Refactor fetch_connect() and fetch_bind() to improve readability and avoid

repeating the same DNS lookups.

MFC after:	3 weeks

lib/libfetch/common.c

@@ -1,5 +1,5 @@
 /*-
- * Copyright (c) 1998-2014 Dag-Erling Smørgrav
+ * Copyright (c) 1998-2016 Dag-Erling Smørgrav
  * Copyright (c) 2013 Michael Gmelin <freebsd@grem.de>
  * All rights reserved.
  *
@@ -240,28 +240,84 @@ fetch_ref(conn_t *conn)
 }
 
 
+/*
+ * Resolve an address
+ */
+struct addrinfo *
+fetch_resolve(const char *addr, int port, int af)
+{
+	char hbuf[256], sbuf[8];
+	struct addrinfo hints, *res;
+	const char *sep, *host, *service;
+	int err, len;
+
+	/* split address if necessary */
+	err = EAI_SYSTEM;
+	if ((sep = strchr(addr, ':')) != NULL) {
+		len = snprintf(hbuf, sizeof(hbuf),
+		    "%.*s", (int)(sep - addr), addr);
+		if (len < 0)
+			return (NULL);
+		if (len >= (int)sizeof(hbuf)) {
+			errno = ENAMETOOLONG;
+			fetch_syserr();
+			return (NULL);
+		}
+		host = hbuf;
+		service = sep + 1;
+	} else if (port != 0) {
+		if (port < 1 || port > 65535) {
+			errno = EINVAL;
+			fetch_syserr();
+			return (NULL);
+		}
+		if (snprintf(sbuf, sizeof(sbuf), "%d", port) < 0) {
+			fetch_syserr();
+			return (NULL);
+		}
+		host = addr;
+		service = sbuf;
+	} else {
+		host = addr;
+		service = NULL;
+	}
+
+	/* resolve */
+	fetch_info("resolving host = %s service = %s af = %d",
+	    host, service, af);
+	memset(&hints, 0, sizeof(hints));
+	hints.ai_family = af;
+	hints.ai_socktype = SOCK_STREAM;
+	hints.ai_flags = AI_ADDRCONFIG;
+	if ((err = getaddrinfo(host, service, &hints, &res)) != 0) {
+		netdb_seterr(err);
+		fetch_info("getaddrinfo() failed: %s", gai_strerror(err));
+		return (NULL);
+	}
+	fetch_info("getaddrinfo() succeeded %p", res);
+	return (res);
+}
+
+
+
 /*
  * Bind a socket to a specific local address
  */
 int
 fetch_bind(int sd, int af, const char *addr)
 {
-	struct addrinfo hints, *res, *res0;
+	struct addrinfo *cliai, *ai;
 	int err;
 
-	memset(&hints, 0, sizeof(hints));
+	if ((cliai = fetch_resolve(addr, 0, af)) == NULL)
-	hints.ai_family = af;
-	hints.ai_socktype = SOCK_STREAM;
-	hints.ai_protocol = 0;
-	if ((err = getaddrinfo(addr, NULL, &hints, &res0)) != 0)
 		return (-1);
-	for (res = res0; res; res = res->ai_next)
+	for (ai = cliai; ai != NULL; ai = ai->ai_next)
-		if (bind(sd, res->ai_addr, res->ai_addrlen) == 0) {
+		if ((err = bind(sd, ai->ai_addr, ai->ai_addrlen)) == 0)
-			freeaddrinfo(res0);
+			break;
-			return (0);
+	if (err != 0)
-		}
+		fetch_syserr();
-	freeaddrinfo(res0);
+	freeaddrinfo(cliai);
-	return (-1);
+	return (err == 0 ? 0 : -1);
 }
 
 
@@ -271,59 +327,77 @@ fetch_bind(int sd, int af, const char *addr)
 conn_t *
 fetch_connect(const char *host, int port, int af, int verbose)
 {
-	conn_t *conn;
+	struct addrinfo *cais = NULL, *sais = NULL, *cai, *sai;
-	char pbuf[10];
 	const char *bindaddr;
-	struct addrinfo hints, *res, *res0;
+	conn_t *conn = NULL;
-	int sd, err;
+	int err = 0, sd = -1;
 
 	DEBUG(fprintf(stderr, "---> %s:%d\n", host, port));
 
+	/* resolve server address */
 	if (verbose)
-		fetch_info("looking up %s", host);
+		fetch_info("resolving server address: %s:%d", host, port);
+	if ((sais = fetch_resolve(host, port, af)) == NULL)
+		goto fail;
+	fetch_info("resolved");
 
