pex: move raw ip send code to sendto_rawudp() in utils.c

[project/unetd.git] / utils.c

diff --git a/utils.c b/utils.c
index abaa73d2367edecaab68f36003e6407efadfdcb5..0c7067173f733681493e4f2c95aeb70c829b8e0d 100644 (file)
--- a/utils.c
+++ b/utils.c
@@ -8,6 +8,10 @@
 #include <arpa/inet.h>
 #include <netdb.h>
 #include <stdio.h>
+#include <netinet/in.h>
+#include <netinet/ip.h>
+#include <netinet/ip6.h>
+#include <netinet/udp.h>
 
 #include <libubox/utils.h>
 
@@ -191,3 +195,137 @@ uint64_t unet_gettime(void)
 
        return ts.tv_sec;
 }
+
+static inline uint32_t
+csum_tcpudp_nofold(uint32_t saddr, uint32_t daddr, uint32_t len, uint8_t proto)
+{
+       uint64_t sum = 0;
+
+       sum += saddr;
+       sum += daddr;
+#if __BYTE_ORDER == __LITTLE_ENDIAN
+       sum += (proto + len) << 8;
+#else
+       sum += proto + len;
+#endif
+
+       sum = (sum & 0xffffffff) + (sum >> 32);
+       sum = (sum & 0xffffffff) + (sum >> 32);
+
+       return (uint32_t)sum;
+}
+
+static inline uint32_t csum_add(uint32_t sum, uint32_t addend)
+{
+       sum += addend;
+       return sum + (sum < addend);
+}
+
+static inline uint16_t csum_fold(uint32_t sum)
+{
+       sum = (sum & 0xffff) + (sum >> 16);
+       sum = (sum & 0xffff) + (sum >> 16);
+
+       return (uint16_t)~sum;
+}
+
+static uint32_t csum_partial(const void *buf, int len)
+{
+       const uint16_t *data = buf;
+       uint32_t sum = 0;
+
+       while (len > 1) {
+               sum += *data++;
+               len -= 2;
+       }
+
+       if (len == 1)
+#if __BYTE_ORDER == __LITTLE_ENDIAN
+               sum += *(uint8_t *)data;
+#else
+               sum += *(uint8_t *)data << 8;
+#endif
+
+       sum = (sum & 0xffff) + (sum >> 16);
+       sum = (sum & 0xffff) + (sum >> 16);
+
+       return sum;
+}
+
+static void fixup_udpv4(void *hdr, size_t hdrlen, const void *data, size_t len)
+{
+       struct ip *ip = hdr;
+       struct udphdr *udp = hdr + ip->ip_hl * 4;
+       uint16_t udp_len = sizeof(*udp) + len;
+       uint32_t sum;
+
+       if ((void *)&udp[1] > hdr + hdrlen)
+               return;
+
+       udp->uh_sum = 0;
+       udp->uh_ulen = htons(udp_len);
+       sum = csum_tcpudp_nofold(*(uint32_t *)&ip->ip_src, *(uint32_t *)&ip->ip_dst,
+                                ip->ip_p, udp_len);
+       sum = csum_add(sum, csum_partial(udp, sizeof(*udp)));
+       sum = csum_add(sum, csum_partial(data, len));
+       udp->uh_sum = csum_fold(sum);
+
+       ip->ip_len = htons(hdrlen + len);
+       ip->ip_sum = 0;
+       ip->ip_sum = csum_fold(csum_partial(ip, sizeof(*ip)));
+
+#ifdef __APPLE__
+       ip->ip_len = hdrlen + len;
+#endif
+}
+
+static void fixup_udpv6(void *hdr, size_t hdrlen, const void *data, size_t len)
+{
+       struct ip6_hdr *ip = hdr;
+       struct udphdr *udp = hdr + sizeof(*ip);
+       uint16_t udp_len = htons(sizeof(*udp) + len);
+
+       if ((void *)&udp[1] > hdr + hdrlen)
+               return;
+
+       ip->ip6_plen = htons(sizeof(*udp) + len);
+       udp->uh_sum = 0;
+       udp->uh_ulen = udp_len;
+       udp->uh_sum = csum_fold(csum_partial(hdr, sizeof(*ip) + sizeof(*udp)));
+
+#ifdef __APPLE__
+       ip->ip6_plen = sizeof(*udp) + len;
+#endif
+}
+
+static void fixup_ip_udp_header(void *hdr, size_t hdrlen, const void *data, size_t len)
+{
+       if (hdrlen >= sizeof(struct ip6_hdr) + sizeof(struct udphdr))
+               fixup_udpv6(hdr, hdrlen, data, len);
+       else if (hdrlen >= sizeof(struct ip) + sizeof(struct udphdr))
+               fixup_udpv4(hdr, hdrlen, data, len);
+}
+
+int sendto_rawudp(int fd, const void *addr, void *ip_hdr, size_t ip_hdrlen,
+                 const void *data, size_t len)
+{
+       const struct sockaddr *sa = addr;
+       struct iovec iov[2] = {
+               { .iov_base = ip_hdr, .iov_len = ip_hdrlen },
+               { .iov_base = (void *)data, .iov_len = len }
+       };
+       struct msghdr msg = {
+               .msg_name = (void *)addr,
+               .msg_iov = iov,
+               .msg_iovlen = ARRAY_SIZE(iov),
+       };
+
+       if (sa->sa_family == AF_INET6)
+               msg.msg_namelen = sizeof(struct sockaddr_in6);
+       else
+               msg.msg_namelen = sizeof(struct sockaddr_in);
+
+       fixup_ip_udp_header(ip_hdr, ip_hdrlen, data, len);
+
+       return sendmsg(fd, &msg, 0);
+}