dns_resolve.rar_V2

/* * Contains the CIFS DFS upcall routines used for hostname to * IP address translation. */ #include <linux/slab.h> #include <linux/dns_resolver.h> #include "dns_resolve.h" #include "cifsglob.h" #include "cifsproto.h" #include "cifs_debug.h" /** * dns_resolve_server_name_to_ip - Resolve UNC server name to ip address. * @unc: UNC path specifying the server (with '/' as delimiter) * @ip_addr: Where to return the IP address. * * The IP address will be returned in string form, and the caller is * responsible for freeing it. * * Returns length of result on success, -ve on error. */ int dns_resolve_server_name_to_ip(const char *unc, char **ip_addr) { struct sockaddr_storage ss; const char *hostname, *sep; char *name; int len, rc; if (!ip_addr || !unc) return -EINVAL; len = strlen(unc); if (len < 3) { cifs_dbg(FYI, "%s: unc is too short: %s\n", __func__, unc); return -EINVAL; } /* Discount leading slashes for cifs */ len -= 2; hostname = unc + 2; /* Search for server name delimiter */ sep = memchr(hostname, '/', len); if (sep) len = sep - hostname; else cifs_dbg(FYI, "%s: probably server name is whole unc: %s\n", __func__, unc); /* Try to interpret hostname as an IPv4 or IPv6 address */ rc = cifs_convert_address((struct sockaddr *)&ss, hostname, len); if (rc > 0) goto name_is_IP_address; /* Perform the upcall */ rc = dns_query(NULL, hostname, len, NULL, ip_addr, NULL); if (rc < 0) cifs_dbg(FYI, "%s: unable to resolve: %*.*s\n", __func__, len, len, hostname); else cifs_dbg(FYI, "%s: resolved: %*.*s to %s\n", __func__, len, len, hostname, *ip_addr); return rc; name_is_IP_address: name = kmalloc(len + 1, GFP_KERNEL); if (!name) return -ENOMEM; memcpy(name, hostname, len); name[len] = 0; cifs_dbg(FYI, "%s: unc is IP, skipping dns upcall: %s\n", __func__, name); *ip_addr = name; return 0; }