From c58e2fa1335322c699a16fa8e12390d0b137b03e Mon Sep 17 00:00:00 2001 From: "Alex Xu (Hello71)" Date: Tue, 5 Jul 2016 18:45:58 -0400 Subject: Fix port reservation, checksumming. --- Makefile | 4 +- src/checksum.c | 124 +++++++++++++++++++++++++++++++++++++++++++++++++++++++++ src/checksum.h | 54 ++++++++++++++++--------- src/client.c | 119 +++++++++++++++++++++++++++++++----------------------- 4 files changed, 232 insertions(+), 69 deletions(-) create mode 100644 src/checksum.c diff --git a/Makefile b/Makefile index ee1c67b..94f6e9f 100644 --- a/Makefile +++ b/Makefile @@ -1,9 +1,9 @@ -CFLAGS += -Wall -Wextra -flto +CFLAGS += -Wall -Wextra LDLIBS := -lev NET_OBJS := src/client.o src/server.o -OBJS := src/udpastcp.o $(NET_OBJS) +OBJS := src/udpastcp.o src/checksum.o $(NET_OBJS) udpastcp: $(OBJS) $(LINK.c) $^ $(LOADLIBES) $(LDLIBS) -o $@ diff --git a/src/checksum.c b/src/checksum.c new file mode 100644 index 0000000..300237d --- /dev/null +++ b/src/checksum.c @@ -0,0 +1,124 @@ +/* + * + * INET An implementation of the TCP/IP protocol suite for the LINUX + * operating system. INET is implemented using the BSD Socket + * interface as the means of communication with the user level. + * + * IP/TCP/UDP checksumming routines + * + * Authors: Jorge Cwik, + * Arnt Gulbrandsen, + * Tom May, + * Andreas Schwab, + * Lots of code moved from tcp.c and ip.c; see those files + * for more names. + * + * 03/02/96 Jes Sorensen, Andreas Schwab, Roman Hodek: + * Fixed some nasty bugs, causing some horrible crashes. + * A: At some points, the sum (%0) was used as + * length-counter instead of the length counter + * (%1). Thanks to Roman Hodek for pointing this out. + * B: GCC seems to mess up if one uses too many + * data-registers to hold input values and one tries to + * specify d0 and d1 as scratch registers. Letting gcc + * choose these registers itself solves the problem. + * + * This program is free software; you can redistribute it and/or + * modify it under the terms of the GNU General Public License + * as published by the Free Software Foundation; either version + * 2 of the License, or (at your option) any later version. + */ + +/* Based on code from the Linux kernel. */ + +#include + +/* Revised by Kenneth Albanowski for m68knommu. Basic problem: unaligned access + kills, so most of the assembly has to go. */ + +static inline unsigned short from32to16(unsigned int x) +{ + /* add up 16-bit and 16-bit for 16+c bit */ + x = (x & 0xffff) + (x >> 16); + /* add up carry.. */ + x = (x & 0xffff) + (x >> 16); + return x; +} + +static unsigned int do_csum(const unsigned char *buff, int len) +{ + int odd; + unsigned int result = 0; + + if (len <= 0) + goto out; + odd = 1 & (unsigned long) buff; + if (odd) { +#if __BYTE_ORDER == __LITTLE_ENDIAN + result += (*buff << 8); +#else + result = *buff; +#endif + len--; + buff++; + } + if (len >= 2) { + if (2 & (unsigned long) buff) { + result += *(unsigned short *) buff; + len -= 2; + buff += 2; + } + if (len >= 4) { + const unsigned char *end = buff + ((unsigned)len & ~3); + unsigned int carry = 0; + do { + unsigned int w = *(unsigned int *) buff; + buff += 4; + result += carry; + result += w; + carry = (w > result); + } while (buff < end); + result += carry; + result = (result & 0xffff) + (result >> 16); + } + if (len & 2) { + result += *(unsigned short *) buff; + buff += 2; + } + } + if (len & 1) +#if __BYTE_ORDER == __LITTLE_ENDIAN + result += *buff; +#else + result += (*buff << 8); +#endif + result = from32to16(result); + if (odd) + result = ((result >> 8) & 0xff) | ((result & 0xff) << 8); +out: + return result; +} + +/* + * computes the checksum of a memory block at buff, length len, + * and adds in "sum" (32-bit) + * + * returns a 32-bit number suitable for feeding into itself + * or csum_tcpudp_magic + * + * this function must be called with even lengths, except + * for the last fragment, which may be odd + * + * it's best to have buff aligned on a 32-bit boundary + */ +uint16_t csum_partial(const void *buff, int len, uint16_t wsum) +{ + uint16_t sum = wsum; + uint16_t result = do_csum(buff, len); + + /* add in old sum, and carry.. */ + result += sum; + if (sum > result) + result += 1; + return result; +} diff --git a/src/checksum.h b/src/checksum.h index d9e6bda..f788ff1 100644 --- a/src/checksum.h +++ b/src/checksum.h @@ -1,27 +1,45 @@ +#include #include +#include -static inline uint16_t do_csum(const char *buf, unsigned size) { - unsigned int sum = 0; - unsigned int i; +// based on code from RFCs 1071 and 1624 - for (i = 0; i < size - 1; i += 2) - sum += *(uint16_t *)&buf[i]; - - if (size & 1) - sum += (uint8_t)buf[i]; +/* +static inline uint16_t csum_update(const void *ptr, uint16_t new_value, uint16_t wsum) { + uint32_t sum = *(uint16_t *)ptr + (~ntohs(*(uint16_t *)&new_value) & 0xffff) + ntohs(wsum); + sum = (sum & 0xffff) + (sum >> 16); + return htons(sum + (sum >> 16)); +} +static inline uint16_t fold_sum(uint32_t sum) { while (sum >> 16) - sum = (sum & 0xFFFF) + (sum >> 16); - - return ~sum; + sum = (sum & 0xffff) + (sum >> 16); + return sum; } -static inline uint16_t csum_partial(const void *buff, int len, uint16_t wsum) { - unsigned int sum = (unsigned int)wsum; - unsigned int result = do_csum(buff, len); +static inline uint16_t do_csum(const void *ptr, size_t len) { + uint32_t sum = 0; + + while (len > 1) { + sum += *(uint16_t *)ptr++; + len -= 2; + } - result += sum; - if (sum > result) - result += 1; - return result; + if (len > 0) + sum += *(uint8_t *)ptr; + + return ~fold_sum(sum); +} + +static inline uint16_t csum_partial(uint16_t sum, const void *ptr, size_t len, ...) { + va_list ap; + va_start(ap, len); + do { + sum = ~fold_sum(~sum + ~do_csum(ptr, len)); + } while ((ptr = va_arg(ap, const void *)) && (len = va_arg(ap, size_t))); + va_end(ap); + return sum; } +*/ + +uint16_t csum_partial(const void *buff, int len, uint16_t wsum); diff --git a/src/client.c b/src/client.c index 21f6217..23d5eac 100644 --- a/src/client.c +++ b/src/client.c @@ -1,3 +1,4 @@ +#include #include #include #include @@ -17,7 +18,19 @@ #include "client.h" #include "uthash.h" -#define PORTS_IN_INT sizeof(int) * CHAR_BIT +#define PORTS_IN_INT (sizeof(int) * CHAR_BIT) + +struct c_data { + const char *r_host; + const char *r_port; + struct o_c_sock *o_socks_by_caddr; + struct o_c_rsock *o_rsocks; + struct sockaddr_storage pkt_addr; + int s_sock; + int i_sock; + socklen_t s_addrlen; + uint16_t csum_p; +}; struct o_c_rsock { struct sockaddr *r_addr; @@ -27,8 +40,8 @@ struct o_c_rsock { ev_io io_w; UT_hash_handle hh; int fd; - uint16_t csum_a; socklen_t r_addrlen; + uint16_t csum_p; }; struct o_c_sock { @@ -39,38 +52,27 @@ struct o_c_sock { ev_timer tm_w; UT_hash_handle hh_lp; UT_hash_handle hh_ca; + uint16_t csum_p; uint16_t seq_num; in_port_t l_port; uint8_t status; int8_t syn_retries; }; -struct c_data { - const char *r_host; - const char *r_port; - struct o_c_sock *o_socks_by_caddr; - struct o_c_rsock *o_rsocks; - struct sockaddr_storage pkt_addr; - socklen_t s_addrlen; - int s_sock; - int i_sock; -}; - static struct c_data *global_c_data; static const uint8_t tcp_syn_retry_timeouts[] = { 3, 6, 12, 24, 0 }; static inline int check_resv_poff(unsigned int *used_ports, uint16_t poff) { - if (used_ports[poff / PORTS_IN_INT] & (1 << poff % PORTS_IN_INT)) { - used_ports[poff / PORTS_IN_INT] |= 1 << poff % PORTS_IN_INT; - return poff; - } - return 0; + if (used_ports[poff / PORTS_IN_INT] & (1 << (poff % PORTS_IN_INT))) + return 0; + used_ports[poff / PORTS_IN_INT] |= 1 << (poff % PORTS_IN_INT); + return poff; } /* reserve a local TCP port (local addr, remote addr, remote port are usually * fixed in the tuple) */ -static uint16_t reserve_port(unsigned int *used_ports) { +static inline uint16_t reserve_port(unsigned int *used_ports) { long r; // randomly try 16 places @@ -78,10 +80,10 @@ static uint16_t reserve_port(unsigned int *used_ports) { r = random(); if (check_resv_poff(used_ports, r % 32768)) - return 32768 + r; + return 32768 + (r % 32768); if (check_resv_poff(used_ports, (r >> 16) % 32768)) - return 32768 + (r >> 16); + return 32768 + ((r >> 16) % 32768); } // give up and go sequentially @@ -285,50 +287,63 @@ static void cc_cb(struct ev_loop *loop, ev_io *w, int revents __attribute__((unu } } -#define SIX_OR_FOUR(sa, six, four, neither) \ - (((struct sockaddr *)(sa))->sa_family == AF_INET6 ? (six) : ((struct sockaddr *)(sa))->sa_family == AF_INET ? (four) : abort(), neither) - -#define EXTRACT_IN_ADDR(sa) \ - SIX_OR_FOUR((struct sockaddr *)(sa), &(((struct sockaddr_in6 *)(sa))->sin6_addr), &(((struct sockaddr_in *)(sa))->sin_addr), NULL), \ - SIX_OR_FOUR((struct sockaddr *)(sa), sizeof(struct in6_addr), sizeof(in_addr_t), 0) - -static int c_rsock_init(struct o_c_sock *sock, struct addrinfo *res) { - sock->rsock = malloc(sizeof(*sock->rsock)); - memset(&sock->rsock->used_ports, 0, sizeof(sock->rsock->used_ports)); - sock->rsock->r_addr = malloc(res->ai_addrlen); +static inline struct o_c_rsock * c_rsock_init(struct addrinfo *res) { + struct o_c_rsock *rsock; + rsock = malloc(sizeof(*rsock)); + memset(&rsock->used_ports, 0, sizeof(rsock->used_ports)); + rsock->r_addr = malloc(res->ai_addrlen); - memcpy(sock->rsock->r_addr, res->ai_addr, res->ai_addrlen); - sock->rsock->r_addrlen = res->ai_addrlen; + memcpy(rsock->r_addr, res->ai_addr, res->ai_addrlen); + rsock->r_addrlen = res->ai_addrlen; freeaddrinfo(res); - sock->rsock->o_socks_by_lport = NULL; + rsock->o_socks_by_lport = NULL; - sock->rsock->fd = socket(sock->rsock->r_addr->sa_family, SOCK_RAW, IPPROTO_TCP); - if (!sock->rsock->fd) { + rsock->fd = socket(rsock->r_addr->sa_family, SOCK_RAW, IPPROTO_TCP); + if (!rsock->fd) { perror("socket"); - return 