abstract common tcp operations to a base class

common/CMakeLists.txt

@@ -1,6 +1,7 @@
 
 add_library(accordion-common STATIC
     LoggerService.cpp
+    TcpBase.cpp
     config/ConfigService.cpp
 )
 

common/LoggerService.cpp

@@ -101,5 +101,7 @@ void LoggerService::write(std::string component, LogFlag flag, std::string messa
     if(configuration_.fileEnabled) {
         outfile_ << finalmessage << std::endl;
     }
+
+    // TODO: if its an error flag we should automatically log the errno
 }
 

common/TcpBase.cpp

@@ -0,0 +1,121 @@
+
+#include "TcpBase.hpp"
+
+#include <sys/socket.h>
+#include <string.h>
+
+TcpBase::TcpBase(LoggerService* logger) : logger_(logger) {
+
+}
+
+TcpBase::~TcpBase() {
+
+}
+
+ssize_t TcpBase::tcpRead(int fd, void* buffer, size_t maxBytes) {
+
+    // read header first
+    char header[kHeaderSize];
+    ssize_t bytesReceived = receiveFull(fd, &header, kHeaderSize);
+    if(bytesReceived != kHeaderSize) {
+        logger_->log("TcpNetworker", LogFlag::Error, "Unable to receive header.");
+        return -1;
+    }
+
+    // parse header: 4 bytes payload length 4 bytes message type
+    uint32_t payloadLength;
+    uint32_t messageType;
+    memcpy(&payloadLength, header, sizeof(payloadLength));
+    memcpy(&messageType, header + sizeof(payloadLength), sizeof(messageType));
+    size_t payloadLengthS = static_cast<size_t>(payloadLength);
+
+    if(maxBytes < payloadLength) {
+        logger_->log("TcpNetworker", LogFlag::Warning,
+            "Payload length is larger than buffer size; payload may be truncated.");
+        payloadLengthS = maxBytes;
+    }
+
+    // read payload
+    bytesReceived = receiveFull(fd, buffer, payloadLengthS);
+    if(bytesReceived != payloadLengthS) {
+        logger_->log("TcpNetworker", LogFlag::Error, "Did not receive amount of expected data.");
+    }
+    return bytesReceived;
+
+}
+
+ssize_t TcpBase::tcpTimedRead(int fd, void* buffer, size_t maxBytes, int timeoutPlaceholder) {
+    return 0;
+}
+
+ssize_t TcpBase::tcpSend(int fd, const void* buffer, size_t numBytes) {
+
+    // assemble header
+    char header[kHeaderSize];
+    uint32_t payloadLength = static_cast<uint32_t>(numBytes & 0xffffffffffffffff);
+    uint32_t messageType = 0; // placeholder
+    memcpy(header, &payloadLength, sizeof(payloadLength));
+    memcpy(header + sizeof(payloadLength), &messageType, sizeof(messageType));
+
+    // send header
+    ssize_t bytesSent = sendFull(fd, header, kHeaderSize);
+    if(bytesSent != kHeaderSize) {
+        logger_->log("TcpNetworker", LogFlag::Error, "Error sending header.");
+    }
+
+    // send payload
+    bytesSent = sendFull(fd, buffer, numBytes);
+    if(bytesSent != numBytes) {
+        logger_->log("TcpNetworker", LogFlag::Error, "Error sending payload.");
+    }
+    return bytesSent;
+}
+
+ssize_t TcpBase::tcpTimedSend(int fd, const void* backuffer, size_t numBytes, int timeoutPlaceholder) {
+    return 0;
+}
+
+ssize_t TcpBase::receiveHeader(int fd, void* buffer, size_t maxBytes) {
+    return 0;    
+}
+
+ssize_t TcpBase::receivePayload(int fd, void* buffer, size_t maxBytes) {
+    return 0;
+}
+
+ssize_t TcpBase::sendHeader(int fd, const void* buffer, size_t maxBytes) {
+    return 0;
+}
+
+ssize_t TcpBase::sendPayload(int fd, const void* buffer, size_t maxBytes) {
+    return 0;
+}
+
+ssize_t TcpBase::receiveFull(int fd, void* buffer, size_t maxBytes) {
+    ssize_t total = 0;
+    // attempt to receive maxBytes bytes; continue receiving until we have received maxBytes bytes
+    while(total < maxBytes) {
+        ssize_t bytesReceived = recv(fd, static_cast<char*>(buffer) + total, maxBytes - total, 0);
+        if (bytesReceived <= 0) return bytesReceived; // error or connection closed
+        total += bytesReceived;
+    }
+
+    return total;
+}
+
+ssize_t TcpBase::sendFull(int fd, const void* buffer, size_t numBytes) {
+    ssize_t total = 0;
+    // attempt to receive maxBytes bytes; continue receiving until we have received maxBytes bytes
+    while(total < numBytes) {
+        ssize_t bytesSent = send(fd, static_cast<const char*>(buffer) + total, numBytes - total, 0);
+
+        // last arg is flags, 0=default
+        // MSG_PEEK: read without consuming the message from the queue
+        // MSG_WAITALL: block until all of the specified size is received
+        // MSG_DONTWAIT: non-blocking receive, returns -1 immediately if queue is empty
+
+        if (bytesSent <= 0) return bytesSent; // error or connection closed
+        total += bytesSent;
+    }
+    return total;
+}

common/TcpBase.hpp

@@ -0,0 +1,44 @@
+
+#pragma once
+
+#include "ErrorCodes.hpp"
+#include "LoggerService.hpp"
+
+// TcpBase contains common tcp I/O operations for the tcp client and tcp server
+// Abstracts away the networking methods into an accordion common protocol (ACP)
+class TcpBase {
+
+public:
+
+    TcpBase(LoggerService* logger);
+    ~TcpBase();
+
+    // read from a tcp socket, blocking
+    ssize_t tcpRead(int fd, void* buffer, size_t maxBytes);
+
+    // read from a tcp socket, blocking with timeout
+    ssize_t tcpTimedRead(int fd, void* buffer, size_t maxBytes, int timeoutPlaceholder);
+
+    // send over a tcp socket, blocking
+    ssize_t tcpSend(int fd, const void* buffer, size_t numBytes);
+
+    // send over a tcp socket, blocking with timeout
+    ssize_t tcpTimedSend(int fd, const void* buffer, size_t numBytes, int timeoutPlaceholder);
+
+protected:
+
+    LoggerService* logger_;
+
+private:
+
+    ssize_t receiveHeader(int fd, void* buffer, size_t maxBytes);
+    ssize_t receivePayload(int fd, void* buffer, size_t maxBytes);
+    ssize_t sendHeader(int fd, const void* buffer, size_t maxBytes);
+    ssize_t sendPayload(int fd, const void* buffer, size_t maxBytes);
+
+    ssize_t receiveFull(int fd, void* buffer, size_t maxBytes);
+    ssize_t sendFull(int fd, const void* buffer, size_t numBytes);
+
+    static constexpr size_t kHeaderSize = 8; // 4 bytes for length, 4 bytes for type
+
+};