diff options
Diffstat (limited to 'omfwd.c')
| -rw-r--r-- | omfwd.c | 370 |
1 files changed, 370 insertions, 0 deletions
@@ -41,6 +41,7 @@ #include <assert.h> #include <errno.h> #include <ctype.h> +#include <unistd.h> #ifdef USE_PTHREADS #include <pthread.h> #endif @@ -113,6 +114,375 @@ CODESTARTdbgPrintInstInfo printf("%s", f->f_un.f_forw.f_hname); ENDdbgPrintInstInfo +/* CODE FOR SENDING TCP MESSAGES */ + +/* get send status + * rgerhards, 2005-10-24 + */ +static void TCPSendSetStatus(selector_t *f, enum TCPSendStatus iNewState) +{ + assert(f != NULL); + assert(f->f_type == F_FORW); + assert(f->f_un.f_forw.protocol == FORW_TCP); + assert( (iNewState == TCP_SEND_NOTCONNECTED) + || (iNewState == TCP_SEND_CONNECTING) + || (iNewState == TCP_SEND_READY)); + + /* there can potentially be a race condition, so guard by mutex */ +# ifdef USE_PTHREADS + pthread_mutex_lock(&f->f_un.f_forw.mtxTCPSend); +# endif + f->f_un.f_forw.status = iNewState; +# ifdef USE_PTHREADS + pthread_mutex_unlock(&f->f_un.f_forw.mtxTCPSend); +# endif +} + + +/* set send status + * rgerhards, 2005-10-24 + */ +static enum TCPSendStatus TCPSendGetStatus(selector_t *f) +{ + enum TCPSendStatus eState; + assert(f != NULL); + assert(f->f_type == F_FORW); + assert(f->f_un.f_forw.protocol == FORW_TCP); + + /* there can potentially be a race condition, so guard by mutex */ +# ifdef USE_PTHREADS + pthread_mutex_lock(&f->f_un.f_forw.mtxTCPSend); +# endif + eState = f->f_un.f_forw.status; +# ifdef USE_PTHREADS + pthread_mutex_unlock(&f->f_un.f_forw.mtxTCPSend); +# endif + + return eState; +} + + +/* Initialize TCP sockets (for sender) + * This is done once per selector line, if not yet initialized. + */ +static int TCPSendCreateSocket(selector_t *f, struct addrinfo *addrDest) +{ + int fd; + struct addrinfo *r; + + assert(f != NULL); + + r = addrDest; + + while(r != NULL) { + fd = socket(r->ai_family, r->ai_socktype, r->ai_protocol); + if (fd != -1) { + /* We can not allow the TCP sender to block syslogd, at least + * not in a single-threaded design. That would cause rsyslogd to + * loose input messages - which obviously also would affect + * other selector lines, too. So we do set it to non-blocking and + * handle the situation ourselfs (by discarding messages). IF we run + * dual-threaded, however, the situation is different: in this case, + * the receivers and the selector line processing are only loosely + * coupled via a memory buffer. Now, I think, we can afford the extra + * wait time. Thus, we enable blocking mode for TCP if we compile with + * pthreads. + * rgerhards, 2005-10-25 + */ +# ifndef USE_PTHREADS + /* set to nonblocking - rgerhards 2005-07-20 */ + fcntl(fd, F_SETFL, fcntl(fd, F_GETFL) | O_NONBLOCK); +# endif + if (connect (fd, r->ai_addr, r->ai_addrlen) != 0) { + if(errno == EINPROGRESS) { + /* this is normal - will complete during select */ + TCPSendSetStatus(f, TCP_SEND_CONNECTING); + return fd; + } else { + dprintf("create tcp connection failed, reason %s", + strerror(errno)); + } + + } + else { + TCPSendSetStatus(f, TCP_SEND_READY); + return fd; + } + close(fd); + } + else { + dprintf("couldn't create send socket, reason %s", strerror(errno)); + } + r = r->ai_next; + } + + dprintf("no working socket could be obtained"); + + return -1; +} + +/* Sends a TCP message. It is first checked if the + * session is open and, if not, it is opened. Then the send + * is tried. If it fails, one silent re-try is made. If the send + * fails again, an error status (-1) is returned. If all goes well, + * 0 is returned. The TCP session is NOT torn down. + * For now, EAGAIN is ignored (causing message loss) - but it is + * hard to do something intelligent in this case. With this + * implementation here, we can not block and/or defer. Things are + * probably a bit better when we move to liblogging. The alternative + * would be to enhance the current select server with buffering and + * write descriptors. This seems not justified, given the expected + * short life span of this code (and the unlikeliness of this event). + * rgerhards 2005-07-06 + * This function is now expected to stay. Libloging won't be used for + * that purpose. I have added the param "len", because it is known by the + * caller and so safes us some time. Also, it MUST be given because there + * may be NULs inside msg so that we can