Allow putting data in a buffer at an arbitrary offset.

[utcp] / utcp.c

diff --git a/utcp.c b/utcp.c
index f062319fa33a1daa665faaa96f3c567eb488f245..e6f6cf9ede28360df84fad0161b0a993e01a3c0f 100644 (file)
--- a/utcp.c
+++ b/utcp.c
@@ -130,16 +130,30 @@ static int32_t seqdiff(uint32_t a, uint32_t b) {
 // TODO: convert to ringbuffers to avoid memmove() operations.
 
 // Store data into the buffer
-static ssize_t buffer_put(struct buffer *buf, const void *data, size_t len) {
+static ssize_t buffer_put_at(struct buffer *buf, size_t offset, const void *data, size_t len) {
        if(buf->maxsize <= buf->used)
                return 0;
-       if(len > buf->maxsize - buf->used)
-               len = buf->maxsize - buf->used;
-       if(len > buf->size - buf->used) {
+
+       debug("buffer_put_at %zu %zu %zu\n", buf->used, offset, len);
+
+       size_t required = offset + len;
+       if(required > buf->maxsize) {
+               if(offset >= buf->maxsize)
+                       return 0;
+               abort();
+               len = buf->maxsize - offset;
+               required = buf->maxsize;
+       }
+
+       if(required > buf->size) {
                size_t newsize = buf->size;
-               do {
-                       newsize *= 2;
-               } while(newsize < buf->used + len);
+               if(!newsize) {
+                       newsize = required;
+               } else {
+                       do {
+                               newsize *= 2;
+                       } while(newsize < buf->used + len);
+               }
                if(newsize > buf->maxsize)
                        newsize = buf->maxsize;
                char *newdata = realloc(buf->data, newsize);
@@ -148,11 +162,17 @@ static ssize_t buffer_put(struct buffer *buf, const void *data, size_t len) {
                buf->data = newdata;
                buf->size = newsize;
        }
-       memcpy(buf->data + buf->used, data, len);
-       buf->used += len;
+
+       memcpy(buf->data + offset, data, len);
+       if(required > buf->used)
+               buf->used = required;
        return len;
 }
 
+static ssize_t buffer_put(struct buffer *buf, const void *data, size_t len) {
+       return buffer_put_at(buf, buf->used, data, len);
+}
+
 // Get data from the buffer. data can be NULL.
 static ssize_t buffer_get(struct buffer *buf, void *data, size_t len) {
        if(len > buf->used)
@@ -282,7 +302,12 @@ static struct utcp_connection *allocate_connection(struct utcp *utcp, uint16_t s
 
        c->src = src;
        c->dst = dst;
+#ifdef UTCP_DEBUG
+#warning debugging
+       c->snd.iss = 0;
+#else
        c->snd.iss = rand();
+#endif
        c->snd.una = c->snd.iss;
        c->snd.nxt = c->snd.iss + 1;
        c->rcv.wnd = utcp->mtu;
@@ -360,7 +385,7 @@ static void ack(struct utcp_connection *c, bool sendatleastone) {
        } *pkt;
 
        pkt = malloc(sizeof pkt->hdr + c->utcp->mtu);
-       if(!pkt->data)
+       if(!pkt)
                return;
 
        pkt->hdr.src = c->src;
@@ -465,11 +490,8 @@ static void retransmit(struct utcp_connection *c) {
        pkt->hdr.dst = c->dst;
 
        switch(c->state) {
-               case LISTEN:
-                       // TODO: this should not happen
-                       break;
-
                case SYN_SENT:
+                       // Send our SYN again
                        pkt->hdr.seq = c->snd.iss;
                        pkt->hdr.ack = 0;
                        pkt->hdr.wnd = c->rcv.wnd;
@@ -479,6 +501,7 @@ static void retransmit(struct utcp_connection *c) {
                        break;
 
                case SYN_RECEIVED:
+                       // Send SYNACK again
                        pkt->hdr.seq = c->snd.nxt;
                        pkt->hdr.ack = c->rcv.nxt;
                        pkt->hdr.ctl = SYN | ACK;
@@ -488,28 +511,35 @@ static void retransmit(struct utcp_connection *c) {
 
