ipcpd: Single UDP port for the ipcpd-udp0.18.0

The UDP layer will now use a single (configurable) UDP port, default
3435. This makes it easer to allocate flows as a client from behind a
NAT firewall without having to configure port forwarding rules. So
basically, from now on Ouroboros traffic is transported over a
bidirectional <src><port>:<dst><port> UDP tunnel. The reason for not
using/allowing different client/server ports is that it would require
reading from different sockets using select() or something similar,
but since we need the EID anyway (mgmt packets arrive on the same
server UDP port), there's not a lot of benefit in doing it. Now the
operation is similar to the ipcpd-eth, with the port somewhat
functioning as a "layer name", where in UDP, the Ethertype functions
as a "layer name".

Signed-off-by: Dimitri Staessens <dimitri@ouroboros.rocks>
Signed-off-by: Sander Vrijders <sander@ouroboros.rocks>

1 files changed, 71 insertions, 155 deletions

diff --git a/src/ipcpd/udp/main.c b/src/ipcpd/udp/main.c
index dba831ff..4314b330 100644
--- a/src/ipcpd/udp/main.c
+++ b/src/ipcpd/udp/main.c
@@ -67,10 +67,8 @@
 #define DNS_TTL                  86400
 #define FD_UPDATE_TIMEOUT        100 /* microseconds */
 
-#define SERV_PORT                udp_data.s_saddr.sin_port;
-#define SERV_SADDR               ((struct sockaddr *) &udp_data.s_saddr)
-#define CLNT_SADDR               ((struct sockaddr *) &udp_data.c_saddr)
-#define SERV_SADDR_SIZE          (sizeof(udp_data.s_saddr))
+#define SADDR                    ((struct sockaddr *) &udp_data.s_saddr)
+#define SADDR_SIZE               (sizeof(udp_data.s_saddr))
 #define LOCAL_IP                 (udp_data.s_saddr.sin_addr.s_addr)
 
 #define MGMT_EID                 0
@@ -106,20 +104,17 @@ struct mgmt_frame {
 
 /* UDP flow */
 struct uf {
-        int d_eid;
-        /* IP details are stored through connect(). */
-        int skfd;
+        int                d_eid;
+        struct sockaddr_in r_saddr;
 };
 
 struct {
         struct shim_data * shim_data;
 
         uint32_t           dns_addr;
-        /* server socket */
+
         struct sockaddr_in s_saddr;
         int                s_fd;
-        /* client port */
-        int                clt_port;
 
         fset_t *           np1_flows;
         struct uf          fd_to_uf[SYS_MAX_FLOWS];
@@ -148,10 +143,8 @@ static int udp_data_init(void)
         if (pthread_mutex_init(&udp_data.mgmt_lock, NULL))
                 goto fail_mgmt_lock;
 
-        for (i = 0; i < SYS_MAX_FLOWS; ++i) {
-                udp_data.fd_to_uf[i].skfd  = -1;
+        for (i = 0; i < SYS_MAX_FLOWS; ++i)
                 udp_data.fd_to_uf[i].d_eid = -1;
-        }
 
         udp_data.np1_flows = fset_create();
         if (udp_data.np1_flows == NULL)
@@ -187,12 +180,12 @@ static void udp_data_fini(void)
         pthread_mutex_destroy(&udp_data.mgmt_lock);
 }
 
-static int ipcp_udp_port_alloc(int             skfd,
-                               uint32_t        s_eid,
-                               const uint8_t * dst,
-                               qosspec_t       qs,
-                               const void *    data,
-                               size_t          dlen)
+static int ipcp_udp_port_alloc(const struct sockaddr_in * r_saddr,
+                               uint32_t                   s_eid,
+                               const uint8_t *            dst,
+                               qosspec_t                  qs,
+                               const void *               data,
+                               size_t                     dlen)
 {
         uint8_t *         buf;
         struct mgmt_msg * msg;
@@ -222,7 +215,9 @@ static int ipcp_udp_port_alloc(int             skfd,
         memcpy(msg + 1, dst, ipcp_dir_hash_len());
         memcpy(buf + len, data, dlen);
 
