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    Contents of /trunk/mkinitrd-magellan/busybox/libbb/udp_io.c

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    Revision 984 - (show annotations) (download)
    Sun May 30 11:32:42 2010 UTC (13 years, 11 months ago) by niro
    File MIME type: text/plain
    File size: 5283 byte(s) 
    -updated to busybox-1.16.1 and enabled blkid/uuid support in default config
    1 /* vi: set sw=4 ts=4: */
    2 /*
    3 * Utility routines.
    4 *
    5 * Copyright (C) 2007 Denys Vlasenko
    6 *
    7 * Licensed under GPL version 2, see file LICENSE in this tarball for details.
    8 */
    9 #include "libbb.h"
    10
    11 /*
    12 * This asks kernel to let us know dst addr/port of incoming packets
    13 * We don't check for errors here. Not supported == won't be used
    14 */
    15 void FAST_FUNC
    16 socket_want_pktinfo(int fd)
    17 {
    18 #ifdef IP_PKTINFO
    19 setsockopt(fd, IPPROTO_IP, IP_PKTINFO, &const_int_1, sizeof(int));
    20 #endif
    21 #if ENABLE_FEATURE_IPV6 && defined(IPV6_PKTINFO)
    22 setsockopt(fd, IPPROTO_IPV6, IPV6_PKTINFO, &const_int_1, sizeof(int));
    23 #endif
    24 }
    25
    26
    27 ssize_t FAST_FUNC
    28 send_to_from(int fd, void *buf, size_t len, int flags,
    29 const struct sockaddr *to,
    30 const struct sockaddr *from,
    31 socklen_t tolen)
    32 {
    33 #ifndef IP_PKTINFO
    34 (void)from; /* suppress "unused from" warning */
    35 return sendto(fd, buf, len, flags, to, tolen);
    36 #else
    37 struct iovec iov[1];
    38 struct msghdr msg;
    39 union {
    40 char cmsg[CMSG_SPACE(sizeof(struct in_pktinfo))];
    41 # if ENABLE_FEATURE_IPV6 && defined(IPV6_PKTINFO)
    42 char cmsg6[CMSG_SPACE(sizeof(struct in6_pktinfo))];
    43 # endif
    44 } u;
    45 struct cmsghdr* cmsgptr;
    46
    47 if (from->sa_family != AF_INET
    48 # if ENABLE_FEATURE_IPV6
    49 && from->sa_family != AF_INET6
    50 # endif
    51 ) {
    52 /* ANY local address */
    53 return sendto(fd, buf, len, flags, to, tolen);
    54 }
    55
    56 /* man recvmsg and man cmsg is needed to make sense of code below */
    57
    58 iov[0].iov_base = buf;
    59 iov[0].iov_len = len;
    60
    61 memset(&u, 0, sizeof(u));
    62
    63 memset(&msg, 0, sizeof(msg));
    64 msg.msg_name = (void *)(struct sockaddr *)to; /* or compiler will annoy us */
    65 msg.msg_namelen = tolen;
    66 msg.msg_iov = iov;
    67 msg.msg_iovlen = 1;
    68 msg.msg_control = &u;
    69 msg.msg_controllen = sizeof(u);
    70 msg.msg_flags = flags;
    71
    72 cmsgptr = CMSG_FIRSTHDR(&msg);
    73 if (to->sa_family == AF_INET && from->sa_family == AF_INET) {
    74 struct in_pktinfo *pktptr;
    75 cmsgptr->cmsg_level = IPPROTO_IP;
    76 cmsgptr->cmsg_type = IP_PKTINFO;
    77 cmsgptr->cmsg_len = CMSG_LEN(sizeof(struct in_pktinfo));
    78 pktptr = (struct in_pktinfo *)(CMSG_DATA(cmsgptr));
    79 /*pktptr->ipi_ifindex = 0; -- already done by memset(u...) */
    80 /* In general, CMSG_DATA() can be unaligned, but in this case
    81 * we know for sure it is sufficiently aligned:
    82 * CMSG_FIRSTHDR simply returns &u above,
    83 * and CMSG_DATA returns &u + size_t + int + int.
