + if (err) { + int is_conflict = + (gpg_err_code(err) == GPG_ERR_CONFLICT); + if ((flags & OTRL_MSGFLAGS_IGNORE_UNREADABLE)) { + edata.ignore_message = 1; + break; + } + format = is_conflict ? "We received an unreadable " + "encrypted message from %s." : + "We received a malformed data message from %s."; + buf = malloc(strlen(format) + strlen(sender) - 1); + if (buf) { + sprintf(buf, format, sender); + if ((!(ops->display_otr_message) || + ops->display_otr_message(opdata, + accountname, protocol, sender, + buf)) && ops->notify) { + ops->notify(opdata, OTRL_NOTIFY_ERROR, + accountname, protocol, sender, + "OTR Error", buf, NULL); + } + free(buf); + } + if (ops->inject_message) { + ops->inject_message(opdata, accountname, protocol, + sender, is_conflict ? "?OTR Error: " + "You transmitted an unreadable " + "encrypted message." : + "?OTR Error: You transmitted " + "a malformed data message"); + } + edata.ignore_message = 1; + break; + } + + /* If the other side told us he's disconnected his + * private connection, make a note of that so we + * don't try sending anything else to him. */ + if (otrl_tlv_find(tlvs, OTRL_TLV_DISCONNECTED)) { + otrl_context_force_finished(context); + } + + /* If TLVs contain SMP data, process it */ + nextMsg = context->smstate->nextExpected; + tlv = otrl_tlv_find(tlvs, OTRL_TLV_SMP1Q); + if (tlv && nextMsg == OTRL_SMP_EXPECT1) { + /* We can only do the verification half now. + * We must wait for the secret to be entered + * to continue. */ + char *question = (char *)tlv->data; + char *qend = memchr(question, '\0', tlv->len - 1); + size_t qlen = qend ? (qend - question + 1) : tlv->len; + otrl_sm_step2a(context->smstate, tlv->data + qlen, + tlv->len - qlen, 1); + } + tlv = otrl_tlv_find(tlvs, OTRL_TLV_SMP1); + if (tlv && nextMsg == OTRL_SMP_EXPECT1) { + /* We can only do the verification half now. + * We must wait for the secret to be entered + * to continue. */ + otrl_sm_step2a(context->smstate, tlv->data, tlv->len, + 0); + } + tlv = otrl_tlv_find(tlvs, OTRL_TLV_SMP2); + if (tlv && nextMsg == OTRL_SMP_EXPECT2) { + unsigned char* nextmsg; + int nextmsglen; + OtrlTLV *sendtlv; + char *sendsmp; + otrl_sm_step3(context->smstate, tlv->data, tlv->len, + &nextmsg, &nextmsglen); + + if (context->smstate->sm_prog_state != + OTRL_SMP_PROG_CHEATED) { + /* Send msg with next smp msg content */ + sendtlv = otrl_tlv_new(OTRL_TLV_SMP3, nextmsglen, + nextmsg); + err = otrl_proto_create_data(&sendsmp, + context, "", sendtlv, + OTRL_MSGFLAGS_IGNORE_UNREADABLE); + if (!err) { + err = otrl_message_fragment_and_send(ops, + opdata, context, sendsmp, + OTRL_FRAGMENT_SEND_ALL, NULL); + } + free(sendsmp); + otrl_tlv_free(sendtlv); + } + free(nextmsg); + } + tlv = otrl_tlv_find(tlvs, OTRL_TLV_SMP3); + if (tlv && nextMsg == OTRL_SMP_EXPECT3) { + unsigned char* nextmsg; + int nextmsglen; + OtrlTLV *sendtlv; + char *sendsmp; + err = otrl_sm_step4(context->smstate, tlv->data, + tlv->len, &nextmsg, &nextmsglen); + /* Set trust level based on result */ + if (context->smstate->received_question == 0) { + set_smp_trust(ops, opdata, context, + (err == gcry_error(GPG_ERR_NO_ERROR))); + } + + if (context->smstate->sm_prog_state != + OTRL_SMP_PROG_CHEATED) { + /* Send msg with next smp msg content */ + sendtlv = otrl_tlv_new(OTRL_TLV_SMP4, nextmsglen, + nextmsg); + err = otrl_proto_create_data(&sendsmp, + context, "", sendtlv, + OTRL_MSGFLAGS_IGNORE_UNREADABLE); + if (!err) { + err = otrl_message_fragment_and_send(ops, + opdata, context, sendsmp, + OTRL_FRAGMENT_SEND_ALL, NULL); + } + free(sendsmp); + otrl_tlv_free(sendtlv); + } + free(nextmsg); + } + tlv = otrl_tlv_find(tlvs, OTRL_TLV_SMP4); + if (tlv && nextMsg == OTRL_SMP_EXPECT4) { + err = otrl_sm_step5(context->smstate, tlv->data, + tlv->len); + /* Set trust level based on result */ + set_smp_trust(ops, opdata, context, + (err == gcry_error(GPG_ERR_NO_ERROR))); + } + tlv = otrl_tlv_find(tlvs, OTRL_TLV_SMP_ABORT); + if (tlv) { + context->smstate->nextExpected = OTRL_SMP_EXPECT1; + } + if (plaintext[0] == '\0') { + /* If it's a heartbeat (an empty message), don't + * display it to the user, but log a debug message. */ + format = "Heartbeat received from %s.