-        if (write(skfd, msg, len + dlen) < 0) {
+        if (sendto(udp_data.s_fd, msg, len + dlen,
+                   MSG_CONFIRM,
+                   (const struct sockaddr *) r_saddr, sizeof(*r_saddr)) < 0) {
                 free(buf);
                 return -1;
         }
@@ -232,14 +227,14 @@ static int ipcp_udp_port_alloc(int             skfd,
         return 0;
 }
 
-static int ipcp_udp_port_alloc_resp(int          skfd,
-                                    uint32_t     s_eid,
-                                    uint32_t     d_eid,
-                                    int8_t       response,
-                                    const void * data,
-                                    size_t       len)
+static int ipcp_udp_port_alloc_resp(const struct sockaddr_in * r_saddr,
+                                    uint32_t                   s_eid,
+                                    uint32_t                   d_eid,
+                                    int8_t                     response,
+                                    const void *               data,
+                                    size_t                     len)
 {
-        struct mgmt_msg *  msg;
+        struct mgmt_msg * msg;
 
         msg = malloc(sizeof(*msg) + len);
         if (msg == NULL)
@@ -253,7 +248,9 @@ static int ipcp_udp_port_alloc_resp(int          skfd,
 
         memcpy(msg + 1, data, len);
 
-        if (write(skfd, msg, sizeof(*msg) + len) < 0) {
+        if (sendto(udp_data.s_fd, msg, sizeof(*msg) + len,
+                   MSG_CONFIRM,
+                   (const struct sockaddr *) r_saddr, sizeof(*r_saddr)) < 0 ) {
                 free(msg);
                 return -1;
         }
@@ -270,26 +267,9 @@ static int ipcp_udp_port_req(struct sockaddr_in * c_saddr,
                              const void *         data,
                              size_t               len)
 {
-        struct timespec ts        = {0, FD_UPDATE_TIMEOUT * 1000};
-        struct timespec abstime;
-        int             skfd;
-        int             fd;
-
-        skfd = socket(AF_INET, SOCK_DGRAM, IPPROTO_UDP);
-        if (skfd < 0) {
-                log_err("Could not create UDP socket.");
-                return -1;
-        }
-
-        /* Remote listens on server port. Mod of c_saddr allowed. */
-        c_saddr->sin_port = udp_data.s_saddr.sin_port;
-
-        /* Connect stores the remote address in the file descriptor. */
-        if (connect(skfd, (struct sockaddr *) c_saddr, sizeof(*c_saddr)) < 0) {
-                log_err("Could not connect to remote UDP client.");
-                close(skfd);
-                return -1;
-        }
+        struct timespec    ts        = {0, FD_UPDATE_TIMEOUT * 1000};
+        struct timespec    abstime;
+        int                fd;
 
         clock_gettime(PTHREAD_COND_CLOCK, &abstime);
 
@@ -304,7 +284,6 @@ static int ipcp_udp_port_req(struct sockaddr_in * c_saddr,
         if (ipcp_get_state() != IPCP_OPERATIONAL) {
                 log_dbg("Won't allocate over non-operational IPCP.");
                 pthread_mutex_unlock(&ipcpi.alloc_lock);
-                close(skfd);
                 return -1;
         }
 
@@ -313,14 +292,13 @@ static int ipcp_udp_port_req(struct sockaddr_in * c_saddr,
         if (fd < 0) {
                 pthread_mutex_unlock(&ipcpi.alloc_lock);
                 log_err("Could not get new flow from IRMd.");
-                close(skfd);
                 return -1;
         }
 
         pthread_rwlock_wrlock(&udp_data.flows_lock);
 
-        udp_data.fd_to_uf[fd].skfd  = skfd;
-        udp_data.fd_to_uf[fd].d_eid = d_eid;
+        udp_data.fd_to_uf[fd].r_saddr = *c_saddr;
+        udp_data.fd_to_uf[fd].d_eid   = d_eid;
 
         pthread_rwlock_unlock(&udp_data.flows_lock);
 
@@ -335,44 +313,27 @@ static int ipcp_udp_port_req(struct sockaddr_in * c_saddr,
         return 0;
 }
 
