/** \file net.c Networking-related helper functions. */
-#include <netdb.h> /* hostent */
+#include <netdb.h>
#include "para.h"
#include "error.h"
memset(&addr->sin_zero, '\0', 8);
}
+/**
+ * Determine the socket type for a given layer-4 protocol.
+ *
+ * \param l4type The symbolic name of the transport-layer protocol.
+ *
+ * \sa ip(7), socket(2)
+ */
+static inline int sock_type(const unsigned l4type)
+{
+ switch (l4type) {
+ case IPPROTO_UDP: return SOCK_DGRAM;
+ case IPPROTO_TCP: return SOCK_STREAM;
+ case IPPROTO_DCCP: return SOCK_DCCP;
+ }
+ return -1; /* not supported here */
+}
+
+/**
+ * Pretty-print transport-layer name.
+ */
+static const char *layer4_name(const unsigned l4type)
+{
+ switch (l4type) {
+ case IPPROTO_UDP: return "UDP";
+ case IPPROTO_TCP: return "TCP";
+ case IPPROTO_DCCP: return "DCCP";
+ }
+ return "UNKNOWN PROTOCOL";
+}
+
+/**
+ * Resolve IPv4/IPv6 address and create a ready-to-use active or passive socket.
+ *
+ * @param l3type The layer-3 type (\p AF_INET, \p AF_INET6, \p AF_UNSPEC)
+ * @param l4type The layer-4 type (\p IPPROTO_xxx).
+ * @param passive Whether this is a passive (1) or active (0) socket/
+ * @param host Remote or local hostname or IPv/6 address string.
+ * @param port_number Decimal port number.
+ *
+ * This creates a ready-made IPv4/v6 socket structure after looking up the necessary
+ * parameters. The interpretation of \a host depends on the value of \a passive:
+ * - on a passive socket host is interpreted as an interface IPv4/6 address
+ * (can be left NULL);
+ * - on an active socket, \a host is the peer DNS name or IPv4/6 address to connect to;
+ * - \a port_number is in either case the numeric port number (not service string).
+ * Furthermore, bind(2) is called on passive sockets, and connect(2) on active sockets.
+ * The algorithm tries all possible address combinations until it succeeds.
+ *
+ * \return This function returns 1 on success and \a -E_ADDRESS_LOOKUP when no matching
+ * connection could be set up (with details in the error log).
+ *
+ * \sa ipv6(7), getaddrinfo(3), bind(2), connect(2)
+ */
+int makesock(unsigned l3type, unsigned l4type, int passive,
+ const char *host, unsigned short port_number)
+{
+ struct addrinfo *local = NULL, *src,
+ *remote = NULL, *dst, hints;
+ char *port = make_message("%u", port_number);
+ int rc, on = 1, sockfd = -1,
+ socktype = sock_type(l4type);
+
+ /*
+ * Set up address hint structure
+ */
+ memset(&hints, 0, sizeof(hints));
+ hints.ai_family = l3type;
+ /* getaddrinfo does not really work well with SOCK_DCCP */
+ if (socktype == SOCK_DGRAM || socktype == SOCK_STREAM)
+ hints.ai_socktype = socktype;
+
+ /* only use addresses available on the host */
+ hints.ai_flags = AI_ADDRCONFIG;
+ if (l3type == AF_INET6)
+ /* use v4-mapped-v6 if no v6 addresses found */
+ hints.ai_flags |= AI_V4MAPPED | AI_ALL;
+
+ if (passive && host == NULL)
+ hints.ai_flags |= AI_PASSIVE;
+
+ /*
+ * Obtain local/remote address information
+ */
+ if ((rc = getaddrinfo(host, port, &hints, passive ? &local : &remote))) {
+ PARA_ERROR_LOG("can not resolve %s address %s#%s: %s.\n",
+ layer4_name(l4type),
+ host? : (passive? "[loopback]" : "[localhost]"),
+ port, gai_strerror(rc));
+ return -E_ADDRESS_LOOKUP;
+ }
+
+ /*
+ * Iterate over all src/dst combination, exhausting dst first
+ */
+ for (src = local, dst = remote; src != NULL || dst != NULL; /* no op */ ) {
+ if (src && dst && src->ai_family == AF_INET
+ && dst->ai_family == AF_INET6) /* v4 -> v6 is not possible */
+ goto get_next_dst;
+
+ sockfd = socket(src ? src->ai_family : dst->ai_family, socktype, l4type);
+ if (sockfd < 0)
+ goto get_next_dst;
+
+ /*
+ * Set those options that need to be set before establishing the connection
+ */
+ /* Reuse the address on passive (listening) sockets to avoid failure on restart */
+ if (passive && setsockopt(sockfd, SOL_SOCKET, SO_REUSEADDR, &on, sizeof(on)) == -1) {
+ PARA_ERROR_LOG("can not set SO_REUSEADDR: %s\n", strerror(errno));
+ return -ERRNO_TO_PARA_ERROR(errno);
+ }
+
+ if (src) {
+ if (bind(sockfd, src->ai_addr, src->ai_addrlen) < 0) {
+ close(sockfd);
+ goto get_next_src;
+ }
+ if (!dst)
+ break; /* bind-only completed successfully */
+ }
+
+ if (dst && connect(sockfd, dst->ai_addr, dst->ai_addrlen) == 0)
+ break; /* connection completed successfully */
+ close(sockfd);
+get_next_dst:
+ if (dst && (dst = dst->ai_next))
+ continue;
+get_next_src:
+ if (src && (src = src->ai_next))
+ dst = remote; /* restart inner loop */
+ }
+ if (local)
+ freeaddrinfo(local);
+ if (remote)
+ freeaddrinfo(remote);
+
+ if (src == NULL && dst == NULL) {
+ PARA_ERROR_LOG("can not create %s socket %s#%s.\n", layer4_name(l4type),
+ host? : (passive? "[loopback]" : "[localhost]"), port);
+ return -ERRNO_TO_PARA_ERROR(errno);
+ }
+ return sockfd;
+}
+
+/**
+ * Create a passive / listening socket.
+ * \param l3type The network-layer type (\p AF_xxx)
+ * \param l4type The transport-layer type (\p IPPROTO_xxx).
+ * \param port The decimal port number to listen on.
+ *
+ * \return Positive integer (socket descriptor) on success, negative value otherwise.
+ * \sa makesock(), ip(7), ipv6(7), bind(2), listen(2).
+ */
+int para_listen(unsigned l3type, unsigned l4type, unsigned short port)
+{
+ int ret, fd = makesock(l3type, l4type, 1, NULL, port);
+
+ if (fd > 0) {
+ ret = listen(fd, BACKLOG);
+ if (ret < 0) {
+ close(fd);
+ return -ERRNO_TO_PARA_ERROR(errno);
+ }
+ PARA_INFO_LOG("listening on %s port %u, fd %d\n",
+ layer4_name(l4type), port, fd);
+ }
+ return fd;
+}
+
/*
* Send out a buffer, resend on short writes.
*
}
#endif /* HAVE_UCRED */
-/** how many pending connections queue will hold */
-#define BACKLOG 10
-
/**
* Create a tcp socket, bind it and listen on the given port.
*
projects / paraslash.git / commitdiff