separate basic TCP RX handling
This commit is contained in:
Michael Davidsaver
+250
@@ -0,0 +1,250 @@
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/**
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* Copyright - See the COPYRIGHT that is included with this distribution.
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* pvxs is distributed subject to a Software License Agreement found
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* in file LICENSE that is included with this distribution.
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*/
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#include <epicsAssert.h>
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#include <pvxs/log.h>
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#include "conn.h"
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DEFINE_LOGGER(connsetup, "pvxs.tcp.setup");
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DEFINE_LOGGER(connio, "pvxs.tcp.io");
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namespace pvxs {
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namespace impl {
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ConnBase::ConnBase(bool isClient, bufferevent* bev, const SockAddr& peerAddr)
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:peerAddr(peerAddr)
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,peerName(peerAddr.tostring())
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,bev(bev)
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,isClient(isClient)
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,peerBE(true) // arbitrary choice, default should be overwritten before use
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,expectSeg(false)
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,segCmd(0xff)
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,segBuf(evbuffer_new())
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,txBody(evbuffer_new())
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{
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// initially wait for at least a header
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bufferevent_setwatermark(this->bev.get(), EV_READ, 8, tcp_readahead);
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}
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ConnBase::~ConnBase() {}
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const char* ConnBase::peerLabel() const
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{
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return isClient ? "Server" : "Client";
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}
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void ConnBase::enqueueTxBody(pva_app_msg_t cmd)
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{
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auto tx = bufferevent_get_output(bev.get());
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to_evbuf(tx, Header{cmd,
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uint8_t(isClient ? 0u : pva_flags::Server),
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uint32_t(evbuffer_get_length(txBody.get()))},
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hostBE);
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auto err = evbuffer_add_buffer(tx, txBody.get());
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assert(!err);
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}
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#define CASE(Op) void ConnBase::handle_##Op() {}
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CASE(ECHO);
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CASE(CONNECTION_VALIDATION);
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CASE(CONNECTION_VALIDATED);
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CASE(SEARCH);
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CASE(AUTHNZ);
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CASE(CREATE_CHANNEL);
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CASE(DESTROY_CHANNEL);
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CASE(GET);
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CASE(PUT);
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CASE(PUT_GET);
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CASE(MONITOR);
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CASE(RPC);
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CASE(CANCEL_REQUEST);
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CASE(DESTROY_REQUEST);
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CASE(GET_FIELD);
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CASE(MESSAGE);
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#undef CASE
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void ConnBase::bevEvent(short events)
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{
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if(events&(BEV_EVENT_EOF|BEV_EVENT_ERROR|BEV_EVENT_TIMEOUT)) {
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if(events&BEV_EVENT_ERROR) {
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int err = EVUTIL_SOCKET_ERROR();
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const char *msg = evutil_socket_error_to_string(err);
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log_err_printf(connio, "%s %s connection closed with socket error %d : %s\n", peerLabel(), peerName.c_str(), err, msg);
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}
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if(events&BEV_EVENT_EOF) {
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log_debug_printf(connio, "%s %s connection closed by peer\n", peerLabel(), peerName.c_str());
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}
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if(events&BEV_EVENT_TIMEOUT) {
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log_warn_printf(connio, "%s %s connection timeout\n", peerLabel(), peerName.c_str());
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}
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bev.reset();
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}
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if(!bev)
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cleanup();
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}
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void ConnBase::bevRead()
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{
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auto rx = bufferevent_get_input(bev.get());
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while(bev && evbuffer_get_length(rx)>=8) {
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uint8_t header[8];
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auto ret = evbuffer_copyout(rx, header, sizeof(header));
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assert(ret==sizeof(header)); // previously verified
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if(header[0]!=0xca || header[1]==0
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|| (isClient ^ !!(header[2]&pva_flags::Server))) {
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log_hex_printf(connio, Level::Err, header, sizeof(header),
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"%s %s Protocol decode fault. Force disconnect.\n", peerLabel(), peerName.c_str());
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bev.reset();
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break;
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}
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log_hex_printf(connio, Level::Debug, header, sizeof(header),
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"%s %s Receive header\n", peerLabel(), peerName.c_str());
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if(header[2]&pva_flags::Control) {
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// Control messages are not actually useful
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evbuffer_drain(rx, 8);
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continue;
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}
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// application message
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peerBE = header[2]&pva_flags::MSB;
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// a bit verbose :P
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FixedBuf L(peerBE, header+4, 4);
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uint32_t len = 0;
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from_wire(L, len);
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assert(L.good());
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if(evbuffer_get_length(rx)-8 < len) {
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// wait for complete payload
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// and some additional if available
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size_t readahead = len;
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if(readahead < std::numeric_limits<size_t>::max()-tcp_readahead)
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readahead += tcp_readahead;
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bufferevent_setwatermark(bev.get(), EV_READ, len, readahead);
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break;
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}
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evbuffer_drain(rx, 8);
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{
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unsigned n = evbuffer_remove_buffer(rx, segBuf.get(), len);
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assert(n==len); // we know rx buf contains the entire body
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}
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// so far we do not use segmentation to support incremental processing
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// of long messages. We instead accumulate all segments of a message
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// prior to parsing.