not rely on strlen(). Please note + * that the restrictions outlined above do not existin in multi-threaded + * mode, which we assume will now be most often used. So there is no + * real issue with the potential message loss in single-threaded builds. + * rgerhards, 2006-11-30 + * + * In order to support compressed messages via TCP, we must support an + * octet-counting based framing (LF may be part of the compressed message). + * We are now supporting the same mode that is available in IETF I-D + * syslog-transport-tls-05 (current at the time of this writing). This also + * eases things when we go ahead and implement that framing. I have now made + * available two cases where this framing is used: either by explitely + * specifying it in the config file or implicitely when sending a compressed + * message. In the later case, compressed and uncompressed messages within + * the same session have different framings. If it is explicitely set to + * octet-counting, only this framing mode is used within the session. + * rgerhards, 2006-12-07 + */ +static int TCPSend(selector_t *f, char *msg, size_t len) +{ + int retry = 0; + int done = 0; + int bIsCompressed; + int lenSend; + char *buf = NULL; /* if this is non-NULL, it MUST be freed before return! */ + enum TCPSendStatus eState; + TCPFRAMINGMODE framingToUse; + + assert(f != NULL); + assert(msg != NULL); + assert(len > 0); + + bIsCompressed = *msg == 'z'; /* cache this, so that we can modify the message buffer */ + /* select framing for this record. If we have a compressed record, we always need to + * use octet counting because the data potentially contains all control characters + * including LF. + */ + framingToUse = bIsCompressed ? TCP_FRAMING_OCTET_COUNTING : f->f_un.f_forw.tcp_framing; + + do { /* try to send message */ + if(f->f_file <= 0) { + /* we need to open the socket first */ + if((f->f_file = TCPSendCreateSocket(f, f->f_un.f_forw.f_addr)) <= 0) { + return -1; + } + } + + eState = TCPSendGetStatus(f); /* cache info */ + + if(eState == TCP_SEND_CONNECTING) { + /* In this case, we save the buffer. If we have a + * system with few messages, that hopefully prevents + * message loss at all. However, we make no further attempts, + * just the first message is saved. So we only try this + * if there is not yet a saved message present. + * rgerhards 2005-07-20 + */ + if(f->f_un.f_forw.savedMsg == NULL) { + f->f_un.f_forw.savedMsg = malloc(len * sizeof(char)); + if(f->f_un.f_forw.savedMsg == NULL) + return 0; /* nothing we can do... */ + memcpy(f->f_un.f_forw.savedMsg, msg, len); + f->f_un.f_forw.savedMsgLen = len; + } + return 0; + } else if(eState != TCP_SEND_READY) + /* This here is debatable. For the time being, we + * accept the loss of a single message (e.g. during + * connection setup in favour of not messing with + * wait time and timeouts. The reason is that such + * things might otherwise cost us considerable message + * loss on the receiving side (even at a timeout set + * to just 1 second). - rgerhards 2005-07-20 + */ + return 0; + + /* now check if we need to add a line terminator. We need to + * copy the string in memory in this case, this is probably + * quicker than using writev and definitely quicker than doing + * two socket calls. + * rgerhards 2005-07-22 + *//* + * Some messages already contain a \n character at the end + * of the message. We append one only if we there is not + * already one. This seems the best fit, though this also + * means the message does not arrive unaltered at the final + * destination. But in the spirit of legacy syslog, this is + * probably the best to do... + * rgerhards 2005-07-20 + */ + + /* Build frame based on selected framing */ + if(framingToUse == TCP_FRAMING_OCTET_STUFFING) { + if((*(msg+len-1) != '\n')) { + if(buf != NULL) + free(buf); + /* in the malloc below, we need to add 2 to the length. The + * reason is that we a) add one character and b) len does + * not take care of the '\0' byte. Up until today, it was just + * +1 , which caused rsyslogd to sometimes dump core. + * I have added this comment so that the logic is not accidently + * changed again. rgerhards, 2005-10-25 + */ + if((buf = malloc((len + 2) * sizeof(char))) == NULL) { + /* extreme mem shortage, try to solve + * as good as we can. No point in calling + * any alarms, they might as well