From fc10c88395f3fefd3b30f3ef9354c45cef7136a6 Mon Sep 17 00:00:00 2001
From: Nikias Bassen
Date: Wed, 6 Mar 2024 03:15:47 +0100
Subject: socket: Make sure errno is always set on error, and always return a
 meaningful error code

---
 src/socket.c | 102 ++++++++++++++++++++++++++++++++++++++++++++++++++++++++---
 1 file changed, 97 insertions(+), 5 deletions(-)

diff --git a/src/socket.c b/src/socket.c
index 6f85f2f..5276b1e 100644
--- a/src/socket.c
+++ b/src/socket.c
@@ -150,6 +150,51 @@ enum poll_status
 	poll_status_error
 };
 
+#ifdef WIN32
+static inline __attribute__((always_inline)) int WSAError_to_errno(int wsaerr)
+{
+	switch (wsaerr) {
+		case WSAEINVAL:
+			return EINVAL;
+		case WSAENOTSOCK:
+			return ENOTSOCK;
+		case WSAENOTCONN:
+			return ENOTCONN;
+		case WSAESHUTDOWN:
+			return ENOTCONN;
+		case WSAECONNRESET:
+			return ECONNRESET;
+		case WSAECONNABORTED:
+			return ECONNABORTED;
+		case WSAECONNREFUSED:
+			return ECONNREFUSED;
+		case WSAENETDOWN:
+			return ENETDOWN;
+		case WSAENETRESET:
+			return ENETRESET;
+		case WSAEHOSTUNREACH:
+			return EHOSTUNREACH;
+		case WSAETIMEDOUT:
+			return ETIMEDOUT;
+		case WSAEWOULDBLOCK:
+			return EWOULDBLOCK;
+		case WSAEINPROGRESS:
+			return EINPROGRESS;
+		case WSAENOBUFS:
+			return ENOBUFS;
+		case WSAEINTR:
+			return EINTR;
+		case WSAEACCES:
+			return EACCES;
+		case WSAEFAULT:
+			return EFAULT;
+		default:
+			break;
+	}
+	return wsaerr;
+}
+#endif
+
 // timeout of -1 means infinity
 static inline __attribute__((always_inline)) enum poll_status poll_wrapper(int fd, fd_mode mode, int timeout)
 {
@@ -387,8 +432,17 @@ int socket_connect_unix(const char *filename)
 				socklen_t len = sizeof(so_error);
 				getsockopt(sfd, SOL_SOCKET, SO_ERROR, (void*)&so_error, &len);
 				if (so_error == 0) {
+					errno = 0;
 					break;
 				}
+				errno = so_error;
+			} else {
+				int so_error = 0;
+				socklen_t len = sizeof(so_error);
+				getsockopt(sfd, SOL_SOCKET, SO_ERROR, (void*)&so_error, &len);
+				if (so_error != 0) {
+					errno = so_error;
+				}
 			}
 		}
 		socket_close(sfd);
@@ -1064,7 +1118,20 @@ int socket_connect_addr(struct sockaddr* addr, uint16_t port)
 					errno = 0;
 					break;
 				}
+#ifdef WIN32
+				so_error = WSAError_to_errno(so_error);
+#endif
 				errno = so_error;
+			} else {
+				int so_error = 0;
+				socklen_t len = sizeof(so_error);
+				getsockopt(sfd, SOL_SOCKET, SO_ERROR, (void*)&so_error, &len);
+				if (so_error != 0) {
+#ifdef WIN32
+					so_error = WSAError_to_errno(so_error);
+#endif
+					errno = so_error;
+				}
 			}
 		}
 		socket_close(sfd);
@@ -1173,8 +1240,23 @@ int socket_connect(const char *addr, uint16_t port)
 				socklen_t len = sizeof(so_error);
 				getsockopt(sfd, SOL_SOCKET, SO_ERROR, (void*)&so_error, &len);
 				if (so_error == 0) {
+					errno = 0;
 					break;
 				}
+#ifdef WIN32
+				so_error = WSAError_to_errno(so_error);
+#endif
+				errno = so_error;
+			} else {
+				int so_error = 0;
+				socklen_t len = sizeof(so_error);
+				getsockopt(sfd, SOL_SOCKET, SO_ERROR, (void*)&so_error, &len);
+				if (so_error != 0) {
+#ifdef WIN32
+					so_error = WSAError_to_errno(so_error);
+#endif
+					errno = so_error;
+				}
 			}
 		}
 		socket_close(sfd);
@@ -1208,7 +1290,7 @@ int socket_check_fd(int fd, fd_mode fdm, unsigned int timeout)
 	if (fd < 0) {
 		if (verbose >= 2)
 			fprintf(stderr, "ERROR: invalid fd in check_fd %d\n", fd);
-		return -1;
+		return -EINVAL;
 	}
 
 	int timeout_ms;
@@ -1229,10 +1311,10 @@ int socket_check_fd(int fd, fd_mode fdm, unsigned int timeout)
 		default:
 			if (verbose >= 2)
 				fprintf(stderr, "%s: poll_wrapper failed\n", __func__);
-			return -1;
+			return -ECONNRESET;
 	}
 
-	return -1;
+	return -ECONNRESET;
 }
 
 int socket_accept(int fd, uint16_t port)
@@ -1286,13 +1368,16 @@ int socket_receive_timeout(int fd, void *data, size_t length, int flags, unsigne
 	}
 	// if we get here, there _is_ data available
 	result = recv(fd, data, length, flags);
-	if (res > 0 && result == 0) {
+	if (result == 0) {
 		// but this is an error condition
 		if (verbose >= 3)
 			fprintf(stderr, "%s: fd=%d recv returned 0\n", __func__, fd);
 		return -ECONNRESET;
 	}
 	if (result < 0) {
+#ifdef WIN32
+		errno = WSAError_to_errno(WSAGetLastError());
+#endif
 		return -errno;
 	}
 	return result;
@@ -1308,7 +1393,14 @@ int socket_send(int fd, void *data, size_t length)
 #ifdef MSG_NOSIGNAL
 	flags |= MSG_NOSIGNAL;
 #endif
-	return send(fd, data, length, flags);
+	int s = (int)send(fd, data, length, flags);
+	if (s < 0) {
+#ifdef WIN32
+		errno = WSAError_to_errno(WSAGetLastError());
+#endif
+		return -errno;
+	}
+	return s;
 }
 
 int socket_get_socket_port(int fd, uint16_t *port)
-- 
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