-static int ipcp_udp_port_alloc_reply(uint32_t     s_eid,
-                                     uint32_t     d_eid,
-                                     int8_t       response,
-                                     const void * data,
-                                     size_t       len)
+static int ipcp_udp_port_alloc_reply(const struct sockaddr_in * saddr,
+                                     uint32_t                   s_eid,
+                                     uint32_t                   d_eid,
+                                     int8_t                     response,
+                                     const void *               data,
+                                     size_t                     len)
 {
-        struct sockaddr_in t_saddr;
-        socklen_t          t_saddr_len;
-        int                ret         = 0;
-        int                skfd        = -1;
-
-        t_saddr_len = sizeof(t_saddr);
-
         pthread_rwlock_wrlock(&udp_data.flows_lock);
 
-        skfd = udp_data.fd_to_uf[s_eid].skfd;
-        if (skfd < 0) {
+        if (memcmp(&udp_data.fd_to_uf[s_eid].r_saddr, saddr, sizeof(*saddr))) {
                 pthread_rwlock_unlock(&udp_data.flows_lock);
-                log_err("Got reply for unknown UDP eid: %u.", s_eid);
+                log_warn("Flow allocation reply for %u from wrong source.",
+                         s_eid);
                 return -1;
         }
 
-        udp_data.fd_to_uf[s_eid].d_eid = d_eid;
+        if (response == 0)
+                udp_data.fd_to_uf[s_eid].d_eid = d_eid;
 
         pthread_rwlock_unlock(&udp_data.flows_lock);
 
-        if (getpeername(skfd, (struct sockaddr *) &t_saddr, &t_saddr_len) < 0) {
-                log_dbg("Flow with fd %d has no peer.", s_eid);
-                close(skfd);
-                return -1;
-        }
-
-        if (connect(skfd, (struct sockaddr *) &t_saddr, sizeof(t_saddr)) < 0) {
-                log_dbg("Could not connect flow to remote.");
-                close(skfd);
-                return -1;
-        }
-
         if (ipcp_flow_alloc_reply(s_eid, response, data, len) < 0) {
                 log_dbg("Failed to reply to flow allocation.");
                 return -1;
@@ -381,7 +342,7 @@ static int ipcp_udp_port_alloc_reply(uint32_t     s_eid,
         log_dbg("Flow allocation completed on eids (%d, %d).",
                  s_eid, d_eid);
 
-        return ret;
+        return 0;
 }
 
 static int ipcp_udp_mgmt_frame(const uint8_t *    buf,
@@ -416,7 +377,8 @@ static int ipcp_udp_mgmt_frame(const uint8_t *    buf,
         case FLOW_REPLY:
                 assert(len >= sizeof(*msg));
 
-                return ipcp_udp_port_alloc_reply(ntoh32(msg->s_eid),
+                return ipcp_udp_port_alloc_reply(&c_saddr,
+                                                 ntoh32(msg->s_eid),
                                                  ntoh32(msg->d_eid),
                                                  msg->response,
                                                  buf + sizeof(*msg),
@@ -543,8 +505,9 @@ static void * ipcp_udp_packet_writer(void * o)
         pthread_cleanup_push(cleanup_writer, fq);
 
         while (true) {
-                int fd;
-                int eid;
+                struct sockaddr_in saddr;
+                int                eid;
+                int                fd;
                 fevent(udp_data.np1_flows, fq, NULL);
                 while ((fd = fqueue_next(fq)) >= 0) {
                         struct shm_du_buff * sdb;
@@ -576,7 +539,7 @@ static void * ipcp_udp_packet_writer(void * o)
                         pthread_rwlock_rdlock(&udp_data.flows_lock);
 
                         eid = hton32(udp_data.fd_to_uf[fd].d_eid);
-                        fd = udp_data.fd_to_uf[fd].skfd;
+                        saddr = udp_data.fd_to_uf[fd].r_saddr;
 
                         pthread_rwlock_unlock(&udp_data.flows_lock);
 
@@ -585,7 +548,10 @@ static void * ipcp_udp_packet_writer(void * o)
                         pthread_cleanup_push((void (*)(void *))
                                              ipcp_sdb_release, (void *) sdb);
 
-                        if (write(fd, buf, len + OUR_HEADER_LEN) < 0)
+                        if (sendto(udp_data.s_fd, buf, len + OUR_HEADER_LEN,
+                                   MSG_CONFIRM,
+                                   (const struct sockaddr *) &saddr,
+                                   sizeof(saddr)) < 0)
                                 log_err("Failed to send packet.");
 
