diff options
| -rw-r--r-- | astraceroute.c | 150 |
1 files changed, 106 insertions, 44 deletions
diff --git a/astraceroute.c b/astraceroute.c index 21e9a90..d70802a 100644 --- a/astraceroute.c +++ b/astraceroute.c @@ -266,56 +266,128 @@ static void __assemble_data(uint8_t *packet, size_t len, const char *payload) } } -static void __assemble_icmp4(uint8_t *packet, size_t len) +static void __assemble_icmp4(uint8_t *packet, size_t len, const struct ctx *ctx) { + uint8_t *data; + size_t data_len; struct icmphdr *icmph = (struct icmphdr *) packet; - bug_on(len < sizeof(struct icmphdr)); + bug_on(len < sizeof(*icmph)); icmph->type = ICMP_ECHO; icmph->code = 0; icmph->checksum = 0; + + data = packet + sizeof(*icmph); + data_len = len - sizeof(*icmph); + + __assemble_data(data, data_len, ctx->payload); + + icmph->checksum = csum((unsigned short *)packet, len / 2); } -static void __assemble_icmp6(uint8_t *packet, size_t len) +static void __assemble_icmp6(uint8_t *packet, size_t len, const struct ctx *ctx, + const struct sockaddr *dst, const struct sockaddr *src) { + uint8_t *data; + size_t data_len; + struct ip6_hdr ip6hdr; struct icmp6hdr *icmp6h = (struct icmp6hdr *) packet; - bug_on(len < sizeof(struct icmp6hdr)); + bug_on(len < sizeof(*icmp6h)); icmp6h->icmp6_type = ICMPV6_ECHO_REQUEST; icmp6h->icmp6_code = 0; icmp6h->icmp6_cksum = 0; -} -static void __assemble_tcp(uint8_t *packet, size_t len, int syn, int ack, - int urg, int fin, int rst, int psh, int ecn, - int dport) -{ - struct tcphdr *tcph = (struct tcphdr *) packet; + data = packet + sizeof(*icmp6h); + data_len = len - sizeof(*icmp6h); + + __assemble_data(data, data_len, ctx->payload); + + memcpy(&ip6hdr.ip6_src, &((const struct sockaddr_in6 *) src)->sin6_addr, + sizeof(ip6hdr.ip6_src)); + memcpy(&ip6hdr.ip6_dst, &((const struct sockaddr_in6 *) dst)->sin6_addr, + sizeof(ip6hdr.ip6_dst)); - bug_on(len < sizeof(struct tcphdr)); + icmp6h->icmp6_cksum = p6_csum(&ip6hdr, packet, sizeof(*icmp6h) + data_len, IPPROTO_ICMPV6); +} +static size_t __assemble_tcp_header(struct tcphdr *tcph, const struct ctx *ctx) +{ tcph->source = htons((uint16_t) rand()); - tcph->dest = htons((uint16_t) dport); + tcph->dest = htons((uint16_t) ctx->dport); tcph->seq = htonl(rand()); - tcph->ack_seq = (!!ack ? htonl(rand()) : 0); + tcph->ack_seq = (!!ctx->ack ? htonl(rand()) : 0); tcph->doff = 5; - tcph->syn = !!syn; - tcph->ack = !!ack; - tcph->urg = !!urg; - tcph->fin = !!fin; - tcph->rst = !!rst; - tcph->psh = !!psh; - tcph->ece = !!ecn; - tcph->cwr = !!ecn; + tcph->syn = !!ctx->syn; + tcph->ack = !!ctx->ack; + tcph->urg = !!ctx->urg; + tcph->fin = !!ctx->fin; + tcph->rst = !!ctx->rst; + tcph->psh = !!ctx->psh; + tcph->ece = !!ctx->ecn; + tcph->cwr = !!ctx->ecn; tcph->window = htons((uint16_t) (100 + (rand() % 65435))); - tcph->urg_ptr = (!!urg ? htons((uint16_t) rand()) : 0); tcph->check = 0; + tcph->urg_ptr = (!!ctx->urg ? htons((uint16_t) rand()) : 0); + + return tcph->doff * 4; +} + +static void __assemble_tcp(uint8_t *packet, size_t len, const struct ctx *ctx, + const struct sockaddr *dst, const struct sockaddr *src) +{ + + uint8_t *data; + size_t tcp_len, data_len; + struct ip iphdr; + struct tcphdr *tcph = (struct tcphdr *) packet; + + bug_on(len < sizeof(*tcph)); + + tcp_len = __assemble_tcp_header(tcph, ctx); + + data = packet + tcp_len; + data_len = len - tcp_len; + + __assemble_data(data, data_len, ctx->payload); + + memcpy(&iphdr.ip_src, &((const struct sockaddr_in *) src)->sin_addr.s_addr, + sizeof(iphdr.ip_src)); + memcpy(&iphdr.ip_dst, &((const struct sockaddr_in *) dst)->sin_addr.s_addr, + sizeof(iphdr.ip_dst)); + + tcph->check = p4_csum(&iphdr, packet, tcp_len + data_len, IPPROTO_TCP); +} + +static void __assemble_tcp6(uint8_t *packet, size_t len, const struct ctx *ctx, + const struct sockaddr *dst, const struct sockaddr *src) +{ + uint8_t *data; + size_t tcp_len, data_len; + struct ip6_hdr ip6hdr; + struct tcphdr *tcph = (struct tcphdr *) packet; + + bug_on(len < sizeof(*tcph)); + + tcp_len = __assemble_tcp_header(tcph, ctx); + + data = packet + tcp_len; + data_len = len - tcp_len; + + __assemble_data(data, data_len, ctx->payload); + + memcpy(&ip6hdr.ip6_src, &((const struct sockaddr_in6 *) src)->sin6_addr, + sizeof(ip6hdr.ip6_src)); + memcpy(&ip6hdr.ip6_dst, &((const struct sockaddr_in6 *) dst)->sin6_addr, + sizeof(ip6hdr.ip6_dst)); + + tcph->check = p6_csum(&ip6hdr, packet, tcp_len + data_len, IPPROTO_TCP); } static int assemble_ipv4(uint8_t *packet, size_t len, int ttl, int proto, @@ -323,7 +395,7 @@ static int assemble_ipv4(uint8_t *packet, size_t len, int ttl, int proto, const struct sockaddr *src) { uint8_t *data; - size_t data_len, off_next = 0; + size_t data_len; struct iphdr *iph = (struct iphdr *) packet; bug_on(!src || !dst); @@ -345,28 +417,24 @@ static int assemble_ipv4(uint8_t *packet, size_t len, int ttl, int proto, iph->daddr = ((const struct sockaddr_in *) dst)->sin_addr.s_addr; iph->protocol = (uint8_t) proto; + iph->check = 0; data = packet + sizeof(*iph); data_len = len - sizeof(*iph); switch (proto) { case IPPROTO_TCP: - __assemble_tcp(data, data_len, ctx->syn, ctx->ack, ctx->urg, - ctx->fin, ctx->rst, ctx->psh, ctx->ecn, ctx->dport); - off_next = sizeof(struct tcphdr); + __assemble_tcp(data, data_len, ctx, dst, src); break; + case IPPROTO_ICMP: - __assemble_icmp4(data, data_len); - off_next = sizeof(struct icmphdr); + __assemble_icmp4(data, data_len, ctx); break; + default: bug(); } - data = packet + sizeof(*iph) + off_next; - data_len = len - sizeof(*iph) - off_next; - - __assemble_data(data, data_len, ctx->payload); iph->check = csum((unsigned short *) packet, ntohs(iph->tot_len) >> 1); @@ -378,7 +446,7 @@ static int assemble_ipv6(uint8_t *packet, size_t len, int ttl, int proto, const struct sockaddr *src) { uint8_t *data; - size_t data_len, off_next = 0; + size_t data_len; struct ip6_hdr *ip6h = (struct ip6_hdr *) packet; bug_on(!src || !dst); @@ -403,24 +471,18 @@ static int assemble_ipv6(uint8_t *packet, size_t len, int ttl, int proto, switch (proto) { case IPPROTO_TCP: - __assemble_tcp(data, data_len, ctx->syn, ctx->ack, ctx->urg, - ctx->fin, ctx->rst, ctx->psh, ctx->ecn, ctx->dport); - off_next = sizeof(struct tcphdr); + __assemble_tcp6(data, data_len, ctx, dst, src); break; + case IPPROTO_ICMP: case IPPROTO_ICMPV6: - __assemble_icmp6(data, data_len); - off_next = sizeof(struct icmp6hdr); + __assemble_icmp6(data, data_len, ctx, dst, src); break; + default: bug(); } - data = packet + sizeof(*ip6h) + off_next; - data_len = len - sizeof(*ip6h) - off_next; - - __assemble_data(data, data_len, ctx->payload); - return ntohl(ip6h->ip6_flow) & 0x000fffff; } @@ -501,7 +563,7 @@ static int check_ipv6(uint8_t *packet, size_t len, int ttl __maybe_unused, struct ip6_hdr *ip6h_inner; struct icmp6hdr *icmp6h; - if (ip6h->ip6_nxt != 0x3a) + if (ip6h->ip6_nxt != IPPROTO_ICMPV6) return -EINVAL; if (memcmp(&ip6h->ip6_dst, &(((const struct sockaddr_in6 *) ss)->sin6_addr), sizeof(ip6h->ip6_dst))) |