                case ESTABLISHED:
                case FIN_WAIT_1:
+               case CLOSE_WAIT:
+               case CLOSING:
+               case LAST_ACK:
+                       // Send unacked data again.
                        pkt->hdr.seq = c->snd.una;
                        pkt->hdr.ack = c->rcv.nxt;
                        pkt->hdr.ctl = ACK;
-                       uint32_t len = seqdiff(c->snd.nxt, c->snd.una);
-                       if(c->state == FIN_WAIT_1)
-                               len--;
+                       uint32_t len = seqdiff(c->snd.last, c->snd.una);
                        if(len > utcp->mtu)
                                len = utcp->mtu;
-                       else {
-                               if(c->state == FIN_WAIT_1)
-                                       pkt->hdr.ctl |= FIN;
+                       if(fin_wanted(c, c->snd.una + len)) {
+                               len--;
+                               pkt->hdr.ctl |= FIN;
                        }
+                       c->snd.nxt = c->snd.una + len;
                        buffer_copy(&c->sndbuf, pkt->data, 0, len);
                        print_packet(c->utcp, "rtrx", pkt, sizeof pkt->hdr + len);
                        utcp->send(utcp, pkt, sizeof pkt->hdr + len);
                        break;
 
-               default:
-                       // TODO: implement
+               case CLOSED:
+               case LISTEN:
+               case TIME_WAIT:
+               case FIN_WAIT_2:
+                       // We shouldn't need to retransmit anything in this state.
 #ifdef UTCP_DEBUG
                        abort();
 #endif
+                       timerclear(&c->rtrx_timeout);
                        break;
        }
 
@@ -984,7 +1014,7 @@ reset:
 }
 
 int utcp_shutdown(struct utcp_connection *c, int dir) {
-       debug("%p shutdown %d at %u\n", c ? c->utcp : NULL, dir, c->snd.last);
+       debug("%p shutdown %d at %u\n", c ? c->utcp : NULL, dir, c ? c->snd.last : 0);
        if(!c) {
                errno = EFAULT;
                return -1;
@@ -996,13 +1026,26 @@ int utcp_shutdown(struct utcp_connection *c, int dir) {
                return -1;
        }
 
-       // TODO: handle dir
-       // TODO: check that repeated calls with the same parameters should have no effect
+       if(!(dir == UTCP_SHUT_RD || dir == UTCP_SHUT_WR || dir == UTCP_SHUT_RDWR)) {
+               errno = EINVAL;
+               return -1;
+       }
+
+       // TCP does not have a provision for stopping incoming packets.
+       // The best we can do is to just ignore them.
+       if(dir == UTCP_SHUT_RD || dir == UTCP_SHUT_RDWR)
+               c->recv = NULL;
+
+       // The rest of the code deals with shutting down writes.
+       if(dir == UTCP_SHUT_RD)
+               return 0;
 
        switch(c->state) {
        case CLOSED:
-               return 0;
        case LISTEN:
+               errno = ENOTCONN;
+               return -1;
+
        case SYN_SENT:
                set_state(c, CLOSED);
                return 0;
@@ -1150,6 +1193,17 @@ struct timeval utcp_timeout(struct utcp *utcp) {
        return diff;
 }
 
+bool utcp_is_active(struct utcp *utcp) {
+       if(!utcp)
+               return false;
+
+       for(int i = 0; i < utcp->nconnections; i++)
+               if(utcp->connections[i]->state != CLOSED && utcp->connections[i]->state != TIME_WAIT)
+                       return true;
+
+       return false;
+}
+
 struct utcp *utcp_init(utcp_accept_t accept, utcp_pre_accept_t pre_accept, utcp_send_t send, void *priv) {
        struct utcp *utcp = calloc(1, sizeof *utcp);
        if(!utcp)
@@ -1252,3 +1306,10 @@ void utcp_set_poll_cb(struct utcp_connection *c, utcp_poll_t poll) {
        if(c)
                c->poll = poll;
 }
+
+void utcp_set_accept_cb(struct utcp *utcp, utcp_accept_t accept, utcp_pre_accept_t pre_accept) {
+       if(utcp) {
+               utcp->accept = accept;
+               utcp->pre_accept = pre_accept;
+       }
+}