\n"; + buf = malloc(strlen(format) + strlen(sender) - 1); + if (buf) { + sprintf(buf, format, sender); + if (ops->log_message) { + ops->log_message(opdata, buf); + } + free(buf); + } + edata.ignore_message = 1; + } else if (edata.ignore_message == 0 && + context->their_keyid > 0) { + /* If it's *not* a heartbeat, and we haven't + * sent anything in a while, also send a + * heartbeat. */ + time_t now = time(NULL); + if (context->lastsent < (now - HEARTBEAT_INTERVAL)) { + char *heartbeat; + + /* Create the heartbeat message */ + err = otrl_proto_create_data(&heartbeat, + context, "", NULL, + OTRL_MSGFLAGS_IGNORE_UNREADABLE); + if (!err) { + /* Send it, and log a debug message */ + if (ops->inject_message) { + ops->inject_message(opdata, accountname, + protocol, sender, heartbeat); + } + free(heartbeat); + + context->lastsent = now; + + /* Log a debug message */ + format = "Heartbeat sent to %s.\n"; + buf = malloc(strlen(format) + strlen(sender) + - 1); + if (buf) { + sprintf(buf, format, sender); + if (ops->log_message) { + ops->log_message(opdata, buf); + } + free(buf); + } + } + } + } + + /* Return the TLVs even if ignore_message == 1 so + * that we can attach TLVs to heartbeats. */ + if (tlvsp) { + *tlvsp = tlvs; + } else { + otrl_tlv_free(tlvs); + } + + if (edata.ignore_message != 1) { + *newmessagep = plaintext; + edata.ignore_message = 0; + } else { + free(plaintext); + } + break; + } + break; + + case OTRL_MSGTYPE_ERROR: + if ((policy & OTRL_POLICY_ERROR_START_AKE)) { + char *msgtosend = otrl_proto_default_query_msg( + context->accountname, policy); + if (msgtosend && ops->inject_message) { + ops->inject_message(opdata, context->accountname, + context->protocol, context->username, + msgtosend); + } + free(msgtosend); + } + + if (context->msgstate == OTRL_MSGSTATE_ENCRYPTED) { + /* Mark the last message we sent as eligible for + * retransmission */ + context->may_retransmit = 1; + } + + /* In any event, display the error message, with the + * display_otr_message callback, if possible */ + if (ops->display_otr_message) { + const char *otrerror = strstr(message, "?OTR Error:"); + if (otrerror) { + /* Skip the leading '?' */ + ++otrerror; + } else { + otrerror = message; + } + if (!ops->display_otr_message(opdata, accountname, protocol, + sender, otrerror)) { + edata.ignore_message = 1; + } + } + break; + + case OTRL_MSGTYPE_TAGGEDPLAINTEXT: + /* Strip the tag from the message */ + bestversion = otrl_proto_whitespace_bestversion(message, + &startwhite, &endwhite, policy); + if (startwhite && endwhite) { + size_t restlen = strlen(endwhite); + char *strippedmsg = _strdup(message); + + if (strippedmsg) { + memmove(strippedmsg + (startwhite - message), + strippedmsg + (endwhite - message), restlen+1); + *newmessagep = strippedmsg; + edata.ignore_message = 0; + } + } + if (bestversion && context->msgstate != OTRL_MSGSTATE_ENCRYPTED + && (policy & OTRL_POLICY_WHITESPACE_START_AKE)) { + switch(bestversion) { + case 2: + err = otrl_auth_start_v2(&(context->auth)); + send_or_error_auth(ops, opdata, err, context); + break; + case 1: + /* Get our private key */ + privkey = otrl_privkey_find(us, context->accountname, + context->protocol); + if (privkey == NULL) { + /* We've got no private key! */ + if (ops->create_privkey) { + ops->create_privkey(opdata, + context->accountname, + context->protocol); + privkey = otrl_privkey_find(us, + context->accountname, + context->protocol); + } + } + if (privkey) { + err = otrl_auth_start_v1(&(context->auth), NULL, 0, + privkey); + send_or_error_auth(ops, opdata, err, context); + } + break; + default: + /* Don't start the AKE */ + break; + } + } + + /* FALLTHROUGH */ + case OTRL_MSGTYPE_NOTOTR: + if (context->msgstate != OTRL_MSGSTATE_PLAINTEXT || + (policy & OTRL_POLICY_REQUIRE_ENCRYPTION)) { + /* Not fine. Let the user know. */ + + /* Don't use g_strdup_printf here, because someone + * (not us) is going to free() the *message pointer, + * not g_free() it. */ + const char *plainmsg = (*newmessagep) ? *newmessagep : message; + const char *format = "The following message received " + "from %s was not encrypted: [</b>%s<b>]"; + char *buf = malloc(strlen(format) + strlen(context->username) + + strlen(plainmsg) - 3); + /* Remove "%s%s", add username + message + '\0' */ + if (buf) { + sprintf(buf, format, context->username, plainmsg); + if (ops->display_otr_message) { + if (!ops->display_otr_message(opdata, accountname, + protocol, sender, buf)) { + free(*newmessagep); + *newmessagep = NULL; + edata.ignore_message = 1; + } + } + if (edata.ignore_message != 1) { + free(*newmessagep); + *newmessagep = buf; + edata.ignore_message = 0; + } else { + free(buf); + } + } + } + break; + + case OTRL_MSGTYPE_UNKNOWN: + /* We received an OTR message we didn't recognize. Ignore + * it, but make a log entry. */ + if (ops->log_message) { + const char *format = "Unrecognized OTR message received " + "from %s.