                         pthread_cleanup_pop(true);
@@ -633,22 +599,17 @@ static int ipcp_udp_bootstrap(const struct ipcp_config * conf)
                 goto fail_socket;
         }
 
-        if (setsockopt(udp_data.s_fd, SOL_SOCKET, SO_REUSEADDR,
-                       &i, sizeof(i)) < 0)
-                log_warn("Failed to set SO_REUSEADDR.");
-
         memset((char *) &udp_data.s_saddr, 0, sizeof(udp_data.s_saddr));
         udp_data.s_saddr.sin_family      = AF_INET;
         udp_data.s_saddr.sin_addr.s_addr = conf->ip_addr;
-        udp_data.s_saddr.sin_port        = htons(conf->srv_port);
+        udp_data.s_saddr.sin_port        = htons(conf->port);
 
-        if (bind(udp_data.s_fd, SERV_SADDR, SERV_SADDR_SIZE) < 0) {
+        if (bind(udp_data.s_fd, SADDR, SADDR_SIZE) < 0) {
                 log_err("Couldn't bind to %s.", ipstr);
                 goto fail_bind;
         }
 
         udp_data.dns_addr = conf->dns_addr;
-        udp_data.clt_port = htons(conf->clt_port);
 
         ipcp_set_state(IPCP_OPERATIONAL);
 
@@ -674,12 +635,11 @@ static int ipcp_udp_bootstrap(const struct ipcp_config * conf)
                 }
         }
 
-        sprintf(portstr, "%d", conf->clt_port);
+        sprintf(portstr, "%d", conf->port);
 
         log_dbg("Bootstrapped IPCP over UDP with pid %d.", getpid());
         log_dbg("Bound to IP address %s.", ipstr);
-        log_dbg("Client port is %s.", conf->clt_port == 0 ? "random" : portstr);
-        log_dbg("Server port is %u.", conf->srv_port);
+        log_dbg("Using port %u.", conf->port);
         log_dbg("DNS server address is %s.", dnsstr);
 
         return 0;
@@ -997,13 +957,8 @@ static int ipcp_udp_flow_alloc(int             fd,
                                size_t          len)
 {
         struct sockaddr_in r_saddr; /* Server address */
-        struct sockaddr_in c_saddr; /* Client address */
-        socklen_t          c_saddr_len;
-        int                skfd;
         uint32_t           ip_addr = 0;
-        char               ip_str[INET_ADDRSTRLEN];
-
-        c_saddr_len = sizeof(c_saddr);
+        char               ipstr[INET_ADDRSTRLEN];
 
         log_dbg("Allocating flow to " HASH_FMT ".", HASH_VAL(dst));
 
@@ -1011,70 +966,36 @@ static int ipcp_udp_flow_alloc(int             fd,
 
         assert(dst);
 
-        skfd = socket(AF_INET, SOCK_DGRAM, IPPROTO_UDP);
-        if (skfd < 0) {
-                log_err("Could not create socket.");
-                return -1;
-        }
-
-        /* This socket is for the flow. */
-        memset((char *) &c_saddr, 0, sizeof(c_saddr));
-        c_saddr.sin_family      = AF_INET;
-        c_saddr.sin_addr.s_addr = LOCAL_IP;
-        c_saddr.sin_port        = udp_data.clt_port;
-
-        if (bind(skfd, (struct sockaddr *) &c_saddr, sizeof(c_saddr)) < 0) {
-                log_dbg("Could not bind socket to client address.");
-                close(skfd);
-                return -1;
-        }
-
-        if (getsockname(skfd, (struct sockaddr *) &c_saddr, &c_saddr_len) < 0) {
-                log_err("Could not get address from fd.");
-                close(skfd);
-                return -1;
-        }
-
         if (!shim_data_dir_has(udp_data.shim_data, dst)) {
                 log_dbg("Could not resolve destination.");
-                close(skfd);
                 return -1;
         }
 
         ip_addr = (uint32_t) shim_data_dir_get_addr(udp_data.shim_data, dst);
 