-	/* look up host name and set up socket address structure */
+	/* resolve client address */
-	snprintf(pbuf, sizeof(pbuf), "%d", port);
-	memset(&hints, 0, sizeof(hints));
-	hints.ai_family = af;
-	hints.ai_socktype = SOCK_STREAM;
-	hints.ai_protocol = 0;
-	if ((err = getaddrinfo(host, pbuf, &hints, &res0)) != 0) {
-		netdb_seterr(err);
-		return (NULL);
-	}
 	bindaddr = getenv("FETCH_BIND_ADDRESS");
+	if (bindaddr != NULL && *bindaddr != '\0') {
+		if (verbose)
+			fetch_info("resolving client address: %s", bindaddr);
+		if ((cais = fetch_resolve(bindaddr, 0, af)) == NULL)
+			goto fail;
+	}
 
-	if (verbose)
+	/* try each server address in turn */
-		fetch_info("connecting to %s:%d", host, port);
+	for (err = 0, sai = sais; sai != NULL; sai = sai->ai_next) {
-
+		/* open socket */
-	/* try to connect */
+		if ((sd = socket(sai->ai_family, SOCK_STREAM, 0)) < 0)
-	for (sd = -1, res = res0; res; sd = -1, res = res->ai_next) {
+			goto syserr;
-		if ((sd = socket(res->ai_family, res->ai_socktype,
+		/* attempt to bind to client address */
-			 res->ai_protocol)) == -1)
+		for (err = 0, cai = cais; cai != NULL; cai = cai->ai_next) {
-			continue;
+			if (cai->ai_family != sai->ai_family)
-		if (bindaddr != NULL && *bindaddr != '\0' &&
+				continue;
-		    fetch_bind(sd, res->ai_family, bindaddr) != 0) {
+			if ((err = bind(sd, cai->ai_addr, cai->ai_addrlen)) == 0)
-			fetch_info("failed to bind to '%s'", bindaddr);
+				break;
-			close(sd);
-			continue;
 		}
-		if (connect(sd, res->ai_addr, res->ai_addrlen) == 0 &&
+		if (err != 0) {
-		    fcntl(sd, F_SETFL, O_NONBLOCK) == 0)
+			if (verbose)
+				fetch_info("failed to bind to %s", bindaddr);
+			goto syserr;
+		}
+		/* attempt to connect to server address */
+		if ((err = connect(sd, sai->ai_addr, sai->ai_addrlen)) == 0)
 			break;
+		/* clean up before next attempt */
 		close(sd);
+		sd = -1;
 	}
-	freeaddrinfo(res0);
+	if (err != 0) {
-	if (sd == -1) {
+		if (verbose)
-		fetch_syserr();
+			fetch_info("failed to connect to %s:%s", host, port);
-		return (NULL);
+		goto syserr;
 	}
 
-	if ((conn = fetch_reopen(sd)) == NULL) {
+	if ((conn = fetch_reopen(sd)) == NULL)
-		fetch_syserr();
+		goto syserr;
-		close(sd);
+	if (cais != NULL)
-	}
+		freeaddrinfo(cais);
+	if (sais != NULL)
+		freeaddrinfo(sais);
 	return (conn);
+syserr:
+	fetch_syserr();
+	goto fail;
+fail:
+	if (sd >= 0)
+		close(sd);
+	if (cais != NULL)
+		freeaddrinfo(cais);
+	if (sais != NULL)
+		freeaddrinfo(sais);
+	return (NULL);
 }
 
 #ifdef WITH_SSL

lib/libfetch/common.h

@@ -76,6 +76,7 @@ void		 fetch_syserr(void);
 void		 fetch_info(const char *, ...);
 int		 fetch_default_port(const char *);
 int		 fetch_default_proxy_port(const char *);
+struct addrinfo *fetch_resolve(const char *, int, int);
 int		 fetch_bind(int, int, const char *);
 conn_t		*fetch_connect(const char *, int, int, int);
 conn_t		*fetch_reopen(int);

lib/libfetch/ftp.c

@@ -768,8 +768,8 @@ ftp_transfer(conn_t *conn, const char *oper, const char *file,
 			fetch_info("opening data connection");
 		bindaddr = getenv("FETCH_BIND_ADDRESS");
 		if (bindaddr != NULL && *bindaddr != '\0' &&
-		    fetch_bind(sd, sa.ss_family, bindaddr) != 0)
+		    (e = fetch_bind(sd, sa.ss_family, bindaddr)) != 0)
-			goto sysouch;
+			goto ouch;
 		if (connect(sd, (struct sockaddr *)&sa, sa.ss_len) == -1)
 			goto sysouch;