0; + return NULL; } - if (connect(sock->rsock->fd, sock->rsock->r_addr, sock->rsock->r_addrlen) == -1) { + if (connect(rsock->fd, rsock->r_addr, rsock->r_addrlen) == -1) { perror("connect"); - return 0; + return NULL; } - if (fcntl(sock->rsock->fd, F_SETFL, O_NONBLOCK) == -1) { + if (fcntl(rsock->fd, F_SETFL, O_NONBLOCK) == -1) { perror("fcntl"); - return 0; + return NULL; } struct sockaddr_storage our_addr; socklen_t our_addr_len = sizeof(our_addr); - int r = getsockname(sock->rsock->fd, (struct sockaddr *)&our_addr, &our_addr_len); + int r = getsockname(rsock->fd, (struct sockaddr *)&our_addr, &our_addr_len); if (r == -1) { perror("getsockname"); - return 0; + return NULL; } - //sock->rsock->csum_a = csum_partial(EXTRACT_IN_ADDR(sock->rsock->r_addr), csum_partial(EXTRACT_IN_ADDR(&our_addr), 0)); + char proto[] = { 0, IPPROTO_TCP }; + + if (((struct sockaddr *)rsock->r_addr)->sa_family != our_addr.ss_family) + abort(); + + switch (our_addr.ss_family) { + case AF_INET: + rsock->csum_p = csum_partial(&((struct sockaddr_in *)&our_addr)->sin_addr, sizeof(in_addr_t), + csum_partial(&((struct sockaddr_in *)rsock->r_addr)->sin_addr, sizeof(in_addr_t), 0)); + break; + case AF_INET6: + rsock->csum_p = csum_partial(&((struct sockaddr_in6 *)&our_addr)->sin6_addr, sizeof(struct in6_addr), + csum_partial(&((struct sockaddr_in6 *)rsock->r_addr)->sin6_addr, sizeof(struct in6_addr), 0)); + break; + default: + abort(); + } - return 1; + rsock->csum_p = csum_partial(&((struct sockaddr_in *)rsock->r_addr)->sin_port, sizeof(in_port_t), + csum_partial(proto, sizeof(proto), rsock->csum_p)); + + return rsock; } static void cs_cb(EV_P_ ev_io *w, int revents __attribute__((unused))) { @@ -368,7 +383,8 @@ static void cs_cb(EV_P_ ev_io *w, int revents __attribute__((unused))) { if (!sock->rsock) { DBG("could not locate remote socket to host, initializing new raw socket"); - if (!c_rsock_init(sock, res)) { + sock->rsock = c_rsock_init(res); + if (!sock->rsock) { ev_break(EV_A_ EVBREAK_ONE); return; } @@ -382,6 +398,7 @@ static void cs_cb(EV_P_ ev_io *w, int revents __attribute__((unused))) { } uint16_t l_port = reserve_port(sock->rsock->used_ports); + assert(l_port >= 32768); DBG("using port %hu", l_port); if (!l_port) { fputs("we ran out of ports?\n", stderr); @@ -390,6 +407,8 @@ static void cs_cb(EV_P_ ev_io *w, int revents __attribute__((unused))) { } sock->l_port = htons(l_port); + sock->csum_p = csum_partial(&sock->l_port, sizeof(in_port_t), sock->rsock->csum_p); + HASH_ADD_KEYPTR(hh_ca, c_data->o_socks_by_caddr, sock->c_address, addresslen, sock); HASH_ADD(hh_lp, sock->rsock->o_socks_by_lport, l_port, sizeof(in_port_t), sock); @@ -398,10 +417,12 @@ static void cs_cb(EV_P_ ev_io *w, int revents __attribute__((unused))) { struct tcphdr buf = { .th_sport = sock->l_port, .th_dport = ((struct sockaddr_in *)sock->rsock->r_addr)->sin_port, - .th_seq = htonl(sock->seq_num++), + .th_seq = htonl(sock->seq_num), .th_flags = TH_SYN, - .th_off = 5 + .th_off = 5, }; + uint16_t tsz = htons(sizeof(buf)); + buf.th_sum = ~csum_partial(&buf.th_seq, 16, csum_partial(&tsz, sizeof(tsz), sock->csum_p)); sock->pending_data = malloc(sz); memcpy(sock->pending_data, rbuf, sz); -- cgit v1.2.3-54-g00ecf