-        inet_ntop(AF_INET, &ip_addr, ip_str, INET_ADDRSTRLEN);
-        log_dbg("Destination UDP ipcp resolved at %s.", ip_str);
+        inet_ntop(AF_INET, &ip_addr, ipstr, INET_ADDRSTRLEN);
+        log_dbg("Destination UDP ipcp resolved at %s.", ipstr);
 
-        /* Connect to server and store the remote IP address in the skfd. */
         memset((char *) &r_saddr, 0, sizeof(r_saddr));
         r_saddr.sin_family      = AF_INET;
         r_saddr.sin_addr.s_addr = ip_addr;
         r_saddr.sin_port        = udp_data.s_saddr.sin_port;
 
-        if (connect(skfd, (struct sockaddr *) &r_saddr, sizeof(r_saddr)) < 0) {
-                log_dbg("Could not connect socket to remote.");
-                close(skfd);
-                return -1;
-        }
-
-        if (ipcp_udp_port_alloc(skfd, fd, dst, qs, data, len) < 0) {
+        if (ipcp_udp_port_alloc(&r_saddr, fd, dst, qs, data, len) < 0) {
                 log_err("Could not allocate port.");
-                close(skfd);
                 return -1;
         }
 
         pthread_rwlock_wrlock(&udp_data.flows_lock);
 
-        udp_data.fd_to_uf[fd].d_eid = -1;
-        udp_data.fd_to_uf[fd].skfd  = skfd;
+        udp_data.fd_to_uf[fd].d_eid   = -1;
+        udp_data.fd_to_uf[fd].r_saddr = r_saddr;
 
         pthread_rwlock_unlock(&udp_data.flows_lock);
 
         fset_add(udp_data.np1_flows, fd);
 
-        log_dbg("Flow pending on fd %d, UDP src port %d, dst port %d.",
-                fd, ntohs(c_saddr.sin_port), ntohs(r_saddr.sin_port));
+        log_dbg("Flow to %s pending on fd %d.", ipstr, fd);
 
         return 0;
 }
@@ -1084,10 +1005,10 @@ static int ipcp_udp_flow_alloc_resp(int          fd,
                                     const void * data,
                                     size_t       len)
 {
-        struct timespec ts  = {0, FD_UPDATE_TIMEOUT * 1000};
-        struct timespec abstime;
-        int             skfd;
-        int             d_eid;
+        struct timespec    ts  = {0, FD_UPDATE_TIMEOUT * 1000};
+        struct timespec    abstime;
+        struct sockaddr_in saddr;
+        int                d_eid;
 
         if (resp)
                 return 0;
@@ -1115,12 +1036,13 @@ static int ipcp_udp_flow_alloc_resp(int          fd,
 
         pthread_rwlock_rdlock(&udp_data.flows_lock);
 
-        skfd  = udp_data.fd_to_uf[fd].skfd;
+        saddr = udp_data.fd_to_uf[fd].r_saddr;
         d_eid = udp_data.fd_to_uf[fd].d_eid;
 
         pthread_rwlock_unlock(&udp_data.flows_lock);
 
-        if (ipcp_udp_port_alloc_resp(skfd, d_eid, fd, resp, data, len) < 0) {
+        if (ipcp_udp_port_alloc_resp(&saddr, d_eid, fd, resp, data, len) < 0) {
+                fset_del(udp_data.np1_flows, fd);
                 log_err("Failed to respond to flow request.");
                 return -1;
         }
@@ -1135,23 +1057,17 @@ static int ipcp_udp_flow_alloc_resp(int          fd,
 
 static int ipcp_udp_flow_dealloc(int fd)
 {
-        int skfd = -1;
-
         ipcp_flow_fini(fd);
 
         fset_del(udp_data.np1_flows, fd);
 
         pthread_rwlock_wrlock(&udp_data.flows_lock);
 
-        skfd = udp_data.fd_to_uf[fd].skfd;
-
         udp_data.fd_to_uf[fd].d_eid = -1;
-        udp_data.fd_to_uf[fd].skfd  = -1;
+        memset(&udp_data.fd_to_uf[fd].r_saddr, 0, SADDR_SIZE);
 
         pthread_rwlock_unlock(&udp_data.flows_lock);
 
-        close(skfd);
-
         flow_dealloc(fd);
 
         log_dbg("Flow with fd %d deallocated.", fd);