improvements in networking code

clib/tcpnet.cpp

@@ -1,18 +1,17 @@
 
-#include <stdio.h>
+#include <cstdio>
-#include <stdlib.h>
+#include <cstdlib>
 #include <unistd.h>
-#include <string.h>
+#include <cstring>
-#include <sys/types.h>
 #include <sys/socket.h>
 #include <netinet/in.h>
 #include <netdb.h> 
+#include <cerrno>
 
 #include "tcpnet.h"
 
 
-#define TCPNET_BUFFER_SIZE 131072
+#define TCPNET_BUFFER_SIZE 16384
-
 
 
 void error(const char *msg) {
@@ -21,23 +20,21 @@ void error(const char *msg) {
 }
 
 // TODO do it as RAII
-TcpNet::TcpNet() {}
+TcpNet::TcpNet() = default;
 
 
 
-int TcpNet::server(int portno, std::function<std::pair<bool, std::string>(std::string)> process_request) const {
+int TcpNet::server(int portno, const std::function<std::pair<bool, std::string>(std::string)>& process_request) const {
 	int sockfd, newsockfd;
 	socklen_t clilen;
 
-	char buffer[TCPNET_BUFFER_SIZE];
  	struct sockaddr_in serv_addr, cli_addr;
  
- 	int n;
 	sockfd = socket(AF_INET, SOCK_STREAM, 0);
 	if (sockfd < 0) 
 		error("ERROR opening socket");
 
- 	bzero((char *) &serv_addr, sizeof(serv_addr));
+	memset((char *) &serv_addr, 0, sizeof(serv_addr));
 	serv_addr.sin_family = AF_INET;
 	serv_addr.sin_addr.s_addr = INADDR_ANY;
 	serv_addr.sin_port = htons(portno);
@@ -65,19 +62,17 @@ int TcpNet::server(int portno, std::function<std::pair<bool, std::string>(std::s
 			error("ERROR on accept");
 	
 		while (true) {
-			bzero(buffer,TCPNET_BUFFER_SIZE);
+			std::string request = read_from_socket(newsockfd);
-			n = read(newsockfd,buffer,TCPNET_BUFFER_SIZE - 1);
+			if (request.empty()) break;
-			if (n == 0) break;	// nothing to read from client anymore
-			if (n < 0) error("ERROR reading from socket");
 
-			std::string request{buffer};
 			std::pair<bool, std::string> response = process_request(request);
 
 			shutdown = response.first;
 			std::string response_str = response.second;
 
-			n = write(newsockfd, response_str.c_str(), response_str.size());
+			auto response_len = response_str.size();
-			if (n < 0)
+			auto n = write(newsockfd, response_str.c_str(), response_len);
+			if (n < 0 || response_len != n)
 				error("ERROR writing to socket");
 
 			requests_processed++;
@@ -93,13 +88,11 @@ int TcpNet::server(int portno, std::function<std::pair<bool, std::string>(std::s
 
 
 std::vector<std::string> TcpNet::client(const std::string &address, int portno, const std::vector<std::string> &requests) const {
-	int sockfd, n;
+	int sockfd;
 	struct sockaddr_in serv_addr;
 	struct hostent *server;
 	std::vector<std::string> responses;
 
-    	char buffer[TCPNET_BUFFER_SIZE];
-    
 	sockfd = socket(AF_INET, SOCK_STREAM, 0);
 	if (sockfd < 0) 
 		error("ERROR opening socket");
@@ -110,7 +103,7 @@ std::vector<std::string> TcpNet::client(const std::string &address, int portno,
 		exit(0);
 	}
 
-	bzero((char *) &serv_addr, sizeof(serv_addr));
+	memset((char *) &serv_addr, 0, sizeof(serv_addr));
 	serv_addr.sin_family = AF_INET;
 	bcopy((char *)server->h_addr, (char *)&serv_addr.sin_addr.s_addr, server->h_length);
 	serv_addr.sin_port = htons(portno);
@@ -121,16 +114,10 @@ std::vector<std::string> TcpNet::client(const std::string &address, int portno,
 
 	responses.reserve(requests.size());
 	for(const auto &req : requests) {
-		n = write(sockfd, req.c_str(), strlen(req.c_str()));
+		write_to_socket(sockfd, req);
-		if (n < 0) 
-			error("ERROR writing to socket");
 
-		bzero(buffer, TCPNET_BUFFER_SIZE);
+		std::string response = read_from_socket(sockfd);
-		n = read(sockfd,buffer, TCPNET_BUFFER_SIZE - 1);
+		responses.push_back(response);
-		if (n < 0)
-			error("ERROR reading from socket");
-
-		responses.push_back(std::string(buffer));
 	}
 
 	close(sockfd);
@@ -145,3 +132,38 @@ std::string TcpNet::client(const std::string &address, int portno, const std::st
 
 	return response[0];
 }
+
+std::string TcpNet::read_from_socket(int sockfd) {
+	char buffer[TCPNET_BUFFER_SIZE];
+	std::string request;
+
+	long n;
+	do {
+		memset(buffer, 0, TCPNET_BUFFER_SIZE);
+		n = read(sockfd, buffer, TCPNET_BUFFER_SIZE - 1);
+		if (n == 0) break;    // nothing to read from client anymore
+		if (n < 0) {
+			if (errno == ECONNRESET) break;    // connection reset by peer
+
+			std::string err_desc{"ERROR reading from socket "};
+			err_desc.append(strerror(errno));
+			error(err_desc.c_str());
+		}
+
+		std::string part{buffer};
+		request.append(part);
+	} while (n == TCPNET_BUFFER_SIZE - 1);	// TODO what if data exactly of this size
+
+	return request;
+}
+
+void TcpNet::write_to_socket(int sockfd, const std::string &str) {
+	const char * buffer = str.c_str();
+	int pos = 0;
+	long n;
+	do {
+		n = write(sockfd, buffer + pos, (int)(str.length() - pos));
+		if (n < 0)
+			error("ERROR writing to socket");
+	} while (pos + n < str.length());
+}

clib/tcpnet.h

@@ -10,11 +10,13 @@ public:
 	TcpNet();
 
 	// starts listening on port
-	int server(int port, std::function<std::pair<bool, std::string>(std::string)> process_request) const;
+	int server(int port, const std::function<std::pair<bool, std::string>(std::string)>& process_request) const;
 
 	// writes request to server on address:port and returns response
-	std::string client(const std::string &address, int portno, const std::string &request) const;
+	[[nodiscard]] std::string client(const std::string &address, int portno, const std::string &request) const;
-
+	[[nodiscard]] std::vector<std::string> client(const std::string &address, int portno, const std::vector<std::string> &requests) const;
-	std::vector<std::string> client(const std::string &address, int portno, const std::vector<std::string> &requests) const;
 
+private:
+	static std::string read_from_socket(int sockfd) ;
+	static void write_to_socket(int sockfd, const std::string &str) ;
 };