run out + * of memory (the risk is very high, so we + * do NOT risk that). If we have a message of + * more than 1 byte (what I guess), we simply + * overwrite the last character. + * rgerhards 2005-07-22 + */ + if(len > 1) { + *(msg+len-1) = '\n'; + } else { + /* we simply can not do anything in + * this case (its an error anyhow...). + */ + } + } else { + /* we got memory, so we can copy the message */ + memcpy(buf, msg, len); /* do not copy '\0' */ + *(buf+len) = '\n'; + *(buf+len+1) = '\0'; + msg = buf; /* use new one */ + ++len; /* care for the \n */ + } + } + } else { + /* Octect-Counting + * In this case, we need to always allocate a buffer. This is because + * we need to put a header in front of the message text + */ + char szLenBuf[16]; + int iLenBuf; + + /* important: the printf-mask is "%d<sp>" because there must be a + * space after the len! + *//* The chairs of the IETF syslog-sec WG have announced that it is + * consensus to do the octet count on the SYSLOG-MSG part only. I am + * now changing the code to reflect this. Hopefully, it will not change + * once again (there can no compatibility layer programmed for this). + * To be on the save side, I just comment the code out. I mark these + * comments with "IETF20061218". + * rgerhards, 2006-12-19 + */ + iLenBuf = snprintf(szLenBuf, sizeof(szLenBuf)/sizeof(char), "%d ", (int) len); + /* IETF20061218 iLenBuf = + snprintf(szLenBuf, sizeof(szLenBuf)/sizeof(char), "%d ", len + iLenBuf);*/ + + if((buf = malloc((len + iLenBuf) * sizeof(char))) == NULL) { + /* we are out of memory. This is an extreme situation. We do not + * call any alarm handlers because they most likely run out of mem, + * too. We are brave enough to call debug output, though. Other than + * that, there is nothing left to do. We can not sent the message (as + * in case of the other framing, because the message is incomplete. + * We could, however, send two chunks (header and text separate), but + * that would cause a lot of complexity in the code. So we think it + * is appropriate enough to just make sure we do not crash in this + * very unlikely case. For this, it is justified just to loose + * the message. Rgerhards, 2006-12-07 + */ + dprintf("Error: out of memory when building TCP octet-counted " + "frame. Message is lost, trying to continue.\n"); + return 0; + } + + memcpy(buf, szLenBuf, iLenBuf); /* header */ + memcpy(buf + iLenBuf, msg, len); /* message */ + len += iLenBuf; /* new message size */ + msg = buf; /* set message buffer */ + } + + /* frame building complete, on to actual sending */ + + lenSend = send(f->f_file, msg, len, 0); + dprintf("TCP sent %d bytes, requested %d, msg: '%s'\n", lenSend, len, + bIsCompressed ? "***compressed***" : msg); + if((unsigned)lenSend == len) { + /* all well */ + if(buf != NULL) { + free(buf); + } + return 0; + } else if(lenSend != -1) { + /* no real error, could "just" not send everything... + * For the time being, we ignore this... + * rgerhards, 2005-10-25 + */ + dprintf("message not completely (tcp)send, ignoring %d\n", lenSend); +# if USE_PTHREADS + usleep(1000); /* experimental - might be benefitial in this situation */ +# endif + if(buf != NULL) + free(buf); + return 0; + } + + switch(errno) { + case EMSGSIZE: + dprintf("message not (tcp)send, too large\n"); + /* This is not a real error, so it is not flagged as one */ + if(buf != NULL) + free(buf); + return 0; + break; + case EINPROGRESS: + case EAGAIN: + dprintf("message not (tcp)send, would block\n"); +# if USE_PTHREADS + usleep(1000); /* experimental - might be benefitial in this situation */ +# endif + /* we loose this message, but that's better than loosing + * all ;) + */ + /* This is not a real error, so it is not flagged as one */ + if(buf != NULL) + free(buf); + return 0; + break; + default: + dprintf("message not (tcp)send"); + break; + } + + if(retry == 0) { + ++retry; + /* try to recover */ + close(f->f_file); + TCPSendSetStatus(f, TCP_SEND_NOTCONNECTED); + f->f_file = -1; + } else { + if(buf != NULL) + free(buf); + return -1; + } + } while(!done); /* warning: do ... while() */ + /*NOT REACHED*/ + + if(buf != NULL) + free(buf); + return -1; /* only to avoid compiler warning! */ +} + + /* get the syslog forward port from selector_t. The passed in * struct must be one that is setup for forwarding. * rgerhards, 2007-06-28 |