picotcp/lwip ipv4/ipv6 fully functional, needs stress testing

tests/api_test/tcpclient6.c

@@ -0,0 +1,72 @@
+#include <stdio.h>
+#include <stdlib.h>
+#include <unistd.h>
+#include <string.h>
+
+#include <sys/types.h>
+#include <sys/socket.h>
+#include <netinet/in.h>
+#include <netdb.h>
+
+void error(char *msg) {
+    perror(msg);
+    exit(0);
+}
+
+int main(int argc, char *argv[]) {
+    int sockfd, portno, n;
+    struct sockaddr_in6 serv_addr;
+    struct hostent *server;
+    char buffer[256] = "This is a string from client!";
+
+    if (argc < 3) {
+        fprintf(stderr, "Usage: %s  \n", argv[0]);
+        exit(0);
+    }
+    portno = atoi(argv[2]);
+
+    printf("\nIPv6 TCP Client Started...\n");
+    
+    //Sockets Layer Call: socket()
+    sockfd = socket(AF_INET6, SOCK_STREAM, 0);
+    if (sockfd < 0)
+        error("ERROR opening socket");
+
+    //Sockets Layer Call: gethostbyname2()
+    server = gethostbyname2(argv[1],AF_INET6);
+    if (server == NULL) {
+        fprintf(stderr, "ERROR, no such host\n");
+        exit(0);
+    }
+
+    memset((char *) &serv_addr, 0, sizeof(serv_addr));
+    serv_addr.sin6_flowinfo = 0;
+    serv_addr.sin6_family = AF_INET6;
+    memmove((char *) &serv_addr.sin6_addr.s6_addr, (char *) server->h_addr, server->h_length);
+    serv_addr.sin6_port = htons(portno);
+
+    //Sockets Layer Call: connect()
+    if (connect(sockfd, (struct sockaddr *) &serv_addr, sizeof(serv_addr)) < 0)
+        error("ERROR connecting");
+
+    
+    //Sockets Layer Call: send()
+    n = send(sockfd,buffer, strlen(buffer)+1, 0);
+    if (n < 0)
+        error("ERROR writing to socket");
+
+    printf("sent %d bytes\n", n);
+    memset(buffer, 0, 256);
+    
+    //Sockets Layer Call: recv()
+    printf("reading...\n");
+    n = recv(sockfd, buffer, 255, 0);
+    if (n < 0)
+        error("ERROR reading from socket");
+    printf("Message from server: %s\n", buffer);
+
+    //Sockets Layer Call: close()
+    close(sockfd);
+        
+    return 0;
+}