    84 * Thus direct assignment is ok:
    85 */
    86 pktptr->ipi_spec_dst = ((struct sockaddr_in*)from)->sin_addr;
    87 }
    88 # if ENABLE_FEATURE_IPV6 && defined(IPV6_PKTINFO)
    89 else if (to->sa_family == AF_INET6 && from->sa_family == AF_INET6) {
    90 struct in6_pktinfo *pktptr;
    91 cmsgptr->cmsg_level = IPPROTO_IPV6;
    92 cmsgptr->cmsg_type = IPV6_PKTINFO;
    93 cmsgptr->cmsg_len = CMSG_LEN(sizeof(struct in6_pktinfo));
    94 pktptr = (struct in6_pktinfo *)(CMSG_DATA(cmsgptr));
    95 /* pktptr->ipi6_ifindex = 0; -- already done by memset(u...) */
    96 pktptr->ipi6_addr = ((struct sockaddr_in6*)from)->sin6_addr;
    97 }
    98 # endif
    99 msg.msg_controllen = cmsgptr->cmsg_len;
    100
    101 return sendmsg(fd, &msg, flags);
    102 #endif
    103 }
    104
    105 /* NB: this will never set port# in 'to'!
    106 * _Only_ IP/IPv6 address part of 'to' is _maybe_ modified.
    107 * Typical usage is to preinit 'to' with "default" value
    108 * before calling recv_from_to(). */
    109 ssize_t FAST_FUNC
    110 recv_from_to(int fd, void *buf, size_t len, int flags,
    111 struct sockaddr *from, struct sockaddr *to,
    112 socklen_t sa_size)
    113 {
    114 #ifndef IP_PKTINFO
    115 (void)to; /* suppress "unused to" warning */
    116 return recvfrom(fd, buf, len, flags, from, &sa_size);
    117 #else
    118 /* man recvmsg and man cmsg is needed to make sense of code below */
    119 struct iovec iov[1];
    120 union {
    121 char cmsg[CMSG_SPACE(sizeof(struct in_pktinfo))];
    122 # if ENABLE_FEATURE_IPV6 && defined(IPV6_PKTINFO)
    123 char cmsg6[CMSG_SPACE(sizeof(struct in6_pktinfo))];
    124 # endif
    125 } u;
    126 struct cmsghdr *cmsgptr;
    127 struct msghdr msg;
    128 ssize_t recv_length;
    129
    130 iov[0].iov_base = buf;
    131 iov[0].iov_len = len;
    132
    133 memset(&msg, 0, sizeof(msg));
    134 msg.msg_name = (struct sockaddr *)from;
    135 msg.msg_namelen = sa_size;
    136 msg.msg_iov = iov;
    137 msg.msg_iovlen = 1;
    138 msg.msg_control = &u;
    139 msg.msg_controllen = sizeof(u);
    140
    141 recv_length = recvmsg(fd, &msg, flags);
    142 if (recv_length < 0)
    143 return recv_length;
    144
    145 # define to4 ((struct sockaddr_in*)to)
    146 # define to6 ((struct sockaddr_in6*)to)
    147 /* Here we try to retrieve destination IP and memorize it */
    148 for (cmsgptr = CMSG_FIRSTHDR(&msg);
    149 cmsgptr != NULL;
    150 cmsgptr = CMSG_NXTHDR(&msg, cmsgptr)
    151 ) {
    152 if (cmsgptr->cmsg_level == IPPROTO_IP
    153 && cmsgptr->cmsg_type == IP_PKTINFO
    154 ) {
    155 # define pktinfo(cmsgptr) ( (struct in_pktinfo*)(CMSG_DATA(cmsgptr)) )
    156 to->sa_family = AF_INET;
    157 /*to4->sin_addr = pktinfo(cmsgptr)->ipi_addr; - may be unaligned */
    158 memcpy(&to4->sin_addr, &pktinfo(cmsgptr)->ipi_addr, sizeof(to4->sin_addr));
    159 /*to4->sin_port = 123; - this data is not supplied by kernel */
    160 # undef pktinfo
    161 break;
    162 }
    163 # if ENABLE_FEATURE_IPV6 && defined(IPV6_PKTINFO)
    164 if (cmsgptr->cmsg_level == IPPROTO_IPV6
    165 && cmsgptr->cmsg_type == IPV6_PKTINFO
    166 ) {
    167 # define pktinfo(cmsgptr) ( (struct in6_pktinfo*)(CMSG_DATA(cmsgptr)) )
    168 to->sa_family = AF_INET6;
    169 /*to6->sin6_addr = pktinfo(cmsgptr)->ipi6_addr; - may be unaligned */
    170 memcpy(&to6->sin6_addr, &pktinfo(cmsgptr)->ipi6_addr, sizeof(to6->sin6_addr));
    171 /*to6->sin6_port = 123; */
    172 # undef pktinfo
    173 break;
    174 }
    175 # endif
    176 }
    177 return recv_length;
    178 #endif
    179 }