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auto seg = header[2]&pva_flags::SegMask;
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bool continuation = seg&pva_flags::SegLast; // true for mid or last. false for none or first
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if((continuation ^ expectSeg) || (continuation && header[3]!=segCmd)) {
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log_crit_printf(connio, "%s %s Peer segmentation violation %c%c 0x%02x==0x%02x\n", peerLabel(), peerName.c_str(),
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expectSeg?'Y':'N', continuation?'Y':'N',
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segCmd, header[3]);
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bev.reset();
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break;
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}
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if(!seg || seg==pva_flags::SegFirst) {
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expectSeg = true;
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segCmd = header[3];
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}
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if(!seg || seg==pva_flags::SegLast) {
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expectSeg = false;
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// ready to process segBuf
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switch(segCmd) {
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default:
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log_debug_printf(connio, "%s %s Ignore unexpected command 0x%02x\n", peerLabel(), peerName.c_str(), segCmd);
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evbuffer_drain(segBuf.get(), evbuffer_get_length(segBuf.get()));
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break;
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#define CASE(OP) case CMD_##OP: handle_##OP(); break
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CASE(ECHO);
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CASE(CONNECTION_VALIDATION);
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CASE(CONNECTION_VALIDATED);
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CASE(SEARCH);
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CASE(AUTHNZ);
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CASE(CREATE_CHANNEL);
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CASE(DESTROY_CHANNEL);
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CASE(GET);
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CASE(PUT);
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CASE(PUT_GET);
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CASE(MONITOR);
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CASE(RPC);
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CASE(CANCEL_REQUEST);
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CASE(DESTROY_REQUEST);
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CASE(GET_FIELD);
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CASE(MESSAGE);
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#undef CASE
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}
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// handlers may have cleared bev to force disconnect
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if(!bev)
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break;
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// silently drain any unprocessed body (forward compatibility)
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if(auto n = evbuffer_get_length(segBuf.get()))
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evbuffer_drain(segBuf.get(), n);
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// wait for next header
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bufferevent_setwatermark(bev.get(), EV_READ, 8, tcp_readahead);
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}
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}
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if(!bev) {
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cleanup();
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}
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}
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void ConnBase::bevWrite() {}
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void ConnBase::bevEventS(struct bufferevent *bev, short events, void *ptr)
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{
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auto conn = static_cast<ConnBase*>(ptr);
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try {
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conn->bevEvent(events);
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}catch(std::exception& e){
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log_crit_printf(connsetup, "%s %s Unhandled error in bev event callback: %s\n", conn->peerLabel(), conn->peerName.c_str(), e.what());
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static_cast<ConnBase*>(ptr)->cleanup();
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}
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}
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void ConnBase::bevReadS(struct bufferevent *bev, void *ptr)
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{
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auto conn = static_cast<ConnBase*>(ptr);
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try {
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conn->bevRead();
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}catch(std::exception& e){
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log_crit_printf(connsetup, "%s %s Unhandled error in bev read callback: %s\n", conn->peerLabel(), conn->peerName.c_str(), e.what());
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static_cast<ConnBase*>(ptr)->cleanup();
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}
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}
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void ConnBase::bevWriteS(struct bufferevent *bev, void *ptr)
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{
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auto conn = static_cast<ConnBase*>(ptr);
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try {
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conn->bevWrite();
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}catch(std::exception& e){
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log_crit_printf(connsetup, "%s %s Unhandled error in bev write callback: %s\n", conn->peerLabel(), conn->peerName.c_str(), e.what());
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static_cast<ConnBase*>(ptr)->cleanup();
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}
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}
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} // namespace impl
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} // namespace pvxs
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