\n"; + char *buf = malloc(strlen(format) + strlen(sender) - 1); + if (buf) { + sprintf(buf, format, sender); + ops->log_message(opdata, buf); + free(buf); + } + } + if (edata.ignore_message == -1) edata.ignore_message = 1; + break; + } + + /* If we reassembled a fragmented message, we need to free the + * allocated memory now. */ + if (fragment_assembled) { + free(unfragmessage); + } + + if (edata.ignore_message == -1) edata.ignore_message = 0; + return edata.ignore_message; +} + +/* Send a message to the network, fragmenting first if necessary. + * All messages to be sent to the network should go through this + * method immediately before they are sent, ie after encryption. */ +gcry_error_t otrl_message_fragment_and_send(const OtrlMessageAppOps *ops, + void *opdata, ConnContext *context, const char *message, + OtrlFragmentPolicy fragPolicy, char **returnFragment) +{ + int mms = 0; + if (message && ops->inject_message) { + int msglen; + + if (otrl_api_version >= 0x030100 && ops->max_message_size) { + mms = ops->max_message_size(opdata, context); + } + msglen = strlen(message); + + /* Don't incur overhead of fragmentation unless necessary */ + if(mms != 0 && msglen > mms) { + char **fragments; + gcry_error_t err; + int i; + int fragment_count = ((msglen - 1) / (mms -19)) + 1; + /* like ceil(msglen/(mms - 19)) */ + + err = otrl_proto_fragment_create(mms, fragment_count, &fragments, + message); + if (err) { + return err; + } + + /* Determine which fragments to send and which to return + * based on given Fragment Policy. If the first fragment + * should be returned instead of sent, store it. */ + if (fragPolicy == OTRL_FRAGMENT_SEND_ALL_BUT_FIRST) { + *returnFragment = _strdup(fragments[0]); + } else { + ops->inject_message(opdata, context->accountname, + context->protocol, context->username, fragments[0]); + } + for (i=1; i<fragment_count-1; i++) { + ops->inject_message(opdata, context->accountname, + context->protocol, context->username, fragments[i]); + } + /* If the last fragment should be stored instead of sent, + * store it */ + if (fragPolicy == OTRL_FRAGMENT_SEND_ALL_BUT_LAST) { + *returnFragment = _strdup(fragments[fragment_count-1]); + } else { + ops->inject_message(opdata, context->accountname, + context->protocol, context->username, fragments[fragment_count-1]); + } + /* Now free all fragment memory */ + otrl_proto_fragment_free(&fragments, fragment_count); + + } else { + /* No fragmentation necessary */ + if (fragPolicy == OTRL_FRAGMENT_SEND_ALL) { + ops->inject_message(opdata, context->accountname, + context->protocol, context->username, message); + } else { + /* Copy and return the entire given message. */ + int l = strlen(message) + 1; + *returnFragment = malloc(sizeof(char)*l); + strcpy(*returnFragment, message); + } + } + } + return gcry_error(GPG_ERR_NO_ERROR); +} + +/* Put a connection into the PLAINTEXT state, first sending the + * other side a notice that we're doing so if we're currently ENCRYPTED, + * and we think he's logged in. */ +void otrl_message_disconnect(OtrlUserState us, const OtrlMessageAppOps *ops, + void *opdata, const char *accountname, const char *protocol, + const char *username) +{ + ConnContext *context = otrl_context_find(us, username, accountname, + protocol, 0, NULL, NULL, NULL); + + if (!context) return; + + if (context->msgstate == OTRL_MSGSTATE_ENCRYPTED && + context->their_keyid > 0 && + ops->is_logged_in && + ops->is_logged_in(opdata, accountname, protocol, username) == 1) { + if (ops->inject_message) { + char *encmsg = NULL; + gcry_error_t err; + OtrlTLV *tlv = otrl_tlv_new(OTRL_TLV_DISCONNECTED, 0, NULL); + + err = otrl_proto_create_data(&encmsg, context, "", tlv, + OTRL_MSGFLAGS_IGNORE_UNREADABLE); + if (!err) { + ops->inject_message(opdata, accountname, protocol, + username, encmsg); + } + free(encmsg); + } + } + + otrl_context_force_plaintext(context); + if (ops->update_context_list) { + ops->update_context_list(opdata); + } +} |